Trio TS-700 CW Modifications
The following modifications align the cw signal to usb and not lsb which is correct for VHF operation.
Side tone generation is also now provided thanks to modifying the 1750c/s tone generator which is of course no longer required, the tuning fork is removed and substituted with capacitors which provide a lower frequency note.
1) Swap the carrier crstals X1 and X2 (CAR unit)
2) Remove and discard the capacitor C3 (across TC3)
3) Swap USB and LSB leads on CAR unit
4) Disconnect lead to OSW pin on FM IF unit, this lead now feeds a relay which is used for a TX audio monitor facility.
5) Connect a lead from the OSW pin on the FM IF unit to the CWT pin on the CAR unit.
6) Remove and discard MF101 and C101 on FM IF unit.
7) Change the value of capacitor C101 to 0.02mfd and fit a 1500pF capacitor across pins P and S (loc MF101) on FM IF unit.
ALIGNMENT
Note that the trimmer TC1 now adjusts LSB car
trimmer TC2 now adjusts USB car
trimmer TC3 as before adjusts CW offset which should be about 800c/s.
The addition of the simple circuit below now provides "key down" switching for the new side tone generator. The key line input comes straight from the key jack socket. The side tone level pot (VR101) on the FM unit should be set to about mid point.
The following modifications align the cw signal to usb and not lsb which is correct for VHF operation.
Side tone generation is also now provided thanks to modifying the 1750c/s tone generator which is of course no longer required, the tuning fork is removed and substituted with capacitors which provide a lower frequency note.
1) Swap the carrier crstals X1 and X2 (CAR unit)
2) Remove and discard the capacitor C3 (across TC3)
3) Swap USB and LSB leads on CAR unit
4) Disconnect lead to OSW pin on FM IF unit, this lead now feeds a relay which is used for a TX audio monitor facility.
5) Connect a lead from the OSW pin on the FM IF unit to the CWT pin on the CAR unit.
6) Remove and discard MF101 and C101 on FM IF unit.
7) Change the value of capacitor C101 to 0.02mfd and fit a 1500pF capacitor across pins P and S (loc MF101) on FM IF unit.
ALIGNMENT
Note that the trimmer TC1 now adjusts LSB car
trimmer TC2 now adjusts USB car
trimmer TC3 as before adjusts CW offset which should be about 800c/s.
The addition of the simple circuit below now provides "key down" switching for the new side tone generator. The key line input comes straight from the key jack socket. The side tone level pot (VR101) on the FM unit should be set to about mid point.
