John,
Since you mentioned PTT I thought I would share some information going beyond the actual question! So here goes...
I forget the manufacture, but it was an enclosed 4 pole double pole-double throw relay. I probably ordered it from Mouser. That goes back about 25 years and it has not failed yet! Gold plated contacts really does not buy you anything for the application in the Ranger. Gold is typically used when switching very low currents. There is ample wiping of the contacts along with enough current through the contacts to make them move slightly which keeps things clean.
I chose to do things a bit different when I did my PTT scheme in the Ranger. It follows closely what Tim, WA1HLR recommended. I switch 4 basic functions when going from transmit to receiver. They are as follows:
1) 120 VAC to the antenna relay contacts on the back of the rig
2) VFO Keying line
3) Screen voltage on modulators
4) Screen voltage on final
The result from switching those items allow for a educed standby current. The rig runs much cooler. For the keying voltage, I rectified and filtered the filament voltage in order to power the coil of the relay. If you do that and you use a very high impedance mike, like a D-104, you need to filter the voltage very well otherwise hum will be picked up in the self contained PTT/ Mic Cable. I have an external PTT switch on a master control rack panel so I don't use the mic cable PTT scheme.
More details on a similar scheme can be found over on Steve's AM Window site:
http://www.amwindow.org/tech/htm/rangptt.htmAs you will notice, Tim used 2 relays with some spare contacts to
'boot". He also used an extra set of contact to control the pilot lamp on the front panel.
As mention, I have used this scheme for over 25 years and it has never given me any problems.
Have fun!
Joe, W3GMS
