I have no experience in building one either, but I would think that the 10.7 MHz IF of a typical FM receiver, designed to feed a 455 KHz 2nd IF, would give ample bandwidth. Follow it with a 100KHz filter, mix with a 14.2xxx LO, into your 24 MHz PA, and you've got a transponder.
I think...
George, KA3HSW
----- Original Message ----- From: "David Giles" vk5dg@amsat.org To: bruninga@usna.edu; "Amsat-Bb@Amsat. Org" amsat-bb@amsat.org Sent: Saturday, June 06, 2009 5:50 PM Subject: [amsat-bb] Re: HF satellite?
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