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  #1  
Old 23rd July 2007, 11:33 AM
Mike Prime Mike Prime is offline
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Default WAD Kit88 Output Transformers

Hi all, this is my first post here, I hope someone doesn't mind helping a newbie.

I have a Kit88 that I built a few years ago, now one of the output transformers has died after the amp was left on with a speaker unplugged. I've heard mention of replacing the original transformers with Sowter UO82s. Does anyone know if this is the same model they still offer? What other modifications to the circuit would be necessary if using the Sowters? Any help would be gratefully received, I am anxious to get my amp working again.
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Old 23rd July 2007, 12:41 PM
Tony Moore's Avatar
Tony Moore Tony Moore is offline
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Default Re: WAD Kit88 Output Transformers

Hi Mike,

Richard can probably comment better than I can on the Kit88 mods necessary to use the Sowters. I installed U082s in my Kit6550 amp a few years ago and I did not _have_ to do any circuit mods to accommodate them. What I _did_ do was to reduce feedback (on Richards recommendation) and that certainly improved the sound once again over the extra quality gained from the Sowters. U082s is still available according to the Sowter website.

I will say that the U082s is larger than the stock OPTs and so I had to cut the case metalwork to suit them.

http://www.btinternet.com/~antony_s_...wad/Inside.jpg

http://www.btinternet.com/~antony_s_...g_1642copy.jpg

Cheers,
Tony
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  #3  
Old 23rd July 2007, 06:12 PM
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Wieslaw Lipowski Wieslaw Lipowski is offline
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Default Re: WAD Kit88 Output Transformers

Hello Mike,

Where did you leave (lose) the green WAD PCBoard that you got with the kit? If you don't need it anymore why don't you...?
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  #4  
Old 26th July 2007, 07:29 AM
John Caswell John Caswell is offline
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Default Re: WAD Kit88 Output Transformers

Hi all,
As I was the original instigator of this mod I can say it does indeed work very well with the standard 8K primary load and the ultra linear taps wired out of the way. You may need to tweak the feedback capacitor for best square wave response but that is about all.
Instead of ordering the drop through types order the upright types (which I prefer aesthetically) and all you may have to do is drill 4 or 5 holes.

John - Dr John
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Old 28th July 2007, 03:36 PM
Mike Prime Mike Prime is offline
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Default Re: WAD Kit88 Output Transformers

Tony, thanks for the quick reply and the photos. Weislaw, sorry, I'm still using the pcb.

Dr. John, your gris-gris is too strong for me. Would you mind spelling out which are the ultra-linear taps, and how I should wire them out of the way? Here is a schematic of the Sowter transformers. Presumably, the 2 orange wires go to centre tap. Which of the other wires on the primary winding are the anode connections, and what do I do with the other two?
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  #6  
Old 28th July 2007, 05:44 PM
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pre65 pre65 is offline
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Default Re: WAD Kit88 Output Transformers

Hi-normally on a PP output transformer the B+ goes to the primary centre tap (orange) and the anodes of each valve to the white + yellow with the screen taps being the violet + pink.

Sowter seem not to stick to the "norm" with centre tap red,and the anode wires blue and brown.


Philip
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Everything in this post is my honest opinion based on what i thought I knew at that very moment in time.
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