[TowerTalk] Grading a ground radial system field strength

[Jim Lux]

----- Original Message -----
From: <Dinsterdog at aol.com>
To: <Jamesnf at aol.com>; <towertalk at contesting.com>
Sent: Saturday, May 14, 2005 3:55 PM
Subject: Re: [TowerTalk] Grading a ground radial system field strength


> Jim,
>
> Thank you for your suggestions.  Others have sent me emails agreeing  with
> you.
>
> Within what distance would you suggest to measure field strength?

Have you got a remotely controlled relay you could use to switch the ground
radials in and out?
Tune your receiver to a distant signal in the band of interest and in the
right direction.  Measure  the received power with the radials connected and
not.  Sure, the signal will be fading, etc., but you'll get a quick
validation of the value of the ground radials.
(mind you, even with the ground radials disconnected, they still help the
antenna)





 What
> protocol? I would think cranking down the rig to minimal power and taking
a
> reading at relative distance of a few hundred feet.  Is there a field
meter  out
> their that will accurately read field strength.  I remember Radio Shack
had one
> in the 70's and 80's during the CB craze.  It had a dopey 4 inch  antenna
on
> top of it but operated as good as a cereal box decoder ring-

Much easier to use a constant RF source, and then use your receiver as the
calibrated measurement system.  For 40m, you could rig up one of those
little 7 MHz crystal oscillators using a hex inverter.  You don't need a
huge amount of power, or an efficient transmitting antenna for "close in"
measurements.  The key is that the output power of the beacon be reasonably
constant (which means regulated voltage and reasonably constant
temperature).