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Peerless 16309 output transfomers

battradio

battradio

Electron trainer
The Peerless 1609 output transformers are known to be less than reliable in the Heat Kit W-5m .

Is it the transformer itself or the way it was used in the circuit , i have one w-5m amp and plan on getting another that looks like it has been rebuilt but still has problems so i'm assuming that the output transformer is flaky . Haven't checked the output on the one i have but if either of them or both are bad i will have to replace the output transfomers with something reliable .

I have a pair of output transfomers that came from Eico HF-20 which look like identical to the power transfomers and are the same physical size which won't fit where the peerless are mounted :tears:

That leaves me with several choices , find a decent pair output transformer to fit in the peerless cans or mount the Eico' output transfomers in place of the power transformer on the Heath chassis in place of the power transformer and put a power transformer that fits where the output transformer was , or strip the entire chassis and make the the Room for the two large potted transfomers that match .

The W5-m chassis makes no sense how it was laid out the power cord comes in by the output transformer and the input and driver tubes are right next to the power transformer and the output terminal . So both the relocating schemes s makes sense to do except to a real purest .

Re stuffing the can with a new transformer makes more sense to me than having something rewound that wasn't dependable to beguin with .

Mark
 
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When I had that amp here I wondered about down scaling it's power to increase longevity, it seems they work that smallish transformer pretty hard. I went on the net and the failures seemed more with the power xformer in these things. Go figger. The original ckt is of course a tapped screen Williamson, which puts plate level voltage at the screens, so no relief there if the original configuration is preserved. Afaik, the tapped screens were a later flourish, the basic concept wasn't designed around it fwiw. Non- tapped otherwise appropriate OPTs or the originals with the taps disconnected and the the screens regulated lower should de-stress the amp.

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http://www.transcendar.com/3.html

A pair of the 6.6k 30 watt transfomers look likely would fit in the cans , i had planed to tame the B+ so it would not be driven as hard about 18 watt out is all i would want out of the existing output transfomers , also located a pair of Fisher outputs that might work in these with the B+ lowered , great sound and dependability is what i'm striving for .

Will leave the driver circuit alone and tweak the feed back a bit to make them more stable , got a line on a 3rd amp also with the same output transformer
 
One of our tube gurus stated that these amps were his overall faves, iirc.

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This is how i will tame and simplify the B+ and get about 406 volts DC , the 100 ohm 4 watt resistor can go , due to the lower B+


Will use the 50UF 900 volt caps as the 2nd and third B+ caps .

http://www.digikey.com/product-search/en?KeyWords= BC2874-ND&WT.z_header=search_go

Will also simply the cathode bias , change the Two 30 ohm resistors in the cathodes to 10 ohms , ground the 330 ohm 7 watt resistor .getting rid of the two 100 ohm resistors . Not sure what i will do with the bias balance pot , may delete it or change it to about 10k for a clipping balance pot .



http://tubedata.tubes.se/sheets/127/5/5881.pdf

http://tubedata.tubes.se/sheets/084/k/KT66_GEC.pdf

Will most like use 5881's in it over KT66's
 
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Clipping balance sounds good, would this make matched tubes less critical?

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Clipping balance is how I matched output tubes in the Mac 75 twins project as well as the earlier tubes for drive, there's no adjustment for it in them.
 
battradio said:




This is how i will tame and simplify the B+ and get about 406 volts DC , the 100 ohm 4 watt resistor can go , due to the lower B+


Will use the 50UF 900 volt caps as the 2nd and third B+ caps .

http://www.digikey.com/product-search/en?KeyWords= BC2874-ND&WT.z_header=search_go

Will also simply the cathode bias , change the Two 30 ohm resistors in the cathodes to 10 ohms , ground the 330 ohm 7 watt resistor .getting rid of the two 100 ohm resistors . Not sure what i will do with the bias balance pot , may delete it or change it to about 10k for a clipping balance pot .



http://tubedata.tubes.se/sheets/127/5/5881.pdf

http://tubedata.tubes.se/sheets/084/k/KT66_GEC.pdf

Will most like use 5881's in it over KT66's
Click to expand...

On further thought, that pot looks like output stage low-level balance and should have some effect on inner detail, smoothness, and such. As most listening will likely be well below clipping I'd keep it as-is and match tubes for clipping balance after making sure the driver tube has balanced triodes.
I may be off base so please set me straight if so.

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What I don't understand is why you're talking about replacing the output transformer before you've even tried it. I'm pretty sure that a portion of the special sound out of these units is tied to the very nice sounding iron which they came with.

Yes, I understand replacing them if they are dead. But why preempt a problem which may never even occur?
 
goldear said:
What I don't understand is why you're talking about replacing the output transformer before you've even tried it. I'm pretty sure that a portion of the special sound out of these units is tied to the very nice sounding iron which they came with.

Yes, I understand replacing them if they are dead. But why preempt a problem which may never even occur?
Click to expand...



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This is the one i'm worried about , it has been in worked on by someone that is competent and then owned by someone that might be a better tech than me so with what has been done to it i suspect output transformer

I look at these on ebay all the time and a high proportion have had the output transfomers replaced not to mention the power transformer also .
 
Pio1980 said:
On further thought, that pot looks like output stage low-level balance and should have some effect on inner detail, smoothness, and such. As most listening will likely be well below clipping I'd keep it as-is and match tubes for clipping balance after making sure the driver tube has balanced triodes.
I may be off base so please set me straight if so.

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Click to expand...

Checking further, according to the W5M page at Stone Vintage Radio the balance control is to balance plate current to minimize distortion at low frequencies. Procedure and discussion at A-K thread "W5 Bass Balance".

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I run 5881s real easy in mine, but like said before, I think it's the PT that gives the most trouble. I heard once it was the potting tar, and you could un-pot, clean with electronic degreaser and heat (not open flame), then re-pot with micro-crystiline wax and all is good. I'm not going to all that trouble on rumor as I've never lost a TX in the 8 or so I own.
 
http://www.mouser.com/ProductDetail...c3ydrPrF6VKmnbjjATP6lr0l6iBovsXIuABPEe%2bWw==

I just ordered these for the power supply to do a way with the series caps in the power supply .

http://www.mouser.com/ProductDetail...1cc3ydrPrF6VKmnbjjATPsGy3RO1E0gHcvfsMRiLnQA==

if you want to retain the 5R4 use the 10uf cap to keep the voltages the same .

Pio PM me your mail box is full

To check the output transfomers i am going to connect another amp to the 8 ohm out put terminals and drive it with a 1KHZ sine wave with two 5k 100 watt resistor on the primary to center tap as a dummy load and monitor the wave form with a scope .
 
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battradio said:
http://www.mouser.com/ProductDetail...c3ydrPrF6VKmnbjjATP6lr0l6iBovsXIuABPEe%2bWw==

I just ordered these for the power supply to do a way with the series caps in the power supply .

http://www.mouser.com/ProductDetail...1cc3ydrPrF6VKmnbjjATPsGy3RO1E0gHcvfsMRiLnQA==

if you want to retain the 5R4 use the 10uf cap to keep the voltages the same .

Pio PM me your mail box is full
Click to expand...

OK. Been having probs with the message que, I have to open the computer and delete a bunch of messages. Either that or my subscriber status has lapsed.

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As was explained elsewhere, there is absolutely no problem with working KT66s off 450V h.t. in UL.

Firstly one must remember tube voltages are quoted 'cathode-to-anode', not common-to-anode. The bias must be subtracted. Then the dissipation is the important matter. Maximum voltage ratings are operation-related, to be safe under all conditions, including some low-brain designs. One is not going to get inter-electrode sparking if the maxima are exceeded by the next 1%. Tube datasheets often indicate safe handling of pulses many times the continuous voltage rating.

UL operation ensures that the screen is lower than its maximum as the anode voltage decreases, which is the dangerous zone for screens, etc. The renowned McIntosh amplifier operated 6L6s at quite higher than rated maximum voltages at the time, and they lasted for years.

I am not promoting wreckless disregard of ratings per se; safe operating conditions are discussed on several internet sites.
 
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The renowned McIntosh amplifier operated 6L6s at quite higher than rated maximum voltages at the time, and they lasted for years.

if your thinking of the mc 30 they originally called for 1614 tubes which have a higher plate rating than a standard 6l6.the chassis on the ealy ones are stamped 1614. they later then stamped them 1614/6l6gc.
 
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Didn't the original Macs run 807s? Same basic guts and archechture as 6L6, I suppose once they'd worked it out for one, it was good for all versions of the same tube, the 225 and 75/275 excepted, afaik, tho the 75/275 is still an upscaled iteration of the others.

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