12-12-2016, 12:01 PM
(12-12-2016, 10:46 AM)pwdrive Wrote: Mullard, amongst others did hearing aid valves:
http://www.r-type.org/exhib/aaa1378.htm
Lawrence.
Thanks. I think that they may have been the ones that Gramps aid had in it. It also used a 15 volt battery for HT similar or same as the type used in the AVO 8 meter.
These are the ones that I have a few of, http://www.radiomuseum.org/tubes/tube_ck6418.html I've found them functionaly equivalent to the JAN6148. I think the commercial version was designed to be a long life version of that. Once switched on, a proximity fuse valve wasn't expected to live long I suspect! However I've never had a JAN 6418 fail either when I've used them. The secret is to keep the filament voltage at no more than 1.2volts, they're great little valves at low power, even at low rf, but very microphonic if pushed. Cheep too, if you buy quantities.
And Nick, if you're interested in unloading a few of your stock, let me know, I'm always tinkering!
Andy.
