Ray, That sounds like you have a problem with the 20/17 meter Low Pass filter in the KPA100. Relays K7 or K8, soldering of L7 or L8, or C4 A, B, C, D or E capacitors. Yes, poorly soldered connections can take several years to develop enough oxidation to create a loss of connection.
To check which of the involved components is the culprit, the easy thing to do is to simply re-flow the soldering using a hot (800 degF) soldering iron. If that does not cure the problem, then you would want to check the relays for continuity. Power only the base K2, set to 20 or 17 meters and see if you have continuity between TP2 and the center conductor of the SO-239 jack. If no continuity, check continuity across relays K7 and K8 to see if one of those is the problem. By powering only the base K2, you can select the band and probe the underside of the KPA100 board. The KPA100 relays are not latching types, so you need to have the base K2 powered on. 73, Don W3FPR On 5/16/2012 8:12 AM, Ray Spreadbury wrote: > Hi Elecrafters > > > > The K2 (# 4099) has the 100W amplifier and external tuner. It appears to > behave normally in all modes on all bands except 20M& 17M. > > > > The K2 has lost all receive sensitivity on both the 20M& 17M bands (no > signals can be heard). > > > > In addition, it will not transmit on these two bands and has a very high SWR > into a 50ohm dummy load on these bands. > > > > Bypassing the external tuner does not improve the situation even when > feeding into the dummy load, so I assume the problem is within the K2 rather > than the external tuner. > > > > I am not sure if these symptoms point to a problem(s) in either the > band-pass and low-pass filters? > > > > Any ideas of what I should be checking please? > > > > Cheers > > Ray G3XLG > > ______________________________________________________________ > 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
