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AO-40 reception?



Yesterday I took out my Drake #2, completely unmodified and bench checked
it with my diode signal source [800 MHz x3] and it worked just fine.  Found
2401 at 123.000 exactly!  Later at home it was 122.995.

In the evening I set up my coffee can diode source on top of my step ladder
about 15-foot in front of the dish.  I now have the Kuhne MKU-232A preamp
mounted on the 5-turn helix feed of the 33 inch dish feeding the "new"
Drake via 12-foot of LMR-400.  I used the confer bias-tee to feed power to
the Drake [produces S-3 noise floor with 2.4G preamp off].  ao40s_2 shows
that I should see the transponder noise floor for a squint of zero.

Applied power to everything and have about S-7 noise floor on the FT-847.
Sun noise rises about 1/2 s-unit.  With -20 dBm at 800.439 MHz into the
diode-gen I got a whopping strong signal [2401.317].  I was able to lower
the drive to -65 dBm to find the threshold [MDS] level.  That just shows up
on the FFTDSP waterfall display.  Of course I have no idea what signal
level the diode produces at 2400 MHz.  I could calculate space loss for 15
feet but... 

Initially the Drake drifted about 200 Hz but settled down to about 30 Hz
over several minutes [and not sure the signal generator is that stable at
800 MHz]...interestingly the generator's [IFR-500] third harmonic has a
definite FM note and produces a trace about 10-15 Hz wide on the waterfall!

With the coffee can diode-gen on the ladder I was able to check antenna
pointing; best I can tell azimuth beamwidth ~10 degrees.  Pointing appears
to line up well.  Interestingly, I could detect [barely] the first
sidelobes on either side of the main-lobe!

At 0537utc AOS of AO-40 was predicted by NOVA at az=90.3.  Since MA=144.8,
I waited for the satellite to rise.  At 0600utc, MA=150 and the beacon
should be on; az=94.2, el=2.1 but this put me into the trees, yet.  Still I
decided to look for the signal with FFTDSP and ao40rcv.   I continued until
local 2330 [0730utc] when az=109.5, el=9.8 but could not detect anything.
The squint was >90.

So a couple questions:  Did anyone copy the beacon from 0600-0730utc.  Was
it turned on?  Anyone successful copying when squints are this high?  Range
was ~65,000 km.

I have a feeling my system is close to operational, but???   Today I will
take Drake #1 to work and determine what failed [see if the LO is working
and test with diode-gen source].  I suspect the front-end is gone as
noise-floor dropped from S-3 to zero and no signal could be found even
driving the diode with +10 dBm [Drake #2 was loud with -20 dBm and
detectable with -40 dBm].  I may have made a "Duck" out of my first Drake!
{see the article in the current Amsat Journal}

Fun 'n games in the arctic midnight sun!

Ed

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