[BC] Remembering our "Ol' Bessies"

[WBRadiolists at aol.com]

In a message dated 03/22/2009 12:25:14 AM Eastern Daylight Time, 
Xmitters at aol.com writes:

> I'm sure there are many stations using tube transmitters. One station I 
know,
>  a 5 kW directional, uses a Collins 820E, which uses two 
> 4C5000A in a  class B 
>  modulator and 1 4CX5000A in the PA; conventional plate modulation. 
> Since that 
>  rig was installed in 1972, I can count the number of failures on one hand, 
>  and still have fingers left over :-)  The same station uses a 20V3 at 
night, 
>  with a similar outstanding track record.

A pair of 5000's in the audio is overkill... I'll bet those tubes lasted a 
good LONG time, tho! That sounds like a much better design than the Ol' Bessie I 
used to tend to, a CCA AM5000D! 

It used a pair of 4-1000's for the audio, and a 3CX2500 for the final. Yes, 
it did 5Kw just fine... but couldn't get much over 105% positive mod without 
starting to fall apart. The plates in those poor 4-1000's were constantly 
glowing *orange* with audio!

In the ealry/mid 90's, my then-Engineer and I modified the thing to use 
4CX3000's for modulators. The modulation didn't improve nearly as much as had been 
hoped. Still, gone were the days of replacing those 4-1000's every 12-18 
months! (Good thing WFIF was a Daytimer!) That last set of modulator tubes wasn't 
even showing signs of going soft when "Ol' Bessie" was finally put out to 
pasture, about 5-6 years later!

Willie...