Hi Don Thank you for your reply. I visually checked the components in the preamp circuit & reflowed the solder of them all including the relay, T6 & Q21, but still got the same results as before. The coil T6 wires have been put in the correct holes but I can't check the wires were tinned correctly without removing it but I think they were.
However, I did a dc voltage check on the transistor Q21 & found some anomalies- the E,B & C should be 1.6vdc, 2.3vdc & 13.3vdc but with the PreAmp OFF they are E 0.00vdc, B 0.00vdc & C 13.36vdc. With the PreAmp switched on, they are E 0.00vdc, B 0.33vdc & C 13.17vdc. (For completeness I checked them with the Attenuator switched on & they were the same as with the PreAmp switched off.) Does it look to you as though the transistor Q21, a 2N5109 is faulty? Regards Ray -----Original Message----- From: Don Wilhelm [mailto:[email protected]] Sent: 24 December 2012 21:38 To: Ray Spreadbury Cc: [email protected] Subject: Re: [Elecraft] K2 #7340 PreAmp Problem Ray, Check every component in the Pre-Amp circuit, including the relay. Do you have the leads of T6 well stripped and tinned? If so, check to see that the leads are in the correct holes. After that look critically at the solder pads for those components around the preamp circuit - look at the schematic sheet 2 to identify those components. You should see the solder flow out to an almost invisible edge on both the solder pad and the component lead. It has been said that the esolder connection should look like a mountain, but not a volcano - if there is a ring around the lead or you do not have concave solder fillets, not enough heat was applied to the connection. 73, Don W3FPR > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
