On 4 Nov 2016 17:48, "Bob Camp" <kb8tq@n1k.org> wrote: > > Hi > > The only practical way to set the 10811 or 10544 is with a >= 10 turn pot on the EFC. I > never have worked out just why there are so many instruments that don’t have a pot on > the EFC. > > Bob I'm amazed my 18 GHz HP 5342A counter has no pot. IIRC the standard TCXO does, but the counter drifts a lot with that. After fitting the optional 10811A OCXO, I discovered it is almost impossible to set the frequency from the mechanical control. I guess I should modify the counter and add a control. It really is odd that there's no such facility. That said, the difference in value between this old counter and the newer microwave counters like the 5351B has fallen. The newer ones are much more sensitive too. Dave.