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" <[email protected]> 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" <[email protected]>; <[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: [email protected] > 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: [email protected] 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
