Indeed, this pp amp with GU81 runs with 3.5KV on the anodes:
http://www.pbase.com/df3kv/image/86725410/original
73
Peter, DJ7WW
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Carl
Sent: Montag, 12. Juni 2017 00:17
To: Chris Wilson; amps@contesting.com
Subject: Re: [Amps] Ferrite Core for 160M PI Output ?
With Teflon insulated wire and Scotch 27 tape between windings probably
4-5KV.
A Hi-Pot tester is great for such things.
Carl
----- Original Message -----
From: "Chris Wilson" <chris@chriswilson.tv>
To: <amps@contesting.com>
Sent: Sunday, June 11, 2017 4:43 PM
Subject: Re: [Amps] Ferrite Core for 160M PI Output ?
>
>
> Hello Carl,
>
> I am beginning to build an LF amp using a GS35B tube, what do you
> reckon the HV limit is for a Pi coil wound on a toroid? At 136 kHz air
> wound coils start to get pretty big nd bulky.... Thanks
>
>
>
> On Sunday, June 11, 2017, you wrote:
>
>
>
>
>> ** The T225-2B is sometimes hard to source so a pair of the A version is
>> equivalent. A pair of the more common T200-2A or 2B is what was used in
>> most
>> amps.
>> Ive run two 200-2A's on 160 for about 30 years in a modified NCL-2000
>> without problems at 1200W including AM.
>> Dont forget to wrap each one with a layer of Scotch 27 HV tape and then
>> wrap
>> the stack before winding. I also used #14 stranded Teflon wire as that
>> was
>> what I found on a big reel at a scrap dealer.
>
>> Carl
>
>
>
>
>
>
> --
> Best regards,
> Chris mailto:chris@chriswilson.tv
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
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