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sunil case

Joe Puma
 

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Use a shielded wire for the Audio into the amp. Even to AGC from amp.?


Joe



On Apr 3, 2019, at 9:41 PM, Sam Tedesco <stedesco619@...> wrote:

Hi everyone... I need a bit more help. I have a v3 board going into a 3.5 sunil enclosure. AGC is calibrating fine. Pegged needle and brought it back to zero. No bounce with audio. Have audio from audio amp "agc v" going to agc audio. Is that correct or does it need to go to volume? For audio to amp, I'm connecting the single relimate wire to c78 (between cap and pin 7 of 2822). Is all of this correct?

thanks,

 

?Most, if not all, of the AGC circuits take their input from the high side of the volume control.
?Some control only audio, some control RF input from antenna.
?And the circuits I like control the gain of the fist IF amp, as well as the RF amp in some instances.
?I plane to use the circuit that control the first IF gain, and add another control to the first IF gain. In my case, it will be a BITX20.
?It also has an ouput for an S Meter, which can be an analog meter.

?Wayne WA2YNE
 

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Yes controlling the gain of the RF stages is a true “Automatic Gain Control” or AGC.? The audio based circuits are better called “Automatic Volume Control” circuits or AVC.?? AGC circuits are far superior because, if designed right, they will prevent ?the radio from over loading along the RF receive path that in turn causes clipping and distortion. ??AVC saves your ears… AGC saves the fidelity of the signal and your ears.

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Wayne Leake
Sent: Thursday, April 4, 2019 12:32 AM
To: [email protected]
Subject: Re: [BITX20] sunil case

?

?Most, if not all, of the AGC circuits take their input from the high side of the volume control.

?Some control only audio, some control RF input from antenna.

?And the circuits I like control the gain of the fist IF amp, as well as the RF amp in some instances.

?I plane to use the circuit that control the first IF gain, and add another control to the first IF gain. In my case, it will be a BITX20.

?It also has an ouput for an S Meter, which can be an analog meter.

?

?Wayne WA2YNE

?


Virus-free.

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…_. _._
 

?I recall, nore or less, the AVC that AM Broadcast radios used to use.
?But maybe it was more AGC.
?They use a dual diode/triode. The triode for first audio amp, one diode? for detector, and the other for the AVC, which, I think, wired into the cathode, or maybe grid circuit(s) of IF amp and? converter, plus RF amp that some radios had. So we didn't get our eears blasted off when going from a weak station to a strong one.
I'll need to take another look at the most common circuits used for the cheap AC/DC radios. Five tubes, with one being the rectifier for the main power.
 

Hi Joe,

I went with your original recommendations and it works great. The issue turned out to be one of the heat sinks was pushed over and intermittently touching a coil and shorting. I got lucky and barely saw a spark cause it was getting dark.
 

Connecting agc audio from the amp board also didn't really cut it. R70 was the ticket. Thanks again!
Joe Puma
 

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That’s great to hear. Glad you got it working. ?There is another issue I read where someone said the H L lines might be crossed at the pot. I noticed this myself when I had the volume down and the meter wasn’t moving that much when connected to R70, or no meter movement at all if I was on the H side. I flipped the H and L going to amp board and it meter was responding the same with volume up or completely off.?

Joe
KD2NFC?



On Apr 4, 2019, at 10:38 AM, Sam Tedesco <stedesco619@...> wrote:

Connecting agc audio from the amp board also didn't really cut it. R70 was the ticket. Thanks again!

 

Yes...mine varies with volume. Need to address that, too. I thought?I read that?H and Sweep that had to be swapped. I'll take a look when I get home. I did find a nice run of 316 coax to use on the audio lines. This project is never going to end!
Joe Puma
 

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Yes try that switch and you’ll see a difference. uBitx is the radio that keeps on giving.....you things to do. ?You gotta love it!

Joe
KD2NFC?


On Apr 4, 2019, at 1:00 PM, Sam Tedesco <stedesco619@...> wrote:

Yes...mine varies with volume. Need to address that, too. I thought?I read that?H and Sweep that had to be swapped. I'll take a look when I get home. I did find a nice run of 316 coax to use on the audio lines. This project is never going to end!

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