While you went looking for more info, wanted to cover this little ditty you mentioned...
.I did notice last night that the voltage on the collector went from 13.5 volts which is what the power supply is providing up to almost 17 volts when the volume knob was increased..
The "measurement" if it was done with a simple DVM - is normal...
Why because the Driver turns on, when the Pre Driver gets a trigger - thru Pin 3 - of the Microphone jack/Plug - that opens the Pin 4 Receiver Speaker Return - in turn, being the Predriver into Driver now there is power going into the BASE of the FINAL - to TX power out - using that power that would otherwise be forced to go thru the speaker.
So when you turn up the volume - this same effect is happening only you see it on the FINAL because as you turn up the Volume to hear the speaker, this same line - goes to the Driver AND FINAL - and the SPEAKER - AT THE SAME TIME - only one section works at one time - until you key up and force the Audio that would otherwise have gone to the Speaker, into the Collector of the FINAL and DRIVER - modulating then feeding them Power. Making the Audio into RF.
How???
because - the Pre-driver supplied the Driver with RF just enough to turn it on, and then apply the Audio you disconnected from the Speaker Return on Pin 4 of the Mic cord, into The Driver and Final - but to turn them on requires RF thru the Pre-driver, into Driver, turning it on by applying RF to the BASE of the Driver. How? By using Ground to complete the Pre-Driver's Power Circuit, done on Mic Pin 3 by grounding it thru to Pin 1 on the Microphone cord this turns on the RF the Predriver makes, just a carrier, but enough to turn on the Driver.
So why does the voltage go up when you turn up the Volume?
Because they share the same feed off of the Audio Transformer (Modulation Transformer) so as you turn up the volume to hear the audio - the audio amp puts more power thru this Transformer - you see it as an increase in voltage - it's the spikes of audio power embedded in the DC signal ADDED into and forms a complex vector of power and DC current into both the Speaker winds and the Driver and Final lines - at the same time.
When you key the Mike - you disconnect a wire thru a set of moving contacts
Those contacts switch over to connect another pair of contacts - which one turns on your TX mode, (ground your Predrivers Power circuit) and the other turns on the Mic element in the Handset to send Mic audio to be amplified and then put thru that Audio Transformer into the Driver and Final