Hi
I'm trying to troubleshoot a Philco FT-9. Unfortunately my tube tester (BK Precision 747B) doesn't have the switch setup for the 6A7, 78, 75, or 41 tubes. Were these superseded by other numbers? Any help would be appreciated.
I don't think you have the sockets for those tubes in that tester either. Check the continuity of the filaments and if those are good, there is a reasonable chance the tubes will be good enough to make it work. Anyone close to you that might have an older tester?
Hi Bill and welcome,
As Bob eluded to your tester is too new and doesn't test the standard base tubes. To answer your question yes they have been superseded but they have different style bases. The "new" self centering octal base tubes came out in 1935. You'll find that the old standard tubes sometimes are used up abt WWII.
GL
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
I have a melted wax capacitor on the 84 rectifier tube of my FT-9. Its labeled 30-4381-S. There is no other data on the capacitor. I have been unable to locate any information other than .01 value on the schematic. Because it is on the rectifier I'm guessing that its probably 1000 VDC. Any help identifying this cap would be appreciated.
I merged your FT-9 threads together. This will keep all your FT-9 Q&A and progress in one thread. (It makes it easier to locate and follow in the future).
I'll let the more experience folks answer whether you need 1000v there...I don't think so.
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
