DRAKE TR7 Service Manual download pdf (Page 9)

The encoder

The encoder included with the VFO really is not a good fit for the TR7. I used a Honeywell 601-VCS

encoder from DigiKey and that one has a shaft long enough to use the Tentec tuning knob, but not long

enough to accommodate the original Drake tuning knob and skirt. Other encoders with longer shafts

are available. The Honeywell goes for $28-40. There are four terminals on the encoder and you'd

expect the layout to be standardized, but it's not. The connections are for +V, Chan A, Chan B, and

Ground. The VFO connector assumes them to be in that order, but the Honeywell encoder is in this

order: +V, Chan A, Ground, Chan B. There is no datasheet available for the Honeywell, so if you use

that encoder make sure you reverse the leads in the connector to match the encoder.

Other Photos

Figure 10: The VFO board mounted using two of the original PTO threaded studs.

The board holes are about 1/8” further apart than the studs, but the long spacers

and screws can be moved just enough to make things fit.

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DRAKE TR7 Service Manual Page 9