700B Silk Screened Faces

WOPL Sniffer

Veteran and General Yakker
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Aug 10, 2015
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Screw it
#1
Ed, I was just discussing with Joe the Silk Screening on the Phase Linear 700B (didn't look at other models), and the question came up as to why PL would silk Screen 2 different faceplate variations (ooooh, the plot thickens). If you look at the "Channel B Level" silk screening, on one amp they are to the right of the knob and on others, they are to the left. Was there any rhyme or reason or dates etc as to what was what????? I looked at several "Originals" and I see them either way. Lee, Guys, you are welcome to jump in here to.......



Thanks

Perry
 

oldphaser

Chief Journeyman
Joined
Sep 8, 2012
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721
#2
Phase Linear 700B front panels

Perry,

I don't know the full story about all of the variations of 700B front panels.

There were indeed several variations including the following:
1.) The meter range switch lettering (i.e. 0, -20dB and -20dB, 0)
2.) The words "Seven Hundred Watts R.M.S" changed to "Laboratory Standard Amplifier" starting around November 1974 as a result of the FTC "Amplifier Rule".

The knobs also changed from solid aluminum machined knobs to plastic insert ("D" shaft) knobs.
The power switch changed from a Arrow Hart SPST switch to a cam operated micro-switch (which took Phase Linear 6 months to design).
These changes also occurred around November 1974.

Ed
 
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