[R-390] Amperite Ballasts

[Steve Hobensack]

   As a rule of thumb, the first number is the operating current in hundreds 
of mills, the second number is the  minimum value of head voltage needed for 
the low end of the  regulation range.  The 3tf7 runs at 300 mills, a minimum 
of 19 volts is needed to hold regulation in the r-390a bfo & pto filament 
circuit.(6 + 6 + 7 = 19)  The supply voltage in the r-390a is 26 volts. If 
the voltage drops below 19, the regulation ability goes below spec. I think 
Amperite has a web site and has a pdf file on ballasts. Some of the older 
octal amperites omit the letters and use only two numbers.
...73...Steve...N8YE

Date: Sun, 25 Dec 2005 02:34:18 -0600
From: Tom Norris <r390a at bellsouth.net>
Subject: [R-390] More Ideas for the Y2.005K FAQ, etc
To: r-390 at mailman.qth.net
Message-ID: <830FB2DE-F040-4E38-8ECB-EB7F66B7CF90 at bellsouth.net>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

Some time ago someone -- was it Nolan? Someone put together a parts
breakdown on Amperite Ballasts that showed the differences between a
3TF7, 3TF4, etc so folks could "decode" any mystery ballasts they
might find out in the wild.  Is that information still floating
around somewhere?

More info as it pops through the cobwebs. :-)

Tom NU4G