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RS-15 revisited



Yes, RS-15 is still there! I'm generally able to start hearing myself at
about 30 degrees AOS and continue until about 20 degrees before LOS which
doesn't sound great until you realize the size of it's footprint. I haven't
heard the beacon in at least a couple of weeks but I'm becoming convinced
that it's not a bad thing as the transponder seems to be on all the time
these days. Of course, now that I've written this, it will probably prove me
a liar and do something bizarre for a couple weeks.

RS-15 is a challenge because it's higher than most satellites and has a weak
downlink signal. Few descriptions point these facts out so the beginner
probably writes it off as another RS-12; You read about it everywhere but it
doesn't really exist. The difference between unusable and usable was the
downlink antenna. For the uplink, I have a high-gain beam (12 db) being fed
50 watts and that seemed sufficient but I could barely hear myself using a
dipole as a downlink antenna. I could hear the signal better with a rotating
dipole but QSB was terrible as it was with a typical turnstile. I took the
turnstile and turned it "sideways" so there's a horizontal and vertical
element. The feed line is attached to the horizontal dipole and that is
attached to the vertical dipole via a 1/4 wave (8') chunk of 50 ohm coax to
give it something of a circular pattern. A dipole has directivity, so the
horizontal element is mounted on a rotor in order to keep it facing the
satellite and the vertical element prevents the deep QSB. Using this
antenna, I'm able to get S5 signals out of the bird when it's close and this
is opposed to the S-Nothing before. I would guess this may be improved by
mounting the whole thing on the rotor in an "X" configuration (as opposed to
the "+" I'm currently using) but I didn't have the space on the boom. I
might also add that it's worked well as a plain old 10 meter antenna.

If you're interested in the challenge of using RS-15, give the turnstile a
shot and look for me around 28.380 MHz if it's passing by FN10. At a
minimum, if you can hear yourself fairly consistently through RS-15, you'll
be king of the hill on RS-13!

73...Mark - KB3CWS

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