K2 ALC problem on 40m

Hi all,

i would like to decribe a problem I am faced with my K2. Every evening I
reconized a AGC problem on 40m band. My signal meter shows S8 to S9 and
it sounds like RF-Gain is turned counter clockwise. If i use ATT to
reduce the signal level it does not help. The signals will drop down but
it still sounds like AGC is to high.

I assume it is related to the big signals from broadcast band here in
europe.

However, further I am not sure if my ALC is working correct. I
recoginized following :

If I disconnect my antenna from K2 and turn AGC ON/OFF I hear a
recognizable difference. I tried to adjust R1 to get the same level. In
my case I got the same level if R1 is set to the minimum value. If I do
so it looks like the RF- Gain pot has no effect anymore. I assume this
is not the intention.

I turned it back to the recommended value to get 3.8 volts now.

Any comments where I can investigate are welcome.



73 de Joerg (DL3QQ)




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[Don Wilhelm-3]

Jeorg,

Yes, I would first look carefully at the AGC section for unsoldered
components and incorrectly placed components.  Let the schematic be your
guide in identifying the components involved.

The BC signals can take over the receiver IF and cause strange results.  I
recommend that you check the AGC action on a band other than 40 meters - if
it is OK on other bands, then you should look at changing the 40 meter
bandpass filter to provide a more narrow response on 40 meters.  There is a
'European' mod to the 40 meter bandpass that may help you - it is an
application note at the Elecraft website, look for it at
http://www.elecraft.com/Apps/eu_40_meter_narrow_bandpass_filt.htm

73,
Don W3FPR

> -----Original Message-----
>
> i would like to decribe a problem I am faced with my K2. Every evening I
> reconized a AGC problem on 40m band. My signal meter shows S8 to S9 and
> it sounds like RF-Gain is turned counter clockwise. If i use ATT to
> reduce the signal level it does not help. The signals will drop down but
> it still sounds like AGC is to high.
>
> I assume it is related to the big signals from broadcast band here in
> europe.
>
> However, further I am not sure if my ALC is working correct. I
> recoginized following :
>
> If I disconnect my antenna from K2 and turn AGC ON/OFF I hear a
> recognizable difference. I tried to adjust R1 to get the same level. In
> my case I got the same level if R1 is set to the minimum value. If I do
> so it looks like the RF- Gain pot has no effect anymore. I assume this
> is not the intention.
>
> I turned it back to the recommended value to get 3.8 volts now.
>
> Any comments where I can investigate are welcome.
>
>
>
> 73 de Joerg (DL3QQ)
>
>

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