Return-Path: X-Spam-DCC: paranoid 1181; Body=3 Fuz1=3 Fuz2=3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_MESSAGE autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id tAEKcA50002220 for ; Sat, 14 Nov 2015 21:38:10 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZxhXV-0007OA-Gr for rs_out_1@blacksheep.org; Sat, 14 Nov 2015 20:35:13 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZxhXV-0007O1-2h for rsgb_lf_group@blacksheep.org; Sat, 14 Nov 2015 20:35:13 +0000 Received: from mail-wm0-f46.google.com ([74.125.82.46]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.86) (envelope-from ) id 1ZxhWa-0006fK-Kn for rsgb_lf_group@blacksheep.org; Sat, 14 Nov 2015 20:35:11 +0000 Received: by wmdw130 with SMTP id w130so67519412wmd.0 for ; Sat, 14 Nov 2015 12:34:00 -0800 (PST) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=rikM7jjIKAPszr9Qrrh6B6FEbnC99N/sGa/ShLb/wN8=; b=hRLETbBNuuFoQGA7VljkzmZ+I+yAKDH1C0bb4HF/vTDgJCsa9OgEWHngfeGeXbSjTO h9vgWU6V2yeGpM4gTIxwF8ZqXLQtK4He7oNfbzUeE6pjk+ff/ol5hZryeNhmGXvx3Mqx G6lppekr0e8woU0YQjGCYrnieZc5Wrpy/SCc9RzNWLUa2wozFq7jmARw+tdfBd4L6ZRE cjw3RMJUQTRIWsYBO+2xI2soOTL+HGvbdAyuJfr+HUBSk9R6mwjbf46gNEg9UBS2NTFg VuMAYxuEX97/TgCjRfw71CpNpcZddb7ny3SyJGnXJCFyh420ouLmJvbh1GDNVAHIMZRT UWWQ== MIME-Version: 1.0 X-Received: by 10.28.225.84 with SMTP id y81mr9285007wmg.87.1447533240588; Sat, 14 Nov 2015 12:34:00 -0800 (PST) Received: by 10.28.130.139 with HTTP; Sat, 14 Nov 2015 12:34:00 -0800 (PST) In-Reply-To: <825751561.20151114200051@chriswilson.tv> References: <4510637253.20151114190626@chriswilson.tv> <825751561.20151114200051@chriswilson.tv> Date: Sat, 14 Nov 2015 20:34:00 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Scan-Signature: efdc09b6b31095aa2dc5c6d2552910d5 Subject: Re: Re[2]: LF: Valve LF amps and tank coil size / voltage rating? Content-Type: multipart/alternative; boundary=001a114b14409b1e1105248618f6 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 5077 --001a114b14409b1e1105248618f6 Content-Type: text/plain; charset=UTF-8 Yes, but that's all an engineering problem. I'm sure the wire probably exists. I've never played with a valve since dabbling in old TVs of the 1970's era, and never high power stuff. However, I have built a highly reliable 700 Watt PA, running direct from rectified mains (340V DC).http://www.g4jnt.com/137tx.pdf OK, I blew FETs designing it in the first place - but even in the early noughties when I was doing it, those FEts only cost a couple of quid each. And once proven, I could replace with bigger FETs that nowadays even those cost peanuts. That direct-from-mains supply could be expanded and at the time I was visualising a 2kW version, but had to see sense considering the smallness of my garden and the possibilities for fires and things. I already lost a plastic shed housing the loading coil from running the 700W thing. http://www.g4jnt.com/Melted_ATU_Cabin.JPG Andy G4JNT On 14 November 2015 at 20:00, Chris Wilson wrote: > Hello Andy, > > Saturday, November 14, 2015 > > > OK, but what about wire breakdown voltages? In all the big air cored > LF tanks I have seen the windings are well spaced on ceramic, or > Paxolin type grooved formers, how do I know a close wound toroidal > coil won't break down? > > > I have built a few HV supplies using decent industrial quality iron > cored transformers, the biggest is 5kV at 1.5 Amps, which can also be > fed from a 40 Amp Variac, to drop the primary down. I use that in my > workshop for running a glue drying machine. > > I was also gifted some NOS ceramic triodes, some US, some Russian, and > would consider having a bash at a valved LF amp, just "because" :) I > have to say my limited experience of ceramic triodes has shown no > unreliability, in fact a zero failure rate so long as they are > gettered before use, if they have lain dormant for years. > > I do have a reasonable collection of failed FET's though :) In > fairness user error was the demise of most of them. > > > Thanks Andy. > > > > I'll say it againV = 4.44.F.N.A.B (all SI units) > > > > THAT is how you size ferrite cores. It tells you more or less > > everything you need to know to make ferrite transformers. Keep B to > > less than 0.1 at these frequencies > > > > But.. why would you want to use valves? > > Expensive, unreliable, high voltages... > > > > 'jnt > > > > > > > > > -- > Best regards, > Chris 2E0ILY mailto:chris@chriswilson.tv > > > --001a114b14409b1e1105248618f6 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Yes, but that's all an engineering problem. I'm su= re the wire probably exists. =C2=A0 I've never played with a valve sinc= e dabbling in old TVs of the 1970's era, and never high power stuff.
However, I have built a highly reliable 700 Watt PA, runni= ng direct from rectified mains (340V DC).http://www.g4jnt.com/137tx.pdf =C2=A0 =C2=A0OK, I blew FETs de= signing it in the first place =C2=A0- but even in the early noughties when = I was doing it, those FEts only cost a couple of quid each.=C2=A0 And once = proven, I could replace with bigger FETs that nowadays even those cost pean= uts.

That direct-from-mains supply could be expand= ed and at the time I was visualising a 2kW version, but had to see sense co= nsidering the smallness of my garden and the possibilities for fires and th= ings.=C2=A0 I already lost a plastic shed housing the loading coil from run= ning the 700W thing. =C2=A0http://www.g4jnt.com/Melted_ATU_Cabin.JPG


Andy =C2=A0G4JNT

On 14 November 2015 at 20:00, Chris Wilson <chris@c= hriswilson.tv> wrote:
Hello Andy,

Saturday, November 14, 2015


OK, but what about wire breakdown voltages? In all the big air cored
LF tanks I have seen the windings are well spaced on ceramic, or
Paxolin type grooved formers, how do I know a close wound toroidal
coil won't break down?


I have built a few HV supplies using decent industrial quality iron
cored transformers, the biggest is 5kV at 1.5 Amps, which can also be
fed from a 40 Amp Variac, to drop the primary down. I use that in my
workshop for running a glue drying machine.

I was also gifted some NOS ceramic triodes, some US, some Russian, and
would consider having a bash at a valved LF amp, just "because" := ) I
have to say my limited experience of ceramic triodes has shown no
unreliability, in fact a zero failure rate so long as they are
gettered before use, if they have lain dormant for years.

I do have a reasonable collection of failed FET's though :) In
fairness user error was the demise of most of them.


Thanks Andy.


> I'll say it againV =3D 4.44.F.N.A.B =C2=A0(all SI units)


> THAT is how you size ferrite cores.=C2=A0 It tells you more or less > everything you need to know to make ferrite transformers.=C2=A0 Keep B= to
> less than 0.1 at these frequencies


> But.. why would you want to use valves?
> Expensive, unreliable, high voltages...


> 'jnt








--
Best regards,
=C2=A0Chris=C2=A0 2E0ILY=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 mailto:chris@chriswilson.tv



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