[TenTec] Information about chokes needed

[Dr. Gerald N. Johnson]

On Sun, 2009-01-18 at 16:52 -0800, Jeff wrote:
> Hello Folks i realize this is not a TenTec question and i am sorry about that. Although i am a very proud Red dot owner. Any how here is my question. I am preparing as we speak a doublet antenna and my first using ladder line. I want to be able to drain static off the ladder line. I have read many places RF Chokes work for this.
> 
> Being a Home brewer kind guy when i can be a want to wind my own, But i can not find any good info on the project that tells the specific information as to how many winds how how big a form etc etc, I asked this question once on another forum, got a bunch nonsense. So i came here where the real Pro's are. all replies will be most welcomed.
> 
> Oh and i need this for  max 1500 watt power levels. Many thanks Jeff
> 
> 
Winding a RF choke that covers 160 to 10 with all the WARC bands is not
a trivial task. Many of the 50s vintage chokes go series resonant in a
WARC band or two.

The best choke winding information has been in the Editors and
Engineer's Radio Handbook in the high power transmitter section.

I suppose for some bands a ferrite balun set of secondaries might be a
start, but they tend to not like the high voltage of being a half wave
of line from the center fed full wave antenna, then the core saturates
and gets hot and they make harmonics. I've seen a balun on the output of
an unbalanced tuner absorb all the RF, so that unhooking the antenna had
no effect on the tuner's input match.

Some of the metal film power resistors stand up to most everything but a
big hammer and might be the best compromise at static drains, like said,
100K or so. Or if static build up is a problem sometimes, that's when I
unhook and ground the antenna and go do something else.

73,  Jerry, K0CQ