My good friend John VK6JY wrote this calculator for the "Fast" Huff & Puff stabiliser. To run it, download the file "faststab.exe" and run it on your Windows machine. It will open in a DOS window and is text based.
Click here to download the .exe.

John says:

It runs under my WinXP here, launched by Win Explorer or WinCmdr.

The calculations are based on the equations presented by Peter Lawton, G7IXH, in Nov'98 QEX. The circuit is Hans Summers, G0UPL and is very much simpler then that used by Lawton.

I find the calculated "STEP" sizes between FLL points agree with my range of XOSC units tested from 12 to 80 MHz. I have not moved the pick-off point on the binary VFO divider as yet, nor done tests on other VFO ranges. These can be tried here easily as I'm using a switchable VFO.