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Hmmm. Looks as if the Gemtronix GTX4040 and 5000 were the only radios I found for that kit. The PLL crystal in that radio is 15.250 MHz. Seems to me that back in those days the EXPO kits only went up or down 44 channels, not 45 like a "10-meter" radio. Adding 440 kHz to 11.250 would be 11.690 for upper channels. Likewise the lower band would be 10.81 MHz.
Don't know where they got that. The schematic shows a 15.25 MHz crystal that mixes with the radio's VCO and then feeds into the PLL. Only other crystal in the radio is 9.785 MHz and it's not part of the PLL.
Please advise me to what is a good replacement mic for my SR-497HPC... Answer: 497 is "wired like Cobra", so many choices available. That radio does not need a power mic, so purchase a stock "coffin style" mic with a decent cord, like the ones that Astatic uses. The Superstar DM-507 is my go-to. https://www.ebay.com/itm/3050474478...adANq91JSiEEnz8EGqPJRBloTgEyaVsBoCtoMQAvD_BwE $12.99 + .99 cent shipping.
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