[TenTec] [SMC] OT: Half inch Andrews Heliax LDF4-50A vs LMR-400

[GARY HUBER]

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 at 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 at 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 at 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 at 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
> > >
> > >
> > >
> > >
> > >
> > +-----------------------------------------------------------------+
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