[EdHolland]

..Wish I'd been here years ago...

Thanks for the tips on protection. With two instruments, I should be in decent shape now, as the Heathkit can take on any direct connection duties. The local surplus place can furnish all the necessary parts. I reckon 5 V Zeners and a cap would do the trick.

It occurs to me now that even the transformer idea needs to be done with care, as a DC path to ground should still be avoided on the device test side, otherwise all sorts of interesting fireworks and blue smoke releases may occur. Plus Morz's point about it passing deadly spikes...

I do have one of those frequency counter displays that could be used in combination with the Heathkit, so the test setup should be robust and accurate.

The old SS generator still has one good O/P, which I might try as the "Exciter" for my low power shortwave beacon. It would be nice to try some different frequencies in the 22 m (ISM) band in the hope of a few more reports. It has limited tuning by pulling the crystal, but that doesn't get me far from the center band noise that predominates on 13,560 kHz.

Cheers and thanks again everyone,

Ed