Thanks for the great tips. I guess I will nail down a manual/schematic and lay down a battle plan from then on. I like the VFO/RF section idea.

73,

Mark


[quote=K3HVG]Mark, I built a control head. No big thing. Also, AM is the deafult.
All you really need do is plug in a mic on the front panel. RF and AF
gain must be controlled externally, of course. The crystals you have
won't do you much good but you can have a set cut for.. say 3885, or
such. That's what I did. I hooked a Heath VFO up to the transmitter
and it worked OK. The 18-S4A receiver is much better than the straight
unit inasmuch as it has a mech filter installed. The straight unit is
as broad as a TCS! Also, I did not use the fixed elements in the TX
tank circuit. I brought out the "untuned" RF into an external
PI-network (instead of the tuner) for 80 meters. That way, I could tune
wherever needed and not worry about the fixed freq. tank components. I
have both original Collins 18-S4 and 18-S4A manuals. Unfortunately, I
no longer have "unlimited copy capability"...hi!