Mike H wrote:I like Nick's idea of the driver transformer secondary in the cathode path. Actually that rings a bell cos sure he's mentioned it elsewhere
Anyway we're thinking in terms of about 500V HT (cos that's all Phil's got) so will require some positive bias
If I go back to cap input with that PSU I could have more HT. It was at 950V when installed on the 845 project.
Or, I could get some bigger transformers, those Antek ones from USA are reasonably priced. Don't want to spoil the ship for h'apath of tar.
My OPT are rated at 120ma or 30W so unless I upgrade them that is my power limit.
The only thing necessary for the triumph of evil is for good men to do nothing.
Ok, reading the link, its got a +ve and -ve output, and there will be 5v between them, so connect the -ve to 0v to make it a +5v supply, or the +ve to 0v to make it a -5v supply.
its a 100w supply, 5 * 20 = 100, so you will need two of these. And I would not hold my breath at what happens if you run it at 100% load. should be ok, but time will tell.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Nick wrote:Ok, reading the link, its got a +ve and -ve output, and there will be 5v between them, so connect the -ve to 0v to make it a +5v supply, or the +ve to 0v to make it a -5v supply.
its a 100w supply, 5 * 20 = 100, so you will need two of these. And I would not hold my breath at what happens if you run it at 100% load. should be ok, but time will tell.
EDIT: not that ripple and noise is 100mv, so -30dB on 5v
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Taking all this into consideration, and having noted that at last sim the plate dis of each 833A is 150W if HT = 950V, it occurred to me that once it's all booted up you would probably want to turn the central heating off.
Could probably make toast on it as well
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
It's confusing. Slight discrepancy re the connections table versus the photograph (see attachment below)
So it's got 2 x 5V outputs? Cos 1.2A x 230V (mains in) = 276W
Nick wrote:its a 100w supply, 5 * 20 = 100, so you will need two of these. And I would not hold my breath at what happens if you run it at 100% load. should be ok, but time will tell
See derating curves on graph on eBay page. A candidate for forced air cooling? (blower fan)
Otherwise can't think what else could do it. Car batteries would have a problem!
Nick wrote:150w will hardly wake them up
I know!
Tried your 1.4 kV etc. set-up, you woz right
Attachments
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
JamesD wrote:
Now I just need a design... well I have knocked one up using PL802 in pp as a driver (see diagram). but I am not sure what operating point for the 8333 to use. I like the look of Va=750V, Ia=350mA and Vg=+25V. It looks like I can get a very linear swing for +/- 25Volts input with maximum input of +/-50volts before clipping the output. This with a 3K OPT. However I am wondering what op points other people have used or would suggest???
I will make the high voltage supply bipolar to half the B+ to earth risk at the cost of doubling the number of caps and chokes in the power supply - a worthwhile trade off for me. I have most of the components for a +/- 400V to +/- 800V supply at 400mA so that will do one channel! Just one to go...
I am lucky that I have two surplus switch-mode psu of 12V at 10A that I can use for filament supplies. I'll feed the psu through CLCLC rf filters to reduce the switching noise even further and connect that to the filaments.
Any suggestions or thoughts are most welcome
Maybe the panel could do something with this.
Maybe James still has the 833s Phil
Why not drop him an email?
