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Path: utzoo!watmath!clyde!cbosgd!ihnp4!qantel!lll-crg!seismo!brl-tgr!tgr!stephany.WBST@Xerox.ARPA
From: stephany.WBST@Xerox.ARPA
Newsgroups: net.ham-radio
Subject: Re: Mil Surplus
Message-ID: <1618@brl-tgr.ARPA>
Date: Wed, 15-Jan-86 14:20:54 EST
Article-I.D.: brl-tgr.1618
Posted: Wed Jan 15 14:20:54 1986
Date-Received: Mon, 20-Jan-86 04:31:17 EST
Sender: news@brl-tgr.ARPA
Lines: 27

I hav a schematic for the BC 348-r.  I own a BC 348-Q and keep it in my
living room for use and a conversation piece.

The BC348 runs on 28 volts DC.  The screen grids are disabled in
xmitting so you have to run a jumper from pins 2 to 6 on the back cable.
The other pins on the socket are for the 28 volts and the output to the
phones or speaker.  You can get the plug and the mounting frame from
Fair Radio, Lima Ohio, as wel as any other parts.

Be sure to run it on 28 and not 24 volts.  People complain about the low
audio volume of the BC 348 but that is due to rinning it on 24 volts.

I have removed the dynamotor from mine and built a power supply inside
the room for the dynamotor.  A 24 volt xformer fits in place of the big
2 microfarad capacitor, which was removed and replaced with a midget 2
mocrofarad.  Originally I put 24 volts AC on the filaments and got the
low volume and some hum and aised the voltage.  I put in a rectifier and
cap to put DC on the filaments and eliminated the Hum.  i use walkman
type earphones which respond to 60 hertz, so use of DC.  I also added a
4000 ohm to 4 ohm output xformer togive a low impedance output.

Send your address and Ill send the schematic.

The BC 348 was used on the B17 and B25 bomers during WW2.  mine was
built in 1943 and is used for SWL evenings.

				Joe  N2XS