RE: K2 #4039 - Distorted transmit audio

[Nicolas Pike]

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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[Stewart Baker]

On Fri, 10 Dec 2004 00:25:23 -0000, nicolas wrote:

> 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?

>> What do you mean by "12v rail modulates" ? Where are you seeing this effect ?
>> Assuming that you are using the same PSU for both K2's, then I would check
>> all the supply rails on the control board 12V, 8A and 5A with a DVM
>> and a scope. It sounds like a power rail rather than an RF problem.
>> Look for any effects on the rails whilst whistling into the mic.
>> Also check around the ALC circuitry.
>> 73
>> Stewart G3RXQ

> Any suggestions, where / what to look for on the control board, or other
> ideas?
> Thanks!!!
> Regards
> Nicolas
> www.m1hog.com
>
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> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.806 / Virus Database: 548 - Release Date: 05/12/2004
>
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