This topic runs and runs with no obvious solution. It should be possible to bread board the affected area of the K2, make measurements, and work out corrective action. It may be easier to analyse the results of any mods by using a received signal than a transmitted one. Here is a post 'that I made earlier'
73 Stewart G3RXQ -------------------------------------------------------------------------------- The problem of a power transformer close to a K2 such as to cause problems on SSB has oft been reported. What I have not seen so far, is, that because it is the PLL that is affected the problem can also be observed on receive. Instead of transmitting a "gungy" signal, asking for reports, moving the PSU or K2 around and repeating the process, I used the following procedure on receive:- I ran SpectroGram with my soundcard connected to the K2 loudspeaker socket. A strong unmodulated carrier (XG1 set to 50uV) was applied to the ANT input. It is necessary to get the smallest frequency resolution (5.4Hz) on SpectroGram so set the Scan Input (F3) to these settings :- Sample Rate 11kHz Resolution 16bits Scale 60dB Freq Scale Linear FFT Size 2048 Average 70 Using either the SSB or CW filters tune in the signal until an audio signal of 800Hz to 1kHz is obtained, and adjust the displayed signal amplitude to around 0dB. The noise floor in the filter is approx -60dB. Any modulation of the K2 PLL will now appear as sidebands to the main signal. They will be spaced at either 50Hz (Europe) or 60Hz. If the problem is intense there may be harmonics. Switch PSU's On/Off to confirm (Not the K2 one !) A small homebrew PSU in a diecast box placed 12in away from my K2 gave sidebands of -40dB. I dread to think what the field from a high power linear amplifier could produce. -------------------------------------------------------------------------------- _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
