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Post by zman on Apr 6, 2011 0:15:55 GMT -5
I have an old Demco Modulator from the early 1960s that id like to wire up to my lafayette HB 400. I cant find any info anywere that shows a schematic.
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Post by rifleman on Apr 6, 2011 8:17:52 GMT -5
Which one do you have ?
The stand-alone model (VM12120), or the one with the speaker built in ?
The VM12120 is from SAMS, and includes the full schematc, photos, and parts list.
Here is the VM12120.......
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Post by rifleman on Apr 6, 2011 8:23:52 GMT -5
Stand alone 1 Attachments:
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Post by rifleman on Apr 6, 2011 8:24:53 GMT -5
Stand alone 2 Attachments:
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Post by rifleman on Apr 6, 2011 8:25:48 GMT -5
Stand alone 3 Attachments:
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Post by rifleman on Apr 6, 2011 8:29:40 GMT -5
The one with the speaker is too large to send through here.
(PS.. It also has some operating instructions)
If you need it, send me a PM with your email address.
Ron
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Post by zman on Apr 6, 2011 15:00:59 GMT -5
Mine is the older one thats all Chrome, has 2 knobs and a large mic connector between the knobs and above the mic connnector there is a neon light.. This thing is oldddd probably made around 1962-64 or so.
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Post by rifleman on Apr 6, 2011 16:51:43 GMT -5
Zman, you have the one in the (3) files I posted above.
The model VM12120. (12 volt / 120 volt)
The earliest Demco modulators were the speaker type that went with the Command/Demco CB's.
The earliest I have seen of your model was in the 1966 Allied catalog.
And I believe they were made into the 1970's, until tube-type CB's started falling out of favor.
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Post by zman on Apr 6, 2011 19:02:54 GMT -5
pic #1 Attachments:
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Post by zman on Apr 6, 2011 19:03:21 GMT -5
pic #2 Attachments:
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Post by zman on Apr 6, 2011 19:10:41 GMT -5
This is what has me stumped. There is a white, Blue, brown, black and a shield. I have no clue what goes to what,. the schematics dont even show the other wires. Attachments:
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Post by rifleman on Apr 6, 2011 21:26:35 GMT -5
Well, it's obvious that your Demco has been bastardized.
(I have two of them here, and someone put different mic jacks on their fronts)
Someone has replaced the output cord on yours.
In stock form it should be 3 wires and a shield.
You are going to have to follow the wires inside the modulator and figure out what is hooked up to what.
BTW... Do you have a schematic for the HB-400 ?
I have a copy of the SAMS for it.
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Post by zman on Apr 8, 2011 19:52:58 GMT -5
I think ill just sell it. I am horrible art following schematics and i dont really have time to tinker on it...
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Post by rifleman on Apr 8, 2011 21:50:38 GMT -5
Well, at least you have the schematics now to go along with selling it.....
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Post by zman on Apr 10, 2011 22:28:12 GMT -5
When i get home im going to look at it again. I know the previous owner and if i cant figure it out ill have him have his tech wire it up for my BH 400. ;D
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Post by rifleman on Apr 11, 2011 7:25:19 GMT -5
Well, good luck with it Zman......
At least you have one in good physical condition, from what I can see.
The modulators are like the Demco radios. The circuitry inside is pretty simple.
The biggest problem is that the faces have a tendency to get a spotty type of rust on them that is hard to clean up.
Again, good luck.
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Post by zman on Apr 13, 2011 19:18:58 GMT -5
Well i just scored another vintage Demco piece, a Demon 500+ amp. LOL ;D
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Post by cbrown on Apr 14, 2011 9:33:33 GMT -5
Nice score, had one for a week or so back in the day, just to play around with.  What kind of shape is it in? |
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Post by zman on Apr 18, 2011 0:24:50 GMT -5
Its got a few bugs but it does work. I can quite figure out what the Mod high low switch is really for. Unless its like a varmit and thats some sort of supermod switch.
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Post by rifleman on Apr 18, 2011 10:24:15 GMT -5
Yes, the circuit is very similar.
The Demco amps were built way before Brewer Labs built the Varmints.
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Post by cbrown on Apr 19, 2011 9:25:20 GMT -5
Looks like it throws a capacitor into the tube circuit, probably gives you more swing on the carrier.
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