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I want to align my 47-1230, but I am not sure when they say to connect the output meter to Terminal 3 (voice coil connection) of the aerial terminal board, where this is. Also , they want me to use an AM Signal Generator, I know that AM is amplitude modulation but will my rf generator work? It is a Paco G-30. One more thing the paco has a setting for output modulation with the RF signal (400herts) but when I look at it with a scope ( mind you I am obviously a beginner with the scope) I don't see any difference in the signal between it being set for rf w/no mod and rf w/mod. I thought the signal would become "distorted" for lack of a better word or something. Is there a way I can check to make sure that modulation is working on the generator? Hopefully these questions aren't to dumb , but I need to find these out to go any further. Thanks for any help on this subject.
(This post was last modified: 02-10-2014, 12:26 AM by Warren.)
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There should be a 3 or 4 lug terminal strip usually on the left back of the chassis. I align using an analog ohm meter connected to the speaker leads. Align BC at 455 on your signal gen with tuning plates closed, your directions should tell you the high end settings, usually somewhere around 1500. Are you getting sound with the sig gen hooked up? Should be a steady tone.
(This post was last modified: 02-10-2014, 12:04 AM by tab10672.)
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I have a terminal strip for the am antenna and a plug for the fm antenna but no other terminal strip. I am trying to hook up the output (vtvm) so I didn't think they meant the antenna strip. I haven't tried it yet since I didn't know where to hook up the meter.
(This post was last modified: 02-10-2014, 12:31 AM by Warren.)
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I also have a PACO G-30, and it works fine for aligning this sort of AM radios.
You can easily test whether your AM modulation is working. Attach a wire from the + output of your signal generator and wrap three or four turns around a piece of scrap wood or cardboard, then tune the signal generator to any frequency in the AM band. If your modulation is working you'll hear the tone on any nearby radio tuned to that same frequency. By nearby, I mean a foot or two away from your loop of wire.
Turn the output, level, and audio controls on the signal generator fairly high.
If your RF is working but not your tone modulation, you still might hear some interference with an AM station at the same frequency. Set any radio on an AM station near the center of the dial, and dial your signal generator up and down to see if you can hear any interference with your antenna loop very near the target radio. But I guess you've already verified the RF on your scope.
For the purposes of a quick test, you could probably even wrap a three or four turns of wire around your hand, or a small book, or anything convenient.
John Honeycutt
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Some Philcos of that era had a terminal on the antenna strip on the back of the chassis that was connected to the output transformer so you could make this connection without taking the chassis out of the cabinet. The instructions for 47-1230 say it's terminal 3. If you look at the schematic, it shows terminal 3 with an arrow pointing to "Z", and the output of the output transformer is also connected to "Z." That way they don't have to show the wire between them on the schematic.
So connect your meter positive lead to antenna terminal 3 and the negative lead to the chassis somewhere. You should be able to see your meter register an AC voltage if you are getting sound out of your speaker, but it might have to be fairly loud to register on your meter.
John Honeycutt
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Any certain type of wire I should use? Probably uninsulated, any certain gauge, stranded, solid? I might have some old guy wire around if that would work. I noticed in the instructions they want you to make a 6 inch around loop about 4 to 6 turns to hook up to the generator for some of the alignment steps.
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It should be insulated, just a length of hook-up wire. It doesn't really matter what kind. You could use uninsulated wire, but then you'd have to be careful not to touch the coils together or touch anything live.
Yes, that 6 inch loop is essentially the same thing I'm suggesting. I don't think the dimensions or the shape are too critical. I made one from some scrap plywood about 6" by 6". I put a couple of small holes in the board, wrapped 4 turns of insulated wire around it about 1/4 inch apart, ran the wire through the holes and held it in place by tying knots in the wire so it would stay put. One end of the wire is unconnected to anything. The other goes to the signal generator through a .01 uF capacitor.
For this test you don't need the capacitor, but any time you attach the signal generator to any part of a radio you should isolate it with a capacitor. Often the alignment instructions will say so.
P.S. Mine is stranded, 20 ga., but I don't think it matters. Stranded is a little easier to tie knots in, but you could use tape or glue or tacks, or anything to hold the wire in place.
John Honeycutt
(This post was last modified: 02-10-2014, 01:17 AM by Raleigh.)
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OK, sounds good, I will see about doing that tomorrow sometime. I should have some insulated wire on a little roll, hopefully it is long enough. Also, does anyone know where that connection is I was asking abut earlier for the vtvm to be connected to? thanks, Warren
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You can hook up the vtvm strait to the speaker after you find a signal from the sig gen
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By the way make sure you use/make a plastic screw driver or your needle will jump around from static and popping. The loop is usually just used to adjust the tuning condenser
(This post was last modified: 02-10-2014, 08:49 AM by tab10672.)
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Warren, look on the back of the chassis. The AM antenna strip has 3 terminals on it, probably screw terminals. Two of them are connected to the AM antenna, or used to be. I don't know whether the screw terminals are numbered or not, but there might be tiny numbers beside the screws. The screw that does not have an antenna wire connected to it is #3. It is the one you want to connect your VTVM to.
The FM strip looks on the schematic like it has 4 terminals, either screw terminals or plug-in sockets, or both. It connects to the FM antenna. That is not the one you want to use for your VTVM.
You probably can't connect the meter directly to the speaker because the speaker plug won't let you get to the wires easily, but if the chassis is out of the cabinet you can connect the meter to the point where the output transformer connects to the speaker wire (the ungrounded one.) It should be on a terminal strip near the output transformer.
John Honeycutt
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Ahh, OK then they do mean on the antenna terminal strip. There are 3 terminals on that. I will try the 3rd to hook up to. Yes the FM uses a plug but the AM is a terminal strip. Thanks, I will let you know how it turns out.
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By the way, I made an antenna by making an X with 2 pieces of 1/4 by 6 inch wood and wrapped the wire around it. Un fortunately when cutting the slot in the middle of the wood so the 2 can fit together I cut my finger pretty deep and had to stop the bleeding , put a splint so I dont bend the finger, etc. so, I didnt get to try it out yesterday. I am hopeing to try it tonight. Will let you know what happens. thanks, Warren.
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OK, i was able to ge the signal generator set to 455k and get a tone coming out of the speaker when I connected it to different test points from the directions to test the am receiver. I would suppose that proves the modulation works. Only thing is when I hooked it up to a test point the directions said the tone should be quite a bit louder than it was at another point, but it is about the same volume. I will have to find out why I suppose...maybe because it isnt aligned yet or there is one resistor I understand might be the problem...Hopefully not the switch tha changes it from am to fm to sw, etc., that would be very hard to do anything with.
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All am radios I have aligned, the sig gen stays connected to the same point while adjusting all 4 screws. Then to align the osc and ant (tuning cap screws) if it has a built in ant I use a loose coupled loop of 6 turns on a strip coil form cut from a coffee can.
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