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Re: FT-847 AO-40 and Doppler Uplink Correction?



A special thanks to Chris Hill, Dave Lamont, and Wayne Estes for seriously
approaching my question and providing an enlightening analysis and ANSWER to
my question. I got three categories of replies:

1. The standard methods of approximating and finding oneself by tuning and
ditting. (not what I was after)

2. You don't need to know that...(really...someone actually took the time to
tell me this) and also "shared" that I posted too much and that
spreadsheets, computers and calculations were ruining modern amateur radio.

3. Several replies that actually answered the precise question I was asking,
without questioning my motives or why I might need to know such information
so precisely.

Thanks to all  who even tried to help, you were very kind. As a result of
the good advice on calculating uplink freq to produce a desired downlink
freq, including the effects of doppler, I was able, on Sunday evening to
hear myself on cw, even when pointing through a tree! My signal stunk...but
it was there.

I also worked through a VERY bad problem with my uplink killing my UEK-3000
downconverter. It was NOT the fault of the equipment, but rather me not
thinking clearly about what I was doing in my haste to get a signal back
from the bird.

I mounted my K1FO 22 el 70cm yagi right next to  (maybe a foot)  the receive
converter. Every time I keyed the mike, there was so much RF going into the
downconverter that the LO would pull about 3 Khz, and FM if I actually
talked or keyed cw. (This was on the great looking pass of Friday night, I
think.)  Anywho...the next morning I went out and moved the tx antenna to
the end of the cross boom, (about 5 feet away from the downconverter), and
when I ran the test noted above where I could hear myself very weakly, I had
no pulling, fm'ing or desense whatever. Lesson learned: 435 and 2400 Mhz are
a long way apart, but putting the tx antenna that close to the downconverter
is a formula for failure. Fortunately, it did not hurt the downconverter.

Thanks to all of you again, who took the time to explain how to calculate
the uplink frequency as precisely as possible in order to look in the
"right" spot on the downlink. It was invaluable for me to be able to find my
extremely weak signal while pointing through the heavy vegetation of the
tree. I would never have found it without your guidance.

I am going to give Dave's program a try and see if it will do the job
automagically for me. Once I have a "normal" signal into the bird, all the
standard techniques and approximations work just fine. Many people suggested
them, but they were not going to work when my signal was "in the noise".

73,

...hasan


----- Original Message -----
From: "Dave Lamont" <lamontd@paradise.net.nz>
To: <amsat-bb@AMSAT.Org>
Sent: Saturday, July 21, 2001 9:19 PM
Subject: Re: [amsat-bb] FT-847 AO-40 and Doppler Uplink Correction?


> Hi
>
> You could run the demo copy of Uni_Trac in the background
> Every aspect of the up and downlink is automatically calculated.
> for AO-40 use.
>


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