Hello Michael, Because the QRN here is very low, I use the preamp most of the time on 40m when "DXing", birdies are important to me, and for some time I have been on a Birdy Hunt.
If all the oscillators in K2 are working well and on their correct frequencies, it is not possible to move a birdy (in frequency) because the IF of the K2's receiver is fixed at say 4915kHz. Although there are others, the three major causes of a a birdy are when one or several of the oscillators, fundamentals and / or harmonics combine to produce a signal at 1) The receiver's tuned frequency 2) At a spurious response frequency of the receiver (the so-called image is only one of these, there are many more) and 3) At the IF. I shall not complicate things by bringing in the isolation between mixer ports or re-mixing. In cases 2 and 3, IF the birdy signal gets in near the antenna connection, then the selectivity of the RF tuned circuits usually, but not always, helps to make the birdy weaker. IF the birdy gets in after the tuned circuits, say near the mixer input, then in most cases the tuned circuits will not help to make the birdy weaker. And I have found that many birdies ARE getting in after the tuned circuits, in the area of relays K16 and K17 on the RF board. Some of these birdies are created by a combination of three oscillators (or their harmonics) falling on a spurious response. So life is hard! Although I had started to "re-engineer" this area, I cannot give you any cures at this time because of an accident and I am walking like a donkey on four legs ! And the job will be difficult. And to be sure, when that is fixed another problem will appear. It interests me that apart from Grobmutter at 14.363, I can only just hear your other birdies but have others. I have suspected for some time that the mechanical construction of K2 might be playing in the birdy game. My apology for a long story, but I would suggest that you avoid your birdies for now. 73, Geoff. GM4ESD ----- Original Message ----- From: "Michael van Hauten" <[EMAIL PROTECTED]> To: <elecraft@mailman.qth.net> Sent: Sunday, February 27, 2005 7:53 PM Subject: [Elecraft] Birdies on 20m > Hello all, > my new k2 (4691)is ready and i had some qso,s with it. I have some > birdies on the 20m-band, at 14030, 14151, 14211, 14272 and a very strong > with s6 at 14363 . > What is to do, to avoid them or to bring them in a range " out of band"? > Thanks for your ideas! > > Michael, DC0ZO _______________________________________________ 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
