Man, this should be called the nostalgia string. Your Esquire made me think of my Fox 15 powered Esquire and of all those times I was flying single channel all alone.
It had a Babcock compound escapement for rudder and a Citizen-Ship escapement for throttle.

I also had a K&B .049 powered Lil Esquire. It had a 3 volt transistorized Citizen-Ship LT3 super regenerative receiver and compound escapement.

That's my green and white Esquire in the photo and it's MRC Arcon Company transistorized relayless superhet receiver and Citizen-Ship 3-tube transmitter.
One transmitter photo shows the DC to DC converter built from an Ace kit that eliminated those two expensive 67.5 volt batteries and the 1.5 volt lantern battery.
Six volts was supplied to the converter by cheap military surplus Ni-Cad wet cells and converted to 135 volts DC.