[Boatanchors] Audio Amp Schematic for Type 48 Tube?

Wilson infomet at embarqmail.com
Tue Jun 23 08:16:24 EDT 2015

Maybe there's a reason we don't see many of these tubes?
You'd have 24W on the filaments and get 3-5W out, if you can find the 
unusual output xfmr!
Then one of the tubes would die?  Just get some 6L6s or 6V6s and go for it!
They need the big filament to get the emission to make current at the low B+ 
and they don't have "modern" high emission cathodes.
All the data you need is on the sheet.  Set the voltages, add some 5K grid 
leaks, and capacity couple in from any phase inverter or xfmr.
If you have an interstage xfmr, you can use a simple single ended driver and 
be done, but the phase inverter from any 6V6 amp will work.

Less work would be a single ended class A stage.  The cathode resistor keeps 
you from having to make a bias supply and at 100V, you can tie the screen to 
B+ on the low sidee of the output xfmr.

Now I'll get ready to charge my own windmill.  At least it runs a KW and 
helps me talk around the world.


-----Original Message----- 
From: William
Sent: Tuesday, June 23, 2015 7:38 AM
To: boatanchor
Subject: [Boatanchors] Audio Amp Schematic for Type 48 Tube?

Hello All,

Came across a pair of Ken Rad 48 tubes in a recent bulk purchase.  They are 
definitely used but test fine.  Big boxy plates in nice ST bottles.

Here is the data sheet:  http://frank.pocnet.net/sheets/021/4/48.pdf

I briefly poked around the web and did not find any audio amp schematics 
right away, so some additional research is on the to-do list.  In the 
meantime, I figured I would ask the community if anyone has designed or seen 
a schematic for an audio amp using these tubes.  A low-power guitar amp is 
also a possibility.

Thank you very much in advance for your comments and suggestions.

Best Regards,

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