Hiya folks,

Been a while, I hope everyone is still kickin' and doing well. I was recently gifted a fairly nice and eminently restorable ERLA S-11, and I'm looking for a schematic.

I've done the precursory web searches, but turned up a big fat nothing-burger. Thus, I'm hoping for a little guidance here, to help me understand what the circuitry is, and so that I can measure C's and R's to see if they're still in reasonable condition, etc.

Thanks in advance!

Fran Pratt

Here's a few photos (the last one of the ant. connections paper label stolen from the interwebs - mine is missing):

Damn nice gift ! Take the guy out & buy him/her a Steak Dinner... From what I've seen these 3 dialers pretty much worked the same way. Somebody more experienced w/them could likely tell you how to hook one up, & could see if it works. & could how to REALLY fine tune one in..

Damn nice gift ! Take the guy out & buy him/her a Steak Dinner... From what I've seen these 3 dialers pretty much worked the same way. Somebody more experienced w/them could likely tell you how to hook one up, & could see if it works. & could how to REALLY fine tune one in..
Thanks, Sandy! He's a really good kid (kid meaning in his mid 20's); we swap acoustic phono goods frequently, and he's incredibly knowledgeable of recording artists from the late 19th/early 20th centuries. His willingness to help this gimped up aging guy, restores my faith in his generation.

He also brought me a bunch of good 78's, including a couple outside start Pathe's, some Victor electrical's, and a very nice Columbia "Flag Label" Bessie Smith Love Me Daddy Blues/Women's Trouble's Blues #14060-D.

He's a true mensch!

I've recently been playing around with an Atwater Kent 20, got it working well. I have a number of other "3-dialers". I'm trying to get better at working on them and understanding the circuitry, which hopefully will make me better at diagnosing more complicated things. There really isn't much to go wrong. Original grid leaks are usually bad; on the A-K I rebuilt the old one, a first for me, easy and a satisfying repair. Mine had an open pot which was also an easy fix. That was pretty much it, the tubes that came with it were all okay. It's handy to have some you can swap as I think that's more reliable than a tube tester in this case.

I have an ERLA "2-dialer" that I think was built from a kit they sold. I sorta got it working once but not very well. Need to try again someday.

I'm assuming that the circuitry of this "5 in a row make it go" (as a friend described it) ERLA should be very similar to others of the era, but is it wrong for me to think the R values would be identical to others?

Best,
Fran

Hiya folks,

I found this schematic whilst cruising the 'net, it appears this radio is only a TRF, without added neutrodyne circuit(s), correct? I can't vouch for the accuracy of this schematic.

Please bear with me as I muddle through my various stages of reacquainting myself with the tech I haven't thought about for a very long time. I now understand there is NO regenerative circuitry involved, only simple 3 tuner TRF.

I'll get there...;)

I'm convinced that's the correct schem for my radio, parts counts are right. I poked around and found matching R's. I'll see if I can find values for the capacitors. :)

Did a little cleaning today. I gotta say, there doesn't appear to be any reason this radio shouldn't work. I managed to adjust the three tuning capacitors so the plates aren't rubbing when being turned. We'll see, I haven't checked for continuity, and resistances yet.

I just got excited and wanted to show you folks how she cleaned up so far. :yes:

Looks very nice! Maybe that battery is weak :)

Looks very nice! Maybe that battery is weak :)
:lmao:

Sooooo...everything measures fine, BUT, the schematic I found doesn't actually match my radio, other than parts count and most of the component values. The 2 rheostats in mine are both 25 ohm, and one (from the detector F-) is connected to only the low side of the pot, so I'm missing a connection going to somewhere.

The wiring is all kind of messed up on the schem. - and I just realized the way it's drawn, the tubes are shown in mirror image to the actual socket connections looking at them from the bottom, so whether you're looking down from the top, or up from the bottom everything is out of whack. I didn't notice that from the quick glance I took of that schematic.

Am I crazy?

It's killing me...

I'll have to redraw it, if I'm going to have any understanding of this radio.

I'll update as progress warrants. Meanwhile, a couple more photos.

Most schematics asside from some 1920s ones have absolutely no correspondence between position of part on the page and mechanical location of part on the chassis.... honestly if you understand circuit theory it is best that the schematic not include mechanical layout to make the power and signal flow easier to read and follow.

The best thing to do is to if you are having trouble matching things on the schematic to the chassis is label each part with the letter-number designator on the schematic (some 20s schematics may need you to add your own designators). Some parts are easy to identify, and if you trace unknown parts to known then look at everything hooked to the known on the schematic you can trace it out.


TV collectors like me have to do this activity accurately on 20-40 tube TV sets regularly.

I may be wrong, but it looks like the grid-leak detector is at one end of the chassis and the 2 audio amp stages at the other end, with the tuned RF stages in the middle. Was this some clever arrangement to reduce feedback? or am I mistaken in my assessment of the layout? :scratch2:

jr

I may be wrong, but it looks like the grid-leak detector is at one end of the chassis and the 2 audio amp stages at the other end, with the tuned RF stages in the middle. Was this some clever arrangement to reduce feedback? or am I mistaken in my assessment of the layout? :scratch2:

jr
You're correct, in regard to the layout.

Those capacitors that are in your radio that are marked "Mica Condensor" can and should be left alone as those are for the tuner and if anything having to do with the tuner is monkeyed around with, then you'll have to screw around with realigning the whole tuner circuitry to match the new parts.
Plus mica based capacitors rarely fail so they will most likely never need to be changed.

Those capacitors that are in your radio that are marked "Mica Condensor" can and should be left alone as those are for the tuner and if anything having to do with the tuner is monkeyed around with, then you'll have to screw around with realigning the whole tuner circuitry to match the new parts.
Plus mica based capacitors rarely fail so they will most likely never need to be changed.
I agree that micas should be considered good till proven bad, however...

Multi-tuning knob TRF sets don't really have alignment. You can tweak how close to the same knob setting each knob gets when you tune a station for peak volume, but that setup isn't at all critical to operation. Normal tuning procedure on a 3-dial TRF is not all that different from aligning a 1 dial 3-stage TRF with a 3-gang tuning capacitor...only every time you tune to a station on a 3 dial you always have to adjust the 3 tuning knobs for peak audio.

Honestly, anything short of a TV or FM radio is fairly easy to align (and even FM you can do a half-decent job of aligning by ear if you know what you are doing).

Thanks guys, I won't be swapping any components, I think this radio will have more value remaining as original - at least to me, anyway.

Here are the capacitances as they're labeled, and measured with my inexpensive LCR meter (respectively):

.005mF (5000pF) = .006mF (6000pF) - 20%
.0025mF (250pF) = .00219mF (2190pF) -10%
.00025mF (250pF) = .00029mF (289pF) - 16%

The resistances as labeled and measured (respectively):

2M = 2.5M - 25%
5R = 8.7R - 75%
10R = 10.8R - 8%

The 2 pots are both 25 ohm, not the published 30 ohm/50 ohm shown on the schematic.

I haven't checked the xformers yet. I'll probably do that sometime today.

As I mentioned earlier, there is a missing connection on one leg of one of the rheostats - the one labeled on the schem. as "50 Ohm". It's only wired to pin one (F+) of the detector tube.

I don't want to assume anything, but shouldn't the other side of this rheostat go directly to ground? Or is it supposed to be connected to one side of the C battery? I now realize the 2 pots are used for regulating the filaments. Is that how relative volume is controlled? Or signal strength? Or both?

My friend sent me a couple of newspaper ads for the ERLA that he came across while he was researching something else.

Wow, $130 in 1926! That wasn't cheap, especially considering the rapidly falling prices of a (quickly becoming obsolete) top of the line Victrola or Edison Phonograph.

Most schematics asside from some 1920s ones have absolutely no correspondence between position of part on the page and mechanical location of part on the chassis.... honestly if you understand circuit theory it is best that the schematic not include mechanical layout to make the power and signal flow easier to read and follow.

The best thing to do is to if you are having trouble matching things on the schematic to the chassis is label each part with the letter-number designator on the schematic (some 20s schematics may need you to add your own designators). Some parts are easy to identify, and if you trace unknown parts to known then look at everything hooked to the known on the schematic you can trace it out.


TV collectors like me have to do this activity accurately on 20-40 tube TV sets regularly.
Yep. That's exactly how I do it, too. It's funny to me that the schems I've examined with similar topographies, centered the circuitry around the Detector.

My goal with this specific schematic, is to check and amend it as compared to my specific radio. The schematic I posted is of unknown origination, and there may very well have been changes by the manufacturer - as this was a very common occurrence in this time period. Technology and markets changed constantly, and manufacturers had to try and quickly respond to public demands, right?

Well, I guess that's that. I'm not getting any continuity or resistance measurements across either transformer, primary or secondary.

I'd think at least one of the four windings would show something. :sigh:

Well, I guess that's that. I'm not getting any continuity or resistance measurements across either transformer, primary or secondary.

I'd think at least one of the four windings would show something. :sigh:

Audio transformers? Try putting A and B voltages to the radio. On 20s sets sometimes the open will weld closed under normal opperating conditions . On a Atwater Kent 40 I fixed for a friend both both windings of the interstage transformer tested open. We were ready to swap in a RC coupling circuit to replace it but we decided to power up the set and test with a signal source first and not only did it work but continuity returned in subsequent tests.

Same thing happened to me recently with a horn speaker that had an open voice coil...tested wide open, but I connected it to my radiola and it worked and tested as having good continuity afterwards.

Even if dead you can still replace with RC circuits with some datasheet searching and maths.

I think I finished the schematic.

I found a couple missing connections, but everything else is intact. The odd thing is the B+ 45V(Maroon) and 90V (Red) color coded wires are apparently attached reversed, in reference to a case label I found with a couple other ERLA S-11 radios. Mine is missing.

Also, I'm confused. Are those transformers, or inductors? I'm getting inductance with my LCR meter, but I'm not getting any resistance with my Fluke 89. :saywhat:

Forgive me for uploading small images, it's been so long since I've used this older message board format, that I've forgotten how to load them in the text window. :scratch2:

Regarding the open end of the rheostat, that should be to A+, normally. On the AK 20 I have on the bench one end of the wire had detached. There was enough in the winding that I could carefully pull out 1/4" and solder that to the lead.

One of the rheostats controls the filament for detectors and the other for amplification. Depending on signal strength you may have to adjust one or both for best results. If one of them is open then some tubes won't light at all. If you needed to temporarily you could run a jumper and run all filaments off of the one good rheostat. For that matter, you could just run 6v direct to the filaments, for testing purposes.

Audio transformers? Try putting A and B voltages to the radio. On 20s sets sometimes the open will weld closed under normal opperating conditions . On a Atwater Kent 40 I fixed for a friend both both windings of the interstage transformer tested open. We were ready to swap in a RC coupling circuit to replace it but we decided to power up the set and test with a signal source first and not only did it work but continuity returned in subsequent tests.

Same thing happened to me recently with a horn speaker that had an open voice coil...tested wide open, but I connected it to my radiola and it worked and tested as having good continuity afterwards.

Even if dead you can still replace with RC circuits with some datasheet searching and maths.
Thank you, I'll try that once I put together a suitable A/B/C PS.

Regarding the open end of the rheostat, that should be to A+, normally. On the AK 20 I have on the bench one end of the wire had detached. There was enough in the winding that I could carefully pull out 1/4" and solder that to the lead.

One of the rheostats controls the filament for detectors and the other for amplification. Depending on signal strength you may have to adjust one or both for best results. If one of them is open then some tubes won't light at all. If you needed to temporarily you could run a jumper and run all filaments off of the one good rheostat. For that matter, you could just run 6v direct to the filaments, for testing purposes.
Thanks Bryan, I amended my schematic to reflect your information. I had a feeling that the rheostats were used for that purpose, but it's good to have confirmation.

There was another suspect connection shown in the "original" schematic I posted earlier, but it doesn't exist in my radio. It is shown coming off V3 pin 1 (F+) in parallel with V5 pin 1 (F+) going to the 25 Ohm pot. Would there have been a connection there, and if so, for what purpose do you think?
199041

As for a signal in, and a loudspeaker or phones, what should I use for a quick and dirty (reliable?) antenna, and what impedance loudspeaker can I get away with? I have a pair of old (1960's) Lafayette headphones that still work, and plenty of speakers laying around. Would an 8 ohm full range speaker be okay? I don't want to kill a good speaker screwing around - if I can help it. :tresbon:

These sets expected 500 ohm headphones / speaker or higher impedance. If you don't have proper 20s era phone's get the audio output transformer from a tube radio and use that to match the impedance.

These sets expected 500 ohm headphones / speaker or higher impedance. If you don't have proper 20s era phone's get the audio output transformer from a tube radio and use that to match the impedance.
Thanks Tom.

An addendum to an earlier post I made:

I uncovered a section of the wiring harness viewed under different lighting, and discovered that the wire I initially thought was Red (B+90V) is actually the Maroon (B+45V).

THAT makes more sense. The schematic has been edited to reflect this discovery. I'm still curious as to why there would've been shown an unknown connection off of V31, and V51?

Why the hell would a link be placed onto the words "wiring harness" in my last post? I didn't do that!

Why the hell would a link be placed onto the words "wiring harness" in my last post? I didn't do that!

Skimlinks add reasources....it is a way for VK to make money. You'll see people intentionally miss spell stuff to avoid skimlinks grabbing it and making it a link...I haven't seen skimlinks in any VK post in years by using Firefox with an ad blocker add on... enough of the ads on the net are exceptionally obnoxious and or full of viruses that I try to eliminate almost all of them.

The lower end of the variable resistor from pin 1 of V1 should connect to ground. And yes, I would replace the missing wire from the antenna coil to ground.

jr

The lower end of the variable resistor from pin 1 of V1 should connect to ground. And yes, I would replace the missing wire from the antenna coil to ground.

jr
Okay, I'll put those connections back into my schematic. Any idea what the external connection shown at V3 1 represented? There is a GRD post topside that isn't shown in the schematic I'm using to redraw. I wonder if this connection was an error by whomever drew the "original". :scratch2:

Perhaps a test point, for setting/monitoring the voltage applied to the filaments of the RF amplifier tubes. :scratch2:

jr

4 out of the 5 UX201A's test very strong, so that's a "plus". I won't be spending any more time on this for now. I'm pretty happy with how well she cleaned up - not a beauty queen by any stretch, but at least I was able to save and preserve her for future generations.

Maybe someday I'll come back to her, build a battery eliminator or appropriate battery box, replace the 2 bad interstage xformers, string up an antenna, and fire her up to dial in that singular 550kHz station...

A sincere "Thank you" to everyone who helped me out. As time progresses, I'll keep her in my thoughts, and add historical information to the file on the ca.1925 ERLA S-11 TRF 5-tube radio I now have alongside my talking machine collection.

Cheers,
Fran

Usually, the RF stages were in the 1,3,5 tube positions, (separation to avoid feedback), and the audio amps in the 2,4 position. Easy enough to figure out, you can start at the antenna or speaker term and trace them out..
1. all the filaments lit? If so, check the plate voltages. Usually, the audio transformers primary windings are open (corrosion) so no plate voltage. Secondaries are not immune..

Usually, the RF stages were in the 1,3,5 tube positions, (separation to avoid feedback), and the audio amps in the 2,4 position. Easy enough to figure out, you can start at the antenna or speaker term and trace them out..
That's exactly what I discovered while I traced out the schematic on my own. Initially I had some difficulty trying to understand the relationship between that hand-drawn schematic I posted back on pg.1, and what was going on with the actually physical layout of the circuitry.

I did eventually identify a few inaccuracies between that suspect schematic, and my radio. Other Model S-11's could be different I suppose (that was very typical for the antique talking machine industry of the same period - and throughout its entire earlier history), but I've reconciled most of my difficulties in understanding what's going on. Thanks for your input.

1. all the filaments lit? If so, check the plate voltages. Usually, the audio transformers primary windings are open (corrosion) so no plate voltage. Secondaries are not immune..
I determined both xformers are open on all 4 windings, sadly, and I won't pursue powering the radio up anytime soon. I'm happy with it being a shelf queen for now. If/when I ever do proceed beyond this point, I'll probably build a battery eliminator, so that I might be able to add more even earlier TRF radios (and especially a "homebrew") to my fairly extensive acoustic phono collection.

Maybe. :scratch2:

With over 30 acoustic spring-wind machines in my home, ranging from 2 minute cylinder players from as early as a ca.1895 Graphophone Type N, and many Edison Phonographs; a couple 4-minute Edison Amberolas (including a very nice and HTF oak Model V); several disc machines ranging from a ca.1901 pre-dog Victor Type C; a couple Victrolas; several Diamond Disc Phonographs produced from as early as 1916 to as late as my ca.1927 Edisonic "Schubert" (and also including an Edison "Long Playing" Model 1-C Phonograph); and books. Tons of books, too. All this takes up the entire downstairs of my home, and a little of my barn.

They're my true passion. :smoke:

Oh, yeah, and then there's the "Audiophile" stuff, too. :banana: Space is always at a premium, as we all know. ;)

Best regards,
Fran

http://videokarma.org/attachment.php?attachmentid=199071&stc=1&d=1566218103

:music: Wow Man , , , , like , Frantastic ! ..... :D

Wow nice acoustic phonographs.

You know you can replace each audio transformer with 2 resistors and a capacitor.... disconnect the old transformers and place a 10K ohm resistor in circuit between the points the plate winding of the audio transformer once connected, take a 1-2M ohm resistor and connect it across the points the grid winding once connected, now connect the plate lead to the grid of the next tube with a .1uF capacitor, rinse and repeat for the other bad audio transformer.....I can draw you a schematic later if you would like.

Have you looked inside the xfmrs? If the core size is 1/2", you may still be able to get a bobbin (windings) from antique electronic in Tempe. I've "rebuilt" a few transformers over the years doing this. It's difficult, and messy, but.... For other sizes I've had to resort to other methods. I did one where I replaced the iron with a piece of pine, (hollowed out to take the modern transformer) and then wire brushed the wood to "line" it so it looked 9under the flat black paint) like laminations.

http://www.oldradiosrus.com/build.html

There are 2 xfmr rebuilds shown on that page...

Hammond 124A xfmr or 124C (coil only)

:music: Wow Man , , , , like , Frantastic ! ..... :D
:D:naughty::beerchug:

Wow nice acoustic phonographs.

You know you can replace each audio transformer with 2 resistors and a capacitor.... disconnect the old transformers and place a 10K ohm resistor in circuit between the points the plate winding of the audio transformer once connected, take a 1-2M ohm resistor and connect it across the points the grid winding once connected, now connect the plate lead to the grid of the next tube with a .1uF capacitor, rinse and repeat for the other bad audio transformer.....I can draw you a schematic later if you would like.
Thanks, I didn't know that. That's a simple solution, for sure - "capacitor coupling" the stages instead of a transformer? Is that the correct terminology for the circuit?

Like this?
http://www.videokarma.org/attachment.php?attachmentid=199081&stc=1&d=1566299592

Have you looked inside the xfmrs? If the core size is 1/2", you may still be able to get a bobbin (windings) from antique electronic in Tempe. I've "rebuilt" a few transformers over the years doing this. It's difficult, and messy, but.... For other sizes I've had to resort to other methods. I did one where I replaced the iron with a piece of pine, (hollowed out to take the modern transformer) and then wire brushed the wood to "line" it so it looked 9under the flat black paint) like laminations.

http://www.oldradiosrus.com/build.html

There are 2 xfmr rebuilds shown on that page...

Hammond 124A xfmr or 124C (coil only)
Thanks Tom! I'm not sure I'll try restuffing the tranny's, but you never know. :scratch2:

:D:naughty::beerchug:


Thanks, I didn't know that. That's a simple solution, for sure - "capacitor coupling" the stages instead of a transformer? Is that the correct terminology for the circuit?

Like this?
http://www.videokarma.org/attachment.php?attachmentid=199081&stc=1&d=1566299592

Yes but the grid resistors need to be 1-2 Megaohms not kiloohms. Once it is passing audio you may want to experiment with caps between .47 and .01, plate resistors between 8k and 15k, etc to optimize volume and tone. Audio amplifiers of that time were spectacularly inexact devices and could opperate deceptively normally with component values far from design or optimum.
What I gave you should get it to pass audio.
You will need a high impedance speaker/headphones or an audio matching transformer and a low impedance speaker... the plate resistance of a 01A is 11k ohms so you want an audio transformer with a primary impedance between 9k and 13k, and a secondary impedance that matches your speaker. Any transformer rated over 5W is probably over kill.

Thanks Tom, my mistake! I'm happy you caught that typo.

Fran

Yes but the grid resistors need to be 1-2 Megaohms not kiloohms. Once it is passing audio you may want to experiment with caps between .47 and .01, plate resistors between 8k and 15k, etc to optimize volume and tone. Audio amplifiers of that time were spectacularly inexact devices and could opperate deceptively normally with component values far from design or optimum.
What I gave you should get it to pass audio.

For posterity, here's the amended (final?) schematic with coupling caps and resistors bypassing the the two transformers:


http://videokarma.org/attachment.php?attachmentid=199091&stc=1&d=1566385424

You will need a high impedance speaker/headphones or an audio matching transformer and a low impedance speaker... the plate resistance of a 01A is 11k ohms so you want an audio transformer with a primary impedance between 9k and 13k, and a secondary impedance that matches your speaker. Any transformer rated over 5W is probably over kill.

I think I'm slowly becoming convinced that I should try this. I'll have to dig around my various parts stashes and see what I may have. :scratch2: I know I have some 70V PA speaker transformers that came with some full range 8" Jensens- would they do the job, do you think, or would the primary impedance be too low? I don't know how to determine those impedances between the windings.

I have some other old 40's-50's radios out in the barn, I can see if I can determine the values of their output trannys.

Sorry for all the probably stupid questions.

Hi Fran , Tom's method will work for you , I've done this many times and in fact I did the very same thing recently to a Temple brand TRF radio and it worked great . A couple of fine tuning tweaks here may be to use smaller capacitors for the coupling , I've usually found that much over .001 caused distortion , and with the Temple there was a bit of a buzz in the sound till I fed the plate resistor(the 10K resistor) with a small RF choke . The radio I did had only one bad interstage transformer and was an A/C powered unit , if you run your's from batteries you may not need the RF choke .

PS , there are no stupid questions here , we are mostly old men (:) Tom being the exception) who have spent a lifetime learning this stuff , and we are here specifically to help people learn what we spent all those years learning . Oh , and I love the "I is for him , E is for her" , my middle name is Francis and many people don't know the I or E spelling for male or female ;)

Hi Fran , Tom's method will work for you , I've done this many times and in fact I did the very same thing recently to a Temple brand TRF radio and it worked great . A couple of fine tuning tweaks here may be to use smaller capacitors for the coupling , I've usually found that much over .001 caused distortion , and with the Temple there was a bit of a buzz in the sound till I fed the plate resistor(the 10K resistor) with a small RF choke . The radio I did had only one bad interstage transformer and was an A/C powered unit , if you run your's from batteries you may not need the RF choke .

PS , there are no stupid questions here , we are mostly old men (:) Tom being the exception) who have spent a lifetime learning this stuff , and we are here specifically to help people learn what we spent all those years learning . Oh , and I love the "I is for him , E is for her" , my middle name is Francis and many people don't know the I or E spelling for male or female ;)
Thanks for the info! I'm an "old guy" myself, or at least closing in on that realm at 61. ;) Suffice it say, I've literally forgotten everything my dad taught me while helping him in my younger years (he was in the Army Radio Corps in WW2, Germany 1945 onward, then an electronics test engineer at General Dynamics and later R.F. Communications). We built tons of stuff before I went out (more or less) on my own at 17.

I just did a quick tutorial on the 70V line matching tx's and how to figure impedances between the primary (70V) and secondaries, and I think I can use one of the Jensens I have. The secondaries are labeled as (Watts) 4, 2, 1, 1/2, 1/4, and 1/8 into an "8 ohm speaker".

http://videokarma.org/attachment.php?attachmentid=199092&stc=1&d=1566396264

http://videokarma.org/attachment.php?attachmentid=199093&stc=1&d=1566396264

http://videokarma.org/attachment.php?attachmentid=199094&stc=1&d=1566396264

If my math is correct - following the innernut tutorials I watched (using the 70V primary and the 1/2 watt secondary):

W=E^2/R

W=5000/R

1/2=5000/R

R = 5000*W(1/2)

R(Impedance) = 10,000 ohms.

Gawd, I hope I didn't screw up the simple algebra. Been a reeeeaaaaalllllly long time. Am I on the right track, as far as the output of the final UX201A impedance?

Edit I see you are progressing on the pa transformer the way I would... I'm too tired to check the math, but it looks like your on the right track.

On the barn parts radios Google the audio output tube I'd number for each tube with the " tube datasheet" tacked onto the end of the search string...you should ring PDFs of pages from old RCA tube manuals and the like scan through the specs and look for plate resistance of the tube anything reasonably close to 11k should have a transformer that will work.....you can also order a new part from Hammond. Hammond makes new transformers for tube gear and probably has something that will work (try to get a part 5w or less or your paying for extra power your output tube will never be able to deliver to it).

Edit I see you are progressing on the pa transformer the way I would... I'm too tired to check the math, but it looks like your on the right track.

On the barn parts radios Google the audio output tube I'd number for each tube with the " tube datasheet" tacked onto the end of the search string...you should ring PDFs of pages from old RCA tube manuals and the like scan through the specs and look for plate resistance of the tube anything reasonably close to 11k should have a transformer that will work.....you can also order a new part from Hammond. Hammond makes new transformers for tube gear and probably has something that will work (try to get a part 5w or less or your paying for extra power your output tube will never be able to deliver to it).

Great! Thanks Tom, I appreciate the help.

Fran