If you pull the detector tube out, is there hum? How about the last IF
tube? How close to the front end can you get before there is still hum
after the tube is pulled out?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

My problem is called "tuneable hum". It has nothing to do with filter
capacitors, transformers coupling, cathode to filament leakage, etc.

It only shows up on certain stations. It depends on the path followed by RF
signal (e.g. if it passes through the rectifiers).

Typical cures a

- bypass capacitor across the power supply rectifiers
- bypasscapacitor between mains and ground.

But there still are some stations affected by a considerable hum. I was seeking
some suggestions on what to do more.

73

Tony I0JX