[TowerTalk] [Bulk] How far away from the shack for that mighty fine tower :-]

[Grant Saviers]

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?