Thank you very much for all your comments. I think I did not explain myself well.
My purpose is to build a PP amplifier using the 807 tubes. That's why the very high HT. On the other hand I'm thinking to use the triode-pentode phase splitter as a challenge and the way to learn something new. If it is too complicated I will desist, and I will try a simple triode-triode phase splitter.
Refugee wrote:Beware of heater cathode voltage with split load phase splitters
My intention is to run the 807 on fixed bias mode with negative voltage supply. Heater-to-cathode voltage limit on the 807 is 135V according to datasheet, while its maximun grid voltage is about 75 V so I see no problem on this. I will also use a separate heater winding for the 807 so I will be able to adjust the heater-to-cathode voltage.
I would like you to explain me what you mean with split load phase splitter
. Sorry mate, I got lost there.
PYE625 wrote:It would be safer and easier to start with a good old standard, like the EL84 Mullard 10watt circuit.
Safer and easier....possibly, but then where is the fun and the challenge.
PYE625 wrote:It could be very expensive to obtain suitable GOOD transformers for a Williamson amplifier
I have a Hammond transformer delivering 365-0-365 V AC and two separate heater windings. I will use a center tapped rectifier with two 1N4007 in series on both ends. My intention is to wind the OPT myself, using a Soviet TCA-70 core.
PYE625 wrote:Then of course there is a bigger risk to health with such a high HT !
I can assure you that I'm aware of that. I worked with 5,5 kV while building my scope, I receive a nasty electric shock from time to time in my bench, so I will take care
: Thanks for your concern.
Terry wrote:I don't think that smoothing capacitors for a 550V HT rail are going to be easy to find anywhere!
Well Terry, remember that my case is special. I do not even think on any project if I'm not sure to have all of the required components since the beginning. I have several 220uF @ 500V electrolytics. I will use them in series with resistors in parallel in order to get 110uF on both legs of a Pi filter.
Terry wrote:If you have, you might consider building one of the Mullard amplifier designs.
I have considered them. If I do not succeed with the triode-pentode circuit, I will try that one.