More than 8 years ago, I played with this valve after Thomas Mayer wrote about it here. It seemed like a good option but despite a few bench tests, I never got around building an amplifier with it.
I’m preparing for ETF.19 and will be bringing my eTracer to the event so I built a few socket adaptors. It was the time for the 12-pin Compactron to come to life.
Through my few Compactron valves, I bumped into the 6HS5 again, so I decided to put it to the mercy of the tracer. I wanted to see the positive grid current behaviour, as haven’t seen curves around with it:
What can we say of the above curves? Well this triode could do 7-8W easily as Thomas says. It has an anode power dissipation of 30-35W. The anode slope is between 7 to 10K so local feedback will be needed. You will need to aim for 600-700V bias at least, probably higher with slightly negative bias. However, you will need a hefty source follower to drive the grid. Look at the grid current. It can be 50mA at 5V and creeps up the higher the grid voltage it goes.
Interesting valve with a 6.3V/1.5A heater, and the high-mu (80-100) can work out as a SPUD amplifier with local feedback. Driver should be able to handle the grid current and low impedance. Not an easy task though.
