New SE With Triode Mode KT120/150

[Cressy Snr]

Had you considered a CCS on the anode ? Single or cascaded.

Thanks Phil. Only fly in the ointment is that a CCS won’t swing to twice the HT voltage and I need all the undistorted drive I can get, this being a two stage design, so anode chokes are the easiest and most obvious choice in this particular application.

[Cressy Snr]

Some decent progress since Saturday:
Top plate has been drilled and punched, valve sockets fitted and the volume pot has been mounted on a bracket underneath. The pot will be reached with a shaft extender (cue DTB) from the front panel, once the thing is built. The plate is braced in both directions on the underside. I’m not putting up with saggy iron; not this time.

Valve lineup looks great.

[simon]

What's the top plate material Steve, stainless steel? Looks great.

[Cressy Snr]

What's the top plate material Steve, stainless steel? Looks great.

Nah, just common or garden aluminium I’m afraid.

[simon]

Wow, looks quite shiny. Just the standard finish or has it had a bit of a polish?

[Cressy Snr]

Wow, looks quite shiny. Just the standard finish or has it had a bit of a polish?

It’s polished ally, which was covered with a plastic film on the shiny side. Being ally, it’s going to dull from exposure to the air. Whether it keeps its finish will depend on whether occasional polishing is practicable once all the iron is fitted. I would have liked stainless, but it’s a complete b’stard to punch holes in and IME it attracts fingermarks like a magnet.

[Cressy Snr]

The globe MH4s will be heated with 4V of regulated DC from an old DIYHS, DHT filament module, running its AC input off the standard 6.3V heater winding on the mains transformer.

[steve s]

Nice work steve.. looks like it coming on well..
My latest discovery is dibond, the local surplus store has off cuts in for next to nowt.. white on one side plain alloy on the other, I've done a log store roof with it, and a couple of amp top plates, it's so easy to work..
Just treat it like wood, the alloy side polishes up beautifully or it looks good sprayed.
I've now got hold of some smaller anodized pieces that will make some great top plates with out the need to spray them.

[pre65]

My latest discovery is dibond, the local surplus store has off cuts in for next to nowt.. white on one side plain alloy on the other, I've done a log store roof with it, and a couple of amp top plates, it's so easy to work..
Just treat it like wood, the alloy side polishes up beautifully or it looks good sprayed.

Thanks for the tip Steve, I see they do two shades of blue, and glossy or mat.
EDIT.
I've ordered an A4 size piece in ultramarine blue to evaluate. At worst I can use it as a clipboard.

[steve s]

My latest discovery is dibond, the local surplus store has off cuts in for next to nowt.. white on one side plain alloy on the other, I've done a log store roof with it, and a couple of amp top plates, it's so easy to work..
Just treat it like wood, the alloy side polishes up beautifully or it looks good sprayed.

Thanks for the tip Steve, I see they do two shades of blue, and glossy or mat.
EDIT.
I've ordered an A4 size piece in ultramarine blue to evaluate. At worst I can use it as a clipboard.

Phil..
It cuts nicely with a track saw, a hole saw goes through it like butter, very fine wet and dry, then polish up the edges. I've found enamal spray paint gives very nice finish on it too, and does not rub off like acrylic crap.. You will have a lovely clip board....

[Cressy Snr]

Why is it, that shortly after you strip the protective sheet off the finished side of your aluminium, you find that there are invariably, half a dozen fecking holes you forgot to drill, no matter how many times you thought you’d checked beforehand?

[steve s]

That's what masking tape is for steve

[Ray P]

Why is it, that shortly after you strip the protective sheet off the finished side of your aluminium, you find that there are invariably, half a dozen fecking holes you forgot to drill, no matter how many times you thought you’d checked beforehand?

Just leave it on,

[pre65]

That's what masking tape is for steve

I purchased a length of plain white Fablon eons ago and I use it on aluminium to mark things out prior to cutting, drilling, filing (and bleeding) etc. Then peel off to reveal the full glory of the material.

Just make sure the aluminium is degreased thoroughly before applying.

Masking tape is good as well.

[Paul Barker]

Had you considered a CCS on the anode ? Single or cascaded.

Thanks Phil. Only fly in the ointment is that a CCS won’t swing to twice the HT voltage and I need all the undistorted drive I can get, this being a two stage design, so anode chokes are the easiest and most obvious choice in this particular application.

You can put a solid state ccs in series with the choke, the choke gives you the ac swing the ccs gives you better isolation and frequency response.