Message-ID: <19980915003601.8522.qmail@www02.netaddress.usa.net>
Date: Tue, 15 Sep 1998 00:36:01
From: Dan Schaefer <dfschaefer@usa.net>
To: lancair.list@olsusa.com
Subject: coax, wire, noise filters, bladder & grape juice
Mime-Version: 1.0

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Boy! Always seems that a lot of stuff shows up over the weekends.
Here's my take on a bit of it.

For coax cable selection there are several things that must be taken 
into account with the most important being the bulk cable's charac-
teristic impedance. For the radios we use in GA, most everything is
designed to use nominal 50-ohm cable. The many variations of RG-58
are all 50 to 53 ohm cable with the major differences in design, such
as solid vs stranded center conductor, jacket materials, dielectric
material, etc.,etc. Whatever you choose for your antennas, just be 
sure the basic cable meets the ELECTRICAL requirements - the rest is 
secondary. Personally, I like the RG-58A/U but that's just one of many
that are suitable. I prefer the stranded center conductor (a little 
more flexibllity), with a solder-on (with screw-on back-shell), BNC 
connector.

Something else to consider while on the subject of coax cables. Be 
careful when spot-tying or clamping these cables. They can be damaged
(subtly) by muscling up on whatever method you choose to hold them
in place or to keep them from flopping about. The cable characteristic
so carefully built in by the manufacturer relies on, among other
things, the internal dimensions from the center conductor to shield. 
Other things also have effect but you don't have much to say about
them once you've brought your raw cable home. So just don't see how
neatly you can tie those surgeon knots in the tie-string or how 
tightly you can pull the zip-ties - you will squish the soft stuff
inside and degrade the cable quality. Even if it doesn't look too bad 
at the start, the guts of the cable will cold-flow with a lot of pinch
and your transmission and/or reception quality will slowly get lousy 
and you wont know why.

While on the subject of wire and cable, for standard hook-up wire, the
best to use is "Tefzel" insulated wire conforming to MIL-W-22759. 
It's the best stuff to come down the road in a long time. Beats plain
Teflon hands down and Vinyl isn't even in the same universe.

And finally, to Dave Jones, I like your method suggested to get 
vertical to pee - my only problem with it is that going straight down 
at Vne + ANYTHING will most likely encourage me to empty other things
in addition to my bladder!!!! A discouraging thought to say the least.

Cheers,

Dan Schaefer


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