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 Post subject: Philco Power Transformer
PostPosted: Feb Thu 19, 2004 4:23 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 105
Location: Meridianville, Al USA
I have a Philco 47-1227 (Riders 19-55). For starters it loooks like I'll need a power transformer. The present transformer only reads about 180 ohms total across the B+ secondary. The radio came to me minus the 5AX4 so before I install a new rectifier tube I'd like to change the transformer. The part # on the original is 32-8248. The transformer has a center tapped B+ secondary winding, a 5 volt and a 6 volt filament winding. I can find no data on current ratings for these windings. Any help would be much appreciated.<BR>Thanks,<BR>Bill<P>------------------<BR>


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 Post subject: Philco Power Transformer
PostPosted: Feb Thu 19, 2004 4:58 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1873
Location: Redmond, WA USA
Hello Bill,<P>I grabbed a new Hammond 373BX power transformer out of the box, and I measured 88.7 ohms across the whole 700 volt center-tapped secondary. Are you sure the tranny is bad?<P>Sams Photofact set 25, folder 22 gives the following specs for the power transformer:<P>Pri: 117V AC @ .78A<BR>Sec 1: 640V CT @ .112A<BR>Sec 2: 4.9V AC @ 2.0A<BR>Sec 3: 6.5V @ 2.2A<BR>Sec 4: 6.6V AC @ .46A<P>It lists Stancor P-4080, Thordarson T22R32, or Merit P-3153 as replacements. The Stancor and Merit need new mounting holes.<P>Although it doesn't seem to be mentioned in Sams, secondary #4 looks to be center tapped.<P>A couple of suitable Hammond transformers:<P>Model: 272DX <BR>300-0-300 125 <BR>5 V@3 A <BR>6.3 V@4 A <BR>Mounting detail: X9<BR>$54.34<P>Model: 276X<BR>320-0-320 150 <BR>5 V@3 A ct<BR>6.3 V@5 A ct <BR>Mounting detail: X10<BR>$74.36<P>Link to xfmr data: <A HREF="http://www.hammondmfg.com/263.htm" TARGET=_blank>http://www.hammondmfg.com/263.htm</A> <P>Small transformer for additional filament circuit: Xicon 6.3V CT @ 1.0A $4.79 (Mouser 41FD010, catalog 617, page 1055). There must be a way to eliminate the need for the extra transformer.<P>Izzy<P><BR>------------------<BR>


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 Post subject: Philco Power Transformer
PostPosted: Feb Thu 19, 2004 4:35 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1295
Location: Arlington, VA USA
180 ohms across the HV secondary doesn't sound bad to me either. Measure the resistance from each leg to the center tap. They should be pretty close. If so, apply a safe voltage like 12vac to the primary and measure the HV output. The transformer is most likly good if each side to center tap is equal.. <P>------------------<BR>


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 Post subject: Philco Power Transformer
PostPosted: Feb Thu 19, 2004 6:33 pm 
Silent Key

Joined: Jan Thu 01, 1970 1:00 am
Posts: 34326
Location: Sandpoint, IDAHO 83864
You will not observe equal resistances from the center tap of the high voltage winding to each outer leg. The windings on the outer part of the core are longer than the windings closer to the core, thus more wire is used for the same number of turns on the outer windings. The resistance you indicate is within reason. Try the low voltage applied to the primary to check it out. Secondary VOLTAGES should be equal from the high voltage center tap to each outer leg. Ohmeters can be very misleading in this respect. It is the voltage, not the resistance that is important.<BR>Curt<P>------------------<BR>Curt, N7AH


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 Post subject: Philco Power Transformer
PostPosted: Feb Thu 19, 2004 9:20 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1827
Location: Sanford, North Carolina
I don’t think the power transformer(That’s transformer ,not Tranny IZZY ) is bad!!<BR>I would check a lot more things, before saying it was Bad<BR><P>------------------<BR>Rick Dippolito<BR>THE PHILCO RESTORER at<BR> <A HREF="http://hometown.aol.com/philcorestorer/myhomepage/index.html" TARGET=_blank>http://hometown.aol.com/philcorestorer/myhomepage/index.html</A>


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 Post subject: Philco Power Transformer
PostPosted: Feb Fri 20, 2004 1:11 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1873
Location: Redmond, WA USA
<IMG SRC="http://IzzyWeird.com/images/ArtMask1.jpg"> <P>Tranny was the slang term my early New Zealand mentors used. It may be an ethnic term, and I'm very ethnic, ya know?<P>Bill, what other evidence do you have to indicate the tranny is bad?<P>Izzy


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 Post subject: Philco Power Transformer
PostPosted: Feb Fri 20, 2004 6:52 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 105
Location: Meridianville, Al USA
Thanks all for the replys, I really appreciate the help.<BR>Izzy, I guess I sorta got suspicious when I received the radio minus the 5AX4 rectifier, I didn't have one so I decided to check the transformer. The schematic shows the winding resistance readings and all were very close except for the B+. The schematic shows 500 ohms total, 250 ohms from either outside leg to the center tap, I only read 90 ohms(180 ohms total). We ordered the tube but before I tried it I wanted to be sure the transformer was good.<BR>Thanks again,<BR>Bill<P>------------------<BR>


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