On Sat, 04 Jun 2005 20:11:38 -0000, (Dave Platt)
wrote:

In article ,
Bob Miller wrote:

For balanced line, it has a "broadband toroidal transformer" according
to the review in a 1980 QST. When I place a VOM multi-meter across the
two balanced line terminals, it shows continuity. Is that normal, or
is the balun cooked or shorted?

Very probably normal... or, at least, to be expected of many types
of balun and thus not diagnostic of a failure. You're probably
reading the DC resistance one or more of the windings, which would be
rather less than an ohm.

Based on what I see in Sevick's book on baluns and ununs, both the
Guanella 4:1 current balun and the various Ruthroff voltage balun
configurations would exhibit this behavior.

I kinda suspected so, but wasn't sure.

A Guanella 1:1 with the
center of the load un-grounded would not, nor would a Reisert or W2DU
1:1 balun.

Now, for something completely different. If you want to revisit an
old controversy, and if you're not adverse to modifying a classic
piece of equipment, you might want to review the various debates about
the pros and cons of the Ultimate Transmatch vs. the SPC
configuration. See if you can locate a copy of the August 1981 QST,
and review the Technical Correspondence column on pages 42-43.

As I understand it, the SPC configuration can be shown to have some
significant technical advantages over the Ultimate Transmatch, in terms
of matching range and harmonic attenuation, when the same component
values are used in each. It is reportedly possible to re-wire an
Ultimate into an SPC configuration little or no cost, as both use a
split-stator capacitor (just in different places in the circuit).

Thanks, Dave, I have a 1985 arrl handbook that shows the differences
between the Ultimate Transmatch and the SPC circuit, and I also have
some modification instructions on the Murch unit itself, but I haven't
tried changing anything yet. Still playing with it, as it came.

Bob
k5qwg