[Amps] NOS 4CX1000A test and reconditioning

[Joe Subich, W4TV]

Paul, 

> Since most commercial broadcast transmitters use directly-heated 
> cathodes, warm-up time is not much of an issue.  Many transmitters 
> use time-delays that far exceed what is required in order to apply 
> excitation to the PA and IPA.  That said, glass tubes used at HF 
> may fare better than the example described above, but the cost v. 
> benefit cannot be justified even in the most intensely competitive 
> major markets.

Most of the TV transmitters used indirectly heated filaments that 
had significant warm-up time.  Timers were typically 10 to 15 
minutes although manufacturers often specified the filament time 
at 5 to 7 minutes. 

When spots in an NCAA "Final Four," Super Bowl, "local" university 
football game, World Series, etc. were going for enough that the 
loss of revenue from one 2 minute local break may have represented 
the salary of the most highly compensated staff person, "hot 
stand-by" was not even a question. 

Now that most UHF transmitters use paralleled amplifiers to make 
the necessary power levels and most of the new VHF transmitters 
are solid state a "hot standby" isn't as common but I know a few 
places that still run them. 

73, 

   ... Joe, W4TV