Program that might be useful to you guys.

[Alan0354]

I used the information from RDH4 Chapter 2 page 40 to 43 to write this program in excel for screen voltage conversion. This program can be used for other power pentodes or beam power tubes. All you have to do is to follow the instruction and enter the plate current values into the program per instruction and graph will be plotted out for you in Fig.2, Fig.3 and Fig.5, Fig.6. As per the book, Fe is best to keep in lower value, so the program provide plots using two different screen voltages given in the data sheet.

If you are interested, download the program, run it and give me feedback. I double check my work, but there can still be mistake. The program is named for 6L6GC as I enter the data for 6L6GC. You can put in data for other tubes, change the Vp and Vg number according to instruction and you get the graph of a different tube.

Hope you can find use of this.

[Wombaticus]

I'm at work right now so I didn't have a chance to look over the RDH4 pages in question. But this looks pretty cool and promising!

It looks like plugging in the Vg=0 plate current values might be a nuisance. The one thing that I noticed is that if I just change the values in the purple box, sometimes the labels for the grid voltages go away.

Why not go the whole hog, and add the ability to overlay both SE and PP (class A and class B portion) load lines? That would be a super useful tool!

[jazbo8]

Awesome, thanks for sharing.

Jaz

[Alan0354]

I'm at work right now so I didn't have a chance to look over the RDH4 pages in question. But this looks pretty cool and promising!

It looks like plugging in the Vg=0 plate current values might be a nuisance. The one thing that I noticed is that if I just change the values in the purple box, sometimes the labels for the grid voltages go away.

Why not go the whole hog, and add the ability to overlay both SE and PP (class A and class B portion) load lines? That would be a super useful tool!

I did this because all the data sheets only give one or two Vs setting. It would be useful to have graph for different screen voltages. It took me a while to get the graph going, so I am going to leave it as is, mainly trouble shooting the program.

You'll notice some of the curves look funny, but I double checked, the calculation is correct to me. Yes, it is tedious to enter the data, took me a while to get the data in. But it would be faster than draw by hand if you have a few tubes to do.

BTW, I am not very good with Excel, the thing I don't know how is to change the Vg label on each of the curve if you change the Vg in Fig.1 and Fig.4. I guess worst case is to click the label and modify it for the particular tube. If anyone know how to make it change automatically when changing the Vg in Fig.1 and Fig.4, let me know.

Yes, I notice when I change the box in purple, the labels disappeared, I don't know what to do. I check the properties, it supposed to display the label. Someone know anything better? The program for calculation is piece of cake, it's the graph that really tricky. I spend over two days on the graph alone, instructions don't match, it's all trial and error!!! My suggestion is to modify the program for the tube of your choice, fix the label and leave it alone. Use another original version for another tube. Don't try to use it as a simulation program and keep changing it. It's a tiny program, you can have many of them, one for each tube. they don't take much memory or disk space.

[jazbo8]

I tried re-formatting one of the charts, is this what you have in mind? If so, I will re-do the rest and post the file.

See the Vs=250V chart:
https://dl.dropbox.com/u/1326040/6L6...ble%20v1.1.xls

Jaz

[Alan0354]

I tried re-formatting one of the charts, is this what you have in mind? If so, I will re-do the rest and post the file.

See the Vs=250V chart:
https://dl.dropbox.com/u/1326040/6L6...ble%20v1.1.xls

Jaz

Your graph looks nice, I did not thing of using dark background to make the color trace pop out!!! I tried changing the Vs in purple, the Vg in the graph don't change either. But yes, that would work. It's all up to you guys. Consider mine is a head start, add whatever you think useful. I consider this is an extension to the data sheet by generating extra graph for people to draw their design load line and all.

If you can make the grids to distinguish between the major and minor grid like what I have, that will make it easier for people to read the numbers. Notice the major grid ( in 100 increments) are black and the minor grid ( in 20) is grey to make it distinguishable?

[jazbo8]

"I tried changing the Vs in purple, the Vg in the graph don't change either."

I did not want to mess up your existing table with the formulas, so if you scroll right, you can see the chart is based on a transposed copy of your table. If I have the time, I can re-arrange your tables, so we can skip the transposing bit. Anyway, you already done the hard work, I am just putting some finishing touches to it. Will try and add the loadline suggested by Paul too, this is going to be a pretty useful tool, since the datasheets seldom show the characteristic curves for the screen voltage that we are actually using.

Jaz

[Alan0354]

"I tried changing the Vs in purple, the Vg in the graph don't change either."

I did not want to mess up your existing table with the formulas, so if you scroll right, you can see the chart is based on a transposed copy of your table. If I have the time, I can re-arrange your tables, so we can skip the transposing bit. Anyway, you already done the hard work, I am just putting some finishing touches to it. Will try and add the loadline suggested by Paul too, this is going to be a pretty useful tool, since the datasheets seldom show the characteristic curves for the screen voltage that we are actually using.

Jaz

Good, I can't wait to get your update.

[jazbo8]

Updated file

Here you go, I updated all the charts including the SE loadlines with the 90% dissipation limit.
You can enter/change the loadline variables on the "Loadline & Pd" tab.

6L6GC Screen Voltage Conversion Table v1.2.xls

Jaz

[Alan0354]

Here you go, I updated all the charts including the SE loadlines with the 90% dissipation limit.
You can enter/change the loadline variables on the "Loadline & Pd" tab.

[ATTACH]19827[/ATTACH]

Jaz

Great.

Where is the input of RL? Also, where is your formulas?

[jazbo8]

RL is just RL_ac shown on the Loadline & Pd tab, the formulas used for the loadline are shown in the cells for the calculated variables near the top of the page. Please check for errors while you are at it, I think I got them right, but you never know...

Jaz

[Alan0354]

RL is just RL_ac shown on the Loadline & Pd tab, the formulas used for the loadline are shown in the cells for the calculated variables near the top of the page. Please check for errors while you are at it, I think I got them right, but you never know...

Jaz

Ha ha!!! I can't find it!!! I tried looking at the location of the data by clicking on the RL and 90% power and follow the location and I cannot find anything. Can you high light the formula where they are so I can look at them?

[jazbo8]

The loadline and Pd data are located in the "Loadline & Pd" tab, rows D, E & G (I gray out the texts, may be that's why you can't see them so well), you enter RL in cell B13 and Pd in cell B14 (where I put 30*0.9). Hope this helps.

Jaz

[Alan0354]

The loadline and Pd data are located in the "Loadline & Pd" tab, rows D, E & G (I gray out the texts, may be that's why you can't see them so well), you enter RL in cell B13 and Pd in cell B14 (where I put 30*0.9). Hope this helps.

Jaz

Believe it or not, I still can't find it!!! I looked at B13 and B14 and I looked at the location shown by clicking the curves, it's not there!!! Maybe something wrong with my program. Here is my version that I downloaded from you. Can you highlight those?

Thanks

Alan

[jazbo8]

Here it is. The cells of interest are highlighted in yellow.
6L6GC Screen Voltage Conversion Table v1.2 Highlighted.xls

Jaz