801a maximised class A2 excursion.

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Paul Barker
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#136 Re: 801a maximised class A2 excursion.

Post by Paul Barker »

OK so slight shift.

Decided to build ACFII, which lead to me finding the start of such a project I must have made at the time Nick was telling me about the ACFII.

https://i.postimg.cc/sXwCWqj0/B62302-E9 ... 9499-B.jpg

So the way it’s based up 6H2n everywhere but output. I obvs put just 1 octal base but if I use 6bx7 which is most likely I’d need a second Octal.

So stupidly I didn’t put two Octals, so I’ll have to mount a pair and leave a vent hole middle for fiddle which I’ll mesh over industrial style or Fast Car grill style you know.

I think the valve spacing probs still OK with pair octals central. There again if I change two existing B9 holes cut for octal holes and move those two 6H2’s two inside row with vent screen in old octal hole it should all look better than my average breadboard. You will see that this is a ground plain design.

So here’s how pretty it is with incorrect base .

[url] ttps://i.postimg.cc/FHqkQC0c/F0-E90535-9498-484-E-8183-97138934-D6-BA.jpg[/url]
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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Joined: Mon May 21, 2007 9:42 pm

#137 Re: 801a maximised class A2 excursion.

Post by Paul Barker »

OK so slight shift.

Decided to build ACFII, which lead to me finding the start of such a project I must have made at the time Nick was telling me about the ACFII.

Image

So the way it’s based up 6H2n everywhere but output. I obvs put just 1 octal base but if I use 6bx7 which is most likely I’d need a second Octal.

So stupidly I didn’t put two Octals, so I’ll have to mount a pair and leave a vent hole middle for fiddle which I’ll mesh over industrial style or Fast Car grill style you know.

I think the valve spacing probs still OK with pair octals central. There again if I change two existing B9 holes cut for octal holes and move those two 6H2’s two inside row with vent screen in old octal hole it should all look better than my average breadboard. You will see that this is a ground plain design.

So here’s how pretty it is with incorrect base .

Image

I must have based it when I decided to use dpln mosfet but I’m not using any solid state for now. This will be all valve as designed hence why I now need another Octal base. I’ll probable position them so that higher voltage valves have shared heater levelling and alter erase negative side also prioritised by heater potential rather than L/R channel.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#138 Re: 801a maximised class A2 excursion.

Post by Paul Barker »

The bias of the dc coupling of output means input potential anything from ground potential to -50v. Which means need ac input protection, I’m thinking Sowter 1475 input transformer configured 1:1 by paralleling the two secondaries. As they’re wound for pp I’ll have to connect after scoping the outputs making sure I’ve got right phasing.

I checked with Brian Sowter on dc potential here’s reply:-
“ 50V is ok so long as no dc flows in the primary.


Let me know if you have any further questions.

Best regards

Brian Sowter”

Sweet man.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#139 Re: 801a maximised class A2 excursion.

Post by Paul Barker »

But I’ll have to save up so I’ll go with cap in the interim.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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