I assume this tone is only present during receive.
Do you receive amateur signals when an antenna is attached? ?
How does the volume of this tone compare with the volume of received signals?
Can you describe the tone? ?Is it a steady dc note? ?What frequency?
Can you do things that cause the volume or frequency of this tone to change?
Does it change in volume when you turn down the volume control? ?(If not. problem is in the LM386)
Does it change in frequency as you tune the radio?
Does it change in frequency when you poke your finger around C102 in the BFO?
I suggest you work you way back through the receiver, shorting the signal to ground at each stage with a piece of wire to determine where the tone is coming from. ?Do you still have the tone when you short the top of C107 to ground? ?R37? ? Crystal side of C31? ?Crystal side of C23? ? Mixer side of C21? ?Mixer side of C13? ?Filter side of C11? ?The antenna? ??
I'm pretty sure it's ok to short those particular nodes to ground, but not my responsibility if you destroy something. ?You should look the schematics over hard, make sure you are probing the correct point, and verify that what you are doing won't cause harm.
> ?I was approved to join this group.
That's most reassuring.
Jerry Gaffke, KE7ER
On Sun, Feb 19, 2017 at 11:40 am, <chucke2@...> wrote:
Hi everyone. I was approved to join this group. I have a Bitx-40 XCVR. I have connected all the components to the board. I turn it on and can tune around. The Rx and Tx both work. But there is a tone coming out of the ¡®386. I cannot find the source of this tone. Has anyone come across this problem? I changed spkrs and have an 8 ohm in there now. Would appreciate any insite into this issue.
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