[BC] the Purple tube...

[Lewis Munn]

Dave, etc.
   
  I liked someone's comment of a light-emitting Zener.  You could tell when the power was on, for sure, and the regulators regulating.  Days of higher voltages and lower currents.
   
  The old Gates Modulation monitor contempoary with the SA39 limiter and SA40 audio gear used an 885 and a relay...same clicking.  The next generation used miniature tubes rather than octal, and was smaller...about 3 RU high but lots deeper, and used the 2D21.  Yes, I remember the clicks.  Dunno that they were all that bad.
   
  Todays do not give you the annoying clicks when overmodulating...so you can more easily ignore the warning lights.  Especially when they are tiny LEDs.
   
  The old 885-version monitors, with a 6X5 RF rectifier, were well built...but after 10 years or so it was time to take them out and replace all capacitors and resistors, as parts drifted from time and temperature...and they only read to 100%, or maybe 110%, modulation.  But they were built for sturdiness and ease of maintenance.
   
  The 885,and the 2D21 were disappointing to see tho...only a slight pinkish glow within the shield plate when they were tickled on.
   
  Looey Munn
  Roundup, MT
  "Always interested in a Radio engineering job!"
  

 

		
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