Topband: Balun question

[Jim Bennett]

I was just looking through the ARRL Antenna Book - if it's RG-8, then 8 turns would work if wound on an 8 inch PVC tube. However, that size PVC may be difficult to find, and certainly wouldn't be to spiffy hung way up the air. But then again, you were thinking about 10 turns on a 12 inch diameter form...? I assume you were going to place it at the apex of the Inverted Vee, right? An alternative would be to get 5 mix 31 ferrite cores, 2.4 inch OD and pass the coax through it six times. That ought to get about 5,000 ohm impedance at 3.5 MHz and would do the trick. I'm using exactly that on my 80 meter Inverted L and it does a fine job. Mouser has those cores for $6-$7 each.

Jim / W6JHB


On   Thursday, Oct 24, 2013, at  Thursday, 4:25 PM, Gary Smith wrote:

> Though this reflector is for 160M I have an 80M question that might 
> be best asked here. My father W1BML is on an 80 meter net nightly. 
> His antenna in an inv-V with 40 & 80 elements though he never uses 40 
> any more. I needed to fell a couple of trees to remove branches that 
> were touching his copperweld and the W2AU balun he had broke in two 
> during the process. (Don't ask, your imagination is probably correct) 
> :) And he would like it put back the way it was, with a balun. He's 
> 96 so I try to keep him happy.
> 
> I'm thinking 10 or so rolls of coax around 1' in diameter ought to be 
> fine for a choke on 80. Any better suggestions?
> 
> Thanks,
> 
> Gary
> KA1J
> _________________
> Topband Reflector