[R-390] Tube Set 390A

[Christian Fandt]

A *complete* tube replacement? Did something happen to the existing tubes?? 
Breakage, theft or just to replace old with new?

If just replacing all with new, you may be in for a complete alignment job. 
Prepare yourself for an adventure if you are not experienced :-)

But why replace all with new? Unless this unit has been run hard and 
absolutely to death, there will be many existing tubes who may still 
perform very well in their present positions. Or maybe the unit was run 
accidentally at 240 volt mains while set at 115 volts for a short time 
which caused some tubes to fail? Been there, done that myself :(

The 3TF7 could be replaced, as an emergency measure at least, with a 12BH7. 
It just controls the filament current to that required by the PTO tube 
filaments. Or even replace the PTO tubes with 12BA6's and short circuit the 
3TF7 socket by plugging a thin copper wire into the two appropriate socket 
pins. Those fixes are very easy to reverse if you prefer to have a 3TF7 
-whenever you find one.

Regards,  Chris

NNNN

Upon the date 12:43 AM 2/6/04 +0100, Schluensen said something like:
>My 67 EAC needs a complete tube replacement. I will look here in Germany 
>for the tubes - but if I can't get some tubes (3TF7 ....) - did someone 
>know a good shop in the US for our 390A tubes?
>
>73,
>Frank, DK1LX
>
>
>--- StripMime Report -- processed MIME parts ---
>multipart/alternative
>   text/plain (text body -- kept)
>   text/html
>The reason this message is shown is because the post was in HTML
>or had an attachment.  Attachments are not allowed.  To learn how
>to post in Plain-Text go to: http://www.expita.com/nomime.html  ---
>_______________________________________________
>R-390 mailing list
>R-390@mailman.qth.net
>http://mailman.qth.net/mailman/listinfo/r-390

Christian Fandt,    Electronic/Electrical Historian
Jamestown, NY  USA      cfandt@netsync.net
         Member of Antique Wireless Association
         URL: http://www.antiquewireless.org/