-----Original Message From: [EMAIL PROTECTED] ----------- I've wanted to eliminate this for some time since there a lot of cw activity between 28025 and 28025. My KPA100 is installed on the K2. The birdie produces about 1 s unit bar with the pre-amp on. Based on Sverre comments, how do I eliminate the birdie? Is it merely the freq of the 18 MHz oscillator. --------------------------------------------------------------
One solution is to shift the 18432 oscillator on the KPA100 to a frequency above the 10m band. The oscillator is only used in a DC-DC converter for producing a voltage for biasing the T/R-switch diodes and the RS232 interface, so the frequency is not critical at all. The only limitation is that the 2N3904 - FT37-61 oscillator may get into trouble as frequency increases. I have a half-built KPA100 so I cannot yet listen for birdies, but I made some tests with two crystals from my junk box: 1. 38.45 MHz: oscillates, but only produces 42 Volts instead of 130 Volts bias voltage 2. 40.00 MHz: oscillates at 1/3 frequency. So it seems as if the oscillator circuit oscillates with less efficiency, perhaps a transistor with a higher fT is required? 73 Sverre LA3ZA http://www.qsl.net/la3za/ _______________________________________________ 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
