[R-390] Antenna balun

[Jim Haynes]

On Wed, 20 Jul 2011, Tisha Hayes wrote:

> Finding the coax and connectors is pretty easy. It is the same stuff that
> was used on IBM ThickNet connections in the bad 'ol mainframe days. Looking
> for it as a radio supply will not yield any results or will show folks who
> know that it can be used for the R-390/A and they charge an arm and a leg
> for it. Surplus IT places will practically beg you to take it away.
>
And, one time in a surplus store, I found some things that had a twinax
connector for the IBM network on one side, and a modular jack on the other
side, and some kind of transformer in the middle.  I never measure the
characteristics, but someone said the transformer is good for the
HF range, and thus the thing makes a good balun for an R-390A.