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Pin 10 adds 64 to the divisor when it is left open. An internal pullup resistor makes that pin a logic high (1) unless you ground it. Forcing pin 10 to zero now adds 128 to the lower divisor bits.

A radio built with the 11.325 crystal has pin 10 floating, logic 1. This is why grounding pin 10 bumps the frequency up 64 channels.

Likewise, in a radio with the 11.1125 crystal, cutting pin 10 loose from ground moves the radio down 64 channels.

Make sure L18 is peaked for max signal on TP10. Or if it's too new to have test points, probe pin 17 of the 8719 chip for peak signal.

This can affect the PLL's lock-in band width.

73

[QUOTE="nomadradio, post: 840750, member: 22"] Pin 10 adds 64 to the divisor when it is left open. An internal pullup resistor makes that pin a logic high (1) unless you ground it. Forcing pin 10 to zero now adds 128 to the lower divisor bits. A radio built with the 11.325 crystal has pin 10 floating, logic 1. This is why grounding pin 10 bumps the frequency up 64 channels. Likewise, in a radio with the 11.1125 crystal, cutting pin 10 loose from ground moves the radio down 64 channels. Make sure L18 is peaked for max signal on TP10. Or if it's too new to have test points, probe pin 17 of the 8719 chip for peak signal. This can affect the PLL's lock-in band width. 73 [/QUOTE]

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