In its present form, the Yaesu CT-58 cable set which Yaesu recommends for use with the Quadra and the FT-710 does not make use of the transceiver's TX REQ lead (which appears on the ring of the 3.5 mm TRS REM/ALC plug).
When grounded, TX REQ keys the exciter to obtain a tuning carrier which the Quadra requires to run the F SET and TUNE functions.
To enable these features when driving the Quadra with the FT-710, connect as follows:
Instead of the 3.5mm T/S to RCA cable supplied with the CT-58 set, use a stereo 3.5 mm TRS to dual RCA cable, length 1m or 2m.
Connect the WHITE RCA plug (Tip, ALC) to ALC 1 on the Quadra rear panel.
Connect the RED plug ((Ring, TX REQ) as follows:
Centre pin to Quadra Band Data 2 Pin 11.
Shell to Band Data 2 Pin 9. This connection can be made via the Band Data 2 cable supplied with the Quadra (DBM15 to RCA) and a double-female RCA barrel connector.
Insert the 3.5mm TRS plug into the REM/ALC jack on the rear panel of the FT-710.
Set exciter RF POWER to 60-65W.
Pressing the F SET or TUNE key on the VL-1000 front panel will now start an F SET or TUNE cycle, respectively.