[TowerTalk] (Long)MFJ259B & PL-259/SO-239 Pair Losses

[L. B. Cebik]

> I am now seriously considering replacing the 220 feet of LMR400
> with a similar length of 450 ohm twin lead,  and use the EFJohnson
> kW Matchbox to feed the Gladiators rather than the unbalanced
> system.

For minimal loss in systems that can effectively replace coax with
parallel transmission line (and not all can), I would suggest open-wire
600-ohm line rather than any of the more convenient but slightly lossier
vinyl-covered lines--even with "windows" in them.  However, to ensure that
such line gives the lowest possible loss of which it is capable, be sure
to follow all the rules regarding spacing from objects, preventing
imbalance, etc.  A less than prefessional-level installation job can wash
out the loss difference.

As Jim has done with his coax system, so too with the parallel line
system:  do not just calculate losses, but actually measure them to ensure
you are getting what you want.

>From the spec sheets that I have here, some hardlines provide losses that
compete effectively with 450-ohm parallel line--although at a price
differential.

-73-

LB, W4RNL

L. B. Cebik, W4RNL         /\  /\     *   /  /    /    (Off)(423) 974-7215
1434 High Mesa Drive      /  \/  \/\     ----/\---     (Hm) (423) 938-6335
Knoxville, Tennessee     /\   \   \ \   /  / || /      (FAX)(423) 974-3509
37938-4443     USA      /  \   \   \ \       ||              cebik@utk.edu
                URL:  http://web.utk.edu/~cebik/radio.html





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