RE: K2 #4039 - Distorted transmit audio

[Nicolas Pike]

Hi,

The distorted audio moves with the Control board, so either K2 can enjoy
distorted transmit audio, if it has the faulty board fitted!

Just to clarify point 3. The 12v rail seemed to modulate on both K2's
when using either the faulty ** OR ** the working Control board!
As this effect is the same for both K2's with either Control board. This
would seem to indicate it is some other measurement (etc) effect, that
we are seeing?

Thanks again!!!

Regards Nicolas


Original posting.

Hi,

Following reports of poor transmitted audio, and aided by a fellow K2
owner we set about a little investigation.

What happens..

Raspy, clipping?, (distorted by RF?), almost Dalek (For UK readers!!),
sounding transmit audio.

We checked the various board, joints etc, swapped things with the known
working K2 and established..

1. The issue is with the control board, when swapped, it gives the same
fault in either K2.

2. No obvious component problems.

3. Another interesting observation on both K2's, was how the 12v rail
modulates when you transmit?

Any suggestions, where / what to look for on the control board, or other
ideas?

Thanks!!!

Regards
Nicolas
www.m1hog.com

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[Don Wilhelm-3]

Nicolas,

I would expect a bit of 'modulation' on the 12 volt line due to the
resistance in the power supply leads and the connectors.  If you find yours
excessive, check all connections for the power leads and consider using a
larger gauge wire (or use a better regulated power supply if the modulation
is seen at the power supply terminals too.)

I would suggest checking the 5 volt and 8 volt for any trace of
'modulation' too - a faulty regulator could cause your problem - Q1 (which
drives the 8T line) could be another potential offender.

U10A and Q8 and their associated components in the ALC area are other
possible problem sources.

73,
Don W3FPR


----- Original Message -----

>
> The distorted audio moves with the Control board, so either K2 can enjoy
> distorted transmit audio, if it has the faulty board fitted!
>
> Just to clarify point 3. The 12v rail seemed to modulate on both K2's
> when using either the faulty ** OR ** the working Control board!
> As this effect is the same for both K2's with either Control board. This
> would seem to indicate it is some other measurement (etc) effect, that
> we are seeing?
>

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