When I built my K3 (with the 2nd receiver) well over a year ago I had lots of birdies between on most of the bands, although very few on 80m. With a dummy load on the antenna port, I logged any birdie S2 or greater (I have a really low noise level at this QTH) and then monitored them all (yes, all of them) as I played around with various cable positions. It soon became obvious that eliminating one birdie often strongly accentuated a different one, so I spent a lot of time trying to find a decent middle ground and then did my best to hold the cables in those positions with cable ties and tape. The SIG RMV software fix that came out a few weeks later was a remarkably innovative godsend and totally fixed any remaining issues.
I tried some out-of-the box methods to reduce the birdies before the software fix came out. One was to buy a sheet of anti-static material (carbon impregnated foam), cut it into sections that fit into sandwich baggies, connect a wire to each of them that could be grounded to the case inside the K3, and position them around the various cables. The idea was to create some sort of lossy shielding to reduce the coupling. It actually helped a bit, but it made a large difference where I connected the wires to ground (understandable since the wire now also act as antennas) and the overall improvement wasn't worth the hassle. By the way, the 2nd receiver is FAR better shielded and I could find only a couple of very weak birdies on it, while I had thirty or more S2 or above (roughly half of which were S3 and about four at S4) on the main receiver. Since I assembled everything before checking for birdies I never did a comparison of main receiver birdies with and without the 2nd receiver installed, but based upon my experience with various cable placements it is my strong belief that having the 2nd receiver installed makes the birdies worse in the main receiver, presumably because the shield of the 2nd receiver creates more coupling between the cables behind the front panel. I still have a couple of birdies on certain frequencies that I never use and haven't bothered with, and as might be expected they are STRONGLY microphonic. Tapping on the case while listening to them can be almost startling. It always made me wonder what the transmitted signal would sound like on the birdie frequencies if the rig was "physically modulated" by other gear on the desk, or even through the air, but I haven't walked myself through the frequency chain to see if it would even be relevant. 73, Dave AB7E On 4/20/2010 8:26 AM, Guy Olinger K2AV wrote: > Routing the cables when adding the second RX was very tricky and > caused birdies to appear and disappear while being moved around. > Though it is an added cost, a premade wiring harness to enforce a > tested good routing would be useful. > > Or perhaps if there was an actual size template of a wiring harness to > be assembled as part of the kit, with some pre-printed stickers to put > on the cables. > > Precise routing is fairly left to chance as currently implemented. > > I also hear far less birdies (next to none relatively) tuning across > the band in CW, vs. SSB. > > To be fair, most birdies are buried in a busy band without effect, and > require a dead band to hear them. In mine there were three that were > obnoxious enough to bother killing them with the menu device. I do > NOT experience related audio gaps as reported by some others. I DO > get gaps if I overcorrect. > > 73, Guy. ______________________________________________________________ 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
