[Milsurplus] PRC-25 Battery Rebuild

[David Stinson]

----- Original Message ----- 
From: "John Watkins" <jpwatkins9 at yahoo.com>
To: "Army Radios" <armyradios at yahoogroups.com>; "Mil Surplus" 
<milsurplus at mailman.qth.net>
Sent: Tuesday, November 15, 2011 11:47 PM
Subject: [Milsurplus] PRC-25 Battery Rebuild


>.... I know that the filament  voltage is 2.5V and current is 0.345 
>amps.

Here's some cheap insurance to protect the filament
 from regulator or other failures that will over-volt the buss:
string 4 silicon 1-amp diodes in series across the filament,
anode to positive side and cathode to negative side.
The four diodes will not conduct until the voltage rises above
2.8 volts, when they will shunt the overvolt.  If it is serious,
like a failed regulator dumping 12 volts to you, the diodes
will short, blow a fuse and save your tube.

Use good diodes, not cheap surplus or junk box.
These have too much variation in forward-bias points.
Quality-controlled power diodes from reputable suppliers
are inexpensive.

73 Dave AB5S