Danny Richardson wrote:
A very narrow range peaked at about 1.58 MHz. (The unit's rated
frequency range is 1-30 MHz.)

I once bought a commercial 4:1 balun wrapped on a
type 2 powdered iron core rated for "all-HF" operation.
The performance sucked. I had the factory measure the
choking impedance and it did indeed suck. Sorry, I don't
remember the exact results but it was designed by Jerry
Sevick, W2FMI, and described on page 34 of "Building
and Using Baluns and Ununs".
--
73, Cecil http://www.w5dxp.com

Because of the folding back of the currents I would not expect the 4:1
step up transformer to be a stirling performer at common mode
rejection...
The best way to approach this is to use the 4:1 transformer balun
strictly as a transformer, then add a 1:1 choke balun in series with
it...
Personally I would wind the coax into a solenoidal choke balun
immediately below the 4:1 transformer being thrifty and all that and
call it good...




denny / k8do