"You" wrote in message
...

It is the part where the PLL Frequency doesn't change because you
at using FM Simplex. There are many reasons for the PLL to change
between Tx and Rx, even with the radio in FM Simplex mode.

1. The receiver may have an IF Frequency of 10.7 Mhz which would
require the PLL to be offset from the Receive Frequncy by the
IF Frequency,

This is classic radio design, the vast majority of crystal controlled VHF
rigs from the seventies and eighties had a separete crystal for TX and RX
because of the IF stage in the receiver. Not true of all rigs though. The
FDK Multi 2000 as well as a PLL VFO has a number of crystal memories and has
a single crystal for each memory, but it's more the exception than the
rule - probably done to reduce cost of two crystals rather than one for each
channel.