Matthew,
Those symptoms are classic for behavior of an unsoldered or poorly
soldered conection. The connection changes to a poor connection when it
is warmed slightly.
You may be able to narrow it down by tapping on some of the components.
Take a look at the S-meter while receiving a steady signal (WWV may be a
good choice) to see whether there is a change in the S-meter response
when the audio volume decreases. If it does, the problem is in the
early stages of the receiver (IF amplifier and toward the antenna), but
if the S-meter does not drop, the problem is at the product detector or
other stages toward the audio section.
It also could be the AGC itself that is causing the problem. Again, the
S-meter is an indicator - if the S-meter increases when the audio drops,
then the problem is with the AGC.
If you find problems with the AGC or the audio itself, check the control
board, and perhaps even reflow the soldering with an iron temperature of
700 to 750 degrees.
If the problem is with the front end of the receiver (antenna to IF
amplifier), then look carefully at the RF board.
Sorry, but in cases like this, I cannot be more specific until you can
provide more data.
73,
Don W3FPR
Matthew Denson wrote:
Hi All,
Building the K2 was a lot of fun, and now my basic K2 (#6210) is on the air.
I've made contacts with OR and MI from my location here in CA. Been able to
answer CQs on the first try both times. Really lovely.
I do have one thing that is nagging at me. The audio level seems low. When I
first turn on the rig the level seems right. I have to turn the AF Gain down
to be comfortable. But after a few minutes (8-10) the audio level drops all at
once. It is still usable but it can't be right.
I am going to build the crystal oscillator to do some signal tracing, but
wanted to ask if there was a particular place I should look? I have very
little experience with this so use small words. hi hi!
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