[amsat-bb] Homebrew 70cm uplink?

[John Mock <kd6pag@xxxxxxx>]

I'd like to have a way that 'no-coders' can do more than mode J-FM
without either buying expensive equipment, especially something they
won't have much use for otherwise.  So a satellite transciever wouldn't
qualify, nor would a transverter using HF gear.  But a 6m transverter
might be OK, since 6m SSB is something that they could use for other
things[*].  Used gear might work if one has an elmer, but without help, 
that sounds like a difficult option for someone who has no idea what
they're buying.

I know that given an AIDC downconverter (or equivalent), a scanner or an 
HT with all-band receive (such at the Kenwood F6A or F7E) is adequate for
hearing AO-40 with a covered BBQ dish, and given an Arrow-type antenna, 
also hear AO-7 and the Fuji birds.  But what about the uplink?

I've thought about building a T2 phasing transmitter kit, but there is
still the problem of going from its QRPp (+10dBm??) output to something
capable of driving 10-35W PA or module.  And then, what to use for that?
One would also need a reasonable stable tunable LO to drive the thing.

One could up-convert from 6m, but MJF 6m QRP rig is USB only.  So i've
thought about using a high level mixer with a ~486 MHz LO followed by
something like a helical resonator or SAW filter to get LSB, which, if
it can handle that much power, might drive said PA.  It could cover 
the passband of AO-40, but it may do little else if the LO is 'rock-
bound'.

It would be neat if the PA could be mast-mounted, eliminating the need
for expensive coax or always operating portable.  After all, according
to my simulations, at most times that squint is decent on AO-40, it 
could be worked with TV rotor and a quasi-polar mount, especially if 
one could tweak the maximum elevation seasonally.

Has anyone else looked at this problem, and what are your thoughts on it?

		         -- KD6PAG  (Networking Old-Timer, Satellite QRPer)


[*] I remember well the first SSB signal i heard in California with a new
MFJ 6m QRP rig and homebrew stretched quad (not even roof-mounted yet).  
It seemed like familiar grid square, but i couldn't place it immediately.  
Then i got it, it was VE6EGN, who i had worked many times on AO-57!  (And 
that was during the quiet part of the solar cycle...)
----
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