[amsat-bb] Re: ISS Crossband Repeater

Patrick STODDARD (WD9EWK/VA7EWK) amsat-bb at wd9ewk.net
Sun Jan 11 20:36:58 PST 2009

Hi Tim!

> My experience in seven months of working the FM satellites and, more
> recently, the ISS, is to leave the transmit frequency alone. Period.

Keep in mind that the ISS TM-D700's receiver is that of a ham mobile
radio, not the broader receivers we're used to on the FM satellites like
AO-51 that are essentially compensating for the small amount of Doppler
shift on your 2m transmit frequency.  Whether or not you have to vary
your 2m transmit frequency for the current ISS crossband repeater will
depend on many variables related to your station and the ISS ham gear.
What may be needed for one pass might not be needed on others.

On an ISS pass yesterday morning, I had to start the pass transmitting
on 145.985 MHz with the PL tone.  Once I was ready to tune the receive
VFO down from 437.810 to 437.805 MHz, I was able to move my transmit
frequency up to 145.990 MHz for the remainder of the pass.  Due to the
buildings around the hamfest site yesterday, I was not able to work that
pass all the way to LOS.  If I had, I might have had to move my transmit
frequency up to 145.995 for the last minute or so.  If I had a 2.5 kHz
tuning step on my radio, I would have used that and started talking on
145.9875 MHz before moving up to 145.990 MHz.

With all of that said, it has been fun to have the cross-band repeater to
use - both in V/U and (previously) U/V modes.  I hope it can be turned on
more often in the future.



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