|[AMRadio] Seeking tubes|
k4kyv at hotmail.com
Fri Jul 8 02:07:39 EDT 2005
>Is the 849 about 10-12" high with the same type of pins? Looks about
>the same but no 'necks'? If so, I have a well used one still in the
>wooden crate and another with a case of the rattles (filament ist
>kapoot, methinks). Might consider trading one for a 204....
The 849 is similar, but bigger than the 204A. It's the predecessor to the
833A. The RCA book says the 849, 204-A and 851 should all be mounted upside
down so that the filament is up and the plate down.
I have run into a couple of hams on the air running 204A's.
The old pre-WW2 kilowatt RCA broadcast transmitter ran four 204A's in
pushpull parallel, with a pair of 849 modulators. Later, they changed to a
pair of 833A's modulated by another pair - and even sold a modification kit
to convert the older transmitter to 833A's.
Those older tubes were always expensive. Back in the mid 30's, a 204A sold
for about $85 - the equivalent to hundreds of dollars in today's money. The
newer 833(A) sold for a fraction of that. That's why BC stations were
interested in retrofitting their transmitters.
In the mid 70's I ran into about a dozen Amperex 849A's piled in a cubby at
Young Engineering in Salem MA. I couldn't get the guy to reduce his price;
he wanted about $20 each for them, as is. No way to test them, but they
looked good. I turned him down, and later, they apparently all got broken
as they shuffled stuff around in the old warehouse.
I still kick myself for not taking a chance on those tubes.
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