Hi Dave, My strategy for the pickup loop "sense coil" will be a wire loop of one-turn (possibly two turns like Kevin did) around the crate. For the connecting cable, I plan on using a small length of 300-ohm TV lead-in wire (like this, but smaller (10 feet) http://www.radioshack.com/search/index.jsp?kwCatId=&kw=tv%20lead%20in%20wire &origkw=tv%20lead%20in%20wire&sr=1 ). The pickup loop can be the same kind of wire you used to string around the crate. After winding the pickup loop, strip about an inch of insulation off each end of the pickup loop. Next, take one end of the TV lead-in wire and strip it back about an inch exposing both wires. Connect both sides of the pickup loop to the each of the 2 wires on the end of the TV lead-in wire, one for one. Soldering these together is a good idea. Then strip an inch of insulation off the other side of the TV lead in wire, exposing the two wires on that end. That side will plug into your radio (Drake R8 in my case). One side will plug into the 500-ohm antenna terminal and the other side will plug into the Ground terminal. It's a good idea to tin the ends going into the radio with a little bit of solder, especially since each of the two conductors consists of strands.
What radio do you have? If your radio doesn't have plug-in antenna terminals like mine, you will need to use 50-ohm coaxial cable instead of TV lead-in. The only problem with that is the impedance mismatch, which even occurs with the TV lead-in, but might not be enough to worry about. The tuned loop which is a tank circuit has very high impedance. Matching using a toroidal inductor is possible. Has anyone tried that with success? Hopefully this explanation wasn't too confusing. If you have any more questions, please let me know. 73 and good luck! Chris -----Original Message----- From: HASCALL, DAVID CIV DFAS [mailto:[email protected]] Sent: Friday, January 02, 2009 2:03 PM To: [email protected]; [email protected] Subject: RE: Antenna Projects (Crate Loop) Hi Chris - I had asked about "direct coupling" of the Crate Loop to a receiver's antenna terminals and Kevin graciously replied and mentioned it needing a "sense coil" (as you also noted). He stated that he may have to try that in the future. This seems to be one of the easiest loop plans that I have seen and maybe there is hope for me - a "tech dummy." 73, Dave in Indy ------------------------------ Message: 5 Date: Fri, 2 Jan 2009 13:34:28 -0700 From: "Chris Knight" <[email protected]> Subject: [IRCA] Antenna Projects To: "Mailing list for the International Radio Club of America" <[email protected]> Message-ID: <[email protected]> Content-Type: text/plain; charset="iso-8859-1" The Crate Loop looks like a great project and I'm going to start building one this weekend to use with a Sony ICF-SW7600GR (light, but not ultra-light) and perhaps with the Drake R8 (using a pick-up turn of wire). The only problem here is the computer hash (5 computers at this QTH). The helically-wound vertical posted by Craig Healy may be the answer to the computer noise. The plan is to build a scaled-down version to go next to the computer in the shack as a noise sense antenna and attempt to phase out some of the hash. Thanks guys for the great ideas/designs and for posting them! 73. Chris Knight Fort Lupton, CO _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
