[Amps] Drake L7 issue

[Paul Christensen]

On a second pass of the schematic, it looks like the fans are not ground 
referenced with either configuration, unless there's path I cannot see.

Paul, W9AC

-----Original Message----- 
From: Paul Christensen
Sent: Friday, September 26, 2014 9:42 PM
To: amps at contesting.com
Subject: Re: [Amps] Drake L7 issue

> "The L7 schematic http://www.qsl.net/ea4bb/EA4BB/Old_Radios_files/L7.pdf
shows the connection to be two lines only (2 lines and ground).  The
120V fans are connected across one of two primaries of the filament
transformer but there is *no* connection to Neutral and the only ground
connection is the chassis of the power supply (and via the power supply
cable to the RF chassis)."

By 1979, I thought all amp manufacturers knew not to use ground as a
current-carrying conductor.  Same issue with the Alpha 70/77 series and some
Henry amps.  The fix for the Alpha 70/77 is to use a 4-wire cord and cut one
jumper on the male Cinch-Jones power connector.  It doesn’t even require
getting into the amp.  To correctly convert the L7 may take a bit more work,
but it looks manageable.   Or, live with it knowing that limitation.

Paul, W9AC


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