[amsat-bb] Finding my Downlink on AO40

["w4tas" <w4tas@xxxxxxx>]

A little help please!!

I have several pages of published AO40 uplink and downlink frequencies. 

My problem is I can't make the indicated frequencies on my radios 
match the charts. I am always about 30 KHz off. I have partially 
compensated for this by listing the actual frequencies I have set up 
in the radios and that usually gets me fairly close. 

I started trying to find the problem yesterday by exactly calculating 
the fequencies that the satellite would see (by using the doppler 
readout on IT 1.5) and trying to get them to match the charts. I am 
putting 2400 in for the beacon frequency in IT 1.5 to get the doppler 
correction. I am ratioing the beacon doppler to 435 MHz to get the 
uplink doppler which will be proportional to the actual frequencies. 

Needless to say I failed to make the numbers match. I was off 
by about 45 KHz. 

I am using the beacon frequency of 2401.323 and the doppler 
correction on IT 1.5 to find the offset of my Transsystem converter. 
It usually turns out to be about 5 to 8 KHz according to the 
outside temperature. It's about 80 F in the day and 60 F at 
night here in Brandon, Florida (eat your heart out). It don't get 
any better that this!!!! But I diverge. 

I have checked the frequency of my uplink transmitter and it is 
within 100 Hz of the indicated frequency. 

Can anyone give me a better way to get on the right frequency
or tell me what I am doing wrong. 

Thanks, 

Tony
W4TAS



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