Hi Alan, VY2WU
It is not a rule of thumb but a simple math calculation for frequency conversion.
As an example :
If you need to receive 435.000 MHz from your UHF downconverter and your LO is 424.996550 MHZ than you have to tune your HF receiver to the IF frequency of 435.000 - 424.996550 = 10.00345 MHz
The image frequency or mixing product will be:
435.000 + 424.996550 = 859.99655 MHz wich is very far from the frequency of 10.00345 MHz to wich the HF receiver is tuned so that don't worry about because the HF receiver have input filters and the image frequency of 859.99655 MHz will be attenuated a lot of dB from the wanted IF frequency of 10.00345 MHz.
73" de
i8CVS Domenico
----- Original Message ----- From: "Alan Beck" becka@eastlink.ca To: amsat-bb@amsat.org Sent: Wednesday, May 09, 2012 1:43 AM Subject: [amsat-bb] frequency conversion
What is the rule of thumb in finding the exact frequency on the HF radio
for a given frequency on a UHF downconverter.
My LO is 424.996550 MHZ.
Does this create a mixing product that I then have to compensate for?
Alan VY2WU
BTW Sold my 1978 VW Westphalia camper to get my new radioes. _______________________________________________ Sent via AMSAT-BB@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