Automatic Level Control (ALC): Why? (
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- Опубликовано: 15 июл 2024
- Ed, K6SDW, asks about ALC in his HF rig. In this video I answer his question, and, as usual, go way beyond. Enjoy and Subscribe!
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Finally, a description of ALC that I can actually understand! All hail Master Casler!
This is about as clear, concise, and useful an explanation of ALC as I have seen. Well done.
73!
Thanks Dave, absolutely the best explanation I've ever read/viewed on ALC behavior and what it does ~73/ k6sdw
Thank you so much Dave!
You seem to grab those great topics and nail 'em down! This channel is such a resource for hams!
73 de N2NLQ
:) Thanks for the information, I bought an IC 7300 last December prior to passing my Tech & General class exams. Recently I put a 80/10 end fed antenna up in my back yard, the wire is transverse to the roof line of my home, sloping down, and angling through the apple trees in my back yard garden. While not exactly the best arrangement, it seems to work. Now I am actually learning how to use the radio.
I finally understand ALC! Keep up the good contented, because it is helping many people.
Finally a good explanation of Alc. thanks
Great run down Mr. Casler. You are always helpful.
Cheers OM! That was very informative. Thanks a bunch. Understanding what ALC is / does was the number 1 point on my list of things to learn. Keep up the good work! See you at the 2022 Hamvention. 73 from Dayton, OH de KE8RDI
Thank you so much Dave. That is a reference video for all amateurs and what i needed to learn.
Thank you, Dave! I finally have a solid understand of ALC. Applying techniques you outlined to the operation of my IC-705.
Thank you for clear description.
WOW, That was the best explanation I've ever heard. THANKS SO MUCH
Thank you Sir for the time you take to explain these very simple concepts🙋🏻♂️
Thank you Dave a clear explanation of the ALC.
Thanks Dave for the fine presentation on ALC. 73
Super Clear , i was looking for a descripiton of ALC, and hear it is,,, thank you 73's
I always learn something from a Dave video!
Great information. Great job on explaining it.
Nice work on the video.
fantastic video , best alc explanation ive seen , ive watched lots of videos and was still none the wiser ,, alls good now cheers
Thanks Dave for an informative and well presented explanation of how ALC works. Particularly relevant for me as an Icom 7300 user. 73. Steven (G3ZDG)
Wow , you are very knowledgeable. Thank you
Thank you.
Usefull video. Great content as normal.
Thanks!
ALC is also a MAJOR KEY to running in AM mode! Been a ham for just short of 3 years, and learned about this early on! (thanks to Tim - WA1HLR teaching me a little lesson) (O: You DO NOT want ANY ALC defection when in AM. Keep that mic gain in check! Thanks Dave for explaining this to the group.
Dave, it is a tough thing to put yourself out there, and subject to peer review. I did not find anything wrong with any of your presentation. I think you covered the subject thoroughly within a sensible time span. An addition (but NOT a correction) is that a couple of my HF rigs internally have an extra internal factor that affects ALC, current draw from the internal power supply. Some of the OEM but external tuners and self tune amplifiers feed ALC back to the rig during the tune process. 73
I suggest 30-50% of the ALC scale results in " Fall out", of your audio. As long as you remain inside the scale there will be no distortion. I recommend approx. 70-80% of scale as average and no more than 90%...Ever under a sustained " AhhhDo". This will also give you the ability to limit compression to no more than 5 db...which is what is really causing the distorted signal assuming you remain within the ALC scale.
Thank you for this really informative video, Dave. 73 de DL6PT
Thank you, this helped a lot. Wish I could get my fellow HAMS to understand this.
I'd love to see the pendulum clock i always hear in the background. I collect clocks. If I had to guess it's an old "gingerbread" clock. As always thank you for being such a great mentor!
Thanks for this video Dave, I am a fairly new ham and never really understood ALC your method of presentation was great and very helpful. I am subscribed and appreciate your videos. Keep up the good work. 73/KD9HAV
Thanks Dave! No mud here. I basically understood ALC but you really clarified it, loved the diagram. I did have a question does the IC-7300 have the ability to sustain 100 watts on CW? My IC-7300 always runs cool as a 🥒 I will now pay attention to ALC on FT8 I see stations coming in and calling CQ but amazed at how many who responded to me but I can't complete the exchange. Maybe you can do a video on the received db level IE -20db vs -5 and so on and what it means for received signal strength in the QSO's
Thank You!Dave! Especially concerning PSK31. On Yaesu FT817(ND) set Output 4,5Wattand use a wattmeter when using Tigertronics Signalink s c drivelevel, never exceed 4,5Watt else it occupies to much of bandwith and You get to much distorsion. I've done that misstake but was caught and corrected it.
Illuminating Dave! Thanks!
73's de Gunnar sm6oer >>\
I'm not sure about the ALC used for SWR foldback. My understanding is the ALC adjusts the transmit signal based on the transmit power sensing voltage, and applies it to the PA Unit. Where the SWR foldback is being handled by the SWR detection circuit (CM coupler and rect. diodes). This then feeds the main CPU, where the CPU decides on the foldback. As the SWR detection unit is in the tuner board, being fed from the PA Unit. And, the PA Unit is being fed by the ALC correction, means the SWR detection/foldback is happening after the ALC.
Thank you Dave for an excellent explanation of a misunderstood function to many Amateurs. 73 de KE8NQL
You need a DVD series!
Russ KD0EIA
St. Charles solar station
Can use ALC and power meter on transceiver to tune antenna ??? without use SWR meter or analyzer.
Great explanation! KY4BDP LCARA HAMRadio
Question - I have the Icom 7300 as well. With compression off I have set my mic gain so the ALC is in the 30-50% range of the red underscored ALC zone. When I apply minimal compression of 1 or 2 the ALC jumps up to about 50-70% range of the ALC zone. Is this considered acceptable or should I reduce mic gain to get back down to the 30-50% ALC range? I have not had any complaints or apparent issues with audio when I ask for reports. What are your thoughts?
How would you hook up a RM BLA 350 plus amp to a IC 7300 radio?
Thank you David for the excellent job at explaining the ALC concept. I would go a bit further and add a note which you briefly presented in the "final thoughts" slide; given ALC is a non-linear system, it will introduce harmonics on your signal the moment it starts to act. This is not a problem for speech, just like any audio compressor is not when operating at reasonable limits. However, for any digital signal/mode you'll want to see no action at all on the ALC meter. This can be confusing as most manufacturers seem to disregard the digital operation of their transceivers when explaining ALC in their operation manuals. i.e. Xiegu g90 presents the number 100 when no ALC and the number will go down the more ALC performed. Also, most of the old transceivers didn't have digital modes in mind (for obvious reasons) when detailing ALC operation and as such will tell nothing about having no ALC action when transmitting digital signals. cheers de CS7AUS
No ALC is not necessarily true. It varies by rig. Set your rig for 50W and do a Tune with full power on the slider from WSJTX or JTDX. You should be able to get 40W without any ALC. That will be your "zero dB" ALC level. Some rigs...like the Elecraft K4 needs 4 bars of ALC -- that's it's 0dB point. Some other rigs will show a bit of ALC at the 40W-out-of-50W level because their meter shows more the ALC range.
@@mdblack98 While it does vary with different rigs, the fundamental concept remains the same. Automatic Level Control, if happening is in itself a non-linear process. While different thresholds might exist in many equipment, if it's happening, then level compression in being performed. Since this is a continuous wave signal the transmitter should be able to reach is maximum output level without ALC action. As an example, "Set your rig for 50W and do a Tune with full power on the slider from WSJTX or JTDX." - I can get any of my rigs putting out the full 100W in FT8 without any ALC action. Nevertheless, and I've stated that before, my concerns on this subject have to do exactly with "it varies by rig": It shouldn't. The way in which a devolper or manufacturer decides to indicate ALC action of the rig should be clear on it's operation. You either have ALC action or you don't. Indicating one or two segments on an LCD with no signal past the threshold point makes no sense in my opininon.
How does this differ from (or relate to) AGC, which seems to have settings of fast, medium and slow? Thanks for all the knowledge you share Dave. Matt, KG8TRS
AGC (automatic gain control) is a receiver function, there are times for example when a crack or pop of a thermostat will cause the AGC to react if set too fast, or the noise might rise in between words or CW characters. Not every setting is ideal for all conditions, the speed of the AGC is a user preference. Hope this helps.
Excellent explanation as per usual. Thanks Dave
De 2e0ggj
Do you have anything on ALC with amps?
Question: When you (and the manual) say, that in SSB mode the mic gain should be adjusted to keep the ALC reading wiithin 30-50% of the "ALC scale", which of the two "ALC scales" is meant? Is it 30-50% of the RED MARKED PART, or is it 30-50% of the FULL SCALE (which would then just mean "keep the ALC inside the red marked part", since the read marked part is half of the full scale)? Thank you very much for all of your fantastic videos!
The most important, stay in the blue part of the scale. 😉
Dave, I have found by experimentation that my amp seems to respond linearly (tested by slowly and carefully incrementing up the power). That power is up to 50W. If I just go in and manually set the power like this, do I need ALC? Also, is ALC universal across all amps/radios despite my amp being vintage and my radio state of the art. 73 de Chris KQ6UP
I don't get it
I am against ALC. If you have variable AF attenuation and a scope, why would you need it? I disable ALC all of the time on all of my HF rigs.
Thinking of the Icom 706-xx and other old rigs where new finals simply do not exist, it would then be a good idea to make Real Damn Sure the ALC was engaged unless you really were keeping an eye on the SWR, no?
There are plenty of transistors that would fit that space. They may have a impedance difference, and require the matching network to be adjusted, but it is doable. Also, I don't belive ALC and SWR foldback to be the same, and know for sure on the 7300, they exist in 2 different boards.
Excellent presentation. Thanks. KE6MIL
nice presentation...makes my new 7300...seem more powerful.
K7AER
Great explanation and very helpful. =73/kb7hfs
4:42 "...on CW....fed a tone..." Transmit CW is now produced with a 700 Hz audio tone transmitted as if it were SSB voice? Really? When did that happen? Decades ago, transmit CW was produced as pure RF, without any transmit audio stages at all. The RF carrier was created (often at IF and mixed and filtered to the desired frequency) and transmitted. Never existed as audio at any point in the transmitter. You sure about the audio origin of modern CW?
Thank you. There is an ALC mod for this Radio on youtube, but seems to produce spurious harmonics from the radios that I have seen on my waterfall. Is their wattmeter just reading higher because of the harmonics? KC9SQQ.