RT85 mods by Alan Beard VK2ZIW
====== RT85 not RT85A to 6m ==
Everybody has a 2m/70cm mobile radio, but with 6m, they are very pricy.

1) Eprom board
	Remove both pin header sockets to lift them up.
Do this:	Solder a thick piece of wire to all 12 pins
		Heat the lot and pull off the pin header sockets
		one by one. Now you have a clear end of the eprom.
		Solder your thick wire to all eprom pins, one side.
		Heat the lot, lever out the eprom, a side at a time.

Solder suck board holes, refit low profile eprom socket, refit
pin header sockets with a strip of vero-board under them.

Eprom file, in this directory: 6metre.bin

2) Rx VCO 
	Add 6.8pf across oscillator coil L702 (under board).
	Add 6.8p across cap to varicap.
	Add 6.8p across L707 & L708.
3) Tx VCO 
	Add 6.8p across osc coil L107
	Add 33p across cap to varicap, C134
	Other mods suggest: Add lOp to C137 (parallel to L107)
	Add 33p across L112 mixer drive coil.
	Add 33p across L114
	Tune L107, set TP101 to 2.0V on 52.525 (channel 0)
	Tune L107, set TP101 to 3.3V on 53.925 (channel 35)
	Screw Synth, RX and TX VCOs board back in.

4) Reciever board	(Moulded coils, cannot be rewound.)
	Add 33pf NPO across coils L201, L202, L204, L205
	Under board. Jaycar part RC5318
	Add 3p9 across LO coils L209 and L210, SMD caps marked f0 (5p)
	C220, C223.

5) TX PA
	All PA mods done from top of board, no need to remove board.
	L503 becomes 5 turns, L507 3 turns, all counted on top
	L512 2 turns, 5mm dia, L513 3 turns

=============== Problems ===================
VCO lock problems:
I suspect, the VCO range is insufficiant, TX in particular.
This happened with 2x 6.8p caps across L107, so I changed
one 6.8p, then 33p across C134, for more lock range (as above).


=============== CTSS =======================
I fitted a tone gen board, set to 123Hz, to P358 pin 6 via 150K
Power from P358 pin 8.
Works for W'gong, Gosford and Lawson.