Thanks for the corrections Arne!
Bill
On 160-40M the number of turns for both the coax and the wire should be 5
NOT 7. The nominal dia is about 6.5 inches. George used #10 or #12 wire
NOT #16 in his article in news letter I have. This is from a NCDXC news
letter article published after the February/March 1980 articles in Ham Radio
magazine.
The version for 10-20M uses 2.5 turns each (wire and coax). Use these and
they work. Be sure to seal well all open ends and around where insulation
was removed (I used RTV and electrical tape and more RTV). Wrapped entire
loop with electrical tape.
73 de Arne N7KA
----- Original Message -----
From: "Bill Tippett" <btippett@alum.mit.edu>
To: <topband@contesting.com>
Sent: Tuesday, December 23, 2003 6:50 PM
Subject: Re: Topband: 160 Meter BALUNS
> Here's a simple balun that works well on 80/160
> which requires only 100 inches of RG-8X coax. I used it
> for many years in Colorado running 1.5 kW to a trapped
> dipole for 80/160 with no problems. The original design
> came from a Ham Radio series but I don't have the
> exact reference. I recall the designer had made
> measurements using an HP Network Analyzer and
> the balance performance was excellent on 80/160
> compared to commercial baluns.
>
> 1. Carefully remove a small ring of the coax cover at
> ~100" from the end.
>
> 2. Solder ~100" of wire around the braid at this point.
> I recall I used #16 insulated wire.
>
> 3. Loosely wind 7 turns of the coax in one direction
> (about a 6 or 7" diameter coil) and loosely wind 7
> turns of the wire in the OPPOSITE direction.
>
> 4. Solder the wire to the inner conductor at the end
> of the coax (after separating 2-3" of braid as a pigtail).
>
> 5. Waterproof the coax ends and the area where the
> wire was attached.
>
> 6. Secure the loosely bundled coil of coax and wire
> with tape or tie-wraps.
>
> 7. Attach the coax shield to one side of the antenna
> and the center conductor (including attached wire)
> to the other side.
>
> Instead of using 50' of coax, this uses only
> a bit over 8' and works well. Maybe someone has
> the exact Ham Radio reference but I'm fairly certain
> my memory of the construction is correct. If I made
> a mistake, hopefully someone will correct it.
>
> 73 & Merry Christmas!
>
> Bill W4ZV
>
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