----- Original Message ----- From: "IK1ZQJ Mario" <mhz1575_69-a...@yahoo.it> To: "AMSAT-BB" <amsat-bb@amsat.org> Sent: Tuesday, August 25, 2009 9:16 PM Subject: [amsat-bb] Re: 23Cm Up converter
> Hello Domenico I8CVS > Coming back to the transverter, do you think that the IF in VHF is > suitable also when I'm working in mode L/S where the Smode is done through > a down converter 2400/144MHz? > I'm scratching the head to take a decision.. > > 73 Mario IK1ZQJ > Mario, My downconverter is also a homebrewed 2400/144 MHz and I have used it for AO-40 where the analog downlink was 2401.225 - 2401.475 MHz and middle beacon was 2400.350 MHz so that only to tune the IF from 145.225 to 145.475 MHz was necessary. In order do not interfere the receiving IF while transmitting I was using an IF from 144 to 145 MHz to drive my 23 cm transverter and get out from 1269.250 to 1269.500 MHz for the uplink into the L1 band or 1268.325 to 1268.575 MHz for the L2 band but obviously two diffent switchable XTAL's where needed into the transverter because time to time for the mode L/S the transponder uplink was switched from the L1 to the L2 band. The above complication was justified at that time because AO-40 and the previously launched satellites OSCAR-10 and OSCAR-13 where the only HEO satellites covering the most part of day time for many and may hours every day. As you can see any transverter with an IF falling into the amateur band has problem for satellite use full duplex and also for frequency agility in terms of changing quickly many operating frequencies in a quick time. Transverters are good if you use the same frequency for RX/TX as for tropo or meteor scatter or EME but for satellite use where the operating mode novadays are many and they changes every week a transverter has many limitation. For the above reason I strongly recommend to receive the S band using the actual downconverter and look for a second hand tranceiver for the rest of it. Best 73" de i8CVS Domenico _______________________________________________ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
