[Antennas] Buried ladder line?

[Robert Lay]

Hey Chris,

> I am planning on using my Ameritron ATR-15  (probably exactly what you say
not to
> use)  However, it is all I have.  I have been collecting coils and
variable capacitors
> to try to make a tuner for balanced work..Very few people know what a
Johnson
> match box looks like, have heard about them that is all.
>
>   Where is there a good plan for making a balanced tuner?

Don't feel bad - I've had to deal with that problem myself. I still haven't
built one from scratch after all these years. I got lucky and found a mint
condition Johnson, KW Matchbox a few years ago and snatched it up.

Meanwhile, if you have the determination for it, the best plan for a
balanced tuner is the one by Dick Measures, published in the Feb 1990 QST. I
have personally seen one built exactly to those plans. The owner/builder was
kind enough to let me examine it and operate it. It is probably even better
and more versatile than the Johnson Matchbox.

Meanwhile, I am hoping to find one of the smaller Johnson Matchboxes that
was designed for about 300 watts (AM service) - they are said to be able to
handle 1500 watts p.e.p. with no trouble.

To build the Dick Measures design you will need one big variable cap and two
identical rotary inductors whose shafts will be ganged together with a
toothed belt and driven by a front panel crank with counter. It's a serious
project. You may want to look at some of the other designs, as well, that
have appeared in the ARRL Antenna Book.

Bob Lay (W9DMK) in Dahlgren, VA
http://www.qsl.net/w9dmk