[Elecraft] K3: sub-rx won't work

[W6NEK]

I had the same sub rcvr RF sensitivity issue.  However, my sub receiver 
performance was intermittent.  When the rig was cool (first turned on) the 
sub rcvr had identical sensitivity (and audio output level) as the main 
receiver.  However after an hour of operation the sub rcvr sensitivity 
dropped almost 20db along with a corresponding drop in speaker audio output. 
After removing and installing the sub rcvr 5 times over a span of 3 months, 
I was able to isolate the fault to the transformer located right next to the 
1st LO TMP input.  Close inspection of the transformer leads revealed that 
the lacquer had not been properly removed from the leads.  Using a small tip 
soldering iron I carefully resoldered all the transformer leads.  That fixed 
my problem.  The sub rcvr performance has been flawless now for over 2 
months.  I never brought this to the attention of Elecraft support because 
of the intermittent nature of the failure.  I'm not saying that you have the 
identical problem but you may want to pop the cover off your sub rcvr and 
inspect the coil connections of the transformers and ensure they are 
properly stripped and soldered to their surface mount headers (which are 
adjacent to the LO TMP input).

Good Luck,
Frank - W6NEK

----- Original Message ----- 
From: "W2LE" <w2le at yahoo.com>
To: "DM4iM" <hamradio at vr-web.de>
Cc: "elecraft" <elecraft at mailman.qth.net>
Sent: Monday, April 06, 2009 5:43 AM
Subject: Re: [Elecraft] K3: sub-rx won't work


> That sounds like the problem I had - the leads on T1 on the sub-in
> module were not soldered, some paint had been left on the leads.  I
> cleaned the paint off and resoldered them.
>
> Paul  W2LE
>
>
> DM4iM wrote:
>> Guys, i still could not solve the problem with the sub-rx.
>> Over the weekend i opened the K3 and checked all TMP-cables,
>> they are in their correct places.
>> The pins of the sub-out and the sub-in board are correctly mated with
>> their sockets.
>> The Aux-DSP ist seated correctly etc etc..
>> In short, to me everything looks fine.
>> I carefully read the manual in order not to make any mistakes with the
>> antenna-connections and/or the selections of the antenna inputs.
>>
>> The sub-rx *will not work*.
>>
>> I have :
>>
>> Noise , but no band noise.
>> Faint signals, but this might be a leakage from the main-rx.
>> A 2.8khz & 400hz filter in position FL 2 & 3 , so even if i counted the
>> positions backwards , one of them should work.
>>
>> So, what can i do? Can i swap some connections to pin down the defective
>> board?
>>
>>
>>
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