I did a web search for Wideband Engineering Co. because I live in the Phoenix area and had never heard of them. It looks like they were in business starting sometime in the 1970s but are no longer operating. The last address for them was a house in a residential area.
Probably was used with a SA in a cable truck, to see if the filters used were doing their job and "preventing" the customer from getting channels they were not paying the premium for. Then the tech would leave, and the customer would open the box and replace the filter with a barrel connector.....
Use 75 ohm cable terminator they are 75 ohm and less than $1 each in ebay. In general there are two types of matching network: Pi network and transformers. There are two web sites that you can calculate the ratio of the transformer or the value of the resistors in the pi network.
We used to use a lot of these in satcom systems back in the 80s and 90s. Generally the systems are 50 ohms at RF but some of the IF systems were 75 ohms. So depending on vendors there were various converters used in the system, some transpads as was your first thought and some transformers like this one. It's been 30 years or so, but my recollection is that the transformers were lower loss. The common IF frequencies for a long time were 70 MHz and then later 140 MHz for wider band systems. Eventually L-band IFs were introduced that operated in the 950 MHz to 1450 MHz range give or take. Then to save cabling costs and use a single IF cable both Tx and Rx were put on the same cable with the IF bands each operating on their own 500 MHz wide chunk from say 800 MHz to 2200 MHz or so, varied by manufacturer. Today for consumer satcom antennas MOCA is a common interface as is straight Ethernet. Now the entire modem and RF up/down conversion and PA/LNA are all inside a feed mounted module right on the antenna.
I was going to ask if those were the same thing I had dozens of from old cable setups. I figured those were worth pennies and chucked them all. A bunch were the cheapo black plastic things that adapted the two antenna wires to coax, but a few were really hefty.
@@ataricom The cheapo seeming ones were probably the transpad style. The hefty ones more likely the transformer style. Many commercial systems used BNC connectors at IF, and when done right the correct impedance connectors were used on the cables. The impedance matching device then had to have the correct BNC connector on each end because 75 ohm and 50 ohm BNC connectors don't mate properly. It's even worse when N connectors were used. Accidentally mating a 50 ohm N male connector to a 75 ohm N female connector typically results in a damaged N female connector.
I built something similar last week-end, but I put a series resistor on the 75 ohms source side(CATV cable) and a 50 ohms load side(HP 8594E) in parallel and it did not work. It seems here that my resistors are superfluous and double-loaded the 50 ohms output..Funny thing; the SA has a 75 ohms input setup if needed, so I plugged in directly.
Funnily, I have something very similar to this thing you show here. It has BNC on one side and a UHF cable connection on the other side, can't remember the connector name for that one. Anyhow, it is built and constructed nearly the same way. Makes me wonder if it was built by the same company possibly.
That could be handy in my radio scanner setup. I have the 50ohm scanner antenna input connected to an RG-6 75ohm coax for a 150 foot run into my homemade flowerpot antenna. The antenna is made at 50ohm and tuned to the 120-150Mhz aircraft band, I wonder if this would improve the reception by converting the load to a closer impedance for the scanner? It would probably not make any noticable difference on a recieve only system, but interesting little unit nonetheless.
@@IMSAIGuy That could be a good thing....I have an airstrip less than 1klm away and some of the air traffic gets rather loud at times, and I have a Hospital 300m away that has helicopters landing and taking off all day long....the radio chatter can sometimes overload the front end on my scanner they are so strong in signal...perhap's I should de-tune my antenna somewhat....
Before I got my Siglent SSA3201X last week(Thanks for the tip, Imsai Guy) I was trying to figure out how to convert two HP 85XX 75 ohm SAs I was trying to use before with mixed results… I found two of these converters on eBay for $28, since they are good to 600 mhz,I think I’m going to try these to adapt the SAs for 50 ohm use (loads simpler than replacing the input plumbing on the 85XX SAs. Hopefully that will give those old HP SAs some extended usefulness for homelab use. Thanks for the info!!!
capacitive (ac) coupling, (removing the dc bias from the signal), for example if you have a signal that varies from 5v to 5.01v the oscilaltions will be very hard to see on the 5v range, so we ac couple and inspect the signal on the 0.01v range.
@@victorman2227 And why would there be a DC offset? Power for antenna motor systems or so? Seems to me you'd just want to terminate the line with the transformer, like the 50 ohm side did.
“DC Blocks are components that prevent the flow of DC signals into systems while allowing higher frequency RF signals to pass through. DC Blocks are placed within a system to stop any signal with a frequency of Zero Hz (DC) from interfering with sensitive RF components. The DC block can be thought of as a high-pass filter allowing only the RF frequencies to pass through and are usually designed by placing capacitors in series with a transmission line.” - everything RF
@@rene0 There could be some DC for (from?) powering some amplifier (bias tee), or for powering / controlling the sat LNB (say, polarization switch). The latter use also 22kHz for selecting the (high) band, and it would also be mostly blocked by a tiny capacitor.
From reading the others comments here it gave me 2 really good reasons for the capacitor. If you have a little bit of DC from your source it'll bias the transformer possibly saturating it (assuming it has an iron core, perhaps not if it runs up to a GHz) or if you have enough DC voltage there it'll simply burn the transformer looking like a short circuit. That'd be a bad day.
@@markusberg2770 P=V²/R≈V²/Z. In transformer V≈N then (Np)²/Zp=(Ns)²/Zs (Np/Ns)²=Zp/Zs Np/Ns=√(Zp/Zs) If Zp=75Ω and Zs=50Ω then Np/Ns=√(1.5)≈1.224≈6:5 cmiiw please
@@iblesbosuokThe parts appears more similar to a Mini-Circuit TC1.5-1+ RF Transformer that has an impedance ratio of 1.5:1, according to their data sheet. Anyway, if you believe 5:6 is the turns ratio on a binocular ferrite-could be? You did say turn ratio.
@@markusberg2770 I applied it for HF transceiver to 0.475𝛌 open dipole matching. 20 turns for 50Ω transceiver and 24 turns for 75Ω for 0.475𝛌 open dipole.
Hi , how do i calculatte the number of turns on that pignose choke? I have an old Marconi Step attuator that has 75 ohm input and output which i would like to convert to 50ohms Thanks in advance
depends on core and wire size and frequency. you need a 1.5:1 turn ratio. I don't know the details, but maybe this helps: www.minicircuits.com/app/AN20-002.pdf since you are attenuating, use a resistive match i.stack.imgur.com/8lpQa.jpg
NOOOO! You misplaced the lid of the apparatus, when mounting it again, ... ! 50-Ohm (print) will now the 75-Ohm side - please swap the lid again. Please take care! Looking at the time-stamp 5:28 in the Video, you can see, the SMA-connector is marked with 75-Ohm now, and vis versa, ... ! An SMA is 50-Ohm and the 'F-connector' should be 75- Ohm. 73 de Markus - db9pz - (JN39fq) - Germany - nr LX - 3miles/5km east of the border to LX! Next big City in DL is Trier. _________________________ cut __________________________ P.S.: At 10:40 I can See that you chanced the lid again, ... ! Also during the messurement? - Could'nt see it, ... - Sorry to make such a 'noise' here, but your videos are always very interesting and I learned a lot from them, ... !
How about doing a slightly better 75 ohm load hack, then looking at return loss as you look into the 50 ohm side? Wouldn't that give you a easier-to-read idea of the frequency range?
What's the combined loss across that? From the 75 on to 50 ohm and then 50 ohm to 75 Just curious, I didn't see if you'd explain that part. Would have been good to know
When designing a circuit of and electric device of radio circuit etc, what determines what impedance is say 50 ohms, or 75 ohms or any other impedance? I know different antennas/test equipment have equipment different antennas and have different impedances but it seems like most outputs are 50 ohms. Why is 50 ohms seem to be the most common??
I have read one story explaining the 50 Ohms standard originating from coaxial cables. A study was made for coaxial cables with different diameters and other dimensions. The variant with the best relation between signal loss, power handling and material (I.e. expensive copper) turned out to have 50 or 52 Ohms chacteristic impedance.
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I did a web search for Wideband Engineering Co. because I live in the Phoenix area and had never heard of them. It looks like they were in business starting sometime in the 1970s but are no longer operating. The last address for them was a house in a residential area.
Probably was used with a SA in a cable truck, to see if the filters used were doing their job and "preventing" the customer from getting channels they were not paying the premium for. Then the tech would leave, and the customer would open the box and replace the filter with a barrel connector.....
Glyptol paint high voltage insulation?
Use 75 ohm cable terminator they are 75 ohm and less than $1 each in ebay.
In general there are two types of matching network: Pi network and transformers.
There are two web sites that you can calculate the ratio of the transformer or the value of the resistors in the pi network.
We used to use a lot of these in satcom systems back in the 80s and 90s. Generally the systems are 50 ohms at RF but some of the IF systems were 75 ohms. So depending on vendors there were various converters used in the system, some transpads as was your first thought and some transformers like this one. It's been 30 years or so, but my recollection is that the transformers were lower loss.
The common IF frequencies for a long time were 70 MHz and then later 140 MHz for wider band systems. Eventually L-band IFs were introduced that operated in the 950 MHz to 1450 MHz range give or take. Then to save cabling costs and use a single IF cable both Tx and Rx were put on the same cable with the IF bands each operating on their own 500 MHz wide chunk from say 800 MHz to 2200 MHz or so, varied by manufacturer.
Today for consumer satcom antennas MOCA is a common interface as is straight Ethernet. Now the entire modem and RF up/down conversion and PA/LNA are all inside a feed mounted module right on the antenna.
I was going to ask if those were the same thing I had dozens of from old cable setups. I figured those were worth pennies and chucked them all. A bunch were the cheapo black plastic things that adapted the two antenna wires to coax, but a few were really hefty.
@@ataricom The cheapo seeming ones were probably the transpad style. The hefty ones more likely the transformer style. Many commercial systems used BNC connectors at IF, and when done right the correct impedance connectors were used on the cables. The impedance matching device then had to have the correct BNC connector on each end because 75 ohm and 50 ohm BNC connectors don't mate properly.
It's even worse when N connectors were used. Accidentally mating a 50 ohm N male connector to a 75 ohm N female connector typically results in a damaged N female connector.
I built something similar last week-end, but I put a series resistor on the 75 ohms source side(CATV cable) and a 50 ohms load side(HP 8594E) in parallel and it did not work. It seems here that my resistors are superfluous and double-loaded the 50 ohms output..Funny thing; the SA has a 75 ohms input setup if needed, so I plugged in directly.
Funnily, I have something very similar to this thing you show here. It has BNC on one side and a UHF cable connection on the other side, can't remember the connector name for that one. Anyhow, it is built and constructed nearly the same way. Makes me wonder if it was built by the same company possibly.
That could be handy in my radio scanner setup. I have the 50ohm scanner antenna input connected to an RG-6 75ohm coax for a 150 foot run into my homemade flowerpot antenna. The antenna is made at 50ohm and tuned to the 120-150Mhz aircraft band, I wonder if this would improve the reception by converting the load to a closer impedance for the scanner? It would probably not make any noticable difference on a recieve only system, but interesting little unit nonetheless.
I don't think it will help. it might actually attenuate.
@@IMSAIGuy That could be a good thing....I have an airstrip less than 1klm away and some of the air traffic gets rather loud at times, and I have a Hospital 300m away that has helicopters landing and taking off all day long....the radio chatter can sometimes overload the front end on my scanner they are so strong in signal...perhap's I should de-tune my antenna somewhat....
Some similar WBE stuff here, with different connectors. Years ago, different types of BNC and N connectors for 75 ohms. Much thinner inner pin
Before I got my Siglent SSA3201X last week(Thanks for the tip, Imsai Guy) I was trying to figure out how to convert two HP 85XX 75 ohm SAs I was trying to use before with mixed results…
I found two of these converters on eBay for $28, since they are good to 600 mhz,I think I’m going to try these to adapt the SAs for 50 ohm use (loads simpler than replacing the input plumbing on the 85XX SAs. Hopefully that will give those old HP SAs some extended usefulness for homelab use.
Thanks for the info!!!
Manufacture says 1MHz to 600 MHz. Thanks Google.
Is that capacitor needed and what's it's function?
capacitive (ac) coupling, (removing the dc bias from the signal), for example if you have a signal that varies from 5v to 5.01v the oscilaltions will be very hard to see on the 5v range, so we ac couple and inspect the signal on the 0.01v range.
@@victorman2227 And why would there be a DC offset? Power for antenna motor systems or so? Seems to me you'd just want to terminate the line with the transformer, like the 50 ohm side did.
“DC Blocks are components that prevent the flow of DC signals into systems while allowing higher frequency RF signals to pass through. DC Blocks are placed within a system to stop any signal with a frequency of Zero Hz (DC) from interfering with sensitive RF components. The DC block can be thought of as a high-pass filter allowing only the RF frequencies to pass through and are usually designed by placing capacitors in series with a transmission line.” - everything RF
@@rene0 There could be some DC for (from?) powering some amplifier (bias tee), or for powering / controlling the sat LNB (say, polarization switch). The latter use also 22kHz for selecting the (high) band, and it would also be mostly blocked by a tiny capacitor.
From reading the others comments here it gave me 2 really good reasons for the capacitor. If you have a little bit of DC from your source it'll bias the transformer possibly saturating it (assuming it has an iron core, perhaps not if it runs up to a GHz) or if you have enough DC voltage there it'll simply burn the transformer looking like a short circuit. That'd be a bad day.
It seemed your diagram at the end left out the resistor you mentioned in the beginning ?
Thanks again
oops. 75ohm resistor to ground at the output connector
I think it would be 5:6 turn ratio.
1.5:1 is the typical ratio for 75 ohm to 50 ohm. Equation: 50 ohms x 1.5 = 75 ohms 73 de KO4CES
@@markusberg2770 P=V²/R≈V²/Z. In transformer V≈N then
(Np)²/Zp=(Ns)²/Zs
(Np/Ns)²=Zp/Zs
Np/Ns=√(Zp/Zs)
If Zp=75Ω and Zs=50Ω then
Np/Ns=√(1.5)≈1.224≈6:5
cmiiw please
@@iblesbosuokThe parts appears more similar to a Mini-Circuit TC1.5-1+ RF Transformer that has an impedance ratio of 1.5:1, according to their data sheet. Anyway, if you believe 5:6 is the turns ratio on a binocular ferrite-could be? You did say turn ratio.
@@markusberg2770 I applied it for HF transceiver to 0.475𝛌 open dipole matching. 20 turns for 50Ω transceiver and 24 turns for 75Ω for 0.475𝛌 open dipole.
Iusnt Impedance transformation with the square of the turns ratio..
Hi , how do i calculatte the number of turns on that pignose choke? I have an old Marconi Step attuator that has 75 ohm input and output which i would like to convert to 50ohms
Thanks in advance
depends on core and wire size and frequency. you need a 1.5:1 turn ratio. I don't know the details, but maybe this helps: www.minicircuits.com/app/AN20-002.pdf
since you are attenuating, use a resistive match
i.stack.imgur.com/8lpQa.jpg
@@IMSAIGuy thank you for the reply.
I need a schematic. I need to build or purchase one like this for 300 ohm antenna to a 50 receiver. Got a link?
just use one of these, it will be close enough: a.co/d/gEXsYQx
NOOOO!
You misplaced the lid of the apparatus, when mounting it again, ... !
50-Ohm (print) will now the 75-Ohm side - please swap the lid again.
Please take care!
Looking at the time-stamp 5:28 in the Video, you can see, the SMA-connector is marked with 75-Ohm now, and vis versa, ... ! An SMA is 50-Ohm and the 'F-connector' should be 75- Ohm.
73 de Markus - db9pz - (JN39fq) -
Germany - nr LX - 3miles/5km east of the border to LX!
Next big City in DL is Trier.
_________________________ cut __________________________
P.S.: At 10:40 I can See that you chanced the lid again, ... !
Also during the messurement? - Could'nt see it, ... -
Sorry to make such a 'noise' here, but your videos are always very interesting and I learned a lot from them, ... !
You're very right! Hopefully he will see the mistake and fix the cover. SMA should be 75 Ohm side, yes.
10:41
How about doing a slightly better 75 ohm load hack, then looking at return loss as you look into the 50 ohm side? Wouldn't that give you a easier-to-read idea of the frequency range?
What's the combined loss across that?
From the 75 on to 50 ohm and then 50 ohm to 75
Just curious, I didn't see if you'd explain that part. Would have been good to know
Should be tiny, less than one of resistive pads. Ideally zero, but nothing is ideal.
Does it have a certain DB loss like 3DB or 1DB or something?
When designing a circuit of and electric device of radio circuit etc, what determines what impedance is say 50 ohms, or 75 ohms or any other impedance? I know different antennas/test equipment have equipment different antennas and have different impedances but it seems like most outputs are 50 ohms. Why is 50 ohms seem to be the most common??
I always wondered why they chose 50ohms for 2way radios. Also the change from 300ohms for over the air tv, then to 75ohms for catv
I have read one story explaining the 50 Ohms standard originating from coaxial cables. A study was made for coaxial cables with different diameters and other dimensions. The variant with the best relation between signal loss, power handling and material (I.e. expensive copper) turned out to have 50 or 52 Ohms chacteristic impedance.
If you want a detailed (long ~20 min) explanation, see video #340 on Dave Caslers YT channel (ruclips.net/video/I-OnQZJv35I/видео.html)
@@kd4nc Hey thanks, I will do that and expand my knowledge base. Always great RUclipss!
W0QE does an impressive demonstration of broadbanding these transformers with extra components: ruclips.net/video/WHBUfcOWoxc/видео.html
Interesting.