I have a number of birdies on 6 and other bands and they sure are annoying. What's the best way to eliminate them? I am not using an external pre-amp.
Allen N5XZ ORIGNAL MESSAGE: Message: 20 Date: Sun, 03 Jul 2011 15:32:21 -0700 From: Jim Brown <[email protected]> Subject: [Elecraft] Zipper Noise and Birdies on 6M -- FIXED! To: Reflector Elecraft <[email protected]> Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Ever since I started using my K3 on 6M I've been troubled with zipper noise as I tune, as well as birdies generated within the K3 that move around as I tune. Today I found and eliminated the coupling mechanism, and the noise and birdies are gone. My setup uses an external ARR 6M preamp at the RXOUT / RXIN patch point. (I use it rather than the Elecraft preamp because I already owned it, and it's a very good preamp). I also have a switch that brings in my Beverages, with a Tee jumper between the AUX input (for the SUB RX) and the RXIN. That Tee was the coupling path. On a hunch, I replaced the Tee with a Mini-Circuits passive splitter that has about 35dB of isolation between outputs, with an insertion loss of 6.6 dB. It's rated for use between 10 MHz and 1 GHz, but it passes my Beverages on 160M just fine. Mini-Circuits is an old line, well respected company based in Brooklyn. I've been specifying their splitters for about 30 years for the VHF and UHF wireless mic systems I designed for performance facilities and churches. The splitter I used with the K3 is a ZFSC-4-175 that is one of several I picked up at a hamfest. While it's a 75 ohm splitter, it works just fine in this application. It's a 4x1 splitter, and a 2x1 would work equally well. For optimum isolation, unused outputs should be terminated in 75 ohms, and I did that. http://www.minicircuits.com/pdfs/ZFSC-4-175.pdf http://www.minicircuits.com/pdfs/ZFSC-2-1+.pdf El cheapo CATV splitters MAY also work -- IF they have enough isolation. 73, Jim Brown K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
