I want to thank everyone who made comments either pro or con regarding my
short run cable dilemma. For those who do not know my background, I did the
licensing work and specified the equipment to be used in thirty-three
commercial repeater systems across the continental U.S. operated by State
Farm Insurance for nearly twenty years. And I used a lot of Andrews Heliax,
mostly LDF5-50A even when Motorola spec'd LDF4.... for those 800 MHz
systems.
I'm pretty much a KISS operator and when I did the math on cable loss below
30 MHz, 75 feet of LMR-400 has but 0.25 dB more loss or right at 0.55 dB
loss at 30 MHz So I thought I could buy 75 feet of LMR-400, Davis Bury
Flex, Belden 9913F7, etc. and feel good..... until I read a piece about
coaxial cable shields with aluminum foil and braided copper, repeated
flexing, and moisture which destroys the aluminum and is a diode action
noise source.
I already have the LDF4 which though used is in really good shape, so I'll
take it from dry storage, unroll it, cut two runs, install new termination
connectors, install new rotor jumpers ( probably Belden 8214 ) with the
splices covered with two layers each, Scotch 88, rubber liner, Scotch 88,
and a good coat of Scotch-kote before its clamped / tied to the tower.
This LDF4 will replace a Belden 9913 run with 8214 jumper and splice
covering as above which has been in place for over 25 years. According to
Club Log, the 9913 and TH-7 at 50 feet along with the ground mounted HV-2
have been instrumental in going from DXCC 214 in 1985 to my current 347. I
don't do much in contesting but as a member of SMC, I join the fray
occasionally.
Thanks again to all who commented.
73 ES DX,
Gary -- AB9M
-----Original Message-----
From: Craig Thompson
Sent: Wednesday, April 24, 2013 12:37 PM
To: Jerry R
Cc: SMC ; TenTec Reflector ; GARY HUBER ; W9AML group-email ;
DX-IS@yahoogroups.com
Subject: Re: [TenTec] [SMC] OT: Half inch Andrews Heliax LDF4-50A vs LMR-400
I had therfc.com make up my cables. They have the tools, connectors and
cable. Call and ask for Joel...he is a ham and knows his stuff.
On Wed, Apr 24, 2013 at 12:13 PM, Jerry R <jerry@daca.net> wrote:
Craig,
Do you have a source for UHF connectors for LDF4-50A
I was told that Andrew does not manufacture those in UHF style anymore....
Maybe my supplier was wrong, or you have a different source to purchase
new
ones...
and I would highly suggest the LDF4 also.... not to discount LMR-400, we
use that
on long runs on DXpeditions and its pretty good stuff
Jerry WB9Z
Craig Thompson <craig@thompsonet.com> wrote ..
> Hi Gary
>
> I would use the 1/2" Heliax. I use both and the outer jacket of the
Heliax
> is superior to the LMR for both water and sun. It also has lower loss. I
> would use LMR400 UF or similar for the rotator loop. Use all UHF
connectors
> for connections.
>
> 73, Craig K9CT
>
>
> On Wed, Apr 24, 2013 at 11:37 AM, GARY HUBER <glhuber@msn.com> wrote:
>
> > As I consider the materials required to replace my 30 year old
> > tower,
> > rotor, antenna and cables, I have several like new runs on LDF4-50A
> > terminated with N-male which could run from my ground window (UHF
female)
> > to the top of my 53 foot tower (60 feet max LDF4-50A cable run) where
a
> > flexible low-loss 10 foot jumper would terminate on a new BN-4000 and
new
> > TH-7 tribander. This configuration would require the 60 feet max
LDF4-50A
> > cable run, two half inch N female to UHF male adapters, one UHF
> > double
> > female and 10 feet of high quality RG8 cable as the jumper to the
BN-4000.
> >
> > The alternative which I’m leaning towards as it seems less likely to
have
> > connector/adapter loss and other potential problems is a single run of
75
> > feet of LMR-400 with factory terminated PL-259s between the BN-4000
> > and
> > ground window UHF female termination. My current installation is 60
feet of
> > RG-9913, a UHF double female adapter and a ten foot RG-8214 jumper.
> >
> > I know the half inch Andrews Heliax has a much lower loss figure
(0.357 db
> > per 100 feet at 30MHz) for a given length versus the same length of
LMR 400
> > (0.7 db per 100 feet at 30MHz) , but I’m thinking those three adapters
(six
> > connection points for loss) and their potential problems make it a
wash or
> > maybe the advantage goes to the 75 foot run of LMR-400.
> >
> > I’d be interested in any comments or experiences you might have on the
> > subject.
> >
> > 73 ES DX,
> > Gary -- AB9M
> >
> >
> >
> >
> >
> +-----------------------------------------------------------------+
> SMC Web Site: http://www.w9smc.com
> List Help: http://mail.w9smc.com/mailman/listinfo/smc_w9smc.com
> Submissions: smc@w9smc.com Problems? Contact: smc-owner@w9smc.com
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|