[R-390] SP600JX17

[Chuck Rippel]

One thing to keep in mind is that SP-600's, even after recapping and taking 
the extra step of adding the mod which regulates the filament voltage to the 
top 4 tubes, still drift quite a bit until the entire chassis heat saturates.

As to setting the input line voltage, the best way to determine the correct A/C 
Line input voltage (@60 cycles!!!!!) is to monitor the tube filament voltage at 
your tube of choice other than the rectifier, regulator or the (12AU7??).   Set 
the line input voltage to a value that yields 6.3VAC at the tube filaments.  That 
puts the other voltages right about where they need to be.

> > << PS: if the input volts are too high, then the 0A2's get very hot,
and very
> > bright !!! No wonder  they drift, and stop regulating....

> > Rodney
> > VK2KTZ >>

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Chuck Rippel, WA4HHG
R390A List Co-Administrator
Reply to: R390A@R390A.com

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1968 Contract Dittmore-Friemuth R390A #38
1967 Contract EAC R390A #2808 with outboard Sherwood SE-3 Sync. Detector
1967 Contract EAC R390A #5295
1967 Contract EAC R390A #5591
1967 Contract EAC R390A #1023

All in regular use as premier Shortwave Broadcast DX Receivers
       -and-
Vintage AM Amateur use
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