1986 build pin voltages. PLEASE LOOK.

stokesdead · Post by **stokesdead** » Mon May 28, 2007 2:24 pm

OK here are my pin voltages. Plate seems high I thinks.
I used early 1986 values w/ 2 16uf caps mounted on the board. Tubes are new production JJ teslas.

Valve position . pin #

1.1 - 165.7
1.3 - 1.36
1.6 - 153.8
1.8 1.37

2.1 - 143
2.3 - .97
2.6 - 262
2.7 - 142.3
2.8 - 144.5

3.1 - 198
3.3 - 33.3
3.6 - 200
3.8 - 33.4

4.3 - 423
4.4 - 420
4.5 - (-37.5)

5.3 - 423
5.4 - 420
5.5 - (-37.5)

What do you guys think?
~Chris Stokes

Flames1950 · Post by **Flames1950** » Mon May 28, 2007 4:41 pm

I don't see a problem with the plate voltages. You might set the bias voltage to as large a negative value as you can before firing it up for too long though.

stokesdead · Post by **stokesdead** » Mon May 28, 2007 8:29 pm

So what would be ideal for the bias readings?
Thanks Flames.
~CS

Flames1950 · Post by **Flames1950** » Mon May 28, 2007 9:51 pm

Kinda depends on the specific tubes. Setting the voltage to the largest negative value for first fire-ups just helps to insure that the tubes start as cold as possible to minimize the chance of damage compared to the bias starting too hot.

stokesdead · Post by **stokesdead** » Mon May 28, 2007 10:08 pm

I am confused. I thought you set the bias from pin 8 readings on the output tubes.
I am running new production JJ E34L.
~CS

Flames1950 · Post by **Flames1950** » Mon May 28, 2007 10:12 pm

That's to read the cathode current. I'm talking about simply setting things as cold as possible for your initial voltage testing, which will be the largest negative voltage on pin 5 that you can get -- that's where the bias voltage comes into play. Cathode current at idle on pin 8 will change upwards as your bias voltage on pin 5 becomes less negative.
You may already be past worrying about this anyway!