Thanks for your technical information Geoff. I was so comatose that I nearly missed your important mail.
73 Stewart G3RXQ On Sat, 16 Jul 2005 21:26:20 +0200, S55M wrote: > Congrats Geoff! > > After a long time some usefull info between tons of knobs,brocoli ecc... > stuff. > > S55M-Adi > ----- Original Message ----- > From: "Geoffrey Mackenzie-Kennedy" <[EMAIL PROTECTED]> > To: "wayne burdick" <[EMAIL PROTECTED]> > Cc: "Elecraft Discussion List" <elecraft@mailman.qth.net> > Sent: Saturday, July 16, 2005 9:17 PM > Subject: [Elecraft] Re: K2 birdie at 28.265 MHz > > >> Hi Wayne, >> >> Many thanks. Believe me I understand the design problem!! I got rid of my >> birdie the 'hard way' by removing the loudspeaker circuit from the > KPA100's >> PCB and hardwiring all the way from the K2's PCB speaker connector to the >> speaker, and clipping a ferrite sleeve onto the ribbon cable - I am sure >> that you know the type. The receiver's 10m spurious responses in my case >> were the 2Fspur = 3Fo - IF and another 3Fspur = 4Fo + IF further down the >> band, where Fspur = 32.578 MHz, the bias oscillator's second harmonic >> frequency. Both were in the region of 7db above noise floor in a bandwidth >> of 1500 Hz, with a dummy load on the antenna input. I have never detected >> the 5Fspur = 7Fo - IF potential birdie even in a 200 Hz bandwidth. >> >> I did the removal the 'hard way' to kill all birdies that involved the > bias >> oscillator in one shot, as other bands were affected. >> >> Again, many thanks. >> >> 73, >> Geoff >> GM4ESD >> >> >> ----- Original Message ----- >> From: "wayne burdick" <[EMAIL PROTECTED]> >> To: "Geoffrey Mackenzie-Kennedy" <[EMAIL PROTECTED]> >> Cc: "Elecraft Discussion List" <elecraft@mailman.qth.net> <[EMAIL PROTECTED]> >> Sent: Saturday, July 16, 2005 6:21 PM >> Subject: Re: K2 birdie at 28.265 MHz >> >> >>> The (-) voltage generator (oscillator) in both the KIO2 or KPA100 >>> generates a couple of weak birdies. They will move around a bit from K2 > to >>> K2, because the birdies are the result of high harmonics of this crystal >>> oscillator mixing with high harmonics of the K2's VCO, and the > fundamental >>> crystal frequency has a tolerance of about +/- 0.5 kHz. >>> >>> We attempted to position the birdies in obscure parts of the spectrum. > If >>> the 10-meter birdie happens to hit close to a beacon that you want to >>> monitor (28.265 is in the beacon area of the band), you should be able > to >>> move it a bit by changing one capacitor in the crystal oscillator. In > the >>> KIO2 case, the best choice would be C14. It is normally 56 pF, but >>> paralleling another 10 pF across it should shift the oscillator a kHz or >>> two, enough to move the signal off a CW beacon. The value of C14 isn't >>> critical; it could change +/- 20% without significantly affecting output >>> of the oscillator. >>> >>> 73, >>> Wayne >>> N6KR >>> >> >> _______________________________________________ >> 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 >> > > _______________________________________________ > 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 _______________________________________________ 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
