[Milsurplus] Batteries for a PRC-77?

Mon, 24 Jun 2002 07:43:07 -0700

Hello:

In the book "Power Up" that's out of print and on the Army Radio web site Dave Storm tells how to take apart many military battery
cases and replace the dead cells with smaller commercial cells.  The problem is that most of the dead batteries needed are not
available today.  His BA-4386 rebuild uses 12 each "C" cells.  A version of this was my first paper design but when you compare about
100 Watt Hours for 12 "C" cells with 180 WH for 10 "D" cells there is some motivation to use the "D" cells.  For comparison two each
BA-5598/U provide only 174 WH.

When connected to my PRC-25 the radio seemed to work OK with an auction BA-4386/U.  When powered from bench supplies the radio put out
twice as much RF power.  Checking the auction BA-4386/U with the PSM-13 showed the auction battery to be almost dead.  Note that the
U-347/PSM-13, the finned Aluminum adapter,  places a 12 Ohm load on the BA-4386 and after waiting 10 seconds for the Magnesium to react
you check the meter.  Later when I powered the radio with my own battery adapter I was surprised at the audio volume and the increased
RF output compared to the auction battery.  Trish also had this experience.

The BA-5598/U batteries that I got from Fair Radio, although they were 12 years past the manufacture date, had 100% capacity when
tested with my TS-4403/A/U.  Note that this is the only tester that can check the state of charge of LiSO2 cells.

    WARNING
    DO NOT USE THE BA-5598/U ON A PRC-25!
    DOING SO MAY BURN OUT THE FILAMENT OF THE FINAL TUBE!

Because of the above problems I have developed an adapter that holds 10 "D" cells and fits into the CY-2562/PRC-25 Battery Box.  It is
taller than a BA-4386 so can not be used in all BA-4386 applications.

I have parts on order for a production build of the 2577BA and should start shipping in July or August.  I found the original BA-4386
socket manufacturer and will be using new sockets in the 2577BA.

Trish, WA6UBE and moderator of the Army Radio mailing list suggested this adapter and has done some beta testing that was very helpful
in finding problems that have been fixed.

Reference web sites:
http://www.armyradio.co.uk/    (turn off Java for this site)
http://www.pacificsites.com/~brooke/PRC25.shtml#DCP
http://www.pacificsites.com/~brooke/PSM13.shtml
http://www.pacificsites.com/~brooke/SOC.shtml
http://www.pacificsites.com/~brooke/2577Battery.shtml
http://www.pacificsites.com/~brooke/2577BA.shtml
http://www.lanset.com/buzz/misc/batteries/batteries.html

73,

Brooke Clarke
my products:  http://www.prc68.com (mostly battery adapters)

> Message: 2
> Date: Sun, 23 Jun 2002 10:46:03 -0400
> To: [email protected]
> From: Alan Tasker <[email protected]>
> Cc: [email protected]
> Subject: [Milsurplus] Batteries for a PRC-77?
>
> Somewhere on the web there is posted a copy of the "Load Up" book which
> discusses this subject, i.e. how to power many of the military portables.
> Maybe a search will turn up where it is, or maybe somebody else out there
> knows.
>
> The PRC-25 needs 3 Volts for the Tx tube filament, and 15 Volts for the
> rest of the radio. The PRC-77 needs just the 15 Volts.
>
> Magnesium batteries (BA-4386) are all over that famous auction site, some
> at reasonable prices, and some from sellers who are obviously gouging. Some
> people have had good luck with them, and some others have apparently
> received batteries from lots stored in wet and/or hot conditions. These
> particular ones are virtually useless.
>
> Fair Radio Sales has out of date code but perfectly good Lithium batteries
> (BA-5598). They are selling for $3.50 each, two for $6.00, and $2.50 each
> in lots of some higher quantity like 10 or so.
>
> S & G Photo in Philadelphia is on that auction site off and on under
> various names (depends on the actual clerk). They have been on the past two
> weeks, selling newer date code lithium batteries at $5.00 each in lots of
> 12 I think it is.