[ARC5] Surplus Radio Conversion Manuals

[Robert Eleazer]

Several years ago I picked up a BC-348-N at a surprisingly low price on ebay.  The guy who did the conversion had done a good job, using the dynamotor mounting plate as a base for an AC power supply, cutting some holes in the rear case for ventilation and covering them with real copper screen (can you even get that today?).  Other than that he left it pretty much original, even leaving the dial light rheostat in place, although disconnected.  He had not even drilled a hole in the front panel for a toggle switch, instead using the original On-Off-MVC-AVC switch for switching on and off the AC. 

And it worked, right out of the box!  Further investigation showed that he had followed the Surplus Conversion Manual exactly, building a classic power supply with a rectifier tube, electrolytic cap, and even a filter choke.  But the conversion manual called for a 300V transformer and that was what was in there!  I rebuilt the power supply, using a piece of 1/8 in AL as the base plate, added proper standoffs to mount the choke, installed a new higher capacity filter cap, and added multiple power resistors in both the AC line and the B+ line to get the voltage down to about 200VDC instead of the 250VDC+ it was running.  Oh, and I put an in-line switch in the AC line so as not to have to use that front panel switch.  It is the only BC-348 I have that I have not de-Hammed

Wayne
WB5WSV      

---
This email has been checked for viruses by AVG.
http://www.avg.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20180426/05134582/attachment.html>