[Lowfer] ERP?

[Eric Smith]

Hi,

Bill mentioned that if I could get a signal report with a calibrated uV/m 
observation that an ERP could be calculated.

I *did* get this observation, from John Reed, and sent it to the 
reflector, but haven't heard back from Bill...you still there, Bill?

I know this can be calculated other ways, but this interested me, so I'd 
like to see how it can be done.  If other info is needed please let me 
know, but the reading was 0.39uV/m at 68 miles.

Here is how he did it:

===============snip=================
I've got a number for you.  It turned out to be not too difficult.  What I
did was first find the voltage amplification from the whip to the receiver
input.  I hooked a length of wire (about 1 meter) onto a high impedance
active probe connected to an HP 312A selective voltmeter (they called them
wave analyzers back in the old days), and tuned it to 1450.  That wire gave
a signal strength of 14 mV for KGFF carrier.  Then I hooked up the active
antenna with 1 meter whip to the voltmeter.  That gave a 50 mV reading for
the same carrier, so the voltage gain for the active antenna is 50/14 or
3.57.  Looks like my homebrew antenna has a gain of about 11 dB.

Next I had to go from the antenna input on the receiver to the signal
analyzer display.  I tuned in your signal (still there today).  It was
running about 1.4 mV with the noise at 200 uV (still a 7 S/N).  Then I
disconnected the antenna and put a signal generator on the receiver.
Without changing anything on the setup I adjusted the generator to give the
same response on the analyzer.  This turned out to be .1 uV gave a 1 mV
response on the analyzer.  There's about a factor of 1000 from the receiver
input to analyzer display.  The overall voltage gain is 3570.  For your
signal on the display of 1.4 mV the antenna input must be about .39
uV/meter.  Hope this all makes sense.
===============snip=================

73
Eric