Preamp, Attenuator on K2 #4901

[Jim K4ZMV]

Hello, All.

I just finished K2 #4901 and it works great.  The only thing I have a question on is the preamp setting.  When the annunciator is on over the preamp, it seems as though background noise goes down and the signal strength is reduced.  In fact, there seems to be little difference between the preamp and att settings.  I've been through the schematic and carefully reviewed the parts installed for the preamp and I can't see anything wrong.  Has anyone experienced this problem, if it is one?

73 and thanks.

Jim, K4ZMV
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[Don Wilhelm-3]

Jim,

Other than a faulty solder connection or an incorrect resistor value (R74,
R75, R76, R77), I can think of only 2 things that might cause the PreAmp to
not work - T6 could be connected incorrectly or the windings shorted
together, or C146 may be faulty.  Try tacking a 0.01 uF capacitor across R77
(bottom of the board) as a check for an open C146 and if that doesn't fix
things, try rewinding T6.

73,
Don W3FPR

> -----Original Message-----
>
> I just finished K2 #4901 and it works great.  The only thing I
> have a question on is the preamp setting.  When the annunciator
> is on over the preamp, it seems as though background noise goes
> down and the signal strength is reduced.  In fact, there seems to
> be little difference between the preamp and att settings.  I've
> been through the schematic and carefully reviewed the parts
> installed for the preamp and I can't see anything wrong.  Has
> anyone experienced this problem, if it is one?
>
> 73 and thanks.
>
> Jim, K4ZMV
>

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[Margaret Leber]

W3FPR - Don Wilhelm wrote:

> Other than a faulty solder connection or an incorrect resistor value
> (R74, R75, R76, R77), I can think of only 2 things that might cause
> the PreAmp to not work - T6 could be connected incorrectly or the
> windings shorted together, or C146 may be faulty.  Try tacking a 0.01
> uF capacitor across R77 (bottom of the board) as a check for an open
> C146 and if that doesn't fix things, try rewinding T6.

>> -----Original Message----- I just finished K2 #4901 and it works
>> great.  The only thing I have a question on is the preamp setting.
>> When the annunciator is on over the preamp, it seems as though
>> background noise goes down and the signal strength is reduced.

Jim--

Definately what Don said. I was in exactly the same situation as you:

> Margaret Leber wrote:
> After reworking a couple of suspect joints in the preamp section and
> removing and reinstalling T6, the preamp in K2 1641 is now working.

73 de Maggie K3XS
Editor, Phil-Mont Mobile Radio Club Blurb - http://www.phil-mont.org
Elecraft K2 #1641


--
-----/___.   _)Margaret Stephanie Leber CCP, SCJP/"The art of progress /
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--/ ) /  |/  |_(_(_(_/_(_/__(__(/_      K3XS / preserve change amid/
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