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Hi all,

As I stated before, I bought a BitX40 at a hamfest a number of months ago, built by an unknown ham. I had to figure out what all the controls are and how they worked since none were labeled at all.

On the front of the radio is a toggle switch which seems to do nothing at all. Opening up the radio, I find that it is attached via three wires to a smaller PC board located under the main pc board. The board has a LM324AN op amp chip, 5 trim pots, and a bright blue LED which lights up when I power up the radio. It stays on no matter which position the switch is in.

I've attached a photo of the board and wonder if anyone recognizes it. the toggle switch is connected to the 3 wire connector plug in the foreground, and the other connections go elsewhere but I haven't yet traced them down. I'm just really curious as to what this board is or does, since as I've said flipping the toggle switch doesn't seem to do anything. However, it must have been important enough for the original builder to put the switch on the front panel.

--
Tom Sevart N2UHC


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On 4/14/2025 20:08, Evan Hand via groups.io wrote:

Hello Tom.
That is an AmateurRadioKits.in AGC board. ?The switch is used to select fast or slow AGC.
Look on the web for the manual that explains how to hook it up. ?There is minimal documentation other than that manual. ?I assume there is a S- Meter connected to it as that is needed to complete setup.
73
Evan
AC9TU

OK, thanks. Yes, there is an S-meter installed in the front panel. I'll give a more careful listen to see if there's an audio difference between the switch positions. So far I can't tell much of a difference. But now that I know what I'm looking for I might be able to determine it.

--
Tom Sevart N2UHC

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On 4/14/2025 21:08, Tom Sevart via groups.io wrote:

OK, thanks.? Yes, there is an S-meter installed in the front panel. I'll give a more careful listen to see if there's an audio difference between the switch positions.? So far I can't tell much of a difference. ?But now that I know what I'm looking for I might be able to determine it.

I don't notice much of a difference in the audio, but when the switch is up, which I'm assuming is the fast position, the meter needle drops faster than it does in the down position. I may remove the switch, jumper the pin in the fast position, and use the spot where the switch is for a CW keyer speed control.

--
Tom Sevart N2UHC

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