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Re: AO-7 Euphoria and ECHO

On Tue, 25 Jun 2002, Robert McGwier wrote:

> People are forgetting that we have signed a contract
> to build a satellite with Spacequest.  The contract
> includes the  receivers and transmitters.  The

The satellite is derived from the microsat design. Unless they've made
radical changes to the receiver and transmitter modules, the satellite's
primary RF hardware can't support a linear transponder anyway.  The 
transmitters in particular are NOT linear.

> only thing not under contract is the TSFR module
> for our experiment if I read the recent article
> and filter it with discussions held here.   I would
> bet there is no provision in our contract for
> changing these details.  Maybe FRH could give us
> the details of the contract ;-) and tell us if we
> could make such a significant change.   I don't think
> we could fit a Mode B transponder in the TSFR module.

An analog reciever could certainly fit, and a low power (couple of watts
max) transmitter as well.  The AO-27 "bent pipe" RF deck is entirely
inside the TSFR module, taps off the 2M antenna for RX and has a dedicated
1/4 whip on the -Z face for TX.  So a very simple linear bent-pipe
(IF-to-IF) might fit, at the cost of whatever else is vying for the space.

There remains the problems of a decent antenna, frequency compatibility
with the primary RX and TX, and POWER BUDGET.  I think the combination of
a low power downlink, marginal antenna gain, and limited power make flying
an linear transponder on a microsat a challenge at best.  We'd all prefer 
something with the performance of RS10/12/13, or AO7, over, say, RS15!

Just my 2 sheckels.

Stephan A. Greene     sgreene@patriot.net        ka1lm@amsat.org

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