Pi/Pi-L Spreadsheet

[Detroit47]

I am in the process of building my final amplifier, and I have been playing around with different plate load calculators. Bill Ore says one thing in his older books and something different in his newer ones. I came upon this spread sheet in an old thread. http://www.ifwtech.co.uk/g3sek/ 
The thread is http://amfone.net/Amforum/index.php?topic=28018.0. I didn't want to restart the thread being as it was old. But I wanted to know if anybody has any feedback on his spread sheet? I compare the calculations to mine with a calculator and they were similar. I went to my Eimac spec sheet on the tube and they differ significantly. I could always wind my coil by trial and error, but I wanted to try and do it with math for a change of pace.

John N8QPC

[KC2ZFA]

I've found this http://tonnesoftware.com/piel.html to be accurate.

It's a windows program but can be run in linux/osx with wine.

Peter

[W2VW]

The inductance formula in some ARRL handbooks is incorrect.

The Edison method isn't all that bad with coils because cheap multi meters can measure capacitance within a couple dozen percent accuracy.

Calculate plate load and fab a non inductive resistor made of junk box carbon comps or whatever. Clip it from plate to gnd. Feed a small sample RF into the output and check SWR.

First did this 20 years ago and was amazed how the amp followed in actual service. Unfortunately I haven't learned much since then.

[VE3LYX]

 "coil by trial and error,"
After one has made a few dozen coils trial and error it becomes I will need ___ number on turns on this dia form for ___ meters. An error of more then a turn will be rare and in a PI/L there is plenty of room tuning. Once one has one band in hand the rest are quickly figured out. my referance point is always the 40M band and on my forms I usually use freq X2 gets me the number of turns instantly (for 40m only.)
Then coils can be made quicker then the math can be done. Once one gets there it becomes redundant to go through the painful & questionable process.  
It is sort of like all the magic formulas for antennas . A 1/4 antenna for 40M would be 10 M long. Whats the big deal? Whats a meter? 3 and1/2 feet or 39 inches. Sometimes and more often then not we complicate things that are simple.  And doing all the gobbly gook does not make it better. 1/4 wave 40M antenna is still 10M long. If you are in the 41 M band still 41/4 . Not sq-root of third harmonic divided by fundemental freq X quotient of wavelength mutiplied by distance in centimeters divided by 345 or some wierd deal. For me anyway coils are the same. Wind the dang thing and git on wth it.
Sorry. just drives me nuts.
Don VE3LYX

[Detroit47]

The inductance formula in some ARRL handbooks is incorrect.

The Edison method isn't all that bad with coils because cheap multi meters can measure capacitance within a couple dozen percent accuracy.

Calculate plate load and fab a non inductive resistor made of junk box carbon comps or whatever. Clip it from plate to gnd. Feed a small sample RF into the output and check SWR.

First did this 20 years ago and was amazed how the amp followed in actual service. Unfortunately I haven't learned much since then.

I have heard of the Edison method but didn't know the name. So if I am correct I would wind my best guess coil and put it together. Then I could check for resonance with my grid dip. After I got the thing resonant I can put the dummy plate load resistor in and check the swr back feeding from the antenna end. Sound simple enough I'll see if I can screw it up.

Thanks John N8QPC

[W2VW]

The inductance formula in some ARRL handbooks is incorrect.

The Edison method isn't all that bad with coils because cheap multi meters can measure capacitance within a couple dozen percent accuracy.

Calculate plate load and fab a non inductive resistor made of junk box carbon comps or whatever. Clip it from plate to gnd. Feed a small sample RF into the output and check SWR.

First did this 20 years ago and was amazed how the amp followed in actual service. Unfortunately I haven't learned much since then.

Forget the dip  meter. Just put the unknown coil into the circuit after measuring C1 and C2 with a handheld multimeter that has capacitance. Keep in mind the circuit stray C and tube adds to C1 which is an issue on higher bands.

I have heard of the Edison method but didn't know the name. So if I am correct I would wind my best guess coil and put it together. Then I could check for resonance with my grid dip. After I got the thing resonant I can put the dummy plate load resistor in and check the swr back feeding from the antenna end. Sound simple enough I'll see if I can screw it up.

Thanks John N8QPC

[KM1H]

The G3SEK spreadsheet is used by many and reports across many amp forums are that it works well. Ive used it for years with no complaints for both linear and Class C circuits; and it has always been right on.

It allows you several options for the "K" factor used in the various Classes.

Carl

[Detroit47]

I would like to thank Dave And Carl. I am doing some machine work today on the mounting brackets for my tank coil. I am using vacuum variables and need to make custom hardware up. I have seen people use hose clamps on vacuum variables in the past, but that is too cheesy for my tastes.

73 John N8QPC