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Re: uplink frequency fo20/29



I've been working FO20 & 29 regularly without trouble.   Except that I
rarely find anyone on the bird working cw ;-)   At any rate....I have a less
than ideal setup, but it works just fine accept for the high elev. passes
(e.g. above 30-35 deg.).   My system is an FT-847 running only 50w max.
Most times I can work them with 25w without any noticable drop in downlink
RST.   My antenna's are horizonal only, no elev.   My feed line is 1/2
Andrew Heliax @ abt 75' from antenna jumpers to the rig.  I only have the
internal FT847 preamps.   I can usually work from horizon to horizon
here....accept my southerly horizon is about 6 deg higher, since there is a
small hill there.   I'm using K1FO 22ele 70cm, and K1FO 12ele 2m antenna's.
Both have respectable gain, and using the Heliax helps on TX/RX losses I'm
sure.

The trouble I've noticed most often on these two birds is that the Doppler
is so fast that it's hard to get everything in sync....sending CW CQ, moving
antenna's, adjusting for doppler....Then I finally do find someone on the
bird sending CW they float off down the transponder because they're not
correcting thier TX to maintain RX downlink freq.

I haven't done this in about 6 years....but seems to me I remember we're
supposed to adjust uplink TX to maintain the downlink RX freq as best we
can....isn't that true?   Otherwise you end up with people's qso's drifting
all over the place....I'd like clarification on that if possible....

When these two birds are low on the horizon from 0-10 deg.  I can usually
work them with 10w or sometimes less....

I can't imagine trying to work them with more than 50w in my
situation....but if I had lossy feed line I guess much of that TX might get
lost on the way to the antenna....

I work AO10 regularly with this setup...and only 50w out.   I can drop my
output on AO10 to 3w sometimes and still hear my downlink.

As for the 847 'birdies' I too have the problem of hearing myself on my
downlink freq but my signal isn't leaving the shack ;-)  ....depending on wh
ere I am trying to work in the passband of the transponders.   I have
noticed that it's most pronounced around the middle of the passband like
around 850.   I usually try working down around 815 on CW, and dont have
this trouble as much there....   It's also pretty easy to find the TRUE
downlink by listening for doppler.   If your downlink isn't drifting you
should suspect that either that bird is coming right straight at you, or
you're hearing your harmonic, or spur or whatever it is that we're all
hearing....  The point is....watch for doppler....if you don't have any on
20 & 29 try moving your antenna off the bird....still hear yourself?   If
you do.....then you're not leaving your own shack ;-)

Tim

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