Re: Alice Springs, Australia
toggle quoted message Show quoted text
I'm now building the original Hoop Loop. Obviously, it is a very impressive antenna! The parts are on hand. The turntable was from Target and the round, wood clock-mount base was from Michael's. Both were only $5 each. The embroidery hoop was close to $6 from Jo-Ann fabrics (I bought three for $18). As far as the terminal for the loop windings, I'm going with a Radio Shack speaker terminal mounted on the inside bottom of the hoop assembly. However, iIt's a little big for that purpose. Any suggestions as to what would work better? As far as ferrite cores I have one FT-114-J. I suppose I'll wind a 7-turn bifilar primary and 60-turn secondary out of Radio Shack magnet wire as you did, provided Type J is equivalent to the type you used. How did you mount the hoop to the wood base? I believe you used adhesive. Kind and brand name?
I just need to refresh my memory on how to do a bifilar winding. Where exactly on the circuit board did you ground the center primary tap? In my line of work I see CHASSIS_GND separate from GND a lot. CHASSIS_GND is usually associated with plated mounting holes and GND is associated with the bulk of the circuit being zero potential.
That's a lot of questions and I could figure it all out, but thought it may help others as well who potentially want to build the Hoop Loop. Once I get this puppy together I'll place it up on Youtube for the benefit of others.
Sent: Sat, May 1, 2010 5:50:00 AM
Subject: [ultralightdx] Alice Springs, Australia
The Hoop Loop antenna is remotely tuned by an inductor and capacitor. The inductor makes up part of a radio-frequency transformer. With Si4734-based radios, from 150-1710 kHz, the tuning capacitor is inside the radio. Above 1710 kHz, the radio switches to the whip antenna and the capacitor is set at a low, fixed value. The term "medium frequency" applies to signals up to 3000 kHz. There isn't much between 1710 and 3000 kHz that the chip can demodulate, as it lacks a BFO. But there are a few stations of interest. Three in particular caught my attention, as they are 50-kW broadcast stations in Australia's Northern Territory. They're on 2310 (Alice Springs), 2325 (Tennant Creek) and 2485 kHz (Katherine).