[amsat-bb] Re: Tuning

Glen Zook gzook at yahoo.com
Sun Apr 19 07:57:17 PDT 2009

Back in the "goode olde dayes", when OSCAR VI and OSCAR VII were the only 2 satellites available, the general consensus was not to try to compensate for Doppler by moving the transmit frequency.  Since everyone knew that Doppler would affect the downlink frequency we just kept a hand on the receiver and manually compensated for the Doppler shift.  Trying to compensate for the Doppler by changing the transmit frequency only complicated things even more.

Also, having a fixed elevation of around 30 degrees on the antenna generally took care of the need for an elevation rotor.  Yes, if you had an elevation rotor you could often extend the coverage by between 10 and 20 percent.  But, for those who did not have an elevation rotor fixing the antennas at around 30 degrees above the horizontal worked pretty darn well.

Glen, K9STH
AMSAT 239/LM 463

Website:  http://k9sth.com

--- On Sat, 4/18/09, Art McBride <kc6uqh at cox.net> wrote:

For the linear transponder Satellites I have found with my IC 820H using the main tuning dial to adjust receive and switching that side and adjust for transmit works the best during Field Day operations. The I-Com is just to clumsy to use the sub receiver, RIT does not have enough range, no easy way to adjust the offset, transmit power, ETC. I calculate the offset VS time using Instant Track in advance and work off of paper data. I set the elevation of the mast to match the pass and a single rotator performs both elevation and azimuth functions. 


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