Philco 41-250 rewire, mystery connector, external speaker
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I completely rewired my Philco 41-250 and replaced the bad output transformer. A good chunk of three days, and lots of solder wick were required. I was completely surprised when it worked the first time I turned it on (using my variable transformer). AM reception and sound are excellent, even though I have not yet touched any of the alignment adjustments! However, the "Police" and shortwave reception are almost completely nil.
It is certainly obvious why people might shy away from the brittle rubber wire- filled Philcos of that era.
Does anyone know the purpose of the three prong connector on the back of the unit? It seems that it may be for an external antenna or other signal source.
The radio has the voice coil output wire going to the speaker and to the leftmost screw terminal in the strip to which the three antenna wires attach. Is that for an external speaker, or for some other purpose?
My next project is to refurbish the two signal generators I have so that I can properly align it and my other radios.
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It almost appears that it could be for an external antenna and ground. I think I've heard in the past that sometimes the ground pin was there also for a convenient place to hook a meter lead into for testing voltages etc.
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The three pin connector is for a special Philco add-on that incorporates a switch, matching network and antenna screw in one unit that looks sort of like an IF transformer, but has the male 3 pin plug integrated into the side of the unit.
It was made to enable use of an external antenna with many 1941 models, such as the 41-250.
If I don't forget, I'll try to post a picture of one of these over the weekend.
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Ron Ramirez
Ferdinand IN
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Here are photos of the Philco Antenna Coupler, designed to enable use of an external antenna on many 1941 and 1942 Philco models.
[Image: http://i326.photobucket.com/albums/k420/...o/ant1.jpg]
As you would see it plugged into the back of your radio, you can see a screw terminal for an external antenna and a switch on top of the unit. There is also a tab with a hole, allowing the unit to be bolted to the chassis.
[Image: http://i326.photobucket.com/albums/k420/...o/ant2.jpg]
Back view of the unit, showing the three-pin connector which matches the three-pin jack on the back of the chassis.
[Image: http://i326.photobucket.com/albums/k420/...o/ant3.jpg]
Viewed from the top, you can see the two-position switch is labeled "LOCAL" and "DISTANCE."
[Image: http://i326.photobucket.com/albums/k420/...o/ant4.jpg]
Underside view of the coupler. You can see a paper capacitor, a mica capacitor, and an inductor. There is also a resistor in there (not visible).
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Ron Ramirez
Ferdinand IN
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Thanks for that excellent information! It will surely also help many others who run across a Philco from that time period.
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You're welcome 
I only happen to have this unit as it came attached to a Philco 41-610P which I own. I removed the antenna coupler, as it is my intention to sell or trade the 41-610 once I get it going.
I am going to attempt to draw a schematic of this coupler and post it later. Looks very simple...yet from studying some Philco schematics last night, it appears that it is only effective on the AM band.
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Ron Ramirez
Ferdinand IN
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The #1 terminal on the antenna strip is intended as a convenient place to attach a positive meter lead to use as an audio output indicator during alignment. Several '41 and '42 radios have this feature in one form or another. I don't see it on the 40-150 schematic, so maybe they only used this feature for a little while.
John Honeycutt
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Ron, I was wondering if you ever had a chance to come up with a schematic on the antenna coupler unit. I own a 41-250 and would like to hook up an external antenna, so I'm curious what is in the Philco coupler.
Harv
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Quote:Ron, I was wondering if you ever had a chance to come up with a schematic on the antenna coupler unit. I own a 41-250 and would like to hook up an external antenna, so I'm curious what is in the Philco coupler.
Ron,
Have you had a chance to do a schematic or at least a simple drawing of the connections of the components necessary to make one of these?
I know you talked about an external antenna using a dead land line in another post but I can't find it now. If I use a dead land line phone line do I stil need one of these?
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No, I have not, sorry. In my recent move I do not even know where my antenna coupler is right now, and frankly, it is not on my priority list at present. I am focused on getting settled in, starting my next semester of college and rebuilding my website's Gallery.
--
Ron Ramirez
Ferdinand IN
Posts: 13,776
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Joined: Sep 2005
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This topic is now continued in the following thread:
http://www.philcoradio.com/phorum/showth...p?tid=2599
F. Stephen Masek has kindly contributed a schematic for a Philco antenna coupler, which you can see in the thread linked above. (Many thanks, Stephen!)
I am going to lock this thread and suggest that continuing discussion be carried out in the new thread.
--
Ron Ramirez
Ferdinand IN
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