K2: added KNB2, now mostly deaf.

[Peter Wollan]

Well.  I put in the noise blanker, and it was recognized, but receive  
was mostly deaf.  I checked the caps suggested in the manual, pulled  
the toroids and re-tinned them, and reheated all the solder joints  
with no improvement.  So I pulled the noise blanker, and tacked back  
in the resistors and W5 -- and it's still deaf.  Mostly deaf -- I can  
hear stations on 40, particularly with the pre-amp on, and one or two  
on 80 and 30.  It seems to be completely deaf on the higher bands,  
though that could be the weather.

The resistors R88, 89, 90 are just tacked in.  Could a bad connection  
there produce this?  Could it be a component somewhere nearby, maybe  
damaged while changing resistors?  Could I have knocked it out of  
alignment somehow?  I'm thinking that I should re-align next;  are  
there things I should check before doing that?

And is there a way to test the noise blanker without pulling the  
resistors and starting this all over again?  Tapping Q21 with a  
screwdriver didn't produce any audible noise (and still doesn't, with  
the NB out).

Lots of questions -- I'm sure grateful for the people on this list,  
who are so incredibly helpful.

K2 #5578, QRP, with SSB and tuner.

        Peter N8MHD
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[Don Wilhelm-4]

Peter,

It will be quite difficult to align the K2 if you cannot hear signals.  
Besides, there is nothing much that could have changed the alignment
just by installing the KNB2.

It is possible that you damaged one or more of the thru-plated holes or
a nearby PC board trace when removing R88, R98 and R90.  To check for
that possibility, temporarily solder a wire on the bottom of the RF
Board between J9 pin 1 and J12 pin 1.  If receive is restored with that
jumper in place, you will have to look for the damaged thru-hole or PC
board trace.

73,
Don W3FPR

Peter Wollan wrote:

> Well.  I put in the noise blanker, and it was recognized, but receive
> was mostly deaf.  I checked the caps suggested in the manual, pulled
> the toroids and re-tinned them, and reheated all the solder joints
> with no improvement.  So I pulled the noise blanker, and tacked back
> in the resistors and W5 -- and it's still deaf.  Mostly deaf -- I can
> hear stations on 40, particularly with the pre-amp on, and one or two
> on 80 and 30.  It seems to be completely deaf on the higher bands,
> though that could be the weather.
>
> The resistors R88, 89, 90 are just tacked in.  Could a bad connection
> there produce this?  Could it be a component somewhere nearby, maybe
> damaged while changing resistors?  Could I have knocked it out of
> alignment somehow?  I'm thinking that I should re-align next;  are
> there things I should check before doing that?
>
> And is there a way to test the noise blanker without pulling the
> resistors and starting this all over again?  Tapping Q21 with a
> screwdriver didn't produce any audible noise (and still doesn't, with
> the NB out).
>
> Lots of questions -- I'm sure grateful for the people on this list,
> who are so incredibly helpful.
>
> K2 #5578, QRP, with SSB and tuner.
>
>

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