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

[Robert Mcgraw]

I'd use the LDF4-50 with the N type connectors.  From there around the
rotor I use good quality RG-8 or RG-213 with a N connector on one end and
a UHF on the other.   At the window I'd change that to a N connector but
not by using an adaptor.

At HF the loss in connectors is not enough to be concerned about.  Plus
the N connectors do maintain a constant impedance where UHF connectors do
not.  Again, this likely makes little to no difference at HF frequencies
even up to 50 MHz.

I don't use 9913 or any version of the series.  I find it to susceptible
to moisture penetration as a result of the type foam insulation used. 
{It works better as a garden hose.☺}

I feed my antennas at 144 MHz, 432 MHz and 1296 MHz with 1/2" and 7/8"
hardline fitted with N connectors.  For HF I use RG-213 with N type
connectors except when the transition to the UHF style connector is
needed.  I use N connectors on the Bird meter so my jumpers are fitted
with N connectors.  I do not use adapters.

73
Bob, K4TAX





> 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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