PL36 PP Amplifier 22W Full construction details

[mario2005]

Hi,
So, today I desing and built :

PL36 PP Amplifier 22W class A , with 6N7 and ECC82

The PL36 pentode was originally intended for use as a line output, (or horizontal deflection) valve in television receivers.

Full construction details and my experience with PL36 PP Amplifier can be posted here, or sent to email if you need that.






Best regards
Mario2005

[Giaime]

Post here Mario, please,

I'm also working on a EL36PP, but in triode mode, should give 10W in class A.

Tell us more about your design!

[mario2005]

Hi,
Schematic

Regards
mario2005

[SY]

The anode and screen voltages appear to be 100V over the maximum ratings (250V). Caution!

[mario2005]

I start with 450V and all work perfect!!!!!!!!!!!!!!

Now 400V.

I have 3 diferent Philips Tungsram and Telam Four matched tubes.

Tungsram is the best.


PL36 is beter then 6L6 and similar with EL34 !!!!!!!


this is maximum from PL36 .

The prototype amplifier has been running almost non stop since It was built. more then 10 hours .

regards
mario2005

[Tubes4e4]

Hi Mario2005,

neat design, but what is the objective of PL36 in (horribly non-linear) pentode mode, when you can get the same power from extremely linear triode strapped PL36 PP?

See this link.

SY: Yes, PL36 is used even more grossly over specs in this design. But they will stand it. I suspect spec sheet design center ratings were really given with TV deflection duty in mind.

Tom

[Geek]

Originally posted by Tubes4e4
SY: Yes, PL36 is used even more grossly over specs in this design. But they will stand it.

You beat me to it.

The E/PL36 is an extremely tough tube. It'll take 22W before plate glow

I have no idea why it wan't used in RF service

[mario2005]

triode mode PL36 PP and 380V

[Giaime]

My take... of course not exceeding EL36 maximum values

10W in class A, DF = 10 with the OPT that I'm waiting

No need for feedback to tame errors: since there aren't any.

[Tubes4e4]

Originally posted by mario2005
triode mode PL36 PP and 380V

If the driver/splitter will work as required (I didn´t check this), you will get about 20W Po in class AB1 using this output stage setup, delivering about 8W in pure class A which should be more than enough for sweet listening.

Damping factor will be about 3,5 w/o any gNFB applied, which is decent already. Nevertheless I would suggest to use about 6dB of gNFB, but nothing more than that is needed. Certainly not the 20dB you mention in the circuit diagram, which probably is just a left-over from the previous plain pentode (errr ... beam power) version.

For EL36/PL36 triode strapped plate curves have a look here, although this plot will not cover the actual Pd you are running your PL36s at. But you can easily prolong the curves

Tom