Hi Christian,

The S-Meters issue you describe does occur on Eddystone valve sets.  The problem is usually one of the resistors forming the bridge circuit either side of the meter going our of tolerance with age.  The S-Meter circuit is similar to that of the 680X (see my restoration article for this receiver) – only the component numbers have changed to protect the innocent…  In the 730/4, I would start by checking R23, R27, R59, R61, R60 (the adjustment pot), C61, contacts on SW14, V9 and V5 (and its remaining associated circuitry), assuming that the set is otherwise working ok and that the meter movement is not damaged.

Regarding the crystal calibrator, the one fitted to my 830/4 provides reasonable strength markers across the whole range of the receiver.  I am not sure how the calibrator signal is coupled into the receiver circuitry in the 730/4, but I would suspect it is by stray coupling, possibly by a short length of wire from the calibrator unit into the tuning gang area of the set (come on guys that own one – help me out here).  Suspect that this needs re-positioning to obtain better injection (if this is how its done on your particular set).  If this seems ok or does not appear to help, then suspect a weak V10, weak crystal, out of tolerance resistors in the calibrator circuit (R51, R52, R53), high-resistance contacts on SW10 or even a leaky C87.  Start by checking the HT voltage is ok with the calibrator switched on.

Good luck and enjoy a great receiver – I wish I had one!

Regards

Gerry, G8GUH