Triode life question

[W7TFO]

Does anyone have personal (read "I've used these, here is the dope") experience with 450TH/TL-6C21 tubes in a 2X2 arrangement for 1kW AM service?

Favorite operating points info would be most appreciated, as the book data to real operation is to "the map is not the territory" axiom.

Obviously the plan is to build said rig and your experience would give me something to look forward to. 

I have years of experience flogging 833A's in Gates BC-series transmitters, and that topology might be a good start to emulate, but with a LOT better looking tubes and cabinetry.

Many thanks in advance!

73DG

[k4kyv]

If you use 6C21s, run the filaments at 7.5 volts.  The specified 8.2 volts is to increase the peak emission capability for radar pulse modulator service, at the expense of greatly reduced tube life. The filament is exactly the same as used in the 450TL/TH.

[Todd, KA1KAQ]

Drop a PM or email to Gary, W2INR. He ran this configuration for a number of years via a converted Collins 21E using 450TLs modulated by 450THs. He could give as good of a report on longevity as anyone I bet.

[KM1H]

Im starting on a bandswitched 160-20M parallel pair of 6C21's modulated by 304TL's using iron from a BC-1T.

Aint been there yet

Carl

[W7TFO]

Don, I have the filament history on the 6C21, and what a surplus bargain they must have been back then.

Todd, Thanks, I already bought a bunch of tubes from him...one datum down.

Carl, Maybe it is a race?  Nah, I'm up in the air building a house (literally) and don't have time for major HB now.  You win.

73DG

[KE6DF]

Attached is a W6SAI note about using 6c21's in ham applications -- including plate modulated AM and GG.

Note that Orr recommends 7.5v on the filaments just like Don did.

[W2PFY]

I've used these, here is the dope

Funny when you read the ad's from the late 50's how they were always giving out the DOPE on something. I've often wonder how that term became popular? The By Golly crowd must have been in the same league.


So that's the dope on that by golly, as he smiles with pipe in mouth, tobacco stained crooked teeth showing through. 

[W9GT]

Im starting on a bandswitched 160-20M parallel pair of 6C21's modulated by 304TL's using iron from a BC-1T.

Aint been there yet

Carl

Me too, except using iron from a Bauer 707.  Should be a nice rig.  Those 6C21s are neat looking tubes.  I was fortunate enough to get a pair of new Eimacs for a good price several years ago.  I also have several new 304TLs  (hope they are good).

73,  Jack, W9GT