Unpotted Peerless 16309 OPT from Heath W5m

[walker112]

I unpotted one of my broken Peerless 16309 OPTs. The smaller of the two OPTs seen in the W-5m. See the attached pictures.

A few observations:

1. The transformer core is relatively tiny for a 20watt amplifier. 3"x2.5"x1.5" . A lot of these OPTs fail and I wonder if it is a thermal problem and the isulation just gives out due to heat. Today's superior insulation and better insulated magnet wire would probably improve the reliability immensely.

2. There is a compensation cap between the plate and UL tap on both sides of the primary. It's an Aerovox branded one and looks like a mica. I'll measure one eventually. Micas are pretty stable and should be close to the original value.

3. near the center of the stack there are what looks like many nickel laminations between the M6 ones. The other, larger Peerless 16458 opt from the W-5m does not have these nickel lams.

I'd like to get these rewound. Haven't got around to budgeting for it yet...

[tubewade]

Interesting. I've got a dead one but never got around to dismantling it for inspection. Nice to see what's inside.

[Bandersnatch]

That would be an inch and half stack of 1" center leg E-I scrappless. The caps are an interesting additions; the S265Q and S271S I had Heyboer take down did not have such things. The S271S did have the Ni in about the same thickness on a thicker stack. Until I saw it myself, I had no idea of its existence; nobody making them today, regardless of the 'exactly to print' claims ever thought to mention them.

Also, the rumour started about the demise of Heyboer's winding of OPT's they've been hired to unwind and clone is greatly exagerated...
cheers,
Douglas

[MQracing]

Hi Walker:

Don't let core size in isolation fool you or form the basis of "goodness".

What you really also need to know is how many pri turns (and the volts across these turns) are energizing that core and at what lowest frequency.

So that a smaller core with a larger number of pri turns may have a lower flux density than a larger core with fewer pri turns.

And--- the smaller (but equal as above) core may have some other optimalities due to it's size.

MSL

[pjanda1]

Interestingly, if you didn't have the the nickel laminations, those would be the spitting image of the OPTs in my Scott 222B (which I assume are Stancor). Not that I've seen many OPTs in my time, but the laminations look the same and the size is right (if you add 1/4" for the nickel). The next version of the Scott had very different looking OPTs (bigger but sloppier looking lams).

thanks for the pics,

pj

[kevinkr]

Originally posted by pjanda1
Interestingly, if you didn't have the the nickel laminations, those would be the spitting image of the OPTs in my Scott 222B (which I assume are Stancor). Not that I've seen many OPTs in my time, but the laminations look the same and the size is right (if you add 1/4" for the nickel). The next version of the Scott had very different looking OPTs (bigger but sloppier looking lams).

thanks for the pics,

pj

Scott actually manufactured their output and power transformers in house, this from many former employees of Scott who I have met over the years. (I lived next town over from Maynard during most of the 1990s - you would never guess they had been there.. )

[tarzanalog]

Sorry to hijack, but I've been sitting on an old Heathkit W-5M that I was planning on turning into a Root666 guitar amp (Dr. Z Route 66 clone) but a '73 Ampeg B-15S just caught my eye (and ears) and I am cleaning house to raise the funds.

I believe the iron to be good (Peerless 16458 OT!) but the electrolytics are shot (I'm guessing), the power tubes were lifeless and have been discarded (I think the Rectifier is still good and the 12AU7s were fine), and there is no pre-amp with it. It's not the prettiest belle at the ball, but I've seen the output tranny alone go for $200 and up on the 'Bay. I can email pics to those that are interested. PM me with questions.

Help me get my dream bass amp...

Thanks,
Roy

[Brian Connolly]

Hello Walker:

How did the Peerless rebuild turn out? I'm getting ready to un-pot a bad one myself. How did you do it without destroying the finish on the can? I don't know yet if I'm going to have the original rewound or have a new one made.

If you need a brand new power transformer for the KT-66 equipped W-5M use Pacific Transformer (PAC TRAN) 18125A. It is identical in size and performance to the original. I know because they designed it for me from a working original. Consequently, you won't need to pay the NRE cost.

thanks for the thread,

brian

[Bandersnatch]

hey Walker,
I've worked with a few amp restorers in these parts and our conclusion to the toasty 16309 problem is to replace it with the tougher S265Q. With Heyboer doing the winding, we also have the opportunity to put in the U-L taps in the 40%( or any 10% increment for that matter) location. It has two separate secondaries so either 8 and 16 Ohms are available, or in parallel for 4 w/o any re-configuring. No more worry about a marginal OPT.
cheers,
Douglas

[walker112]

Originally posted by Brian Connolly
Hello Walker:

How did the Peerless rebuild turn out? I'm getting ready to un-pot a bad one myself. How did you do it without destroying the finish on the can? I don't know yet if I'm going to have the original rewound or have a new one made.

If you need a brand new power transformer for the KT-66 equipped W-5M use Pacific Transformer (PAC TRAN) 18125A. It is identical in size and performance to the original. I know because they designed it for me from a working original. Consequently, you won't need to pay the NRE cost.

thanks for the thread,

brian

Hi Brian,

After corresponding with a "well known transformer house", we decided it probably wasn't worth the effort (or cost) to have these 16309's rewound since the we would need to preserve the nickel laminations since they are so hard to get. The problem is that the laminations might get bent in the process.

It's not impossible, but with the availability of really good (proven) transformers from the same source, the process of getting these rewound would be basically for curiosity's sake.

If somebody's willing to share the cost with me of getting the transformer unwound and the specs recorded, send me a PM. I might still be interested in going this route since I still have several of these dead 16309's.

I unpotted mine by putting them in a conventional oven set just above the boiling point of water. I laid the transformer down on a wet towel to minimize hot spots and checked the tar for softness. At some point I was able to pull out the core by tugging on the leads. You don't want to completely liquify the tar and stink up your kitchen. You want to heat it just enough so the bond that the tar makes with the potting can is broken.

I let the unpotted core cool and froze the thing solid in the freezer so I could easily chip off the tar to expose the core. If i could get the encased core colder with say a liquid N2 bath, I could probably shatter most of the tar off cleanly with a hard blow from a plastic mallet. But I needed to chip at it since the tar was still a bit soft.

Walker