Peerless 16309 output transfomers

16309 transformers have a center layer of nickel E's and I's, see the picture of one disassembled that I have attached. The nickel supposedly flattened out the response curve a bit over the 16458. If one looks close, one can also see a capacitor attached to the primary. I should mention, I did not take these pictures, I was given them by a gentleman that bought a dozen or so W5's from me a few years ago. He was from Michigan and seemed to know a lot of Heathkit history.
 

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stanko said:
16309 transformers have a center layer of nickel E's and I's, see the picture of one disassembled that I have attached. The nickel supposedly flattened out the response curve a bit over the 16458. If one looks close, one can also see a capacitor attached to the secondary.
Click to expand...

How is the cap employed, and is it a failure prone point?

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I cannot say at the moment. I have (2) 16309 transformers to rewind that the gentleman from Michigan left me to play with, but I haven't gotten to them yet. This discussion is actually getting my curiosity up, I may have to take them apart and check them out. In answer to the second question, I wouldn't be a bit surprised if a bad cap showed up in a transformer, they show up bad everywhere else. Just my opinion, of course.
 
The UTC transformers i use have a permalloy core , it has nickle added the core and is more like a high quality microphone transformer .

I still want to lower the B+ ,it will improve the longevity of all the parts
 
battradio said:
The UTC transformers i use have a permalloy core , it has nickle added the core and is more like a high quality microphone transformer .

I still want to lower the B+ ,it will improve the longevity of all the parts
Click to expand...

Definitely would agree about derating, they really whipped these things to excess imo.

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I suspect the cap is nothing more than a shunt to prevent high frequency oscillations. It's too small to really do much else.
 
stanko said:
I suspect the cap is nothing more than a shunt to prevent high frequency oscillations. It's too small to really do much else.
Click to expand...

The design description mentions tweeter protection, I assume this might be that?

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Much better they should have been external on the terminal board for replacement in event of failure.


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stanko said:
My thoughts exactly.
Click to expand...

Protection caps across output transfomers are usually 1,500 volts or more and still have a tendency to short .

The roll off filter in the W-5M circuit is between the the first and second 12AU7 , and connected to the B+ instead of ground .



The 4.7K ohm and the 220 PF cap are grounded through the 20UF cap . When that 20uf cap starts to rise in ESR with age the filter becomes less effective and allows high frequency oscillations to develop which would cause the protection cap to short or worse open and allow the output transformer to fail .

I plan on moving the end of that 220PF cap to ground at the 470 ohm resistor that is the bottom of the feedback loop .
 
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battradio said:
Protection caps across output transfomers are usually 1,500 volts or more and still have a tendency to short .

The roll off filter in the W-5M circuit is between the the first and second 12AU7 , and connected to the B+ instead of ground .



The 4.7K ohm and the 220 PF cap are grounded through the 20UF cap . When that 20uf cap starts to rise in ESR with age the filter becomes less effective and allows high frequency oscillations to develop which would cause the protection cap to short or worse open and allow the output transformer to fail .

I plan on moving the end of that 220PF cap to ground at the 470 ohm resistor that is the bottom of the feedback loop .
Click to expand...

All makes perfect sense to me. I do wonder how many failed opts may just be that cap.

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"How is the cap employed, and is it a failure prone point?"

Legend has it that the internal cap in the 16309 is paralleled across one side of the primary to balance out internal winding capacitance on either side of the CT. Legend also has it that the value of the capacitance was specifically selected for each individual transformer. This is quite similar to what EICO did with their bigger tube amps, notably the HF50/60 and HF89 except these caps were external. Normally a cap in this position would have primarily an AC voltage across it so failures ought to be rare...I've never heard of this compared to frequent reports of open primary windings and evidence of shorted turns. I'm told that the primary was wound with unusually fine wire and tend to believe it because the primary DC resistance is relatively high for a 10K ohm/25W transformer.

One other point is that the internal opt cap is not the "tweeter protector" some have referred to. Heath's tweeter protector circuit is the 47R/0.1uF series network across the com/16 ohm tap. It's purpose is to provide a mostly resistive load at ultrasonic frequencies regardless of connected load.

Overall, the 16309 is a very good sounding OPT, warts and all. It's responsible for a large part of the W5s character and I for one would be reluctant to replace it with something else except maybe a16458. As always, YMMV.
 
Steve O said:
"How is the cap employed, and is it a failure prone point?"

Legend has it that the internal cap in the 16309 is paralleled across one side of the primary to balance out internal winding capacitance on either side of the CT. Legend also has it that the value of the capacitance was specifically selected for each individual transformer. This is quite similar to what EICO did with their bigger tube amps, notably the HF50/60 and HF89 except these caps were external. Normally a cap in this position would have primarily an AC voltage across it so failures ought to be rare...I've never heard of this compared to frequent reports of open primary windings and evidence of shorted turns. I'm told that the primary was wound with unusually fine wire and tend to believe it because the primary DC resistance is relatively high for a 10K ohm/25W transformer.

One other point is that the internal opt cap is not the "tweeter protector" some have referred to. Heath's tweeter protector circuit is the 47R/0.1uF series network across the com/16 ohm tap. It's purpose is to provide a mostly resistive load at ultrasonic frequencies regardless of connected load.

Overall, the 16309 is a very good sounding OPT, warts and all. It's responsible for a large part of the W5s character and I for one would be reluctant to replace it with something else except maybe a16458. As always, YMMV.
Click to expand...

Thnx for the fill-in corrections, that makes perfect sense having the cap potted and inaccessible. Having a pair to live with for a while has been on my bucket list. A pair of unity coupled Macs would be nice as well, and perhaps a Citation V before I get too old. So many amps, so little time.

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