[Milsurplus] tube question]

[john p hutchins]

Jim -

Thanks for the link, quite a good article I have some bad 76's 77's and 
6a7's Yes an LM- Freq meters.  While new/NOS  tubes are some what rare I 
think this procedure is worth a try.

For typical receiving tubes:

The indirectly heated cathode is the more modern type of emitter. It 
consists of a metal sleeve with the oxide layer on the exterior and the 
filament mounted within the interior. The indirectly heated cathodes 
include the a.c. heater types such as the 24, 27 and the Kellogg tubes. 
The oxide emitter types should initially be operated at rated filament 
voltage for at least one hour and then checked for quality and stability.

If they still are not satisfactory, then the following procedure should 
be used. With the tube in the tube tester, increase the filament voltage 
to 120% of rating while carefully watching the plate current or tube 
tester meter reading. The meter reading will slowly increase, hit a 
peak, then start to decrease. At the point of maximum reading, reduce 
the filament voltage back to rated value. Continue to operate the tube 
at rated filament voltage for at least four hours, then test. When two 
tests spaced one hour apart provide the same reading, the tube is 
rejuvenated as much as is possible.

Later
Hutch


Jim Whartenby wrote:

>Hutch
>Check out: http://www.antiquewireless.org/otb/rejuve.htm
>Regards,
>Jim
>
>--- john p hutchins <olegerityincj at austin.rr.com> wrote:
>
>  
>
>>Group -
>>
>>Is there a way to reguvanate a reciver tube lip 76 77 6A7 ?
>>Can this be done?
>>Thanks
>>Hutch