DRAKE TR7 Service Manual download pdf (Page 7)

RIT Details

I used the existing RIT pot on the TR7 after removing the existing wires from the terminals (clip the

bare ends and use a piece of heat shrink to seal the ends). You no longer need to use the RIT button

since the new VFO RIT activates when you turn the RIT pot off of center position.

Interfacing with the TR7

Other than the switches and LEDs, there are a few other connections you'll have to make in the TR7.

These are identified in the VFO instructions in general terms, leaving you to fill in the details. In the

following, you'll see photos of where I made the connections in the TR7.

The connections you'll need include:

1. DC power supply (Pin 1 of VFO J6 connector)

2. VFO output to TR7

3. Tx/Rx line (Pin 3 of VFO J1 connector)

Since the original TR7 dial lamp was no longer needed, I used the + lead from that lamp as the source

of DC power for the VFO. That provides approximately 13.6 VDC.

Unlike the original PTO, the VFO uses a coaxial lead to deliver RF to the TR7 motherboard. Luckily,

the motherboard already has an unused hole in the board ground plane right next to the RF input hole

and I used that for the coax braid.

Photo 8: The original RF connection from the PTO to the motherboard is the light

green wire just above the screw head.

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DRAKE TR7 Service Manual Page 7