Novice Help AC DC Loadlines 6J5

[GP53]

Howdy,

6J5 Triode Circuit

I'm looking for some help. Why when I use an AC plate
supply(250VAC/RMS), are the voltage values in the circuit different than
when I use a DC plate supply(250VDC) in the same circuit. The grid
supply is -4VDC and I've got a 25K sense resistor in series to the
plate(10ma of current). All the numbers using DC calculate out just
fine. When I use an AC supply, voltages are different. TIA.

GP53

 

[John Fields]

On Wed, 1 Dec 2004 18:59:34 GMT, GP53 <..> wrote:

Howdy,

6J5 Triode Circuit

I'm looking for some help. Why when I use an AC plate
supply(250VAC/RMS), are the voltage values in the circuit different than
when I use a DC plate supply(250VDC) in the same circuit. The grid
supply is -4VDC and I've got a 25K sense resistor in series to the
plate(10ma of current). All the numbers using DC calculate out just
fine. When I use an AC supply, voltages are different. TIA.

---
What do you mean by "AC plate supply"?

--
John Fields

 

[Tim Williams]

"GP53" <..> wrote in message news:I824r9.HA6@news.boeing.com...

I'm looking for some help. Why when I use an AC plate
supply(250VAC/RMS)

I'm with John, what's the AC about eh?

All the numbers using DC calculate out just
fine. When I use an AC supply, voltages are different. TIA.

It'll be at least half due to the plate half-wave rectifying the input.
Depending on the circuit (and how you measure it) it may be anywhere from
peak value, to a nonlinear middle point, or negative. (The nonlinearity
being how the tube responds according to a 3/2 power law, as opposed to
assuming the tube is a constant resistance = Rp while forward biased.)

Tim

--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
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Website @ http://webpages.charter.net/dawill/tmoranwms

 

[GP53]

John,

In order to curve trace this circuit on a scope, an AC supply is used as
a sweeping voltage. One leg of 250VAC secondary to anode, and the other
though the sense resistor, then to the cathode.

Alan

John Fields wrote:

On Wed, 1 Dec 2004 18:59:34 GMT, GP53 <..> wrote:

Howdy,

6J5 Triode Circuit

I'm looking for some help. Why when I use an AC plate
supply(250VAC/RMS), are the voltage values in the circuit different than
when I use a DC plate supply(250VDC) in the same circuit. The grid
supply is -4VDC and I've got a 25K sense resistor in series to the
plate(10ma of current). All the numbers using DC calculate out just
fine. When I use an AC supply, voltages are different. TIA.

---
What do you mean by "AC plate supply"?

--
John Fields

 

[John Fields]

On Wed, 1 Dec 2004 21:52:47 GMT, GP53 <..> wrote:

John,

In order to curve trace this circuit on a scope, an AC supply is used as
a sweeping voltage. One leg of 250VAC secondary to anode, and the other
though the sense resistor, then to the cathode.

---
OK. Then it's probably because 250VRMS is 354VPK!

--
John Fields