[HCARC] Ditching and Electrical To Antenna Farm

[Kerry Sandstrom]

Hi Gary,

You've asked a bunch of questions and none of them have short answers.

First, the coax cable.  There are two basic ways water gets in to coax: one 
is through non-weatherproof connectors and the other is through "pinholes" 
in the outer jacket.  I'm not sure how the coax is specified, but there is 
coax that is rated to not have pinholes.  That is what you need for a long 
run buried or in conduit that might leak.  For weatherproof connectors, you 
need to use Type N or one of its cousins such as Type C.  When properly 
installed, these connectors are weatherproof.  UHF connectors are never 
weatherproof.  If you are concerned, avoid them and learn how to use Type 
N's.  There are plenty around surplus and they really aren't any more 
expensive than good UHF connectors.

I would never run an AC power line alongside my coax.  First, I think there 
are some safety issues and I would certainly consult the National Electric 
Code (NEC) if I was going to seriously consider that.  I believe the NEC may 
also require that power lines be run in a specific color/type of plastic 
conduit.  I know the NEC is not enforced out here, however some of their 
requirements are based on safrety issues and should be followed.

The reason I wouldn't run them together even if I could is because of noise 
pickup.  Power lines tend to be noisy and some of that noise is at HF and 
VHF.  With the lines running next to each other for 200 or more feet, there 
will be a lot of coupling.  I believe the LMR cables have a single braided 
shield and an aluminum foil shield.  These materials provide good shielding 
at higher HF and VHF frequencies, however, they are very poor at shielding 
lower frequencies.  The main problem is magnetic fields.  Low frequency 
magnetic field shielding requires ferrous metal and lots of it.  If I 
expected to listen to the AM broadcast band or lower, I'd be worried about 
power line noise.  It may even be an issue at 160m and 80m.  Because of 
noise, I'd be reluctant to even have AC power out near the antenna.  An 
extension cord may be a nuisance, but at least its not a noise source when 
you put it away.  My antenna is 100 ft away from power and, no, I didn't run 
AC power out there.

I don't think you should need any more than #16 or #18 wire for the DC.  A 
relay should be less than an Amp of current.  Many guys use bias-T's to 
carry the low voltage DC down the coax to the vicinity of the antenna where 
the relay is.  Be aware that there will be noise on the DC lines too unless 
you have filters to clean it up.  Once you contaminate the area where your 
antenna is, there isn't much you can do to clean it up.

Lets see what this generates!

Kerry