[UK-CONTEST] OT: Aerial installation advice

[John Lemay]

Hi Keith

I don't think you're far OT at all !

I would recommend that you replace the complete run(s) of cable with ECO.
The main run between the rig and rotator is important because it is (I
assume) the longest and therefore lossiest. The shorter run to the aerial is
important because the loss there directly adds to the noise figure of your
pre-amp.

You should have no difficulty making a loop of ECO 15 for the rotator, and
I've had no problems in the past in this area. Use N Types wherever possible
in preference to PL-259's.

If I recall correctly, the Vargarda aerial requires a direct cable entry to
the driven element and I suspect that ECO 15 may be too large. So either use
a short tail of RG213, or consider using ECO 10 from the feed point to
pre-amp.

Changing out cables generally provides small improvements rather than
dramatic changes (unless you've accidentally got water cooled coax!). But a
number of small improvements really do add up to something useful. You could
try and prove this to yourself during the changeover by putting a power
meter at the far end, before and after.

Regards

John G4ZTR (G0VHF)

-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Keith Maton
Sent: 14 March 2010 11:12
To: uk-contest
Subject: [UK-CONTEST] OT: Aerial installation advice

There's a lot of knowledge on here so I hope you'll excuse me this slightly
OT post although it does have a contesting connection :)

We did some aerial work at the club contest station a couple of weeks ago
and it's made me realise that I need to improve my home station.  I have a 9
element Vargarda fed with some "RG-213".  I'm going to upgrade this to
EcoFlex 15, replace the old rotator and fit a masthead pre-amp.

Is it worth me taking the effort to replace the entire coax run right to the
aerial or simply trim back the current stuff to the stub mast where the
pre-amp will be located and run the new cable from there down to the shack?
That will leave me with 2-3 metres of the existing cable.

I know it will make a slight difference replacing that tail but will it be
too negligible to even notice?  

73
Keith, G6NHU
Martello Tower Group, G0PKT






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