[Lowfer] ERP?

[Bill Ashlock]

>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.

Eric, this number is too low, maybe 10X. If the S/N is 7X that would place 
the noise at .39/7 = .0557 uv/m which is way too low. In this area, on a 
very quiet winter day, maybe at 12:00 noon, the AT noise out in the 
countryside is about 0.3uv/m. I'll study the following "snip" when I find a 
moment and see if I can figure out where he goes wrong.

Bill A


>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
>
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