[NLRS] [] VHF/UHF rotator loops

Sun Mar 20 17:07:53 EDT 2022

(NOTE: 99% of my experience is below 50 MHz)

Davis Bury Flex is VERY good cable.  I have a couple hundred feet of it here
and have used thousands of feet of it in customers' stations over the years.
The outer jacket is very tough and very smooth.  It probably has no more or
less loss than any of the other good RG-213 cables, but I think its physical
construction is better, which should make it last longer.  

Crimp connectors are fine.  If, and ONLY if, you use quality connectors and
the proper connector and crimp die for your cable.  I like especially like
crimps for cables that have both a foil and braid shield (LMR, Bury-Flex,
9913F7) because you get a good connection to both the foil and the braid.
The traditional solder type PL259 or clamp N connectors do not always give a
good connection to the foil.

----
73,
Mike Cizek W0VTT

-----Original Message-----
From: nlrs-bounces at mailman.qth.net <nlrs-bounces at mailman.qth.net> On Behalf
Of scsueepe at mtcnet.net
Sent: Sunday, 20 March, 2022 12:55
To: 'Bill Davis' <cqbilld at yahoo.com>; 'NLRS Reflector'
<nlrs at mailman.qth.net>
Subject: Re: [NLRS] [] VHF/UHF rotator loops

Bill, my 2 cents here..

Used LMR-400, LMR-400UF, LMR-600, LMR-600UF and 1/2" superflex for rotor
loops.

The LMR-600UF was not good, seems like the center conductor migrated over
time.  And one always had to solder the center conductor due to stranding
center...

The Superflex was good and did that for years on 902 and 1296.  Now those
transverters and amps are on the tower mast, so I use LMR-400 as the IF
cable and rotor loop.

For the rotor loops, I now use combination LRM-400 and 600 depending on
frequency.  Is it stiff?  You bet, but I do multiple smaller loops (like 3
turns around the mast) so none of it seems to compress too much, or expand
too much.  Kind of like a spring.  The multiple loops are taped together and
support each other in a way.  Taped liberally where then transitioning to
the vertical mast so no stress is put on the connector whatsoever.

99% of the connectors used here in the last 10 years are spring center pin
captive and crimp braid, no soldering, then heat shrink cover.  N-Male Times
microwave EZ-600-NMH-X or EZ-400-NMH-X.  High power all the way up thru
1296.  Never had an issue while using the Times Microwave LMR tools for
cutting, stripping, deburring and crimping.  All vertical runs up the tower
are LMR-600 except for HF.  Not a single failure or replacement needed so
far.

As for weatherproofing, I quit using that goop tape, worked, but messy stuff
if you want to remove or change something.  Over the heat shrink piece that
comes with the times microwave connectors, I use the silicone self-adhesive
tape over everything, then retape over it with high grade 3M black.  Been
working good.  Easy to cut and take off if you need to redo something.

Only solder connectors here are PL-259s from DXE... solder center pin only,
and crimp body.... Not many in use here, just where needed.

Never tried a 3rd party cable, was always wondering about Davis RF bury
flex... but never got around to trying it.  Never used 9913, was always
afraid of the water ingress stories...

I have bought most of my LMR cable thru Bill at Pulse Products in
Minneapolis.  Scanner put me on to him a long time ago and he has been a
great resource for my cables for several years.  Its been a few years since
I called him to order anything, not sure if he is there anymore or not, or
if their numbers are still competitive.

73 and GL

Mike - KM0T

-----Original Message-----
From: nlrs-bounces at mailman.qth.net <nlrs-bounces at mailman.qth.net> On Behalf
Of Bill Davis via NLRS
Sent: Saturday, March 19, 2022 12:19 PM
To: NLRS Reflector <nlrs at mailman.qth.net>
Subject: [] [NLRS] VHF/UHF rotator loops

  This spring I need to plan on replacing many of my coax drops from the
antennas to the hard lines at the top of the tower, including the rotator
loops. The old coax lines are over 20yrs old and are 9913 superflex (NOT
cellular coax). I have had no KNOWN issues until the day before the arrival
this year of "real winter" when I discovered WATER in the 1296 coax.
(Elevated SWR) which had NEVER been observed in the past. I have never known
this to be an issue before. Given the lateness I did no trouble shooting of
this cable since I would have had no opportunity to replace it regardless. I
just drained it for 2 days.
  The question is --- "this day and time" what are people using for such
cables. LMR400UF ?? or ??.  It looks like LMR400UF is over $2 a foot. I sure
do NOT look forward to this job and want the job to last without service for
hopefully 15yrs or more. I HAVE NOT used any crimped type connectors before.
Not sure if I will this time or not. All connecters solder type and are type
N with the exception of a couple. (2m 6m)
  Comments - recommendations - etc are being solicited. 
  Are there cable brands to avoid since so many different outfits are
selling LMR400UF "equal" coax? Retailers? etc
  Thanks 73  -  Bill  K0AWU
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