kevin gilmore

its all about the size of the box. if you go with a bigger box you certainly can use the more extensive power supply which is far more voltage stable and substantially less noise.

the schematic capture auto numbers stuff, and I never pay any attention to that when I do the board. what I should do is use the netlist, but that is just so much work. the problem happens when you go back and change the schematic, and the board no longer matches... if I actually did this for a living, I might pay more attention. then again, for things like the step attenuator where a schematic never existed in the first place...

i definitely have all the parts. And an unlimited supply of both liquid and gas N2. I even have a pair of oxford standalone N2 gas generators which have never been used. hmmm... what i want is some metal balls with a liquid sodium center, stick in LN2 to get them super cold, then use as long lasting icecubes that can't melt.

each ssdynalobal board pulls about 180ma at 20v

you should ask this question in the megatron thread, but there is a constant current source at the cathodes, and you can't do dual current sources. The current source at the cathode is necessary to keep the differential gain high. you could replace the cathode constant current source with a resistor, then do more of the same current sources as the second stage.

bad input tube usually causes this.

kgst, kgbh,kgbhse,kgdt and T2 all use constant current plate supplys as well as the srx revisited. So the tube tester would need to be modified because the resulting curves would be very diffent.

every direct drive electrostatic amp i know of is balanced. the luminare piece of crap drives the transformer unbalanced only with asymetrical drive, and has very different rise and fall slew rates.

I still have a bottle of some Cuban liquor that my parents brought back from their honeymoon 63 years ago. Still tastes great. If scotch (or any other whiskey) only lasts 6 months, I'm going to have to take the next 2 months off of work and go on a real bender.

board getting there http://gilmore.chem.northwestern.edu/tubehybrid.jpg

the 15 second startup delay is intentional. you can change the resistor string to make it more or less sensitive

test circuit certainly worked, and I don't believe in virtual grounds for all sorts of reasons. when you are running a dynahi with 400ma of bias, 25ma to turn on the relay seems tiny

It appears that the LM339s are powered by V+/V- rather than V+/GND? yes The LM339 has 4 comparators in it. It appears that 2 are being paralleled for each input signal? yes, one for the + limit, the other for the - limit and then repeated 4 times for each of the signals The input protection diodes run from V+/V-? to the inputs of the lm339, not as shown. this should make it easier http://gilmore.chem.northwestern.edu/protector3.jpg

yep. if you match the fets with the transistor tester you can get that 2.2V down to about 100mv but you need a bunch of them, over a 4:1 range on idss done

lots of variation in the fets. i had to hand pick, and throw out a few. the 1.45 volt is not that out of range, i can actually get mine to 160ma. you measuring the 2V without the servo? the servo takes about 30 seconds to bring it to about .1v or less.

this circuit is ground referenced, so not suitable for megatron style stuff. Unfortunately, the only thing that works there is the T2 circuit, or something like it due to having to drive the output tube at -500V was not aware of the other Fairchild parts, definitely in this case better than the higher voltage parts. Really only need 200V parts

so this has been kicking around for a while, decided to publish. take my ubaltobal converter, cut it in half, and then take the top piece, replace the input transistor with a tube... high impedance input... DC coupled, no negative feedback, less than .01% thd, 10db gain... just add a high power bipolar output buffer, and cheap tube hybrid with lots of plankton. work in progress http://gilmore.chem.northwestern.edu/tubehybrid.pdf 100 volt power supply real simple with TI TL783 high voltage regulator +/-30 supplies with lm317/lm337 with boosters cheap!

100ma AC it sure would be nice if transformer manufacturers would understand that what i want is a specific DC current, given a diode bridge and a capacitor and then calculate what the peak AC current is, then build the transformer that way. But none of the manufacturers seem to have the slightest clue.

slightly updated board file

They float on the board too. not tied to the outputs. For power supply caps i like to do complete solder to ground as the thermals have some impedance, especially at higher currents.

you want the pps washers http://www.aavid.com/product-group/accessories/washers they go most of the way into the ceramic insulator and prevent arc's thru the center of the insulator pretty sure I use the 7721-300sg will look later

For filament lines, best to have 2 or 3 oz copper, so either you make the trace a bunch wider, or you get thicker copper. Amperes of filament current... the high voltage eventually jumps around the insulator, so best to use the ceramic insulator with the special feedthru that goes along with it. then and only then can you use the metal screws.

just posted cfp2 to the boards directory I have not had boards made yet, or tested, prototype works fine. someone needs to check the board.

andy built a diy-T2 as his first audio project...

18ma @ 20 volts power supply is 360mw. about 1/3 of full power, and they definitely get hot. But you can crank it if you want.