[amsat-bb] Re: HF satellite?

David Giles vk5dg at amsat.org
Sat Jun 6 15:50:22 PDT 2009

Hello Bob and others,

Just to get the ball rolling on what you require for the 10m/12m 
transponder.  I have no experience in building anything like this, just 
a lot of questions buzzing around.

What are the maximum physical sizes?
What is the power supply voltage and maximum current?
Does it need a beacon, be it a keyed input or even a continuous carrier?
Can it use any sections of the #2 transponder? e.g. an IF output from 
the 29MHz section.  Or will they just share an antenna?
How much bandwidth should it be?  Can it be based on a ceramic filter 
e.g. 50kHz at 4.5MHz from a TV or 25kHz at 45MHz used in FM radios.
What is the expected 12m power output?
Are there any link budget calculations?
Is there any segment of the 12m band that will be better suited?  In VK 
SSB is recommended from 24.930-24.990MHz

73 de David VK5DG

Robert Bruninga wrote:
> We are considering an HF transponder for our next long range
> CUBESAT mission planning.  It can have three modes:
> 1) APRS 1200 baud for command and control and APRS on 145.825
> 2) PSK-31 multi-user SSB uplink on 29 MHz and FM down link on
> 145.825
> 3) 29 MHz uplink and 24 MHz downlink SSB transponder
> We will welcome someone in the AMSAT community that wants to
> contribute to mission 3, the HF transponder.  We tried the #2
> PSK-31 mission on PCSAT2 and RAFT, both failed due to HF antenna
> deployment problems.  Now we are going to try again...
> Bob, WB4APR
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