[NLRS] preamps 222

[Bruce Richardson]

Hi Dave:

I'm neither a purist, nor a Electrical Engineer.  And I don't really know
what I'm talking about :-) .  But because the internet allows anyone with a
keyboard to blather on, here's a dose from me :-)

Specs on the pre-amp sound fine.  Price, maybe just a tad high.  I think
100-120 particularly if used.

The quibble I have is with shack mounted pre-amps.  A pre-amp in the
shack--AFTER the Feedline--would only be needed if you have an (older)
deaf/insensitive rig or transverter.  It's my understanding that rigs and
transverters for 222 really haven't been deaf/insensitive in the past 15
years.  After the feedline, what's lost is gone and can't be recovered.

The key, I think, is to have mast mounted pre-amps to REALLY get the
benefit of going to the cost/effort.  I remember roving in EN-44 in a
January contest a number of years back.  I stopped by W0UC (the VHF portion
of AIH in those days).  That was my only visit ever to the farm.  It was
midnight to 1am on Sat night. I had a rig I needed to pick-up or drop off
from Paul--I forget.  So I'm driving along listening on the rover beam as I
pull into the farm.  I step into the shack and was blown away by the things
he was hearing that weren't even audible on my rover set-up.  Sure, it was
antennas with gain up high, but it was also nice pre-amps up on the tower
that removed the feedline from being a loss issue.  And that's the point
I'm trying to make.  I was taught that mast-mounted pre-amps swamp/mask
(and effectively remove) the loss offered by feedlines.  Further, I was
taught that they "set" the system noise figure by being before loss
elements.

I know mast mounting means a box and relays on the tower.  That is where
other fixed station ops can chirp up and give some hints/tips.  The one tip
that I think sounds attractive is inserting DC on the coax to power the
pre-amp.

I look forward to seeing the other responses. I hope someone addresses
"system noise figure" with and without a mast-mounted pre-amp.
73
Bruce Richardson
W9FZ