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Re: Microwave IF's for working AO-40 (was: Link budgets??)



Jerry Pixton (W6IHG) wrote:

> Any thoughts on S Band Converter output frequency? Choices seem to be
> 2 meters or 70 cm. If there really is some problem with 70 cm
> transmitter then 70cm might be the uplink band and therefore the
> Converter should downlink from 13cm to 2 meters??

Current L-band and S-band transverters from Down East Microwave
  http://www.downeastmicrowave.com
use a 2 meter IF (144-148 MHz).  They also sell an additional adapter
board that will convert any of their 2 meter IF transverters to a 10
meter IF.  So my initial thought was to strap the two transverters to
the crossboom of my antenna array (once I put it up with the elevation
rotor next Spring), and then add 2 pairs of coaxial relays so that one
transverter comes down to the shack "direct" on 2 meters and the other
one comes down through the extra board on 10 meters.  That way, any
combination of any pair of valid uplink and downlink modes, from HF
through S-band would be possible.  (I'll be ecstatic to get L and S
going, the "really micro" microwaves can come later!)

If you don't like the idea of coax relays to pick an IF, then another
solution that comes to mind would be to see if the 2 Meter to 10 Meter
IF converter could be modified to convert 2 Meters to 6 Meters instead
(or see if Down East was interested in making a properly designed
version of such.)  At least for those of us with a Yaesu FT-847, one
could put the L-band uplink on 6M which is not a satellite band, put
the S-band uplink/downlink on 10M, and the only combination that
would be unattainable is HF up and S-band down, a small loss I think.

Before you all pull out the flamethrowers, let me say that I *THINK*
that the FT-847 allows you to use 6M as one of the bands when in
satellite mode, though I keep forgetting to test this (and the radio
is 17 miles away from me as I write this). I seem to remember that
the wording in the user's manual says something like "you can pick
any two bands for uplink/downlink that are associated with a
different antenna connector on the back of the radio", and those four
connectors are HF, 6M, 2M, and 70cm.

Of course, Down East has wisely not finalized the design of their
Oscar-type S-band and L-band transverters, so they may have plans to
use a different IF also.  (Actually, the 23cm transverters they are
selling now, which are an upgrade from the model I use, have dual
sub-band capability, i.e. 1269 satellite and 1296 terrestrial
capability right now.)  But now that the bird is in orbit, we can
expect to see them start coming out with the new products.

And, of course, there are other products out there too!  SSB
Electronics is one that comes to mind.
  http://www.ssbusa.com
 
> Waiting and preparing.

Same here!

John (KBØZEV)

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