# [Amps] A Naive Question...

John Lyles jtml at losalamos.com
Wed Jan 18 00:20:25 EST 2023

```I always use the Fourier series calculation based on using a selected
load line on the constant current characteristic curves. Using a series
of 8 - 10 points (i forget) along this load line, plug them into the
equations and it gives the approximate DC parameters. This also gives
grid dissipation. The formulas are programmed into an ancient program I
wrote, but there are others equally valid in doing this. Its the method
described by Eimac in electron tube calculator #5. Its also in their
Care and Feeding of Power Grid Tubes book online.

John

K5PRO

On 1/13/23 10:00 AM, amps-request at contesting.com wrote:
> Message: 1
> Date: Thu, 12 Jan 2023 22:59:58 -0600
> From: Kim Elmore <cw_de_n5op at sbcglobal.net>
> To: amps at contesting.com
> Subject: [Amps] A Naive Question...
>
> When I look at transmit tube ratings, I see that they're always
> specified in watts, which makes perfect sense because the grid structure
> can dissipate only so much heat before all manner of Bad Things will
> happen. Every amp I've seen measures grid current, and the spec sheets
> specify currents for "typical" operating conditions for the various
> tubes. But... How do I convert grid current to grid dissipation? Do I
> need some kind of grid impedance to do that?
>
> Kim N5OP
>
> ------------------------------
>
> Message: 2
> Date: Fri, 13 Jan 2023 00:09:48 -0500
> From: "Lou Everett, Sr." <loueverettsr at gmail.com>
> To: Kim Elmore <cw_de_n5op at sbcglobal.net>
> Cc: amps at contesting.com
> Subject: Re: [Amps] A Naive Question...
>
> Will one or both of these calculators assist you?  Let me know.
>
> *https://robrobinette.com/Tube_Bias_Calculator.htm
> <https://robrobinette.com/Tube_Bias_Calculator.htm>*
>
> *https://eepower.com/tools/power-dissipation-calculator/#
> <https://eepower.com/tools/power-dissipation-calculator/#>*
>
> Lou WA5LOU
```