[radionut1929]

Dear Servicemen and Radio Techs,
I have completed the most of the work on the set but when I put the set through final burn in the transformer partly went south and I need to find a replacement.
Also I need to know the numbering layout of the transformer panel on the bottom right hand corner of the transformer. Can you find the transformers at Antique Radio Supply or any other place on the net that any one might suggest? Also, I need to know the resistances of the big power multi tap resistor and the wattage used on that big resistor bar.
I thank you for your time.

[Radioroslyn]

So what makes you think the power transformer is bad?
Terry

[radionut1929]

So what makes you think the power transformer is bad?
Terry

There was smoke coming out of the transformer and it was making crackling sounds and I nearly lost half of the B+.
Do you know where I can get a replacement transformer?
If you do, please let me know.
Thank you Terry

[Radioroslyn]

Well it sounds like it's shorted.Unfortunately you will have to find a set that has the same tube line up so you'll have the proper filament voltages for all of the tubes. There is a model 87 up on epay but I don't think it has all the voltages you need.
Terry

[codefox1]

Agree.

[radionut1929]

A little known fact is that if half of the secondary winding is open, it is possible that the set might be run again with a set of voltage doubling diodes if the remaining winding is sufficient. Of course if it is more than a few shorted windings this may not be possible. Best test is to run the set with no rectifier and see what it does, get hot, crap out (blow the fuse that yopu should have installed,) or whatever.

So take out the tubes, fire it up, and see what you can see.

You mentioned voltage doubling diodes. Where would you install them?
And what are the type of doubling diodes should I use?
What are the part numbers of the doubling diodes?
Thank you for responding.

[radionut1929]

Well it sounds like it's shorted.Unfortunately you will have to find a set that has the same tube line up so you'll have the proper filament voltages for all of the tubes. There is a model 87 up on epay but I don't think it has all the voltages you need.
Terry

Do you know where I can get a modern replacement for this transformer or do you think I need to have this transformer rewound and where would I get rewound?
Thank you Terry

[Ron Ramirez]

Hi

You have three choices regarding your power transformer if you need to replace:

• Replace with a transformer from a junk 511 Series set.
  Replace with a transformer from a Model 86 (not 87 - see below).
  Have a new one made by Heyboer Transformers (slow, and expensive, but sometimes they are your only option).[/list:u]
  
  A transformer from a model 87 will not work unless you change the output tube from a 71A to a 45. Since the 511 Series is Philco's first line of radios, I would not want to do that.
  
  A transformer from a model 86 has all of the right voltages, plus a little extra current capacity since it was designed for use with two 71A output tubes instead of one. The 86 transformer also has provisions for a "high-low" input voltage switch. (Incidentally, that switch should be set on high in every 511 and 86 set due to today's higher line voltages.)
  
  The 86 transformer has an extra center tap on the 27 filament winding which is not used in the 511 since the 511 uses a hum control potentiometer across this winding (the 86 does not). You can just leave this center tap disconnected - just be sure to insulate that extra wire so that it does not touch anything.

[Radioroslyn]

Trying to find a replacement for it is going to be tough. You'll need one with 2,5v windings one for the 80 &one for the audio tubes, a 2.5v winding for the 27 tube, and a 1.5v winding for the 26's. The Atwater Kent mod 40 uses one but it's in a can full of tar with two chokes and some caps. They can be had cheap but will be some work to get it apart and in the 511.
I hate to disagree with a fellow Phourm member but I wouldn't think of using a doubler to generate the needed HV across half the HV winding. Bad idea. What you are asking a half of burned up transformer is to deliver twice the current across one half of the HV winding. It's asking for trouble.

For a replacement look in the resources section. These a company that will build one to your spec. Will be pricey like $100-150. Rewinding would be about the same.
Sorry OM
Terry

[gvel]

Check out this site, they may have what you need:

http://www.oldradioparts.com/

If you find something there, make sure you adhere to their rules, when you inquire/order.

As mentioned, Heyboer is an option. I purchased one of theirs, and received it in warp speed time...3 days. As a matter of fact, I mailed them a check, as payment. There is no way it could have cleared, before it shipped.

Good luck!

[radionut1929]

Hi

You have three choices regarding your power transformer if you need to replace:

• Replace with a transformer from a junk 511 Series set.
  Replace with a transformer from a Model 86 (not 87 - see below).
  Have a new one made by Heyboer Transformers (slow, and expensive, but sometimes they are your only option).[/list:u]
  
  A transformer from a model 87 will not work unless you change the output tube from a 71A to a 45. Since the 511 Series is Philco's first line of radios, I would not want to do that.
  
  A transformer from a model 86 has all of the right voltages, plus a little extra current capacity since it was designed for use with two 71A output tubes instead of one. The 86 transformer also has provisions for a "high-low" input voltage switch. (Incidentally, that switch should be set on high in every 511 and 86 set due to today's higher line voltages.)
  
  The 86 transformer has an extra center tap on the 27 filament winding which is not used in the 511 since the 511 uses a hum control potentiometer across this winding (the 86 does not). You can just leave this center tap disconnected - just be sure to insulate that extra wire so that it does not touch anything.

Hi Ron,

I might have found a replacement transformer for the radio
I have found in my junk pile a good transformer from a Kolster radio from 1928 and the only thing is that it put out 2.2 volts on the 27 tube filament power.
Which is still within tolerance. I might have to adjust the hum control some, but other than that, it looks like it might work.
And it might require some adjustment to make it fit.
Could you please provide numbering layout on the transformer and if you could that would be very helpful for me.

Sincerely
Radionut

[Ron Ramirez]

You can see how the original Philco transformer is connected here:
http://www.philcoradio.com/tech/images/511.jpg

Can't help you with the Kolster as I would need to know which Kolster model it came from, plus I can't possibly know which wires do what on your proposed replacement. Hopefully they are all labeled. If not, you can figure them all out with a multimeter set to read ohms, but that will take a bit of time.

[radionut1929]

You can see how the original Philco transformer is connected here:
http://www.philcoradio.com/tech/images/511.jpg

Can't help you with the Kolster as I would need to know which Kolster model it came from, plus I can't possibly know which wires do what on your proposed replacement. Hopefully they are all labeled. If not, you can figure them all out with a multimeter set to read ohms, but that will take a bit of time.

Hi Ron,

The transformer came out of a Kolster radio model K27.
What are the resistance of the primary windings, remember that the model K27 has a high and low setting for line volatges, and secondaries for the filament voltages such as the 26, 27, 80, and 71a. Last but not least the high voltage secondary too.
The Kolster transformer has like I have said before is nearly indentical to the Philco transformer except the 27 filament is 2.2 volts.
If I were going to get the transformer rewound from the Heyboer company what kind of data on the windings should I give them and could you pass on the data to me?

Sincerely,
Radionut

[codefox1]

You know what?" I don't think you can do any further damage by trying this out. If the filament voltage is about the same, and you can get some proper B+ and have not popped the fuse that I hope you put in there , maybe 1 amp you might be good to go to the next stage.

[Ron Ramirez]

Well, I looked at the schematic of the Kolster K-27. At first, it appears that the Kolster transformer would substitute for the Philco 511 transformer.

But it won't. Why?

Notice the Kolster transformer's high voltage winding is 600 VCT (300-0-300).

After some searching, I finally found the Philco's ratings. Its high voltage winding is only 375 VCT (187.5-0-187.5).

To use the Kolster transformer would make the B+ run too high throughout the Philco, and would likely cause the B+ on the 71A plate to exceed its design ratings (180 volts max.).

You can do what you wish, but I personally would not do it.

Here are rough specifications for the Philco transformer. I can't guarantee the current specification of the high voltage secondary is correct, but 60 mA is greater than the total plate current draw of the entire set which according to Bulletin 5 adds up to just over 34 mA. Bulletin 5 specifies "30 mA per plate" on the plates of the 80 rectifier. Therefore, 60 mA was selected as a nice round figure. Anyone is, of course, welcome to add their two cents' worth to this. The filament currents were obtained from a tube manual - the 1.5V filament current is equal to the total filament current draw of four 26 tubes.

Primary - 125 volts AC, tapped at roughly 110
Secondary #1: 375 VCT (187.5-0-187.5), looks like 60 mA
Secondary #2 (26 tubes): 1.5V, 4.2A
Secondary #3 (27): 2.5V, 1.75A
Secondary #4 (71A): 5VCT, 0.75 to 1A? (0.5A for 71A tube plus additional current of pilot lamp)
Secondary #5 (80): 5V, 2A