If the filter is OK in receive, it will also be good in transmit. The
only things which differ are diodes D4 and D14 on the KSB2 board.
I would look for one of 2 things - RF Feedback and a bad microphone.
To check for RF Feedback, operate the K2 into a dummy load and listen
with a monitor receiver using a wire for an antenna placed near enough
to the dummy load to obtain an S-9 signal in CW.
To check for a bad microphone, the best way is to substitute another mic
of the same kind.
A question - did you change from an Elecraft microphone to something
else? If that 'new' mic is a dynamic type, did you remove the bias
resistor? If the bias resistor is left in and a dynamic mic is used,
the bias voltage will drive the mic diaphram off center causing it to
"sound funny".
73,
Don W3FPR
On 2/1/2019 11:13 AM, mustang65 wrote:
Hi!
I have hade my k2 about 14 years with number 4503 and it been a pleasure to
build and operate it
but now I got problems with distorsion on the TX audio.
It will usully work fine when it been resting over the night but after a
while the distorsion slowly comes.
I t start with the base in the audio are reduced and then the treble are
cracking up. It sounds like you driving a audioamplifier just alittle to
hard.
The problem is the same with thek2/100 or when it removed from the k2.
I have used a 2 tone signalgenerator and loked with a scope att the signal
after the ne602 and after the 10w amplifier
and it looks fine to me but the bandwith of the scope is just 15Mhz so I
might be missing something.
I have replaced u5, Q1, D2and some capacitors on the ksb2 board, tried to
find any bad soldering but no luck.
Can it be a bad capicotor in the ssb filter or in the Tx signal path?
Grateful for any advise.
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