Authored by VE3EFJ
8.0 RV-3 AND RV-4 REMOTE VFOS
These units are functionally compatible to both the TR-3 and 4. To have the RV-4 work with TR-3 only a minor change is required. Both units use a 12AU7 in the buffer stage. The RV-3 uses a 6AU6 for the oscillator; the RV-4 is solid state using an FET. The RV-4C uses the dual dial plates common to all the C line and the SPR4.
The RV-3 will work with the TR-4any, but the RV-4 will not work with the TR-3 unless the TR-3 is modified. On the remote VFO plug on the TR-3, cut the jumper wire running between pin 2 and 8. If in the future you remove the remote VFO, you must restore the jumper or make up a dummy plug from a Cinch Jones connector.
Summary of Remote PTOs
 | RV-3 All vaccuum tube. Will work with the TR-4 series. |
| RV-4 Remote VFO for the TR-4. Single dial plate. |
| RV-4C Essentially an RV-4 with C series dial plates. It and the RV-4 will work with the TR-3 with slight TR-3 modification. |
| RV-7 Remote VFO for the TR-7. Uses standard PTO. Seems to come or have been adaptable to 'full' length (TR-7 depth) or 'half' length. Dedicated Cinch cable for use with the TR-7. |
| RV-75 Consider it a remote VFO for the TR-5. Will not work with the TR-7 without the harness cable adaptor. Rare and expensive. This is a digital VFO and can be considered 'driftless'. |
