[R-390] Line Voltage Survey

[Perry Sandeen]

List,

When checking the voltages on a SP 600 I discovered a problem primarily with my filament voltages.

The basic problem is that in my semi-rural Tennessee area my line voltage consistently is 124 to 125 volts.  This was also true of my rural Colorado house.  Both also suffer from small surges and very short drop-outs.

With the transformer tap set to 117 volts the filament voltage is:   

Line Voltage	B+ Volts	Filament Volts	Bias (S/B -51V)	Tap Setting
117 (Variac)	244	6.3	-52	117
124	252	6.7	-55.2	117
124	227	5.87	-48.3	130

Tube manuals rate receiving tube voltages as plus or minus 5 percent.  So the acceptable value is 5.985 to 6.615.  So from a filament standpoint, the 130 volt setting is the lessor of two evils, while not considering the effects of the lower B+ and Bias voltages.

This poses several questions:
1.  What do others have for their line voltage?  Please reply off list.  I’ll report the results to the list.

2.  Has anyone been able to test a SP 600 with a signal generator to see what, if any performance difference this might make.  (My signal generator is packed away for the moment.)

The R390A largely avoids this filament problem as the power transformers I have are marked as 6.1 volts for the filaments.

Thoughts?
  
Regards,

Perrier