PT100 technical questions

[tcrash]

I am wanting to bump up the bias little on my PT100.
Inside in the circuit board there is 2 small trim pots. No typical bias pot as I am used to seeing.
Is one of these trim pots the bias pot?
If so, what is the other?
If not, what are each of them?

What is the standard bias point on this amp? plate voltage is 461, bias currently at 30ma. I was going to bump this up to 33-35ma

 

[Seitz333]

You could bump the bias up to 37-38mA.

One of the pots is the bias pot and the other controls the amount of boost on ch 3. You should see bias printed on the circuit board near the bias pot.

Hope this helps,

Chuck

 

[tcrash]

You could bump the bias up to 37-38mA.

One of the pots is the bias pot and the other controls the amount of boost on ch 3. You should see bias printed on the circuit board near the bias pot.

Hope this helps,

Chuck

Yeah, I figured it out. Beside one of the trim pots, it was marked "IAS" looks like the B was cut out when the board was punched. I bumped it up to 35ma, sounds great.
So, If my PT100 has a seperate "Gain 3" and a "Level 3" The other trim pot inside controls what actually.

 

[Seitz333]

You could bump the bias up to 37-38mA.

One of the pots is the bias pot and the other controls the amount of boost on ch 3. You should see bias printed on the circuit board near the bias pot.

Hope this helps,

Chuck

Yeah, I figured it out. Beside one of the trim pots, it was marked "IAS" looks like the B was cut out when the board was punched. I bumped it up to 35ma, sounds great.
So, If my PT100 has a seperate "Gain 3" and a "Level 3" The other trim pot inside controls what actually.

Since the boost function is tied together for channels 2-3 this pot controls the amount of boost for channel 3.

Chuck

 

[Suhr]

I am wanting to bump up the bias little on my PT100.
Inside in the circuit board there is 2 small trim pots. No typical bias pot as I am used to seeing.
Is one of these trim pots the bias pot?
If so, what is the other?
If not, what are each of them?

What is the standard bias point on this amp? plate voltage is 461, bias currently at 30ma. I was going to bump this up to 33-35ma

It should be set at .035vdc across the 1 ohm 1% resistor on each socket
The trim is marked bias and is on the right side near the power tubes

BE CAREFUL!