My friend Norris, VE3FBQ, is putting up a new F12 C3S beam. Per the instruction book, he wants to use an 8-turn choke coil wound from the coax feedline. The question is... how should he orient the co
Wind the coil on a piece of 4" PVC pipe. Make the pipe a few inches longer than the coil. Use a U-bolt to hold the PVC pipe to the boom. This may not work so well in big-wind areas. The area of the P
I may be wrong, but I thought the coils need to be at least 8" in diameter to work. Isn't winding RG8 in a 4" circle kinda stressing it a bit? 73 Tom W7WHY List Sponsored by AN Wireless: AN Wireless
Tom, Bill: I've got a Mosley Classic 33 WARC and they recommend an 8 inch diameter coil of RG8 for that antenna, 10 inch if you use the 40m kit on the ends of the driven element. Tom, WW5L List Spons
Ed Gilbert's famous posting about coiled coax baluns mentions using a 4" form. It should not be a problem so long as a solid dielectric coax is used. Foam dielectric coax might suffer from some cente
How many turns? One problem with a coaxial balun is you don't want too many turns. You have to have enough turns to give sufficient inductive reactance at the lowest frequency, but too many turns act
An easy method of mounting these choke baluns wound around (or inside) a PVC form is to suspend a 2" (or whatever needed to fit over the boom) piece of PVC inside the larger form, then slip it over t
How do you keep the boom from being a shorted turn, and reducing inductance of the balun to nearly zero? Any time a conductive slug or ring is placed inside a coil, the counter magnetic forces from
That is a good question Tom. It would be interesting to know what effect running an aluminum tube through the middle of one of these baluns is. I know that aluminum does little or nothing to block el
Aluminum is a very effective shield if it is thicker than a few skin depths. Anyway, easy enough to measure something I already have laying around. I just measured what I used as an 80-meter 4" air
As I recall 8 turns. Tom, WW5L List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems, Trylon Titan towers, coax, hardline and more. Also check out our self supporting towers up to 100
Sri: I was relying on my memory rather than the instructions. 5 turns on a 6 inch diameter at the connection of the feedpoint to the driven element is what's listed on page 7 of the Classic 33 WARC m
Hi Tom, et al. I have my computer monitor setting just above my amplifier, and when I turn the amp on, I can see the 60 cycle vibrations on the screen. Somehow the power transformer is interfering wi
Skin depth is pretty thick in most materials at 60 Hz, that why effective shields on low frequencies are generally ferrous materials, to divert the magnetic flux. The amp probably was not designed t
Tom: Are you sure that the interference is going throught the air? Could it be going through the power cords? Chris opr VE7HCB List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems, T
I don't think so because when I move the monitor farther away from the amp, the waves quit even though the power cords are going through the same hole on the back of the desk. Tom W7WHY List Sponsore
Tom, I noticed one day that the base line on my SM220 CRT monitor was not straight but kind of wavey. I had an electric clock sitting on top of it. When I removed the clock, the base line was straigh