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AO-40 S2 copy for the very first time




Hi

Using a AIDC-3733 with the stub cut and the Murata filter mod on the second
filter
I could copy AO-40 for the very first time on S2. I was using a barbecue
grid, really
sitting on chair. It was around 22:00 UTC on 10/06, Saturday.
Elevation was 60 degrees, the bird was near apogee and there was no near by
blocking.
Squint was very favorable, less  than 10 degrees. I could solid copy the
beacon but was
not prepared to decode it. I copied several SSB stations so loud that I was
impressed the LEILA
was not catching them. Due to personal scheduled I could not try the
uplink.

On Sunday I tried again but the elevation was low (10 degrees) and there
was obstructions on
the direction the bird was, and squint was also greater. The copy was not
so good. I could copy the
beacon but only a few stations. This time I tried the uplink: 25 watts on a
KLM crossed yagi 18 el.
With 25 watts I could not locate my signal, so I decided to try the 50
watts of other rig, the FT-847.
I was using another TX because was afraid to fry the downconverter, as the
receive mod is not done
yet on the FT-847. After carefully checking all settings on the FT-847
several times with manual open, I
tried the uplink and could easily locate my own signal. The level was not
enough to go phone, but was
more than adequate for CW, unfortunately I discovered that this radio need
a stereo plug for the CW key !!
All my keyer connections are with mono plugs. So no QSO yet.

Chasing for my signal I have discovered that the my FT-847 produces strong
birdies on 145XXX and 123XXX
when  transmitting on 435XXX on the AO-40 uplink passband. I disconnected
the AIDC-3733, moved the
uplink antenna out of the bird position reduced power and analyzed the
birdies. On the 123XXX it almost make the
same conversion rule of the AO-40 U/S2 AIDC-3733 chain, making some
frequencies impossible to use
depending of the doppler shift. On the 145XXX case they are near, but don't
match on the AO-40 passband.
A looked on the FT-847 FAQs but could not see any info about this kind of
birdies.
Mine is new and seems to have been produced by the end of 2000.

Please, if anyone that has a FT-847 can check for this behavior on his
radio I would be grateful, contact me
and I can send a table with some frequency pairs 435xxx/123xxx and
435xxx/145xxx to look for.


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