I really appreciate your videos. After a long career in the wireless industry where our labs were full of expensive hp/tek boxes, I'm setting up a home lab and sorting through used vna's and some newer siglent/rigol... boxes.
Subscribed and watch alot of your video's and have not found any errors yet. You really know your stuff. Love how you break it out on your excellent hand written schematics too. Sometimes I need a refresher and your my choice. Best video's on Tube. Thank you.
I just got one of these at a good price but the 50 ohm model. Great to see this video. You gave me the info I need to keep it in good working order. A lot to learn yet, but covering the fundamentals is always good, no matter how much I learn. Thanks for all of your videos.
Here is another good tip to avoid blowing it up, don't use is as a workshop broadcast receiver as one day you will go home for the weekend and leave the outside antenna connected and it takes a lightning strike. Great channel.
Thanks a lot for your reply! After watching this video I watched "Use the scope to measure the length and impedance of coax" and I understood what was going on. Thank you for this free knowledge!
Thanks for these awesome videos, sometimes just doing the basics over again is a great fundamentals refresher. I always learn something from these no matter how simple they may seem.
Another great explanation, a very good video as always. Many years ago a colleague had a natural gift for blowing up spectrum analysers. One type of measurement we did at the time was mains borne interference, we used a form of high pass filter that you could connect a measuring receiver to. Of course the merit of using a receiver was that the tuned circuits in the front end effectively integrated out mains borne spikes, and the full transient amplitude did not reach any of the active devices. To my knowledge he trashed the mixers in 3 spectrum analysers, one after the other. For general engineering purposes it is probably good practice to keep an attenuator permanently attached to the analyser, that way you think twice about removing it. My own spectrum analyser would not justify a massively expensive repair if I damaged it so I have to look after it! Thank you again for making some excellent videos.
I agree, though I enjoy off the cuff.. I like the way I dont fall asleep in this channel and am able to learn and have it reinforced. Going to Uni next year, its nice seeing the theory in this channel and having a lecture on it.
i am glad you provide such a interesting topic from the theory to practices,can you be kind enough to make another movie and show us how to use spectrum analyzer; i like to know the relationship of RBW and VBW; thanks in advance
Have you seen a product called “RF SNITCH”? It’s a tiny device that is powered by USB-Micro power and has a single SMA female connector. The housing is clear and permits viewing of the internal LEDs. There is a green / 2x orange / red.. I believe they are bi-color or tri-color LEDs because upon “alarm”, I recall they all turn red. You are supposed to connect this to the device you intend to connect to a spectrum analyzer or VNA. If the signal is low enough to use safely with the sensitive test gear, it will light up GREEN. and… you can guess the rest of the operation. I’m not sure about signal levels, but it was reviewed and recommended by RUclipsr IMSAI Guy. (around $50 bucks or so.. I bought mine a year ago and can’t remember the exact pricing) Another great video..Thank You!
Be careful with that 30dBm level for maximum input power. That apply to the front end attenuator. If you set 0dB attn and apply 30dBm you for sure will damage the front end amp or mixer. The front end mixer typically should get more than 0 dBm for safety and for optimum measurement of linear amplitudes should be below -10 dBm. For non linear amplitude (harmonics, intermodulation...) the power to front end mixer on most Spectrum Analyzers (including Agilent ESA) should be around -35dBm.
Very nicely done. Nothing too techy, nothing too dumbed down (for me at least) Just got a spec-ana. Trying to figure it out. (and un-teach the o'scope view)
Hi Alan, nervous about overloading my input, check me on this for rules of thumbs please. I have a RF sampling tap good for 30 db, 1:1000. My Rigol DSA 815 has a max input of 20 dbm 50v DC. The tap then would make 100 watts equal to .1 watts, correct? Which is 20 dbm? So it's safe? Newer to these devices - so nervous about blowing it up I'm afraid of using it! I also understand the sampler manufacturer recommends starting with 10 watts into the sampler, more conservative. So this device would work well with the spectrum analyzer as long as I don't exceed 100 watts into the sampler? 2nd question - Instead of a sampler, I also have a step attenuator, both button based, up to 90db, and another one that is rotary based good for 70db attenuation. I'm assuming those are good as well, i.e. but could you literally hook up your radio directly into the attenuator pad set for 20 db or more driven with 100 watts and it would be fine? I know that's not conservative just want to understand the theory and the limits. I would likely start out with 50 to 70 db attenuation, but I would not need the sampler, just connect the attenuator to the radio, and the other end of the attenuator to the analyzer?
You've got the ratios right. 100W is 50dBm. An RF sampler/coupler with a 30dB tap will give you 20dBm out with 100W in. This is equal to the maximum input rating on your Rigol, so while is it in theory "safe", I personally wouldn't run it that close to the limit. I'd put another 10 or 20dB attenuator between the coupler and the SA input, to give you +10 or 0dBm to the analyzer. Also, be sure to set the Reference Level on the analyzer appropriately. Also, make absolutely sure that the coupler is rated for 100W through the main path, and that the output of the main path of the coupler is properly terminated into a dummy load. In theory, you could also use your step attenuator, BUT it would HAVE to be rated for 100W (which is doubtful, since you don't see high power step attenuators very often). If it was me, I'd use the coupler, dummy load and then the step attenuator between the coupler sample output and the analyzer. Then, adjust the step attenuator as needed (i.e. 20dB or more).
@@w2aew Alan, perfect. One short follow-up - I'm assuming setting the ref level correctly is for accuracy only, doesn't affect safety on any inputs, etc.? Thanks and 73. KM5L
I have a question around spectrum analyzer safety, power levels and preselection: Must the Reference Level always be selected according to the strongest input signal (to not potentially cause damage)? Even when its currently sweeping a different frequency range on a much smaller signal? (my gut feeling is "yes", because 1st mixer will still get everything, so the attenuator should not allow too much of the strongest signal to the mixer - which would also mean that a "peak zoom" function may be dangerous to use on smaller signals - because it'll adjust the overall reference level to that small signal's power) Thanks!
You see from my previous posts that I am alway talking about internal and external attenuator. The general practice is to always put external attenuator (10 dB typically) as close as possible to you measured device. That specially true if you have to use long cable or the Spectrum Analyzer internal attenuation is set to 0 dB. Such approach will improve matching between your device and Spectrum Analyzer. That very important for measurement of non linear parameters (intermodulation, harmonics).
Just bought an Agilent E4411B and I wanted to know where you got the 75 ohms to 50 ohms Minimum Loss Pad. I have seen them cost 200-300 dollars and more. I'm on a budget. Oh BTW, great video. I am so glad I found it.
Great video. However I think there should be mention that dbm measurements will differ depending on the load. Measurements in 50 ohm, 75 ohm and 600 ohm (telecomms) will be different particularly with respect to the voltage. For instance a 1mW reference power level corresponds to 0.224V in a 50 ohm system, 0.274V in a 75 ohm and 0.775V in a 600 ohm system.
***** I forget. Its not Doug keltz our salesman. I'll look it up on my old emails. Was ready to buy it then our SPG system failed and we had to buy a new Main & back up SPG-8000 with Change over unit. That pretty much burned our budget. Had a Tektronix WFM-5200 in there too. Heartbreak.
It would make sense that it wasn't Doug. He works for the Video Products division, and the MDO is made by the Test & Measurement division which is handled by a separate sales force.
picked up a used Rohde & Schwarz CMU200 off ebay for $800. RF input safely supports up to +47dbm, pretty unbelievable. and a nice safety margin for me! also means i don't have to worry about non linear response through any attenuators for most of my work.
The CMU 200 is a great piece of kit, but beware that there are three models. "Engineering model" V02 can only handle 2 Watts. "Service model" V30 can handle 50 Watts. The CMU 200 can show a power overload warning, but this is also related to the vertical scale. The scale and referende level can be set manually to solve this "warning problem". The more sensitive the input, the better the signal quality you'll get. Normally RF2 is the input is most used (except for high power transmitter testing). Maybe this is interesting to read: amateurtele.com/index.php?artikel=251
Thanks Alan, answered all my basic questions in one go, another great video, I will add an adjustable attenuator to my shopping list ;) How much attenuation "span" do these things give, and what's a good range for general in the shack amateur usage? i suppose it depends on the input range of the analyser itself? Cheers :)
Superb videos many thanks, How about a tutorial on the accessories that maybe needed, as this is a bit confusing for the newbie like myself.Im taking delivery of my first real spectrum analyser in a few weeks, so i have gone out a bought a few items like you suggested - DC Block, and a few 10GHz JYE BAO N Type attenuators. But a sampler?, whats this used for exactly? and bias Ts, Splitters, Combiners, Loads, this stuff has got me, when and why to use,
Alan, thanks for another great video. How does the input float voltage limit (+/- 4v, for instance) relate to maximum signal input voltage on a low frequency instrument with high impedance? I can't seem to figure it out. Ken
Can you recommend any videos or video courses for learning the basics (and even more advanced topics) related to of spectrum analyzers? Also .. can you use an Anritsu MT8820C for the channel? ( 30 MHZ - 2.7 GHZ Radio Communications Analyzer) It’s fully functional and was give to me by a friend’s wife after his passing. I initially wanted it for spectrum analyzer use but discovered it couldn’t be used as a standalone SA. So.. it’s just gathering dust.
Following my previous post: Spectrum Analyzer optimum measurement power apply to the internal mixer not the the front of the Spectrum Analyzer. So if you power from the device is let say +10dBm and you measure fundamental frequency amplitude than the reference should be set to +10dBm and the total internal or external attenuation should be more then 20dB. If you measure intermodulation that internal or external attenuation will need to be set to 45dB.
Yes thats what it is. The repeater is for a particular cell carrier but it needs higher power because off the building where the phones are being used and is shutting down another adjacent phone carrier, can a band reject filter be used in this case? Because the repeaters dont have any internal attenuation nor gain controls.
So, if I build a 2m Ham Radio at an output of the typical 5 W, I would use the external attenuator to reduce that input power (voltage) down to 0 V? How does a spectrum analyzer be designed to only handle a 0 V input when RF in the air is typically in the micovolts range (I do understand that wave forms above and below 0 V cancel themselves out to 0 V. Is that the theory here?) Frank Frank Reiser Video/Audio Service
The 0V requirement is for the DC Content of the signal only. Most RF transmitters don't have any DC content, so that part is OK. The other thing you'll have to do is attenuate the signal quite a bit - ideally you'd like about 1mW or so into the spectrum analyzer. For measuring RF transmitter output, it is most common (and safe) to terminate the transmitter into a dummy load rated for the full power, and use some sort of RF Sampler to couple a small amount of energy to the spectrum analyzer. I have a video or two on RF samplers...
I bought my spectrum analyzer off of ebay by winning a bid for only $150, and it is a good one and not too old. Isn't a DC bloc simply a capacitor? Can i build a DC block and power reducer myself with a resistor in series with a capacitor connected to the correct jacks? Frank Frank Reiser Video/Audio Service
Yes, a DC block is a series capacitor. Check your analyzer, it may already have a dc block internal. The allowable DC voltage will likely be printed on the front panel. You can also build an attenuator, but it is not simply a series resistor. The attenuator has to maintain a 50 ohm input and output impedance, needs to be able to handle the transmitter power, and has to be built to have a flat frequency response over the operating range.
It was Carl Hanck. I could really use it for Quam & CODM investigation. Do alot of that. Few months later I see Tek is selling the same box for $7,000 on ebay. Wish I could afford it personally. But I already own a alot of test equipment.
What I marvel at is your command of knowledge in using such instruments. I wonder how did you learn to use such instruments to the level you know how to use them? Did you study the owner's manual or were you taught by someone and learned your way through that?
Its a combination of all of those things. Usually starting with the manual, as well as manufacturer application notes, books, etc., as well as learning from those more knowledgeable. All of these things over the years help contribute to the fluent use of the equipment. Of course, it helps a lot to gain a good understanding of what is happening inside the instrument so that you have a clearer idea of what each control is doing.
Hi Sir, you mentioned about setting the reference level causes the attenuation to be adjusted (under auto mode). Let say the attenuation is auto set to 10dB. So does that mean the peak value reading we take from the screen is already attenuated by 10dB? If that is the case, we need to add back this lost in our final value of the power received?
The analyzer properly scales and adjusts the reading, so it always reflects the proper value, regardless of the attenuation level (as long as the unit isn't overloaded).
Yes, basically the span knob does control the frequency range of the LO (usually more than one LO). However, keep in mind that wideband spectrum analyzers will often use harmonic mixing, so the LO range won't necessarily be as wide as the span.
Could you explain to me what it's for 50 ohm terminator at the entrance to the spectrum analyzer? I do not understand why they put 50 ohm terminator on the input of the oscilloscope too? Anyway, thank you for these wonderful tutorials!
When you lowered down the RBW, the noise floor dropped down. When the noise floor dropped down, what is its effect on the peak of the signal? Did it change as well or did it stay at the same reading?
How can you use a spectrum analyzer to measure CCTS? Somehow you can calculate the Crew Curve of the audio signal by knowing the resonance frequency and the speaker frequency start and stop range. I'm not sure what the crew curve is used for
@@w2aew CCT means circuit. I don't know what the difference in using an FFT sweep compared to using an Audio Sweep because when you use an Audio Sweep you will see more harmonic peaks compared to using FFT sweep? When the spectrum analyzer is displaying harmonics I have been told to use the hybrid superHET filter to remove the harmonics, is this true?
What do you think of using a general coverage HF receiver and modifying it with a swept VCO and also sending the output of the ramp generator to the horizontal input of an oscilloscope. If not where can you get the RF/IF plug in lke you have thanks Jim KD7TU
It could work. You'd probably have to disable the AGC circuit and manually adjust RF gain, and add some kind of detector on the receiver output. You'd be limited in the RBW settings (just the filter settings the radio. It may not be well calibrated, but will at least give you a relative view of the spectrum.
Thanks for the video. Quite informative. couple of questions: 1) if signal is close to Noise floor do we still need to move the whole spectrum up on the Y axis so that the signal peak is just below the reference level? 2) for default attn of 10dB i get some power levels (say -60dBm) but when i increased attn manually to 20dB and beyond the power level moves to-74dBm. Does this mean the 20dBm is optimum attn.? which power level and which attenuation i should trust? Thanks
From your question, I guess what you are looking at is a distortion component of an Amplifier or some thing like that. But since the level of the signal observed is changing when the attenuation is changed means trust the one with 20 dB Attenuation. At 10 dB attenuation the distortion is more due to the spectrum Analyzer you are using. If you change the attenuation to 0 dB, 10 dB, 20 dB while watching the signal (if limited by spectrum Analyzer it will change by 20 dB each if it is 2nd harmonic of some fundamental signal coming in or 30 dB if third harmonic etc) will tell you when you are observing real distortion value.
I hope that you please will answer this question. I can read that Spectrum Analyzer often goes from i.e. 9KHz and up, but what if I want to look at an audio signal at 22Hz?
You can't. There are some spectrum analyzers that go lower than 9kHz, but most do not. For a 22Hz signal, if you want to look at the spectrum, you're better off using the FFT function of an oscilloscope.
Hi there, I wanted to ask if it’s okay with you if I show some of these videos as part of my own twitch stream. I just received my first analyzer and I think it would make an interesting stream to show my „first steps“ with the device, using your videos as a guide. So it would be watching/reacting to a part of your video and then trying it out myself. Thanks in advance, and many greetings from germany :)
If you don't know the frequency you are measuring, what is the quickest way to determine the frequency? Do you just widen the span and adjust the reference level as necessary to detect any weak signal?
So a Signal Analyzer can view the frequency base of a signal as a Spectrum Analyzer does but it needs to convert it from a time base first. So a Signal Analyzer would be more useful in Electronics?
Is it Radio Frequency Interference if I hear an unusual "Hum" sound in a video. (This sound is heard as clear as if it was part of the video, but the first time I saw that video, it wasn't there)
Hello, I am looking into getting my first spectrum analyzer for transmitter tuning and repair. I have my Bird43, the 4275 line sampler, 2205 scope and dummy load. What I would like to do is add my frequency counter and a spectrum analyzer, could you describe how to do it? Perhaps one of your great diagram layouts.Thank your channel has inspired me.
Thank you Alan, would it be advisable to add a "T' somewhere after the scope to insert the frequency counter. I would like to view the scope and frequency counter. I am using a 3 position antenna switch, radio into it, port 1 to Bird meter, port 2 to scope, port 3 to signal generator.Or would it be better to add the frequency counter in line with the bird?I am using 2 separate dummy loads.
You would NEVER want to connect the radio directly to the scope, or the spectrum analyzer, or the frequency counter. Never. Always have the transmitter connected directly to the dummy load, and use the sampler in-line to connect to the scope, counter and spectrum analyzer. If you want to have all three hooked up, you could put a BNC-Tee at the input to the scope and the counter, then run the coax from the sampler to the tee at the scope, from there to the tee at the counter, and then from there to spectrum analyzer. Alternatively, some scopes have an auxiliary OUTPUT on the back panel which is a buffered copy of the signal at the input - you could use this to drive the counter.
Can this spectrum analyser detect GSM signal boosters? If yes... Please, explain and how it works. If no, please tell me the equipment for detecting GSM boosters in an environment. Thank you all for your input.
I see the small spectrum analyzer you have only accepts -30dbm or 1 milliwatt, is there a way without a power meter to measure the 1 milliwatt before you attach it? Could you use a multimeter on ac amps?
Actually, -30dBm is not 1 milliwatt, it is 1 microwatt! For that particular analyzer, the -30dBm refers to the power at the front end mixer. There is a manually controlled attenuator ahead of the mixer. So, you have to manually set the mixer to ensure that you don't exceed -30dBm at the mixer. Most modern spectrum analyzers control the attenuator automatically based on the reference level setting. If you are measuring a signal of unknown power (and you don't have a way to measure its power), the always start with the highest attenuation possible (highest reference level), and work your way down.
Thank you very much for your useful video. I am going to measure the frequency of composite by vibration techniques(impulse frequency) for mechanical properties evaluation. I would like to know I can use a spectrum analyzer for this problem. could you please introduce me a portable or handheld spectrum analyzer? Best Regards,
Alen can you use a basic spectrum analyzer to see interference caused by a cell phone repeater and if by reducing the power of the repiter can all the interference be totally eliminated also what types of interference can the cell phone repeater cause? thanks.
need your advice I bought a used HP 8981a Vector Modulation analyzer without any manual hoping to use it on audio tuner debug. Did I buy the wrong piece of equipment and it looks like I need to purchase a high freq generator. First time i've purchased this kind of equipment and need some help. Thanks
Unfortunately, it does seem like you've got the wrong piece of equipment. This unit is intended to analyze digital modulation quality (such as QPSK, 16QAM, etc.), either on the baseband IQ signals or on a quadrature modulated IF signal. Doesn't sound like it will be of much help debugging analog audio tuner issues.
Thank's for this video, i have a question about the input power, since there is an internal attenuator, does +30 dBm of the maximum input RF power refers to the maximum power when internal attenuation is set to 0 dB, or whatever internal attenuation these +30 dBm should not be exceeded ?
You'd really have to consult the data sheet for your specific analyzer. Generally, the input limit on the front panel applies at any attenuator setting (due to power limit of attenuator)
What will happen if I am measuring very low power signal e.g. -40dBm and suddenly power will change to +25 dBm? Will automatic attenuation react fast enough to protect mixer?
Hello. first of all, thanks a lot for your knowledge condivision about this amazing equipment as a SA is. My question: a 75ohm input impedance equipment is suitable for learning or you misadvise to buy it to a beginner as I am. You are right when you say that you could get it as a really bargain, but due to it would be sure the first but the only one, I would like to buy something which could be useful at all, not only for some nice intelligence game and to leave it off for unsuitability at all. Thanks. Danilo
I think it is perfectly suitable for learning. The absolute power measurements won't be accurate, but most of the time you're using a spectrum analyzer to look at relative power levels anyway. The input SWR when used with 50ohm sources will nominally be 1.5:1 which is perfectly acceptable.
@@w2aew Thanks a lot for feedback. Unfortunately the bargain I was dealing with, has gone to someone else, ( :-( ) but I will not settle about. I am Searching for a new opportunity. THanks again. Danilo
Hello I have a complaint... these Agilent SA make froze when use GPIB, is a good instruments but in my experience works better oldest HP, I was worked in some electronic labs and I prefer old HP SA, the model of these video works fine but manually not in remote mode like latest models, guys if you know how to prevent these please tell me what I can do, regards!
Yes. There is a class of analyzers called Signal Analyzers, more specifically, Vector Signal Analyzers. They can acquire/record signals vs. time and give you the ability to analyze amplitude, frequency, phase, spectral content, and more - all vs. time. Most will do more advanced analysis include modulation quality, pulse analysis, and other signal analysis functions. With these VSAs, phase measurements are 'relative' to the measurement frequency. To measure phase response of a device under test, you would usually need a different type of analyzer called a Vector Network Analyzer.
There are a number of varieties of "digital" spectrum analyzers, so the answer is little more involved... For example: -Some digital analyzers simply digitize the signal in the final IF stage and perform the final RBW filtering and detection in the digital domain. These generally offer more RBW selections than a pure analog SA. - Some digitize the signals at a higher IF stage, potentially offering some RF capture vs. time in addition to the RBW flexibility over time. More advanced units can do vector signal analysis. Basic units simply digitize early to make inexpensive hardware. In these cases, the spectrum might be computed using an FFT or similar. - Some digital SAs directly sample the RF, thus all the spectrum and filtering computations are done in the digital domain. This latter architecture usually doesn't have preselection.
@@w2aewThank you, Alan, I'll study what you say, seems a little complex. I never found this kind of analysis (Analog vs Digital SA), maybe because there are many types, as you said. This is a good topic for a video class. Thanks.
Hello W2AWEW! What happens in the case that I have two tones, assuming that both are 5MHz apart and where the tone of interest is much lower than the other. Does setting a narrow span perform a filter behind to suppress the higher tone? This is important for me because I want to measure the lower tone accurately without over ranging. In general, when we set the reference level, is the gain applied to every tone the spectrum finds or only confined to the span of interest. Thanks alot
It really depends on the analyzer, and the type/configuration of the preselector before the first mixer. A 5MHz spacing is fairly close, so I don't know if this would get adequately filtered away from the front end, even at very narrow spans.
I know its a cowboy way to do this but could I use a multi position switch to sample off (coupled to an unused port). Problem is the attenuation is unkown
Question: just got a RIgol Spectrum Analyzer with tracking generator. Tuning ham radio duplexers, I noticed that when I manually change from say 550 ms to 5 sec sweep time, the point of tune changes. Is there an optimum setting that is best for this kind of work? Also noticed than there's not much change from 5 seconds to 10-15 seconds, but I want accuracy, not speed....suggestions?
Paul Dallard I've never used the Rigol SA, but in general I would tend to put my faith in the slower sweep. At the faster sweeps, you could be seeing a little "delay" affect from the narrow RBW, or a slight offset of TG and SA. To validate this yourself, establish a tuning point and then manually check it using zero-span. See if the fast or slow sweep gives you the most accurate result.
What happens to the accuracy of measurement if I overload the spectrum analyzer? For example, I have a very big fundamental and a much smaller spur close by. If I set the reference lower than the peak of the fundamental, what happens to the amplitude measurement of the smaller spur?
Setting the reference level below the main signal level can result in inaccuracies due to gain compression, growth of Spurs and distortion componespnts, and even possible damage to the front end mixer. Lots of factors affect what will happen, including the design of the specific analyzer being used. Bottom line, don't do it.
Fast Fourier Transforms. Could you recommend some material for my level having not yet gone all the way through Calc. got in a fight with the book due to misprints.
Love your videos. I have a question on the video. I see you are using a 75 to 50 ohms pad. How does this effect the output? Also could you use the pad on say on a sweep generator? Thanks and keep up the great work.
Yes, you can use it on the output of a signal generator. Note that it attenuates the signal by 5.7dB. However, keep in mind that the impedance mismatch between 50 and 75 ohms isn't that terrible (1.5:1 VSWR), so you often can get away without using the pad.
HI W2AEW. I am planning to buy a service monitor for two radios but I would like one which would have a scope, spectrum analyzer. As I would like to use it for service the two way radios and to tune duplexers. What would you recomend. Also that it is not so expensive.. I will be waiting for your response. Thanks
+Yeshua Jes I don't have a service monitor, and have actually never used one - so I can't offer much help in this area. Marconi/IFR/Aeroflex and Motorola seem to be the most popular service monitors and communications analyzers out there.
I would like to reproduce the graph in my AC book. I know I've probably gotten a little off the path for an electronics student but the Spectrum Analyzer relates to so much science and physics I had to try it out. I'm probably not setting it up properly though to start out with. I've tried 5 Spice and Tina 9 with no results. Any suggestions would be helpful. 3H |----------nnn-------------- ~ 1V 60Hz RL 1k ------------------------------ Thanks.
Howdy!, I recently won a Tektronix Model 491 Spectrum Analyser, from eBay, which appears in perfectly serviceable condition, (though I have never powered it up, yet), but I have had zero hits searching for manuals on it: even Tek's website gives no joy. Have you any clues to acquiring manuals for this piece of exquisite T&M aparatus, or hints I can use to bring this puppy back into service? (The listing said it had been recently used, by the owner, and worked satisfactorily, at least up to 2.5 GHz) I would appreciate any hints you could offer. Your tech vids are among the very best I have EVER watched! Keep on Keepin' on (from a 60 YO fossil engineer). Cheers, Dave
+David Cole Here is a link to some manuals for the 491: www.ko4bb.com/manuals/index.php?dir=Tektronix/Tektronix_-_491_Spectrum_Analyzer bama.edebris.com/manuals/tek/491/
+w2aew Howdy, again, and many, MANY thanks! The links you forwarded were PERFECT! I don't know how you found those, but I had looked at Boat Anchor, (BAMA), and found no references: evidently, the Google Fu is powerful in you! One last request; do you have any suggestions for a Tracking Generator that the Sawtooth output could drive (Just the low bands -- I am not Yet ready to go extremely high -- 1 to 3 GHz is MORE than enough) You are a lifesaver (but not the candy). Thanks SO Much, Dave
Thanks. Have you or anyone here tried the SA in Tina v__ software? does it work properly? Thanks for the video glad I haven't bought 1 yet .... cause I'd have blown it out on the first day.
I really appreciate your videos. After a long career in the wireless industry where our labs were full of expensive hp/tek boxes, I'm setting up a home lab and sorting through used vna's and some newer siglent/rigol... boxes.
as an OLD newb, i'd be screwed without your videos. many thanks
Subscribed and watch alot of your video's and have not found any errors yet. You really know your stuff. Love how you break it out on your excellent hand written schematics too. Sometimes I need a refresher and your my choice. Best video's on Tube. Thank you.
This was extremely useful, thank-you! It's good to understand the "why" of taking safety precautions.
I just got one of these at a good price but the 50 ohm model. Great to see this video. You gave me the info I need to keep it in good working order. A lot to learn yet, but covering the fundamentals is always good, no matter how much I learn. Thanks for all of your videos.
Here is another good tip to avoid blowing it up, don't use is as a workshop broadcast receiver as one day you will go home for the weekend and leave the outside antenna connected and it takes a lightning strike. Great channel.
Thanks a lot for your reply! After watching this video I watched "Use the scope to measure the length and impedance of coax" and I understood what was going on. Thank you for this free knowledge!
Thanks for these awesome videos, sometimes just doing the basics over again is a great fundamentals refresher. I always learn something from these no matter how simple they may seem.
Another great explanation, a very good video as always. Many years ago a colleague had a natural gift for blowing up spectrum analysers. One type of measurement we did at the time was mains borne interference, we used a form of high pass filter that you could connect a measuring receiver to. Of course the merit of using a receiver was that the tuned circuits in the front end effectively integrated out mains borne spikes, and the full transient amplitude did not reach any of the active devices. To my knowledge he trashed the mixers in 3 spectrum analysers, one after the other.
For general engineering purposes it is probably good practice to keep an attenuator permanently attached to the analyser, that way you think twice about removing it. My own spectrum analyser would not justify a massively expensive repair if I damaged it so I have to look after it! Thank you again for making some excellent videos.
APU. Great video.
Thank you for your dedication in teaching (entry level) people like me.
Thank you immensely,
David
I agree, though I enjoy off the cuff.. I like the way I dont fall asleep in this channel and am able to learn and have it reinforced. Going to Uni next year, its nice seeing the theory in this channel and having a lecture on it.
Sharing is caring, thanks for taking the time
Its really useful video, it helped when i worked in a satellite station as a freshman
i am glad you provide such a interesting topic from the theory to practices,can you be kind enough to make another movie and show us how to use spectrum analyzer; i like to know the relationship of RBW and VBW; thanks in advance
Have you seen a product called “RF SNITCH”?
It’s a tiny device that is powered by USB-Micro power and has a single SMA female connector.
The housing is clear and permits viewing of the internal LEDs.
There is a green / 2x orange / red..
I believe they are bi-color or tri-color LEDs because upon “alarm”, I recall they all turn red.
You are supposed to connect this to the device you intend to connect to a spectrum analyzer or VNA.
If the signal is low enough to use safely with the sensitive test gear, it will light up GREEN.
and… you can guess the rest of the operation.
I’m not sure about signal levels, but it was reviewed and recommended by RUclipsr IMSAI Guy.
(around $50 bucks or so.. I bought mine a year ago and can’t remember the exact pricing)
Another great video..Thank You!
I've not seen or reviewed that device, but seems like one way to help prevent you from damaging your spectrum analyzer or VNA.
Thank you! There needs to be a complete series on "How not to blow up your..." for all of the common analysis equipment.
You are a great teacher. Thanks a lot for your dedication to teach.
That unit was made for CATV/MATV. Line amps are phantom powered at 60 volts and on 75 ohm coax.
at 3:33 you hold up a bird device, could you explain more about this or point me towards a video that does???
It’s an RF Sampler. See this video ruclips.net/video/0Kk_N_TpDeo/видео.htmlsi=KILnMGn18YbY6g3s
Thank you =) I’m getting my first SA (HP 8560E), and found your advice very helpful. Looks like I need to get a few DC blocking attenuators!
Great Informative Video, a critical reminder at the least. thanks for the contribution.
Be careful with that 30dBm level for maximum input power. That apply to the front end attenuator. If you set 0dB attn and apply 30dBm you for sure will damage the front end amp or mixer. The front end mixer typically should get more than 0 dBm for safety and for optimum measurement of linear amplitudes should be below -10 dBm. For non linear amplitude (harmonics, intermodulation...) the power to front end mixer on most Spectrum Analyzers (including Agilent ESA) should be around -35dBm.
Very nicely done. Nothing too techy, nothing too dumbed down (for me at least) Just got a spec-ana. Trying to figure it out. (and un-teach the o'scope view)
Cal you make cheap rf spectrum analyser using crt tunner and Arduino ?
Hi Alan, nervous about overloading my input, check me on this for rules of thumbs please. I have a RF sampling tap good for 30 db, 1:1000. My Rigol DSA 815 has a max input of 20 dbm 50v DC. The tap then would make 100 watts equal to .1 watts, correct? Which is 20 dbm? So it's safe? Newer to these devices - so nervous about blowing it up I'm afraid of using it! I also understand the sampler manufacturer recommends starting with 10 watts into the sampler, more conservative. So this device would work well with the spectrum analyzer as long as I don't exceed 100 watts into the sampler? 2nd question - Instead of a sampler, I also have a step attenuator, both button based, up to 90db, and another one that is rotary based good for 70db attenuation. I'm assuming those are good as well, i.e. but could you literally hook up your radio directly into the attenuator pad set for 20 db or more driven with 100 watts and it would be fine? I know that's not conservative just want to understand the theory and the limits. I would likely start out with 50 to 70 db attenuation, but I would not need the sampler, just connect the attenuator to the radio, and the other end of the attenuator to the analyzer?
You've got the ratios right. 100W is 50dBm. An RF sampler/coupler with a 30dB tap will give you 20dBm out with 100W in. This is equal to the maximum input rating on your Rigol, so while is it in theory "safe", I personally wouldn't run it that close to the limit. I'd put another 10 or 20dB attenuator between the coupler and the SA input, to give you +10 or 0dBm to the analyzer. Also, be sure to set the Reference Level on the analyzer appropriately. Also, make absolutely sure that the coupler is rated for 100W through the main path, and that the output of the main path of the coupler is properly terminated into a dummy load. In theory, you could also use your step attenuator, BUT it would HAVE to be rated for 100W (which is doubtful, since you don't see high power step attenuators very often). If it was me, I'd use the coupler, dummy load and then the step attenuator between the coupler sample output and the analyzer. Then, adjust the step attenuator as needed (i.e. 20dB or more).
@@w2aew Alan, perfect. One short follow-up - I'm assuming setting the ref level correctly is for accuracy only, doesn't affect safety on any inputs, etc.? Thanks and 73. KM5L
@@patrickbouldinkm5l143 if the reference level is set too low (below the signal level), you risk damage.
I have a question around spectrum analyzer safety, power levels and preselection: Must the Reference Level always be selected according to the strongest input signal (to not potentially cause damage)? Even when its currently sweeping a different frequency range on a much smaller signal? (my gut feeling is "yes", because 1st mixer will still get everything, so the attenuator should not allow too much of the strongest signal to the mixer - which would also mean that a "peak zoom" function may be dangerous to use on smaller signals - because it'll adjust the overall reference level to that small signal's power) Thanks!
You see from my previous posts that I am alway talking about internal and external attenuator. The general practice is to always put external attenuator (10 dB typically) as close as possible to you measured device. That specially true if you have to use long cable or the Spectrum Analyzer internal attenuation is set to 0 dB. Such approach will improve matching between your device and Spectrum Analyzer. That very important for measurement of non linear parameters (intermodulation, harmonics).
Just bought an Agilent E4411B and I wanted to know where you got the 75 ohms to 50 ohms Minimum Loss Pad. I have seen them cost 200-300 dollars and more. I'm on a budget. Oh BTW, great video. I am so glad I found it.
The BNC coaxial unit is available from Mini-Circuits for less than $30
Great video. However I think there should be mention that dbm measurements will differ depending on the load. Measurements in 50 ohm, 75 ohm and 600 ohm (telecomms) will be different particularly with respect to the voltage. For instance a 1mW reference power level corresponds to 0.224V in a 50 ohm system, 0.274V in a 75 ohm and 0.775V in a 600 ohm system.
Tektronix recently came by our shop and demo'ed an MDO4000. OMG what a machine. have watched all your MDO's. More MDO please lol.
I wonder who visited you. I know many of the field people...
***** I forget. Its not Doug keltz our salesman. I'll look it up on my old emails. Was ready to buy it then our SPG system failed and we had to buy a new Main & back up SPG-8000 with Change over unit. That pretty much burned our budget. Had a Tektronix WFM-5200 in there too. Heartbreak.
It would make sense that it wasn't Doug. He works for the Video Products division, and the MDO is made by the Test & Measurement division which is handled by a separate sales force.
Cool video, thanks for sharing.
Do you know much / could you do a quick video on using a spec an to align a ku band satellite?
picked up a used Rohde & Schwarz CMU200 off ebay for $800. RF input safely supports up to +47dbm, pretty unbelievable. and a nice safety margin for me! also means i don't have to worry about non linear response through any attenuators for most of my work.
If I recall correctly, that analyzer has a few RF inputs, and the 47dBm (50W) applies only to one of them. Congrats on the nice find!
The CMU 200 is a great piece of kit, but beware that there are three models. "Engineering model" V02 can only handle 2 Watts. "Service model" V30 can handle 50 Watts. The CMU 200 can show a power overload warning, but this is also related to the vertical scale. The scale and referende level can be set manually to solve this "warning problem".
The more sensitive the input, the better the signal quality you'll get. Normally RF2 is the input is most used (except for high power transmitter testing).
Maybe this is interesting to read: amateurtele.com/index.php?artikel=251
Thanks Alan, answered all my basic questions in one go, another great video, I will add an adjustable attenuator to my shopping list ;) How much attenuation "span" do these things give, and what's a good range for general in the shack amateur usage? i suppose it depends on the input range of the analyser itself? Cheers :)
Superb videos many thanks,
How about a tutorial on the accessories that maybe needed, as this is a bit confusing for the newbie like myself.Im taking delivery of my first real spectrum analyser in a few weeks, so i have gone out a bought a few items like you suggested - DC Block, and a few 10GHz JYE BAO N Type attenuators. But a sampler?, whats this used for exactly? and bias Ts, Splitters, Combiners, Loads, this stuff has got me, when and why to use,
Alan, thanks for another great video. How does the input float voltage limit (+/- 4v, for instance) relate to maximum signal input voltage on a low frequency instrument with high impedance? I can't seem to figure it out.
Ken
Thank you for such a valuable information.
Amaizingly clear. Thanks !
Great presentation. Thanks, Barry
Good information, thank you! 👍
Can you recommend any videos or video courses for learning the basics (and even more advanced topics) related to of spectrum analyzers?
Also .. can you use an Anritsu MT8820C for the channel?
( 30 MHZ - 2.7 GHZ Radio Communications Analyzer)
It’s fully functional and was give to me by a friend’s wife after his passing.
I initially wanted it for spectrum analyzer use but discovered it couldn’t be used as a standalone SA.
So.. it’s just gathering dust.
Following my previous post: Spectrum Analyzer optimum measurement power apply to the internal mixer not the the front of the Spectrum Analyzer. So if you power from the device is let say +10dBm and you measure fundamental frequency amplitude than the reference should be set to +10dBm and the total internal or external attenuation should be more then 20dB. If you measure intermodulation that internal or external attenuation will need to be set to 45dB.
Yes thats what it is. The repeater is for a particular cell carrier but it needs higher power because off the building where the phones are being used and is shutting down another adjacent phone carrier, can a band reject filter be used in this case? Because the repeaters dont have any internal attenuation nor gain controls.
Bom dia preciso o esquema elétrico da fonte power supply ..obrigado...
So, if I build a 2m Ham Radio at an output of the typical 5 W, I would use the external attenuator to reduce that input power (voltage) down to 0 V? How does a spectrum analyzer be designed to only handle a 0 V input when RF in the air is typically in the micovolts range (I do understand that wave forms above and below 0 V cancel themselves out to 0 V. Is that the theory here?)
Frank
Frank Reiser Video/Audio Service
The 0V requirement is for the DC Content of the signal only. Most RF transmitters don't have any DC content, so that part is OK. The other thing you'll have to do is attenuate the signal quite a bit - ideally you'd like about 1mW or so into the spectrum analyzer. For measuring RF transmitter output, it is most common (and safe) to terminate the transmitter into a dummy load rated for the full power, and use some sort of RF Sampler to couple a small amount of energy to the spectrum analyzer. I have a video or two on RF samplers...
I bought my spectrum analyzer off of ebay by winning a bid for only $150, and it is a good one and not too old. Isn't a DC bloc simply a capacitor? Can i build a DC block and power reducer myself with a resistor in series with a capacitor connected to the correct jacks?
Frank
Frank Reiser Video/Audio Service
Yes, a DC block is a series capacitor. Check your analyzer, it may already have a dc block internal. The allowable DC voltage will likely be printed on the front panel. You can also build an attenuator, but it is not simply a series resistor. The attenuator has to maintain a 50 ohm input and output impedance, needs to be able to handle the transmitter power, and has to be built to have a flat frequency response over the operating range.
It was Carl Hanck. I could really use it for Quam & CODM investigation. Do alot of that.
Few months later I see Tek is selling the same box for $7,000 on ebay. Wish I could afford it personally. But I already own a alot of test equipment.
I know Carl, he's on the test & measurement side like me.
What I marvel at is your command of knowledge in using such instruments. I wonder how did you learn to use such instruments to the level you know how to use them? Did you study the owner's manual or were you taught by someone and learned your way through that?
Its a combination of all of those things. Usually starting with the manual, as well as manufacturer application notes, books, etc., as well as learning from those more knowledgeable. All of these things over the years help contribute to the fluent use of the equipment. Of course, it helps a lot to gain a good understanding of what is happening inside the instrument so that you have a clearer idea of what each control is doing.
@@w2aew Good to know. Thanks
Hi Sir, you mentioned about setting the reference level causes the attenuation to be adjusted (under auto mode). Let say the attenuation is auto set to 10dB.
So does that mean the peak value reading we take from the screen is already attenuated by 10dB? If that is the case, we need to add back this lost in our final value of the power received?
The analyzer properly scales and adjusts the reading, so it always reflects the proper value, regardless of the attenuation level (as long as the unit isn't overloaded).
Do you know how to test RF devices, such as a Bluetooth device, WiFi device? Are you familiar with FCC testing procedures or ANSI C63 procedures?
Great video. Wanted to know if I can relate the span nob on the spectrum analyzer to the LO frequency range that will be selected
Yes, basically the span knob does control the frequency range of the LO (usually more than one LO). However, keep in mind that wideband spectrum analyzers will often use harmonic mixing, so the LO range won't necessarily be as wide as the span.
Could you explain to me what it's for 50 ohm terminator at the entrance to the spectrum analyzer? I do not understand why they put 50 ohm terminator on the input of the oscilloscope too? Anyway, thank you for these wonderful tutorials!
When you lowered down the RBW, the noise floor dropped down. When the noise floor dropped down, what is its effect on the peak of the signal? Did it change as well or did it stay at the same reading?
The peak of the signal doesn't change as you lower the RBW, unless the signal occupies a bandwidth greater than the RBW.
How can you use a spectrum analyzer to measure CCTS? Somehow you can calculate the Crew Curve of the audio signal by knowing the resonance frequency and the speaker frequency start and stop range. I'm not sure what the crew curve is used for
I don’t know what CCTS is.
@@w2aew CCT means circuit. I don't know what the difference in using an FFT sweep compared to using an Audio Sweep because when you use an Audio Sweep you will see more harmonic peaks compared to using FFT sweep? When the spectrum analyzer is displaying harmonics I have been told to use the hybrid superHET filter to remove the harmonics, is this true?
Great info!
Think you could do one on measuring channel power?
I did one on making a channel power measurement on a WLAN signal a couple of weeks ago:
How to make a WLAN Channel Power Meas on a Tektronix MDO4000
Hi there would it be possible to do a tutorial on scale fidelity measurements on a spectrum analyser or could you direct me to a video?
Nice. maybe explain the zero span next to have power over time
seek and yee shall find:
ruclips.net/video/Lp6sT-n55N4/видео.html
What do you think of using a general coverage HF receiver and modifying it with a swept VCO and also sending the output of the ramp generator to the horizontal input of an oscilloscope. If not where can you get the RF/IF plug in lke you have thanks Jim KD7TU
It could work. You'd probably have to disable the AGC circuit and manually adjust RF gain, and add some kind of detector on the receiver output. You'd be limited in the RBW settings (just the filter settings the radio. It may not be well calibrated, but will at least give you a relative view of the spectrum.
Thanks for the good advice sir. Most appreciated.
Thanks for the video. Quite informative.
couple of questions:
1) if signal is close to Noise floor do we still need to move the whole spectrum up on the Y axis so that the signal peak is just below the reference level?
2) for default attn of 10dB i get some power levels (say -60dBm) but when i increased attn manually to 20dB and beyond the power level moves to-74dBm. Does this mean the 20dBm is optimum attn.? which power level and which attenuation i should trust?
Thanks
From your question, I guess what you are looking at is a distortion component of an Amplifier or some thing like that. But since the level of the signal observed is changing when the attenuation is changed means trust the one with 20 dB Attenuation. At 10 dB attenuation the distortion is more due to the spectrum Analyzer you are using. If you change the attenuation to 0 dB, 10 dB, 20 dB while watching the signal (if limited by spectrum Analyzer it will change by 20 dB each if it is 2nd harmonic of some fundamental signal coming in or 30 dB if third harmonic etc) will tell you when you are observing real distortion value.
I hope that you please will answer this question.
I can read that Spectrum Analyzer often goes from i.e. 9KHz and up, but what if I want to look at an audio signal at 22Hz?
You can't. There are some spectrum analyzers that go lower than 9kHz, but most do not. For a 22Hz signal, if you want to look at the spectrum, you're better off using the FFT function of an oscilloscope.
Hi there, I wanted to ask if it’s okay with you if I show some of these videos as part of my own twitch stream. I just received my first analyzer and I think it would make an interesting stream to show my „first steps“ with the device, using your videos as a guide. So it would be watching/reacting to a part of your video and then trying it out myself. Thanks in advance, and many greetings from germany :)
Sure, no problem. Just provide a link to your viewers to my channel.
If you don't know the frequency you are measuring, what is the quickest way to determine the frequency? Do you just widen the span and adjust the reference level as necessary to detect any weak signal?
Yes.
How can we test nonlinearity of a spectrum analyzer for L1/L2 band?
So a Signal Analyzer can view the frequency base of a signal as a Spectrum Analyzer does but it needs to convert it from a time base first.
So a Signal Analyzer would be more useful in Electronics?
Is it Radio Frequency Interference if I hear an unusual "Hum" sound in a video. (This sound is heard as clear as if it was part of the video, but the first time I saw that video, it wasn't there)
Hello, I am looking into getting my first spectrum analyzer for transmitter tuning and repair. I have my Bird43, the 4275 line sampler, 2205 scope and dummy load. What I would like to do is add my frequency counter and a spectrum analyzer, could you describe how to do it? Perhaps one of your great diagram layouts.Thank your channel has inspired me.
Since you've got the sampler, you would simply connect the counter or spectrum analyzer to the sample port.
Thank you Alan, would it be advisable to add a "T' somewhere after the scope to insert the frequency counter. I would like to view the scope and frequency counter. I am using a 3 position antenna switch, radio into it, port 1 to Bird meter, port 2 to scope, port 3 to signal generator.Or would it be better to add the frequency counter in line with the bird?I am using 2 separate dummy loads.
You would NEVER want to connect the radio directly to the scope, or the spectrum analyzer, or the frequency counter. Never.
Always have the transmitter connected directly to the dummy load, and use the sampler in-line to connect to the scope, counter and spectrum analyzer. If you want to have all three hooked up, you could put a BNC-Tee at the input to the scope and the counter, then run the coax from the sampler to the tee at the scope, from there to the tee at the counter, and then from there to spectrum analyzer. Alternatively, some scopes have an auxiliary OUTPUT on the back panel which is a buffered copy of the signal at the input - you could use this to drive the counter.
Hi, is there a certification we can get online for Spectrum Analyser Operations?
Can this spectrum analyser detect GSM signal boosters? If yes... Please, explain and how it works. If no, please tell me the equipment for detecting GSM boosters in an environment. Thank you all for your input.
I see the small spectrum analyzer you have only accepts -30dbm or 1 milliwatt, is there a way without a power meter to measure the 1 milliwatt before you attach it? Could you use a multimeter on ac amps?
Actually, -30dBm is not 1 milliwatt, it is 1 microwatt! For that particular analyzer, the -30dBm refers to the power at the front end mixer. There is a manually controlled attenuator ahead of the mixer. So, you have to manually set the mixer to ensure that you don't exceed -30dBm at the mixer. Most modern spectrum analyzers control the attenuator automatically based on the reference level setting. If you are measuring a signal of unknown power (and you don't have a way to measure its power), the always start with the highest attenuation possible (highest reference level), and work your way down.
Thank you very much for your useful video.
I am going to measure the frequency of composite by vibration techniques(impulse frequency) for mechanical properties evaluation.
I would like to know I can use a spectrum analyzer for this problem.
could you please introduce me a portable or handheld spectrum analyzer?
Best Regards,
thanks for the video...please can anyone give me a link and/or tips on how to measure 1/f noise using a signal source analyzer?
Alen can you use a basic spectrum analyzer to see interference caused by a cell phone repeater and if by reducing the power of the repiter can all the interference be totally eliminated also what types of interference can the cell phone repeater cause? thanks.
need your advice I bought a used HP 8981a Vector Modulation analyzer without any manual hoping to use it on audio tuner debug. Did I buy the wrong piece of equipment and it looks like I need to purchase a high freq generator. First time i've purchased this kind of equipment and need some help. Thanks
Unfortunately, it does seem like you've got the wrong piece of equipment. This unit is intended to analyze digital modulation quality (such as QPSK, 16QAM, etc.), either on the baseband IQ signals or on a quadrature modulated IF signal. Doesn't sound like it will be of much help debugging analog audio tuner issues.
Thank's for this video, i have a question about the input power, since there is an internal attenuator, does +30 dBm of the maximum input RF power refers to the maximum power when internal attenuation is set to 0 dB, or whatever internal attenuation these +30 dBm should not be exceeded ?
You'd really have to consult the data sheet for your specific analyzer. Generally, the input limit on the front panel applies at any attenuator setting (due to power limit of attenuator)
Are there any books you recommend that explain exactly what you described as far as setup and taking basic measurement using a spectrum analyzer?
Great video. Extremely useful! Thank you.
What will happen if I am measuring very low power signal e.g. -40dBm and suddenly power will change to +25 dBm? Will automatic attenuation react fast enough to protect mixer?
Most likely NOT!
Hello. first of all, thanks a lot for your knowledge condivision about this amazing equipment as a SA is.
My question: a 75ohm input impedance equipment is suitable for learning or you misadvise to buy it to a beginner as I am. You are right when you say that you could get it as a really bargain, but due to it would be sure the first but the only one, I would like to buy something which could be useful at all, not only for some nice intelligence game and to leave it off for unsuitability at all.
Thanks.
Danilo
I think it is perfectly suitable for learning. The absolute power measurements won't be accurate, but most of the time you're using a spectrum analyzer to look at relative power levels anyway. The input SWR when used with 50ohm sources will nominally be 1.5:1 which is perfectly acceptable.
@@w2aew Thanks a lot for feedback. Unfortunately the bargain I was dealing with, has gone to someone else, ( :-( ) but I will not settle about.
I am Searching for a new opportunity. THanks again.
Danilo
I GOT IT!
LT Spice has been the only one I've had luck with so far but I did use a *.cir file.
Hello I have a complaint... these Agilent SA make froze when use GPIB, is a good instruments but in my experience works better oldest HP, I was worked in some electronic labs and I prefer old HP SA, the model of these video works fine but manually not in remote mode like latest models, guys if you know how to prevent these please tell me what I can do, regards!
Brilliant information, after rf attenuation should the spectrum analyser proceed the osciioscope or doesnt it matter?
Cheers
Andrew
If you're using a splitter, it doesn't matter.
Hello W2AEW, is it possible to measure phase of a signal on a signal analyzer, if so could do a demonstration of the measurement.
Yes. There is a class of analyzers called Signal Analyzers, more specifically, Vector Signal Analyzers. They can acquire/record signals vs. time and give you the ability to analyze amplitude, frequency, phase, spectral content, and more - all vs. time. Most will do more advanced analysis include modulation quality, pulse analysis, and other signal analysis functions. With these VSAs, phase measurements are 'relative' to the measurement frequency. To measure phase response of a device under test, you would usually need a different type of analyzer called a Vector Network Analyzer.
Im a beginner, are these things good for an aspiring design engineer?
Is there some significative difference between Analog and Digital SA? (about scopes I know the lack of single-shot in the analogs) thanks
There are a number of varieties of "digital" spectrum analyzers, so the answer is little more involved... For example:
-Some digital analyzers simply digitize the signal in the final IF stage and perform the final RBW filtering and detection in the digital domain. These generally offer more RBW selections than a pure analog SA.
- Some digitize the signals at a higher IF stage, potentially offering some RF capture vs. time in addition to the RBW flexibility over time. More advanced units can do vector signal analysis. Basic units simply digitize early to make inexpensive hardware. In these cases, the spectrum might be computed using an FFT or similar.
- Some digital SAs directly sample the RF, thus all the spectrum and filtering computations are done in the digital domain. This latter architecture usually doesn't have preselection.
@@w2aewThank you, Alan, I'll study what you say, seems a little complex. I never found this kind of analysis (Analog vs Digital SA), maybe because there are many types, as you said. This is a good topic for a video class. Thanks.
Hello W2AWEW! What happens in the case that I have two tones, assuming that both are 5MHz apart and where the tone of interest is much lower than the other. Does setting a narrow span perform a filter behind to suppress the higher tone? This is important for me because I want to measure the lower tone accurately without over ranging. In general, when we set the reference level, is the gain applied to every tone the spectrum finds or only confined to the span of interest. Thanks alot
It really depends on the analyzer, and the type/configuration of the preselector before the first mixer. A 5MHz spacing is fairly close, so I don't know if this would get adequately filtered away from the front end, even at very narrow spans.
Many thanks for the answer!
I know its a cowboy way to do this but could I use a multi position switch to sample off (coupled to an unused port). Problem is the attenuation is unkown
Yes, you could do this.
the price they gost and they don't have a dc blocker built in?
Question: just got a RIgol Spectrum Analyzer with tracking generator. Tuning ham radio duplexers, I noticed that when I manually change from say 550 ms to 5 sec sweep time, the point of tune changes. Is there an optimum setting that is best for this kind of work? Also noticed than there's not much change from 5 seconds to 10-15 seconds, but I want accuracy, not speed....suggestions?
Paul Dallard I've never used the Rigol SA, but in general I would tend to put my faith in the slower sweep. At the faster sweeps, you could be seeing a little "delay" affect from the narrow RBW, or a slight offset of TG and SA. To validate this yourself, establish a tuning point and then manually check it using zero-span. See if the fast or slow sweep gives you the most accurate result.
Thanks, I will try that. I'm also going to use the automatic setting on VBW and RBW, instyead of manually setting the span, time , and RBW.
More! More! ... :)
Can you do a video on typical Amateur Applications / ... like 'full spectrum' info. (sorry for the pun).
Thank you & 73,
Neil, K7WK
What happens to the accuracy of measurement if I overload the spectrum analyzer? For example, I have a very big fundamental and a much smaller spur close by. If I set the reference lower than the peak of the fundamental, what happens to the amplitude measurement of the smaller spur?
Setting the reference level below the main signal level can result in inaccuracies due to gain compression, growth of Spurs and distortion componespnts, and even possible damage to the front end mixer. Lots of factors affect what will happen, including the design of the specific analyzer being used. Bottom line, don't do it.
Noted. Thanks!
maybe, you can use a oscilloscope with FFT function. or you can collect daha then analysis under matlab.
Fast Fourier Transforms. Could you recommend some material for my level having not yet gone all the way through Calc. got in a fight with the book due to misprints.
Love your videos. I have a question on the video. I see you are using a 75 to 50 ohms pad. How does this effect the output? Also could you use the pad on say on a sweep generator? Thanks and keep up the great work.
Yes, you can use it on the output of a signal generator. Note that it attenuates the signal by 5.7dB. However, keep in mind that the impedance mismatch between 50 and 75 ohms isn't that terrible (1.5:1 VSWR), so you often can get away without using the pad.
Great. Thanks. I will try it both ways and see what I get.
HI W2AEW. I am planning to buy a service monitor for two radios but I would like one which would have a scope, spectrum analyzer. As I would like to use it for service the two way radios and to tune duplexers. What would you recomend. Also that it is not so expensive.. I will be waiting for your response. Thanks
+Yeshua Jes I don't have a service monitor, and have actually never used one - so I can't offer much help in this area. Marconi/IFR/Aeroflex and Motorola seem to be the most popular service monitors and communications analyzers out there.
Thanks a lot.. I will take a look at those brands.
I bought ESA E4407B and date , time is required to set during every ON so plz send the pick of CMOS bty with board
I'm sorry, I can't help you - I no longer own this analyzer.
what happens if you connect a spectrum analyzer in parallel?
I would like to reproduce the graph in my AC book.
I know I've probably gotten a little off the path for an electronics student but the Spectrum Analyzer relates to so much science and physics I had to try it out.
I'm probably not setting it up properly though to start out with.
I've tried 5 Spice and Tina 9 with no results.
Any suggestions would be helpful.
3H
|----------nnn--------------
~ 1V 60Hz RL 1k
------------------------------
Thanks.
Why does the older Tek spectrum analyzer say -30 dbm but the Agilent says +30dbm.
Whats the difference between a Spectrum Analyzer and a Signal Analyzer ?
Howdy!,
I recently won a Tektronix Model 491 Spectrum Analyser, from eBay, which appears in perfectly serviceable condition, (though I have never powered it up, yet), but I have had zero hits searching for manuals on it: even Tek's website gives no joy.
Have you any clues to acquiring manuals for this piece of exquisite T&M aparatus, or hints I can use to bring this puppy back into service? (The listing said it had been recently used, by the owner, and worked satisfactorily, at least up to 2.5 GHz)
I would appreciate any hints you could offer.
Your tech vids are among the very best I have EVER watched!
Keep on Keepin' on (from a 60 YO fossil engineer).
Cheers,
Dave
+David Cole Here is a link to some manuals for the 491:
www.ko4bb.com/manuals/index.php?dir=Tektronix/Tektronix_-_491_Spectrum_Analyzer
bama.edebris.com/manuals/tek/491/
+w2aew
Howdy, again, and many, MANY thanks!
The links you forwarded were PERFECT! I don't know how you found those, but I had looked at Boat Anchor, (BAMA), and found no references: evidently, the Google Fu is powerful in you!
One last request; do you have any suggestions for a Tracking Generator that the Sawtooth output could drive (Just the low bands -- I am not Yet ready to go extremely high -- 1 to 3 GHz is MORE than enough)
You are a lifesaver (but not the candy).
Thanks SO Much,
Dave
Thanks.
Have you or anyone here tried the SA in Tina v__ software?
does it work properly?
Thanks for the video glad I haven't bought 1 yet .... cause I'd have blown it out on the first day.
Is there anything you don't know LOL! Awesome video!
Hi
can anybody help me with a Protek 3290 Analyser I cannot get the free run going ?