In a message dated 1/28/2007 2:15:12 P.M. Eastern Standard Time,
w8ji@w8ji.com writes:
In all the years I've been doing this the single most common
loss of emission I have seen in 3CX800A7's and 3CX1500A7's
has been where the user reduced filament voltage or drew
current from the tube before the cathode was fully up.
Good points Tom, I doubt that the ratings and specs supplied by
manufacturers apply to amateur use in so far as any "time limits" on the
filament of a
tube. Your right, the cycling of the filament with it's in rush current
time and again would certainly play into the "life span" of the filament.
Probably better to keep it running 24/7, but that is not practical in ham use,
so
we usually don't do that. As I have said many times before, I have owned
MANY SB-220 amps and my first order of business with them was to put in a
stand
by switch. When I would sit down in front of the radio to "play" ham radio
I would normally leave the amplifier off. (I am talking SB-220) If I saw the
need to use the amp, I would turn it on and it would stay on until I was
finished with ham radio for that session. If I wanted to go without using the
amp, I would hit the stand by switch and keep the filaments going. Many
similar amplifiers to the Sb-220 had stand-by switches.
As the saying goes " your mileage may vary". Lou
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|