[Milsurplus] RF-10 Tx audio repair

[Robert Nickels]

I posted a link to info on my homebrew RF-10 battery box a week or so 
ago, I thought I'd add that I've since upgraded the battery pack to 4 D 
cells.  The Radio Shack plastic 4D holder fits just fine - the current 
drain of the RF-10 is really too high for the AA cells I used to prove 
out the concept.

Unfortunately my RF-10 came out of the package with very low transmit 
audio.  I first ruled-out a bad mic element, then removed the mic from 
the RF-10 handset and injected audio into the transmitter so I could 
trace the signal through each stage.   I've heard that the technical 
documentation and schematic were classified by the Czech government and 
thus may be impossible to obtain, but with a little deduction I was able 
to identify the audio preamp board (it's the small PCB located just 
behind the headset connector) and function of the wires going to it.   
One of the NPN transistors turned out to be bad, and the radio now works 
just fine.

The transmit audio gain (deviation) level is set by a trimpot on this PC 
board.  Also, I can supply pin-out for the handset connector to anyone 
who needs this information.

73, Bob W9RAN