There were external VFOs that provided all the possible frequencies
for both the xtal osc and the VFO. A Jaapanese company made one. I
think a service monitor will do as well if the output level is high
enough, most have programmable frequencies like scanners. I think if
the weight and size weren't prohibitive the IFR 1500 would be ideal
because it's available cheap and because it has full duplex unlike the
more common 1200/500 series. You could of course just use a sig gen,
again, assuming the level is high enough. No where in the Collins
manuals is the drive level needed specified!


Most hams are such cheap asses the idea they should have a service
monitor would them **** their pants. Then again, most hams are so old
they do that anyway.