Wendell:
My comments embedded below.
73 de
Gene Smar AD3F
-------------- Original message ----------------------
From: Wendell Wyly - W5FL <wendell@wyly.org>
>
> All wire and conduit is new. Plan to have two HF feedlines and one
> 144/440 VHF feedline and 8 cond rotor cable for Hy Gain T2X Rotor and
> a 4 or more small gauge (#24) wires to control the antenna switching
> for 80,40 dipoles and 10/12/15/17 and 20 meter 2 el quad loops or
> maybe a better antenna. Plan to use 360 foot 1 1/2 or 2 inch pvc
> conduit for the feedlines and 3/4 or 1 inch pvc conduit for the
> control lines to be buried about 12 to 18 inches.
I'd recommend a single, larger (4 inch) conduit for ALL cables. Other folks
here have suggested corrugated plastic drain conduit; not a bad idea. No need
to separate control cables you're thinking about from the coax as the control
voltages are below 50 VDC. (BIG assumption here.)
Also, I assume the 144/440 antenna is a dual-band vertical for local repeater
work. See below for applicable comment.
>
> Budget is kinda skimpy but always wanted to use 1/2 inch hardline due
> to low loss, but don't know if it pulls through conduit ok. Trade
> off is LMR 400 or LMR600 or ???. The conduit run is 140 feet to a
> pull box and then 220 feet for a total of 360 feet. 1500 Watts on
> HF and 50 Watts on 144/440 VHF. Looking at using preamp or two band
> amp/preamp on tower for 144/440 vhf due to long coax run, but unsure
> what kind works well and particularly how to power it through the
> conduit run from the house.
W3LPL has developed a series of tables that I used when I selected my coax runs
for my tower: http://www.k1ttt.net/technote/coaxloss.html#tables . I
selected RG-213 for all the runs (HF tribander, 40 dipole and 6/2/440 vertical)
because, at 28 MHz my 110 feet of cable would result in only a little over 1 dB
of loss. I didn't care too much about loss on 440 as I was going to use this
antenna for local repeater work, not weak-signal DXing. For you, half-inch
hardline (LDF4-50A) would give you about 2 dB of loss at 440 MHz and about a
half dB at 28 MHz.
I am not aware of a dual-band pre-amp for 2M and 440. If I'm correct and you
still want to use a single dual-band vertical, you'll have to split the two
bands at the antenna with a duplexer, run them through the separate pre-amps,
then combine through another duplexer into one run of hardline to the shack.
PITA.
Is direct burial coax any better or worse than LMR type or hardline
> in pvc conduit? Soil is both sandy and rocky. The site is rural and
> ups is preferred to truck shipments, so how do they ship hardline so
> it does not get damaged or it is worth fooling with for this
> installation?
If you're going to run the coax inside a conduit, I see know particular benefit
worth the extra $ for buriable cable.
>
> Have never had any coax lightning arrestors, but was considering
> putting them on the coax lines and control lines at the house single
> point ground entry panel if I can find a reasonable cost solution and
> ground the coaxes at the tower base. The house has both lightning
> rods and a good perimeter grounding system.
Figure about $65 per coax for an appropriate Polyphaser lightning suppressor
and ground connectors.
>
> ANY and ALL suggestions and comments will be sincerely appreciated as
> will suggestions to keep the total costs of materials as low as
> practical.
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