I have been making some mods to my RT85 transceivers, most recently was adding a fan to the PA heatsink, using some old Intel Pentium2 fans, simply glued them to the heatsink, added a thermal switch to the internal heatsink, a BC-547 NPN, a couple resistors, so the thermal switch drives the BC-547 which supplies 12v to the fan, radio gets hot on long overs, fan cools it now.
(The thermal switch was a PEPI 46deg from WES Components)
Did this to both my 6metre versions (E-band), one for car and the other in the shack. The third RT85 is a A-band for monitoring on 2metres.
Added a Repeater Reverse switch, for the Repeater Reverse switch, I had already converted the RT85 from 2716 eprom to 2732 eprom, which provided two banks of 80 channels, the 2nd bank has all the rptrs in reverse, so when monitoring a repeater channel, just flick the switch to go to Reverse mode.
Added a Tx Power Hi/Lo switch to the remote head, the Hi/Lo power mode is already available, via a link on the remote head, just added the switch to bring it out to the remote head front panel.
Added LED backlighting to the remote head, this was simply adding a small green led & a resistor and soldering to the front cct board in the remote head, this now backlights the key buttons, so they I can identify the buttons when driving the car at night, instead of guessing which button is which.
Replaced the rubber contact switches in the front panel of the Remote head, used some tactile microswitches ( Jaycar p/n SP-0603 ) Just unsolder the old switches, cut off a pair of diagonal legs of the microswitch, bend in the remaining two legs carefully and push in and solder to the board, get the switch base as close to the cct board as possible.
Added a 3.5mm mono socket for the speaker connection from the remote head., unsoldered the tow spade tags, glued the socket (DSE p/n P-1231) and soldered it in. So can now use a speaker with the standard 3.5mm plug
Added a RJ-11 socket for a microphone connection on the Remote head, used a RJ-11 (Jaycar p/n PS-1470 ) as it had the required 4 pins and was the smallest compared to RJ-12 and RJ-45 sockets., glued the socket on the back of the Remote head, next to the 3.5mm speaker socket, and solder wires around to the pins where the old microphone cable fed to. On the microphone lead, simply cut and spliced a 4 pin RJ11 plug cable to the existing microphone curly cord and heatshrinked it.
So finished all this off last week, put one 6metre in the car, the other in the shack, and the 2metre unit in the shack too.
Will add photos, etc, to the website page at some stage.