6V6 line preamp

[rongon]

What about using a common cathode 6V6-triode preamp into a MOSFET source follower, such as IRFBC20 or IRF820? I'm sure the 6V6 will be able to drive the MOSFET gate well. Has anyone tried that?

 

[Nikos]

Begin to collect parts in my first attempt to make the 6V6 buffer
First the module of the LM317 as Current limiter..
Ι have already order the two tubes 6P6S and the trafo ....

 

[Salas]

Nice fully handmade layouts. Keep us posted.

 

[Nikos]

Thanks Mr Salas..
if someone wants the pcb is free by pm

 

[Nikos]

I collect materials that I had to test and made exactly the circuit shown in Figure 2 PSU Designer II . Τhe choke is from old switching supply about 40 mH.
Feed in with an isolation trafo 230~. Ι measure output 315 VDC and 50mV ripple, with load 5K-15K, the output voltage swing between 313-314-315 VDC.

 

[Nikos]

Here is the measurements probeX10.

 

[Salas]

Thats all nice step by step progress. If you would want passive only filtering then a choke must be in the several Henry territory. But 50mV ripple is fine if you will actively regulate.

 

[Nikos]

Thats all nice step by step progress. If you would want passive only filtering then a choke must be in the several Henry territory. But 50mV ripple is fine if you will actively regulate.

Yes I will use the SSHV2 regulators after.... but i will put and Choke at 20 H.

 

[Salas]

That choke would need to have a core with air gap to can take the full DC mA and still be truly 20H at 100HZ. If its a mains toroid core job it will saturate with very few mA and it will be better to use CRC. SSHVs up the mA spec even more than the tubes bias because they add spare current.

 

[stajo]

Set Psud to a couple of seconds delay and you can experiment with comps and ripple

 

[Nikos]

Thanks Stajo!
I have already done this.

 

[Nikos]

The regulators are alive, also the tubes 6P6S from Russia with love... ,i will set the regulators at 40-45 ma CCS and test with 290 VDC input and regulate it at 250 VDC with 10K/10W resistor, because the available transformer right now is 220:220 VAC ...im waiting for these parts :
1PC 4-Post Tag Turret Terminal Board Strip FR Vintage tube audio Guitar Amp DIY | eBay
1 x New 8Pin EL34 6SN7 KT88 274B 6L6 KT66 6V6 Gold Ceramic Tube Octal Socket | eBay

 

[Salas]

Nice select tubes and sturdy looking sockets

 

[Nikos]

Thanks Nick .No problem with these regulators SSHV2 the results are so good..ProbeX10 voltage 250VDC ,CCS 45mA.

 

[Salas]

Yep they look like doing alright. Only about 1.5mV wide band noise total on that scope in X10, is it a 20MHZ model not introducing too much extended bandwidth noise of its own?

 

[stajo]

Are those black thingies resistors? What function?

 

[Nikos]

Yep they look like doing alright. Only about 1.5mV wide band noise total on that scope in X10, is it a 20MHZ model not introducing too much extended bandwidth noise of its own?

Also Nick the magnifier button its open...

 

[Nikos]

Are those black thingies resistors? What function?

These black resistors are part of PSU my own design ...base on PSU Designer II..

 

[Nikos]

Which is the correct point of the heater 6.07 and 6.11 or 6.35 and 6.29?

 

[vgeorge]

Better on the low side a bit.