[Heathkit] 807 vs 1625 as DX-100B modulator

[L L bahr]

Yes, you can replace 1625 tubes with 807 tubes but as you suggest, the filament voltage is different.  You will also have to change out the tube sockets as 807s have 6 pins rather then 7 pins as on 1625 tubes.  One pair of 1625 tubes should last you a very long time unless maybe a filament burns out.  There were a zillion of them made during WW2 and still can be found on e-bay and local hamfests.  I would think one extra set would keep your DX-100B running for many many years.

Lee, w0vt



One of the modulator tubes in my DX-100B just developed a short 
(confirmed on my TV-7 tube tester) and so I have ordered a few spares 
from RF Parts, hoping that they have some in stock.

I'm told that 1625's are getting a bit hard to find, and in fact the 
only ones that RF Parts has are shown as NOS which makes me wonder if 
anyone is making them anymore.

If the time comes when I can't get 1625's any longer, any particular 
reason I can't just rewire the filaments in series rather than in 
parallel and use 807's?

Rick WA1RKT