Planning helps. I built a spread sheet for all antennas with expected
length of EVERY coax length amplifier SO239 to antenna feedpoint with
the db loss/ft for that particular antennas frequency (or the highest
for multiband antennas).
My goal was less than 1db feedline loss on every band, so then I picked
the lowest cost quality coax to achieve that. Considering what a tower
will cost to get 8db over some wires, it seems foolish IMO to throw away
several db's to save money on coax. So for 10-20m I use 7/8 hardline
(LDF5 and AVA5) from amplifier Buryflex pigtail to rotator pigtail.
Then 1/2 hardline the same on (LDF4) 80/40. Max calculated loss turned
out at 0.8db. My used hardline purchase came with boxes of 7/16 DIN
connectors and they are cheap on ebay for LDF.
I've found that 7/8 (LDF5) is now hard to find used/surplus, if you can
find some LDF5 grab it, as it is no longer in production. The AVA
replacement requires different tools and connectors and is much more
fragile, but I didn't have enough used LDF5 so had to buy 350' new AVA.
LDF4 is still pretty plentiful surplus/used I think. Andrew stuff seems
to last forever so if it is not damaged it is probably ok loss wise.
Lots of hams direct bury hardline but I took the conservative approach
for critter protection and vehicle traffic and used glued joint 3" sch
40 conduit. (why let water in?? ) One for 2xAVA5+1xLDF4, another for
1xAVA5+3xLDF4, and a third for all control cables. If you go bigger
than 3" for conduit consider SDR35 pipe. Also remember all cables
should pull together, probably a must for a 300' run and you may need a
winch plus a Kellem grip on the cables. It takes 4 to 6 people to
safely feed/pull multiple hardlines into a conduit. My underground
pulls were 115' and all went easily by hand with 4 of us.
I recently saw Tessco selling an Andrew competitor 7/8 on sale for less
than $2/ft. That is a good deal. Shop around on the cell system
suppliers websites, it was easy to open an CC account with two I do
business with.
It's pretty hard here to find free spool ends of large diameter CATV
hardline. You may get lucky, but it is 70 ohm.
Grant KZ1W
On 1/8/2016 20:10 PM, dw wrote:
I'm sure everyone has had to deal with this question.
Your better half doesn't really want the property to look like
antenna-ville.
So then what are the issues with distance from the shack?
Say 300 feet away?
Perhaps this is where hard-line becomes earns its keep?
And I would guess the best way is to bury it in some kind of plastic
tubing like 4 inch drainage pipe?
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