What I always did, and I'm sure it was in the manual, was to wind a
few turns of hook-up wire and solder the ends to a coax connector. I
then plugged in the coil at the end of the coax, stuck the GDO coil
through the coil on the connector, and took a reading. I can't recall
that using that method ever mislead me. I think I even have that
little coil on a BNC out in the junkbox.

I sold the Eico GDO that I had for years. In 1999 I acquired a Millen
GDO in mint condition from an estate sale. I sold it on Ebay, but now
wish I had kept it.

Dick - W6CCD

On 31 Aug 2003 16:48:47 GMT, (Fred McKenzie) wrote:


Try http://w1.859.telia.com/~u85920178/use/gdo.htm

BR from Ivan

"Tom Coates" wrote in message
...

How do I couple the meter to the antenna?

Tom, N3

Ivan & Tom-

I've had a couple of old Heath GDOs over the years. I was never able to find a
dip by coupling into the antenna's co-ax. I see that Ivan's article above
contains the "secret" method I finally found that works - you have to
short-circuit the feedpoint of the antenna and couple directly to the element.

The article above suggests that you can form a loop in the antenna wire to
couple more tightly to the GDO. However, that would tend to introduce
inductance which would interfere with the measurement. What I do is lay the
coil next to the antenna element so the antenna wire is parallel with the GDO
coil wire tangent.

For example, take a one meter wire or un-bent coat hanger. A GDO coupled to it
should have a dip at 150 MHz. I expect there will also be a dip around 450
MHz, et cetera (odd harmonics).

73, Fred, K4DII