[morzh]

Arran

I will be able to tell you what radio it is (it is a superhet with 6A7 pentagrid, as I said classic AA5) when come home this evening. Yes while receiving stations it was humming very loudly.

I will need to ask Kirk if he has a 43, he says he sent it to me but it is a 42 which would be the same were it nt for 6.3V filament


As for the idiosyncrasies of the 600, well, in the past when I first saw many of the same tube diagnosed as bad by it when restoring 37-116 and it was suggested that it might be the 600....no, it turned out to be the tubes.
Plus so far it never gave me a short indication on a tube that would not disappear on the same type good tube when tested.

In this case, again, one tube shows it solid when heater is on, another no longer shows it but did first. This tells me the 600 is not misbehaving but the second tube might have something intermittent. Obviously a third tube would be the charm