3. Rotating VLF Loop (by Bill Farmer)
Bill Farmer, W3CSW in Rockville, Maryland, contacted me concerning my SID receiver antenna. Out of our conversation, Bill developed a really effective attic loop that incorporates a rotator. With Bill's permission, I share his design here.
Among other gear, Bill uses a RYCOM Model 6041 Selective Level Meter as a VLF receiver.
Bill's comments and results below are selected from our correspondence:
"This loop now appears self resonant at about 400 kHz and requires about .55 ufd to tune down to 24 kHz. With no additional capacitance switched in, it's useful up to the top end of the AM broadcast band (around 1700 kHz)."
"Since it's a rather large structure, I had to go to extra measures with the weight suspension and pivot points to give my small synchro motor a fighting chance. So far I get good nulls (~15 dB) off the sides and all DF results appear to correlate nicely."
"My VLF/LF data base has grown to about 4 full pages now. Seems all those narrow band beacons are allocated all over the place. I'm hearing them all the way into Canada and down as far as Florida."
"... I'm hearing the Navy transmitter in Lueluelai, Hawaii. He's weak, but he's in there each morning on 21.4 kHz ... Ironically, since now I can DF, I really don't go to the trouble on most signals I hear, but I sure use the null to get rid of local noise and QRM when two signals are on the same freq."
"Each morning one of my first chores around here lately is to log a few AERO beacons. This morning, much to my surprise I'm hearing GLS on 206.0 kHz from Galveston, TX. I think it's about time I drew an arc on a map that starts in mid Florida, goes thru Galveston and swings around up into Canada. My hearability of these low power beacons is simply amazing."
An article by Bill on this project
An updated diagram on Bill's setup.
You can reach Bill at firstname.lastname@example.org
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