[TenTec] OT 75 Ohm twin feeder

[Dr. Gerald N. Johnson]

On Wed, 2008-06-11 at 09:12 -0700, Jim Brown K9YC wrote:
> On Wed, 11 Jun 2008 09:35:20 +0100, Steve Hunt wrote:
> 
> >Grateful for any views.
> 
> I strongly recommend a decent 75 ohm transmitting coax (robust 
> copper braid shield, UV-rated jacket) with a good multi-turn common 
> mode choke wound around toroids. The obvious advantage is greatly 
> reduced receive noise thanks to the choke, and it's widely 
> available. 

In short lengths, so long as the coax wasn't tied to a metal structure,
coax connected between balanced loads might not cause much unbalance
despite the lack of symmetry in the coax. Certainly the common mode
choke would improve the balance seen at the coax terminals. But when
only a couple feet is needed, will the antenna still work when the coax
is twice that long, all coiled up around the toroid(s)?
> 
> I was lucky enough to find 250 ft of Belden 75 ohm KW twinlead New 
> Old Stock at a hamfest about 25 years ago. I used it on a dipole 
> that I also used as a top-loaded vertical for 80 and 160. Nice 
> stuff, but LONG discontinued. 
> 
> 73,
> 
> Jim Brown K9YC
> 
73, Jerry, K0CQ