Thordarson T-19R31

[KC2ZFA]

hello all, does anyone have the connection diagram for
the Thordarson T-19R31 bias transformer ?

It has pins numbered 1 through 6 on one bell, and pins
numbered 7 through 14 on the other bell. Looking with
an ohm-meter produced confusion, I couldn't identify
the primary, maybe there's a primary-secondary short ?

Thanks, Peter

[KE6DF]

I can't find a hookup sheet.

If it's anything like the UTC bias transformer, then both the primary and secondary have multiple taps.

As a first approximation, if it were me, I'd guess that low numbered side was the primary and the high numbered pins were the secondary.

Perhaps put a low voltage (say 5v from a small filament tranny) into pins one and two and see what comes out the other side.

Then try pins one and three etc.

You will probably have to figure it out the hard way -- unless you find someone who has one new in the box with the hookup sheet.

[KA2DZT]

Peter,

The only thing I could find was a schematic with the 19R31, from a Thordarson book.

It only showed terminals 9-10 and 11-12 as the secondary.  Two separate windings with 10 connected to 11 as the center tap for a full wave rectifier.

My guess is that the secondary is two separate windings terminals 7 thru 10 and terminals 11 thru 14.  Terminals 10 and 11 are connected together to make the center tap.  Then you would select what taps on each secondary to give different voltages.  Most likely terminals 7 and 14 give the highest voltage and terminals 9 and 12 the lowest.  Terminals 8 and 13 would be something in between.

My guess is that the primary is a tap winding, terminals 1 thru 6.  One terminal is the common or start (most likely terminal 1).  Then you would connect the 120vac to terminal 1 and any one of terminals 2 thru 6.  Terminals 1 and 2 would give the highest voltage and terminals 1 and 6 the lowest voltage.

Keep in mind, this is just what I think the terminals are. DON'T connect full 120vac to anything until you try to comfirm some of what I'm saying.

The 19R31 is rated at 200ma and is designed to give DC voltage output from 10VDC to 100VDC in 5 volt steps.

Use your ohm meter to measure the windings to see if what I am saying is correct.

Maybe it is, maybe it's not.

Fred

[KC2ZFA]

thanks guys. I will now sort it out.

Fred, thanks for prodding me to go back and look closely at all
the circuits in the Thordarson transmitter book (which I had
downloaded from the bunker of doom, thanks Pat!).

The puzzler is that with the ct (10+11 pin shorted to ground)
this xfmr can get 15 voltages (5 primary taps, and 3 secondary
taps on each side of the ct)...but there are 19 voltages between
10 and 100 

Time to put it under (some) voltage.

Peter

[KE6DF]

The puzzler is that with the ct (10+11 pin shorted to ground)
this xfmr can get 15 voltages (5 primary taps, and 3 secondary
taps on each side of the ct)...but there are 19 voltages between
10 and 100 

Well you could connect 9 to 12 and use that for the CT. That would get you a few more choices. Than you could use 8 connected to 13 for another couple choices.

Probably some of these combinations would yield the same voltage as others, but you probably could get 19 different voltages that way.

Multi-match modulation transformers  get tons of impedance rations with similar tricks.

[KA2DZT]

thanks guys. I will now sort it out.

Fred, thanks for prodding me to go back and look closely at all
the circuits in the Thordarson transmitter book (which I had
downloaded from the bunker of doom, thanks Pat!).

The puzzler is that with the ct (10+11 pin shorted to ground)
this xfmr can get 15 voltages (5 primary taps, and 3 secondary
taps on each side of the ct)...but there are 19 voltages between
10 and 100 

Time to put it under (some) voltage.

Peter

Peter,

You are right about the 19 different voltages.  I did think about that when I wrote my first post.  But, like wb6iyh says, you could use different pairs of terminals for the center tap and get even more steps in voltage.

I'm sure you'll figure it out.

Fred