I made the power and efficiency mods on my 17m Rockmite build. I gently, oh so gently, crushed the living daylights out of the ferrite toroid provided. Woops. So, undaunted, I substituted a T37-2 toroid. Now this turns ratio of 8:3 in a ferrite with AL = 150 is obviously going to yield far more power transfer than the same winding using the #2 material with AL =, uh, 5. What was I thinking? I was thinking I wanted to get out there, just get out there, even if it was going to be with 9 femptowatts. It's usual for me to go ahead and try things, rather than wait on mail order or rip the guts out of something that is already working. Nope, I don't kill off old builds to power new ones. Lots of years in college so I could afford to buy myself some parts. And once something is working, I'm darned if I'm gonna be the one to break it...
What is interesting here is the measured power out. Substituting a toroid with 1/30th as much AL seemed like to me to be asking for 1/30th the power. But, lo and behold, I measured 0.98V peak to peak using my RF probe, and confirmed it in my B&K 15MHz oscilloscope, pretty much looked like 1 volt PTP. Then I did the power calculation for the RF probe measured voltage, remembering to add in the 0.25V for the diode, and arrived at 68 milliwatts. Wow! I have to admit I was surprised.
The ferrites are on order, but it leaves me wondering about the difference in output power. I'll sit down and hit the books and follow up this post with some theory about how that happened.
