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Beginner high-orbit sats



W4SCO wrote:

But if there was a sat up there in space with a high orbit (easier to track)
that
TRANSMITTED on U Band (70 cm) where all these rigs could "LISTEN" to it ...
hams could use their existing radio and antenna to LISTEN to the new
satellite. THEN if they got hooked and could see that they could HEAR it,
then they might opt to buy the L Band module so they could TALK to it.

I will contribute to a new Amsat sat project BUT only to one that does the
above, as its primary mission capability. I believe it will be the best way
to get hams to join the SSB part of amateur satellites in the future... and
to join AMSAT. I contributed a good deal to AO-40.

Could Project Eagle be reworked to do this?

Wayne W9AE replies:

Eagle will satisfy your goal of being usable with an off-the shelf multiband
radio.  It will support mode U/V (435 MHz uplink, 145 MHz downlink).  Due to
the small size of the spacecraft, the 145 MHz downlink will only be with
omnidirectional (or low-gain) antennas, used near perigee.  Even so, mode
U/V will provide longer access windows and much greater DX potential than a
LEO satellite.  A typical new ham with a Tech license might get into ham
radio with a multiband all-mode radio and a VHF/UHF high-gain collinear
vertical antenna, with diplexer.  That setup would allow them to access
Eagle near perigee at low elevations (below 20 degrees), where there is
considerable DX potential.   If they like the taste of satellite DX, they
might then be motivated to upgrade to yagis and az/el rotors to access mode
U/V at higher elevations.  The yagis and rotors would also be a useful
upgrade to their terrestrial VHF/UHF communications capability.  After that
it is a trivial upgrade to add a dish and downconverter to receive the
S-band downlink to greatly increase access time by using the satellite at
apogee.  I remember making near-perigee AO13 contacts with stations that
were using collinear verticals.  It wasn't widely done then because there
were no low-cost HF+VHF+UHF radios at the time.  Nowadays a new ham can buy
a used FT-847, a new collinear VHF/UHF vertical and diplexer for $1000.
It's a GREAT way for a new ham to get a taste of satellite DX with no
investment in satellite-specific antennas.

You could argue that mode U/V isn't a "primary mission" without V-band gain
antennas.  But I think it's a reasonable tradeoff to get Eagle in such a
small package.  Eagle is a high orbit satellite, but its size and mass is
hardly bigger than LEO satellites such as FO29 and AO7.  That's important
when we pay commercial rates for launch.  We need to develop expertise with
small, lightweight high-orbit satellites that we can afford to launch.  By
definition, smaller and lighter means minimal propulsion and a resulting
low-inclination orbit.  I think that's also a good tradeoff to reduce cost
and increase reliability.

Wayne Estes W9AE
Mundelein, IL, USA




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