Cap values for CLC filter

[CarlyBoy]

Hey,

I'm trying to learn how to use PSUD II. Can you folks check how I'm doing...

I'd like to use a couple of 6D22S and a CLC filter to generate about 375V for a circuit drawing 100ma. I'm trying to decide if the caps in the following pi filter are over stressing the 6D22Ss:

47uf, 7H/100ohm, 220uf

Supply transformer is 325V. Throwing all of this in PSUD II gets me ~369V. The "mean" current draw at D1 comes up at ~75ma, the "RMS" is ~238ma.

Two things:

(1) Is the RMS value the more important of the two?, and
(2) Since Svetlana's data sheet for the 6D22S lists 300ma as the max continuous anode current, I should be fine, right? Just wanna be sure..

Thanks!

[Miles Prower]

Originally posted by CarlyBoy
Hey,

I'm trying to learn how to use PSUD II. Can you folks check how I'm doing...

I'd like to use a couple of 6D22S and a CLC filter to generate about 375V for a circuit drawing 100ma. I'm trying to decide if the caps in the following pi filter are over stressing the 6D22Ss:

47uf, 7H/100ohm, 220uf

Supply transformer is 325V. Throwing all of this in PSUD II gets me ~369V. The "mean" current draw at D1 comes up at ~75ma, the "RMS" is ~238ma.

Two things:

(1) Is the RMS value the more important of the two?, and
(2) Since Svetlana's data sheet for the 6D22S lists 300ma as the max continuous anode current, I should be fine, right? Just wanna be sure..

Thanks!

Looks about right. I get an Ip= 620mA (if this is a full wave). Is that within spec for this type?

[ray_moth]

I believe the 6D22S is OK with a first cap up to 50uF. That is what I use. The cap after the choke can be anything you like, I'm using 470uF.

Your current of 100mA should be no problem. This is a very rugged rectifier. In the PSUD circuit, how have you defined the load - as a resistor or a current tap?

[CarlyBoy]

Guess I should have posted this first...



Ray, I noticed you had mentioned the 6D22S in other posts. Good to know you haven't had any probs with 50uf + L + 470uf.

Sorry, Miles, I don't see how you get 620ma. Funny thing is I did this a second time and I get ~292ma RMS. I really don't know if I'm reading this correctly, though. Cool that you replied, Miles, since it's your Vixen amp I'm considering running with the 6D22Ss. What do you think?

[Miles Prower]

Originally posted by CarlyBoy
Sorry, Miles, I don't see how you get 620ma. Funny thing is I did this a second time and I get ~292ma RMS.

I really don't know what that durn thing is doing, unless it's simply telling you what the RMS equivalent of the surge current is based on waveshape and form factor. If it is, then you are still within the 300mA spec.

I figure this the old fashioned way: with a scientific calculator. I don't see anything there that says what your recharge surge current is. However, calculation shows that you are within spec for that VT diode. You're in good shape there.

I really don't know if I'm reading this correctly, though. Cool that you replied, Miles, since it's your Vixen amp I'm considering running with the 6D22Ss. What do you think?

I designed the Vixen with a solid state PS in mind. I think you're gonna have a problem that I didn't have. While those 6D22Ss are warming up, the negative rail is going to come up faster than the 6SN7 drivers can warm up, and you'll be exceeding that type's Vhk rating by a wide margin. A HK flashover will probably take out the DC heater supply.

I would suggest that you connect a 75V Zener between each 6SN7 cathode and DC ground. That way, the cathode voltage can't rise dangerously to possibly cause a HK flashover. The Zeners should drop out once the HV comes up and the 6SN7s have their operating voltages.

[CarlyBoy]

Originally posted by Miles Prower
I would suggest that you connect a 75V Zener between each 6SN7 cathode and DC ground. That way, the cathode voltage can't rise dangerously to possibly cause a HK flashover. The Zeners should drop out once the HV comes up and the 6SN7s have their operating voltages.

Got it, Miles. Just checked the Tee Vee Toob amp. It's right there! Thanks again.