[ARC5] Receiver Voltages.

[Brian]

Hello Dennis,
Neon discharge tubes were available and being used as quasi Voltage 
regulators around the time of Dr Drake's design of what have become known as 
Command receivers.
However, neon tubes radiate noise, while resistors do not. Where would you 
suggest such a neon stack reside in order to provide regulation of the 
screen Voltage without raising the noise floor?
The firing Voltage of neon tubes also depends on ambient light. Where neon 
tubes were used as Voltage regulators, eg, the LM series of heterodyne 
frequency meters, they were inside a completely covering metal box and noise 
was largely irrelevant.
So, I reckon Dr Drake's design team's solution was appropriate for the 
application.
73 de Brian, VK2GCE.

On Friday, May 01, 2015 12:39 AM , Dennis said:

I hear you, Neil, but it still seems excessive to me.  The screen current
is very small and the bouncing of the supply voltage creates far more
variation (via the divider) than the screen currents themselves.  Besides,
a simple neon bulb stack could provide better regulation at a fraction of
the current.   At 250V, that resistor chain pulls 18mA and dissipates 4.5W.
  I respect the original designers, but this is still somewhat of a mystery
to me.  I'm sure they had a good reason.

Dennis AE6C