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Re: AIDC-2733 gain measurement



I did a quick check the other nite on the 3733. I didn't retune the
filters. I was able to hear the sig gen alway down to it's lower limit
of .1uv. I did a quick sweep up and down the band and found a
considerable gain increase as you approached 2.5 and the gain flattens
out above 2.5 and falls off just on the upper side of the stock
bandpass. There was a very deep null around 2407 and a soft broad gain
reduction across the 2300 to 2407 area. I didn't do any exact
measurements just quick observations on the spectrum analyser as I
sweeped across the band. I also didn't want to make any tweaks in the
filter until I got a chance to try it out on the dish. I used the stock
N adapter and was coupled directly into the sig gen with a N turn
around. Output was a 2 foot 75 ohm coax to the spectrum analyser. No
Bias T was used as the spectrum analyser supplies 'dc'.
With it in it's stock condition except for the change out to a drake
xtal I was able to hear AO16 weak but steady thur out most of its pass.
Antenna is the dipole on the unit mounted at focus on the Bar B Q
reflector and a 50' RG8 feed to the FT-736R.

Art Goldman wrote:

> All:
>
> While we wait for our 144 Mhz crystals to arrive, I took my
> 3733 and put it back on the Agilent signal generator and
> spectrum analyzer. This time I had the N Adapter in place of
> the dipole, so I could more accurately measure conversion
> gain.
>
> With 2401.323 Mhz, -80 dBm input I got 123.358 Mhz, -58.86
> dBm output
>
> So at our frequencies, I see a conversion gain of only 21.14
> dB, which is considerably less than the 37 dB gain printed
> on the side label.
>
> Does this correlate with other measurements?
>
> Reason for asking: while in beautiful downtown Atlanta the
> signals were S9+ on Sunday, in rainy and depressed Maryland
> (the Terps lost to Duke) we didn't hear a peep. So we're
> trying to figure out where the problem lies. (And yes, we
> remembered the time change; had the latest keps; and a
> reasonably accurate antenna alignment). We tried both a DEM
> converter and the AIDC, both on a parabolic grid antenna.
> The AIDC had the integral dipole. I've yet to try the N
> adapter hookup.
>
> How much effect should we expect shooting through a maple
> tree with no leaves on it? Enough to completely null the
> signal?
>
> Any other ideas?
>
> Tks,
> Art, N3OY
>
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--
Bill
WA2TQI


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