[amsat-bb] Re: Question about vacuum and power module for linear transponder

[G0MRF@aol.com]

In a message dated 19/12/2009 15:36:41 GMT Standard Time, pe1rah at yahoo.com  
writes:

I also  would like to know if anyone has experience in SSB mode with the 
new power  modules types from Mitsubishi. Like the RA60H1317M, which can give 
60W power  on 2m with only 50mW input power. 
I am looking for some PA behind my  LE005-R2 transponder design, to get a 
small sized high-power linear  transponder. The transponder gives 200mW PEP, 
so the 50mW is no problem at  all.I just wonder how linear these Mitsubishi 
modules are, when using in  linear mode.



Hi William.
 
The RA60H1317M is hopelessly inefficient for use in space. It has  
reliability issues linked with the junction wires where they bond onto the  
substrate.
A better solution would be to build a class AB linear from 2 suitable  FETs.
An even better solution but one requiring a lot of development would be to  
separate the modulation into phase and amplitude and then modulate the gate 
with  phase and drain with amplitude. Efficiency >80%
 
Besides....where is your 60W going?  Venus?  Huge power....
 
David