MV-4 Mod Tranny Connections

[WB4AM]

Hello,

I have a VM-4 mod Tranny, (see Pic) not to get confused with the CVM-4 Tranny which I believe is wrapped in a can but I may be incorrect on this.
It looks to be NOS but for all I know it could be blown, I purchased this a very long time ago off of fleabay.

Anyway I have the box but no paper work.  Does anyway know the configuration of these connections?

My understanding is it is a varimatch mod tranny, so it will depend on what tubes are used, but even if I knew what tubes, let say 813's I still have no
clue on what terminals to use.

Any information that can even lead me to the answer is better then none.  When I search I mostly find CVM-4 and it still does not give the configurations.

Thank you,
Ken
 

[Tom WA3KLR]

The information on the VM-4 is in this UTC 1936 catalog on Patrick's Bunker of Doom site.  What you want is on pages 33, 34 and 35 of the pdf (original printed pages 31-33) .  The connection terminal numbers are on a little chart in the upper left corner of page 34. The VM-4 is for 200 - 600 Watt input PA's and 300 Watts audio max.

http://www.bunkerofdoom.com/xfm/UTC_1936/UTC1936.pdf

You need to know what your modulators are and what your PA impedance is going to be.

Perhaps this info is in newer catalogs he has posted but I found this info in the first catalog I looked in. (Thanks Patrick - Opcom.)

[WB4AM]

Hello Tom,

That's interested because I found that link before hand and even copied the Pdf just because it had something to do with UTC.

I use FireFox for the browser and up in the edit window down at the bottom there is a "Find in this Page" search.  I put in UTC VM-4 and there was nothing
found.

Maybe the words themselves are in a picture format stopping the search?

I will have a look!  Thank you so much for this information, without it I would probably never use it or simply short it out.  Then again even with
this information I still might short it out!

By the way, I still have that 813 linear with supply.  If it was not for you I wouldn't have it today.  Man is that supply heavy.

Thank you again Tom, all the best.

Ken

[Tom WA3KLR]

Hi Ken,

New call! Good luck.

[Opcom]

Many of the PDF files on the site are from images and there was no OCR. Today almost all will have OCR, but back then it was not always done.

[WB4AM]

Hi Ken,

New call! Good luck.

Again, Thank you Tom, I appreciate you.

73
Ken

Many of the PDF files on the site are from images and there was no OCR. Today almost all will have OCR, but back then it was not always done.

There is a lesson here for me to learn.  I use that search under the edit tab in Firefox lots of times.  I probably missed a lot of info because of it.

I suppose the "Find in this Page" (CTRL F) search in Fire Fox can still be used, but when it doesn't appear to show any information, then the manual search is in order.
(In the case as in this past scenario)

[WR6J]

Ken,

I was interested to see your VM-4 photo. I recently obtained a VM-3 - seemingly unused - in the same box. It came with the original documentation. I'm attaching a PDF of it that I found online. I don't think it provides much more information than the 1936 catalog, but it is interesting to see what was provided with the transformer.

I am planning to use it with a pair of 811s or 812s modulating an 810 or 813. What are you hoping to build?

Richard

[Tom WA3KLR]

Thanks for posting the booklet that came with the transformer. After re-looking at what I had dug up, the catalog seemed a little confusing and vague, so I wondered if documentation included with the transformers was the full detail.  Having the actual transformer is a help since you see the terminals and their labels. 

[K1JJ]

While we're on the general subject... does anyone have the frequency response specs either by actual experience or data sheet on the 125 watt Thordarson T-11M76 multimatch modulation transformer?  Or even that line of xfmrs would be helpful. I see nothing in their catalogue related to freq response, inductance, etc... A friend has one he will give me, so thinking of a rig to use it in.

Thanks.

Tom, K1JJ

[WB4AM]

Ken,

I was interested to see your VM-4 photo. I recently obtained a VM-3 - seemingly unused - in the same box. It came with the original documentation. I'm attaching a PDF of it that I found online. I don't think it provides much more information than the 1936 catalog, but it is interesting to see what was provided with the transformer.

I am planning to use it with a pair of 811s or 812s modulating an 810 or 813. What are you hoping to build?

Richard

Its good to see some of these old mod transformers. 
Thank you Richard for the PDF.  From what Tom had mentioned this will be handy too.