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" <w...@yahoo.com> To: "DM4iM" <hamra...@vr-web.de> Cc: "elecraft" <elecraft@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? >> >> >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
