[amsat-bb] Seeking Mode JA System Opinions

[Eric June <ericj@xxxxxxxxxxx>]

Hello all,

I am an old HF guy who is just starting out with the satellites.  I have 
made a dozen or so contacts on RS-12 using equipment lying around the 
shack, and now I would like to take the next step and become QRV on the 
Mode JA LEO birds (FO-20/29, AO-27, UO-14).  My main constraint is some 
vague CC&R language that doesn't specifically prohibit ham antennas, but I 
would like to keep as low of a profile as possible.  I am therefore not 
shooting for an AO-40 or AO-10 capable station at this time.

I currently use my IC-706MKIIG (50W) feeding an M2 Egg Beater via 70-ish 
feet of 9913FX on the 2m uplink.  If I assume that the gain of the antenna 
roughly cancels the coax loss, I get around 50W ERP on 2m.  I may increase 
this 3dB to 100W in the future if I pick up a TS-2000, poor intermod specs 
(?) not withstanding.  I believe that the continued use of this 
omni-directional antenna setup should be fine for the Mode JA uplink on the 
LEO birds, am I correct?

For the 70cm downlink, I haven't been able to locate my "ideal" antenna, 
which would be a crossed yagi with about 6-7 element pairs.  So, I ordered 
a SP-7000 preamp from SSB Electronics (.9 dB NF, 10-20 dB gain) and will 
mount that on the mast with whatever antenna I end up going with.  This 
antenna/preamp would also be fed with 70-ish feet of 9913FX.

For the antenna, I am currently leaning toward a Cushcraft A449-6S, a 6 ele 
end-mounted LP yagi.  This would sit on a mast protruding from my rear deck 
with a Channel Master 9521 TV rotor for Az rotation.  I would incline the 
yagi upward at about 30 deg and do without elevation control.  The yagi is 
designed for the FM portion of the band, I'm not sure what VSWR will be in 
the satellite band, but I don't really care since it is a receive-only 
antenna.

I considered an Arrow II (leaving out the 2m elements) but it is really 
intended for portable operation, and I am in a mountain location where 
70-80 mph driving snow is not unusual.  The M2 436CP30 is way too big for 
my location and would probably be overkill anyway.  An 11 element yagi 
might be nice, but I don't think I can end-mount it.  If the 6 ele 
Cushcraft performs poorly, I suppose I could buy a second and phase them to 
get more gain and CP instead of LP.

I'd appreciate any comments, insights, opinions, or recommendations from 
you satellite veterans.  Do I have enough "oomph" on the downlink?  Any 
better ideas?


73,

Eric, KU6J

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