[AMRadio] Collins Collectors Association First Wednesday AM Night Nov 5th
FIRST WEDNESDAY AM NIGHT !!! Sponsored by the Collins Collectors Association. Cedar Rapids, Iowa (QRZ) - Wednesday Nov 5th on 3880 kcs at 8PM local time marks the start of the latest chapter of First Wednesday AM Night, drawing hundreds of vintage stations from across the country. The event is anchored by a "tall ship" AM station in each time zone, who runs the gathering for an hour, starting at 8PM in each time zone and starting on the East Coast. Stations check-in using Collins and other transmitters with AM capabilities, new and old. The idea is to revel in this nostalgic mode, enjoy giving vintage equipment a "run," and sharing some storytelling about classic vacuum tube homebrew and commercial designs. In months past, anchor stations have included those running the beautiful Collins 300-G, pictured below, as well as those running the amateur KW-1 and other noted models. http://www.amwindow.org/pix/jpg/300g.jpg LISTEN for these anchors and stop by to say hello, won't you? You don't have to be running Collins or vintage gear to be welcomed into the group. 8P-9P East Coast Anchor: Joe N3IBX (Washington Crossing PA) 8P-9P Midwest Anchor: Tony W9JXN (Illinois) 8P-9P Rocky Mountain Anchor: Jim WA0LSB (Colorado) 8P-9P West Coast Anchor: Bill, N6PY (California) comments please to [EMAIL PROTECTED]
RE: [AMRadio] FW: Homebrew receiver
My favorite style was the Collins 75a series I use a 75A4, which is often bashed by the AM folks, but I find it to be about the best receiver I have ever tried. If I find a truly superior receiver to the A4, I'll retire mine and change over to that. The main deficiency of the A4 is the audio. I use an outboard AF amp (an old 50's vintage 10w hi-fi amplifier using a pair of 6V6's in pushpull). I changed the .01 mfd coupling caps in the low level audio stages of the receiver to 0.1. Actually, I just bridged the .1's across the originals, to minimise melted plastic insulation on the wiring in the receiver. I pulled out the original 6AQ5 to save unnecessary drain on the power supply and to reduce heat generation. I also clipped out a couple of 510 pf mica caps that were added in later models to attenuate the high frequency response. From the diode detector to the audio output, the frequncy response is now almost flat from 30~ to about 5000~. On one of my A4's I added an outboard box with additional mechanical filters. The stock 3 selectivities is not enough if you want cw, ssb plus optimum AM under a variety of band condx. Don K4KYV _ Want to check if your PC is virus-infected? Get a FREE computer virus scan online from McAfee. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
RE: [AMRadio] FW: Homebrew receiver
I am not sure how much the RF amp adds to the noise level. A well designed rf amp section can actually reduce noise levels. Noise mostly comes from mixers, and overall tube counts. All mixers add some noise, some designs are much better than others, and the more there are, the more noise you get. I used single conversion, with a quiet mixer setup, and used two tuned circuits of very high Q in the input, along with resonant dipole antennas for 80 and 40 meters, so I don't get any images or other problems, as signals out of band are attenuated very much before making it to the mixer. I think the best mixer designed ever developed used the 7360 or similar beam deflection tube. I'd like other opinions on the subject, if anyone thinks there is anything else that actually surpasses the performance of these tubes in mixer service? Don K4KYV _ See when your friends are online with MSN Messenger 6.0. Download it now FREE! http://msnmessenger-download.com
