Problems with cathodyne

[tAB]

Problems with cathodine

Hi!

I built a driver for PL500. The schema and the pictures of the cathodine signals is in the attachment. The upper side of cathodine has a big distortion 🙁

I was tried with other tube, but nothing changed.

If I pull out the second ECC85, the two signal is full symmetric.

What's the problem?

 

[Geek]

Hi,

Some first impressions - R10, R13, C2 and C3 are all too big.

You have 1M gridleaks on the second ECC85 - make them 100K to 220K and C2, C3 0.1uF and try again.

 

[tAB]

Ok. Thx. I'll try it now.

 

[tAB]

I tried it.

I soldered a 180k paralell with the two 1M, and replaced the 1uF with a 100n. On the picture, you can see that the anode signal have biger distortion. 🙁

 

[SY]

Clearly, the last stage is the issue- you're drawing grid current. Check wiring first. Do a DC voltage map (real voltages, not sims).

 

[tAB]

I checked the wiring, about 10 times 🙂

On the pic, you can see the real voltages with red, I think that's OK.

________________

tAB

 

[SY]

Is that 137V plate to cathode or plate to ground?

 

[tAB]

137V plate to cathode. Voltage of VM3.

 

[jane]

I agree with SY, you are drawing grid current in the last stage..
What is the voltage over R14, about 2.3v?

 

[tAB]

I agree with SY, you are drawing grid current in the last stage..

And what can I do?

What is the voltage over R14, about 2.3v?

I'll check it tomorrow.


_____________

Thx, tAB

 

[SY]

Check grid to cathode voltages in the stage following the cathodyne.

 

[tAB]

Sorry, I can't measure anything in this circuit, because I built a new one, without a cathodyne 🙂

The new scheme is in the attachment. It seems to be working 🙂
I would be grateful, if you check the operating points, because I'm not sure in.

Thank's,

tAB