Clansman PRC-344 repair - UK Vintage Radio Repair and Restoration Discussion Forum

Martin G7MRV · 17th Jan 2019, 9:42 am

This may be of use to someone,

Ive just resurrected from dead a Clansman PRC-344 UHF AM manpack. The issue was with the P.S. Stabilizer modules (regulators), module 6, the 6v regulator was dead short. After repairing it, the 12v regulator module blew!

The cause was the 22uF 35v tantalum capacitor across the supply rail. In the 6v module this was dead short. In the 12v module it was so leaky that the inrush current destroyed the ferrite bead choke on the supply rail!

I replaced these caps with modern 22uF 50v electrolytics, and rewound the choke (14t). I also replaced the same cap in the 3v module as a precaution.

Hope this helps someone,

As an extra, be aware that what looks like a small thick fuse, or varistor, in fuse holder contacts, is in fact a big schottky diode! This is in the supply direct from the battery so make sure you put it back in the right way around!

Martin G7MRV

17th Jan 2019, 9:42 am	#1
Martin G7MRV Heptode Join Date: May 2008 Location: Selby, North Yorkshire, UK. Posts: 951	Clansman PRC-344 repair This may be of use to someone, Ive just resurrected from dead a Clansman PRC-344 UHF AM manpack. The issue was with the P.S. Stabilizer modules (regulators), module 6, the 6v regulator was dead short. After repairing it, the 12v regulator module blew! The cause was the 22uF 35v tantalum capacitor across the supply rail. In the 6v module this was dead short. In the 12v module it was so leaky that the inrush current destroyed the ferrite bead choke on the supply rail! I replaced these caps with modern 22uF 50v electrolytics, and rewound the choke (14t). I also replaced the same cap in the 3v module as a precaution. Hope this helps someone, As an extra, be aware that what looks like a small thick fuse, or varistor, in fuse holder contacts, is in fact a big schottky diode! This is in the supply direct from the battery so make sure you put it back in the right way around! Martin G7MRV __________________ I got food in ma belly and a license for ma telly My Blog - http://g7mrv.blogspot.com