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.
Tuesday, March 3, 2015
Wednesday, February 25, 2015
EMRFD, ARRL, QRP CW, XYZ PDQ, or, How I Stopped Hating Acronyms and Starting Loving The Electron
After many years as an electronics dabbler, something strange happened to me in 2012. Suddenly, my cousin Jeff's (N9IXW) 20+ years of patient badgering took hold and I had to have a ham license. I studied physics at IU back in the 80s under the expert tutelage of the high enery physics "gang" - Dzierba, Pollock, and Brabson. I ended up being a programmer/information scientist, but the physics bug never really let go of me. How can you resist the urge to experiment with something you cannot see or hear or feel, but can measure and demonstrate and wield with such precision?
Finally, though, the hobbyist aspect of electronics technology got hold of me with enough intensity that I wanted to build circuits and test them. Sure, the ISM bands are there, but playing around with GHz+ frequencies requires a lot of skill. Theory is fine, but when the fabrication begins, that is the true test. So, realizing that the HF frequencies are arguably the least demanding place to begin, I ran out and grabbed a General class license so I could play in that sandbox.
The acronyms are astounding in any field. Ham radio is no different. Pretty soon I had to learn Q codes, CW, tons of ham jargon (XYL at QTH gotta QRT), tons more of electronics tech jargon (FTE, VCE, degenerative feedback, not to mention the various DIP SMT MFP PQFP DSOP LGA FCBGA package designations).
Separating the noise from the jargon from the lore was hard, but I eventually stumbled across "Experimental Methods in RF Design" (EMRFD), by Wes Hayward, Bob Larkin, and Rick Campbell. That combined with "The Art of Electronics" by Horowitz and Hill got me really cooking. I didn't care to buy a packaged radio and "hit the repeater" just to make idle chitchat after finding the Neoanderthal (WA7MLH) or the many QRP enthusiast sites out there.
I was especially incensed by the Neoanderthal site - look at that! That guy is building spectrum analyzers and radios and measurement equipment from the god-awfullest pile of electronic junk I ever saw. Solder everywhere! Ugly construction! "IF is 5 crystals at 4421 kHz from a box of them I found at SEAPAC hamfest..." - WHAT!? YOU CAN DO THAT!?
For someone with a freakazoid gadget fetish, hoarding instincts, and intense curiosity of how things work, electronics is a fabulous hobby. Ham radio is quirky in some regards, but the work done there is important and the fellowship is pleasant, too. For me personally, I've made an effort to learn CW out of respect for the old-timers, who knew what works and had good reasons to demand those skills. You don't need that to get a license, though, so I encourage you to broaden your mind and give it a whirl.
This blog will follow some of my painful antics as I learn, the hard way, how to assemble chunks of sand (and sometimes, vacuum captured inside little glass vials) and make it Do Stuff.
Finally, though, the hobbyist aspect of electronics technology got hold of me with enough intensity that I wanted to build circuits and test them. Sure, the ISM bands are there, but playing around with GHz+ frequencies requires a lot of skill. Theory is fine, but when the fabrication begins, that is the true test. So, realizing that the HF frequencies are arguably the least demanding place to begin, I ran out and grabbed a General class license so I could play in that sandbox.
The acronyms are astounding in any field. Ham radio is no different. Pretty soon I had to learn Q codes, CW, tons of ham jargon (XYL at QTH gotta QRT), tons more of electronics tech jargon (FTE, VCE, degenerative feedback, not to mention the various DIP SMT MFP PQFP DSOP LGA FCBGA package designations).
Separating the noise from the jargon from the lore was hard, but I eventually stumbled across "Experimental Methods in RF Design" (EMRFD), by Wes Hayward, Bob Larkin, and Rick Campbell. That combined with "The Art of Electronics" by Horowitz and Hill got me really cooking. I didn't care to buy a packaged radio and "hit the repeater" just to make idle chitchat after finding the Neoanderthal (WA7MLH) or the many QRP enthusiast sites out there.
I was especially incensed by the Neoanderthal site - look at that! That guy is building spectrum analyzers and radios and measurement equipment from the god-awfullest pile of electronic junk I ever saw. Solder everywhere! Ugly construction! "IF is 5 crystals at 4421 kHz from a box of them I found at SEAPAC hamfest..." - WHAT!? YOU CAN DO THAT!?
For someone with a freakazoid gadget fetish, hoarding instincts, and intense curiosity of how things work, electronics is a fabulous hobby. Ham radio is quirky in some regards, but the work done there is important and the fellowship is pleasant, too. For me personally, I've made an effort to learn CW out of respect for the old-timers, who knew what works and had good reasons to demand those skills. You don't need that to get a license, though, so I encourage you to broaden your mind and give it a whirl.
This blog will follow some of my painful antics as I learn, the hard way, how to assemble chunks of sand (and sometimes, vacuum captured inside little glass vials) and make it Do Stuff.
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