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 Post subject: Mystery audio amp?
PostPosted: Nov Fri 29, 2019 4:53 pm 
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Joined: Feb Tue 15, 2011 12:33 am
Posts: 382
Location: Columbia, MO 65202
Hi all:

Here's another little challenge for the forum.

If this had tubes in it, I might be able to make some guess what it is with my limited expertise. That said, I really have no clue. My first guess was some sort of a little audio amplifier. Since there are no terminals for things like audio input and audio output, that seems unlikely. My second guess was some sort of a power supply, maybe another battery eliminator patent for a Farm radio, but I don't know what the seven pin miniature tube would be for. The terminal strip you see in the photos is the only input and output. Maybe the big socket is for B+ rectification and the small socket for a second rectifier for an "a" supply?

Seems like it has an awful lot of mica capacitors for just a power supply.

Anyone have any idea?

Hope everyone had a great Thanksgiving.

Mike


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 Post subject: Re: Mystery audio amp?
PostPosted: Nov Fri 29, 2019 5:45 pm 
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Joined: Feb Wed 07, 2018 6:52 pm
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Location: Stone Mountain, GA
I\d say vibrator power supply.

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 Post subject: Re: Mystery audio amp?
PostPosted: Nov Fri 29, 2019 6:05 pm 
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Joined: Feb Tue 15, 2011 12:33 am
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Location: Columbia, MO 65202
Wowsers!!! I would not have guessed that in 100 years. The configuration of the four pin socket just made me think of a four pin rectifier tube.

So, probably a 6 V car battery between hot and ground?

I am currently attempting to produce a wiring diagram to post here. Could you make any guess as to the seven pin miniature tube? Maybe a 35W4?


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 Post subject: vibrator power supply
PostPosted: Nov Fri 29, 2019 7:01 pm 
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Joined: Feb Tue 15, 2011 12:33 am
Posts: 382
Location: Columbia, MO 65202
Okay, it's crude as heck, but here is a wiring diagram that I believe is reasonably accurate.


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vibrator supply wiring diagram.pdf [87.25 KiB]
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 Post subject: Re: Mystery audio amp?
PostPosted: Nov Fri 29, 2019 7:37 pm 
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Location: Detroit, MI USA
You have to find specs on the transformer to know if it's a 6 volt power source or a 12 volt one. That may be difficult to do.

The rectifier socket is wired to take either a 6X4 or a 12X4 depending upon knowing what the intended power source is.

You could start with a 6 volt vibrator and a 6X4 and see how much B+ it develops.

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 Post subject: Re: Mystery audio amp?
PostPosted: Nov Fri 29, 2019 11:39 pm 
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Joined: Feb Tue 15, 2011 12:33 am
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Location: Columbia, MO 65202
Hi Dennis:

Well rats. I have a 6X4 tube, but no 12X4 tube. I have a 12 V vibrator but no 6 V vibrator. Just ain't my lucky day.

Before I bail out on this thread, am I correct in assuming that the purpose of this device is to power a Farm radio from a wet cell lead acid battery?

Thanks a lot for the help! I don't know if I would ever have figured out what this is without the guys on this forum.

Best

Mike


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 Post subject: Re: Mystery audio amp?
PostPosted: Nov Fri 29, 2019 11:57 pm 
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Location: Detroit, MI USA
It could have been intended for a farm radio power supply, in which case it would be 6 volts.

That doesn't seem likely, based upon the apparent date it was built. The parts all look late 50's, by then almost no farms didn't have electricity, although remote hunting cabins and the like wouldn't have. If it was indeed built in the late 50's or early 60's, it could have been intended for something else other than a farm radio, and 12 volt automotive batteries had already been in common use for several years. The date code on the transformer is somewhat blurred due to the varnish on the part, but the last 3 digits of the second line appear to be 932 which would indicate the part was manufactured in the 32nd week of 1959, so it was likely sold and installed in something at some point after then.

The 1958 Chicago Standard catalog does not list a transformer with part number 55-2, however that could be a proprietary number for whatever company the part was made for as OEM, and it wouldn't have been in their catalog.

What I did find upon further searching, was that Playthings of Past has a used 55-2 transformer listed for sale, and Gary has it identified as 12 volts, with 250 volt secondary @ 60 ma. Since he knows how to test them and figure out reasonable specs, we can presume this is a 12 volt supply to provide B+ voltage to some unknown device.

http://www.oldradioparts.com/2a23ffl.txt near the bottom of the page.

My best guess is that it was an accessory power supply offered in kit form (since it's assembled with screws and not rivets) and that it was sold for use with something like a small two-way radio with transmitter and receiver all in one housing. Heathkit is the first possibility which comes to mind....... 55-2 is definitely a Heathkit part number, so perhaps someone with old Heathkit catalogs around 1960-62 can find a model number for the unit.

EDIT: Some further searching indicates that it's a Heathkit supply, probably an older version of the GP-11 unit since there's a tube type rectifier. That model could have been wired for either 6 or 12 volts depending on the builder's needs. Of course you would need to find the schematic for this model to see if you can determine what it's wired for.

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 Post subject: Re: Mystery audio amp?
PostPosted: Nov Sat 30, 2019 1:36 am 
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Joined: Feb Tue 15, 2011 12:33 am
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Location: Columbia, MO 65202
Hi Dennis!

Good to hear from you again. Thanks for taking the time to try to figure this out.

First, a correction. On my wiring diagram I showed pin four of the vibrator socket going to ground. That is incorrect. It is pin one that goes to ground. I have attached a corrected diagram, for what ever that is worth.

Concerning the date code, there are two rows of numbers on the transformer. The top row you read correctly as 55-2. The bottom row is 138952, manufactured by Chicago standard transformer Corporation.

I can't really recognize that number as a date code, but if you take the last three digits, it would be September 1952.

I dug the two capacitors out of the trash can, and unfortunately there is nothing I recognize as a date code on either of them. The rubber coated wiring, in my experience, is mid 40s to early 50s. By 1960 I think wiring was pretty much vinyl jacketed.

Having said all that, looking at that diagram a little more, the terminal labeled "hot A" is jumpered over to the filament terminal. So the filament of the supplied device runs directly off of the battery, making me think it more likely that it was designed for a 6 V battery. With respect to Gary, I wonder if it is not at least possible that it was a six volt primary and a 125 V secondary. In either case, I believe you are correct that it is not intended for a Farm radio, as those would require a 1.5 V filament supply.

The whole purpose of this futile exercise is an attempt to find a power supply for my little knockout regenerative receiver, which has a UX201A, and needs a 5 V filament supply and 125 V B+ supply.

So, I have arrived at the conclusion that I need a line transformer with a 125 V primary, 125 V secondary, and 5 V secondary. I suppose it would be crazy to just rectify and filter line frequency to get my 125 V B+ supply, and use a 6.3 V filament transformer which I could rectify and filter and then install an appropriate resistor to drop the filament voltage to 5 V. Hmmm. Could it be that simple?

My sweetheart has called me on the intercom to tell me it's supper time. I've got 70 people coming over for Thanksgiving tomorrow. But I will probably look at this thread again in the morning...

Thanks again

Mike


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vibrator supply wiring diagram corrected..pdf [87.98 KiB]
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 Post subject: Re: Mystery audio amp?
PostPosted: Nov Sat 30, 2019 5:39 am 
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Joined: Jan Tue 16, 2007 7:02 am
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Location: Lexington, KY USA
From your schematic sketch, it appears that the transformer has two identical center-tapped primary windings, so it can be connected for either 6V or 12 battery input. Presently the two windings are in parallel, so you are set-up for 6V.

In any case, this vibrator transformer is not the answer for your AC line power supply.

The transformer from it might work for your A supply, only. Feed the AC line into the rectifier winding, then connect the low voltage rectifier to what was intended to be the primary windings. If you put the 120V line across the entire winding, the 115 Hz transformer will probably be happy at 60 or even 50 Hz.

No, you don't want to just rectify the 120V AC line to make a B+ supply. Use a transformer.

At the low power you need for B+, you might use a second low voltage transformer to step the AC back up to what you need for the B+ supply. So, if you have two of these Heathkit vibrator units...

A small 6.3V filament transformer would do. Even a transformer from a wall wart might do what you need.

Ted


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 Post subject: Re: Mystery audio amp?
PostPosted: Nov Sat 30, 2019 3:32 pm 
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Joined: Feb Tue 15, 2011 12:33 am
Posts: 382
Location: Columbia, MO 65202
Thanks Ted!

From what you are telling me here, I agree that this thing is not the solution for my little Knockout regenerative receiver.

I think I need to try to find a transformer and just build something.

I am working on finding a 6 V vibrator for this thing, and I might just put it on my website, as is, if I get it working, and see if somebody maybe wants it. The more I think of it, it might be better to hook it up for 12 V, but that will involve quite a bit of work, and I am not sure I am savvy enough to figure out how to wire the transformer without a diagram of it.

Best regards

Mike


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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Mon 02, 2019 12:28 am 
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Location: Roslyn,Pa 19001
Methinks it's for a Heathkit Lunch Box Something like HW-29, HW-30, and there's one other.
The voltage marked on the vibrator (6 or 12v) will determine which tube to use 6X4 or 12X4.

Terry


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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Mon 02, 2019 12:37 am 
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Joined: Feb Tue 15, 2011 12:33 am
Posts: 382
Location: Columbia, MO 65202
Hi Terry:

No tube and no vibrator in it as I got it. Other folks here observed that they thought the transformer primaries were in parallel, meaning it should be for six volts. Currently working my suppliers for a six volt vibrator. When I get one I will reply to this thread how it all came out.

Thanks for helping

Mike


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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Mon 02, 2019 3:23 am 
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The number on xfomer appears to be 138 032, that's mfgr EIA code 138(chicago Std) along with year & week mfg'd. I'm not totally clear on the important fourth digit but if it's 0, the transformer is probably 1950. Sooo since 12X4 was released in '52, it's not a later P/S...

Also not 1960 as by that time mfgr were using four digit date codes(to avoid repeating), date for 1960 would be 6032.

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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Mon 02, 2019 3:56 pm 
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Location: Columbia, MO 65202
Hi, 35Z5:

The number on the transformer, per my earlier post, is 138952, so based on what you have said, it could be designed to accept either a 6X4 or a 12X4, right?

Other people here have looked at the transformer wiring and concluded that the transformer was chosen to be capable of using either tube, and thought that it was currently wired for a 6 V set up.

I am currently attempting to source the 6 V vibrator. When I find one, I will fire it up and see what I get.

Here is a question: do you guys think a 10 amp bench supply of modern design would be able to power this thing for test purposes, or do I need to use a battery?

Thanks for helping out.

Mike


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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Mon 02, 2019 6:12 pm 
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I'll say it's 1949 week 52...

At that time the 12X4 did not exist(was almost exclusively used in viberator P/S), first 12v auto system was Cadillac introduced in late '51 for the 1952 model. By '55/'56 12v automotive electrical systems had mostly replaced 6v. In 1957 transistors were dominating audio in car radios, fast kicking the viberator P/S into history.

This part dating system was introduced just after WWII, thus by '55 or so it was repeating. At that point became a four digit system, BUT the three digit date system did hang on for awhile. Example meaning 138633 could be 1946 or 1956 week 33, by '58/'59 the change to four digit was probably 99.9%. For OEM usage, the mfgr of of part was rarely shown(your xfomer is a exception), 138 would represent Chicago Standard. If first three digits were 238, would indicate Thordarson-Meissner mfg'd part.

First code(101) belonged to Admiral and last(at least in '58) was 1087, indicating Honeywell.

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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Mon 02, 2019 10:52 pm 
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Location: Columbia, MO 65202
Hi Tom:

That dovetails nicely with my suspicion as well. The thing was wired with rubber jacketed wire which I see in antique radios from the late 30s through the early 50s.

No markings on it at all, some speculated could be a Heathkit product, but I thought they tended to put their name on stuff.

Anyway, probably not of any practical use, but if I get it working I will see if some collector has some interest in it.

Thanks for the help

Mike


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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Tue 03, 2019 1:48 am 
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Agreed on rubber covered wire observation.

For unknowns, I like to use mfgr/date codes as 95+% of the time, year is in front of your face. These dates also often apply to appliance, furnace, automotive etc applications.

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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Tue 03, 2019 2:47 am 
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Joined: Feb Tue 15, 2011 12:33 am
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Location: Columbia, MO 65202
I fixed two way radios at a Motorola service center for about 13 years. They had a date code on all of their parts with a three digit date code until about 1982 when they went to four digit. I kind of hate to admit this, but I got them to replace more than one 10 year warranty part because the date code had rolled over with the single-digit year. What the heck, Motorola had plenty of money in those days, and it was a good deal for my customers


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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Tue 03, 2019 6:33 am 
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Joined: Jun Sat 15, 2019 7:43 pm
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This is a Heathkit power supply from 1959. It uses a Mallory vibrator G1601 and 12X4 rectifier tube

Attachment:
HeathkitVT1.jpg
HeathkitVT1.jpg [ 148.2 KiB | Viewed 147 times ]


DM


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 Post subject: Re: Mystery audio amp?
PostPosted: Dec Tue 03, 2019 6:02 pm 
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Joined: Feb Tue 15, 2011 12:33 am
Posts: 382
Location: Columbia, MO 65202
Hi, DM!

Wowsers!! That looks exactly like it!! Thank you! How the heck did you find that?

From what folks on this forum are telling me, mine appears to be wired for 6 V. I suspect any potential customer would much prefer it to be 12 V, but I will need a wiring diagram to reconfigure the primary. Since I already have a 12 V vibrator that I think will work, I could just order a 12 X4 tube. I'll see if I can find a schematic on the Internet.

I will reply to this post when I get parts.

Thanks again for this. That is just plain outstanding that you found it.

Best regards

Mike


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