[R-390] RE: 390A relay problems

[2002tii]

Bob wrote:

>Perhaps it is too big?, it's a 300 watt limiter. I also notice if I 
>switch past standby and go right to AGC, it immediately pulls right in,

It is certainly too big for a 390 on standby.  I found the following 
on the web, which I think is about the particular unit you have:

"The instant the equipment is turned on, the internal meter will show 
a drop to about 60 VAC, and then it will rise over the next ten 
seconds to a value near 100 VAC. This rise will continue for about 
two minutes where the load voltage will level off and hold for as 
long as the equipment is turned on. The drop in load voltage at 
turn-on from 120 volts to 60 volts represents substantial inrush 
current limiting. This slow built-up to operating voltage is what 
protects your equipment from possible damage. For example, power 
supply filter capacitors in a power supply are present nearly a short 
circuit to load current when they are discharged. Vacuum tube 
filaments will last a lot longer if they are not subject to full 
voltage when they are cold.  After the initial warm-up period, the 
limiter will have a constant voltage drop of about 6 VAC. This 
voltage drop means your vintage equipment will operate at the line 
voltage it was originally designed for, which was about 115 VAC."

This is a very slow ramp, not like the typical inrush current 
limiter, which ramps up over a fraction of a second.  It also 
indicates a steady 6 volt drop, much more than the usual inrush 
limiter.  At the rated 2.5 A, this thing would be dissipating 15 W 
inside its plastic housing!  Can you say, "fire hazard"?  I don't 
think this particular device is likely the best approach to operating a 390.

Best regards,

Don