Copasetic Flow

TouCans is back up and running! The culprit did in fact lie in the path between the power supply and ground in the PA chain. I didn’t see it coming though. Here’s the problem: There was a cold solder joint on one side of the inductor. When KO6BTY and I measured the resistance across the inductor, it was infinite. When we remarked about this, 9 year-old Tawnse immediately said, that’s not what inductors are supposed to do. And yeah, she’ right. They’ supposed to conduct at DC. Anyway, a few minutes later, we’d gone from this Notice the magnet wire tint to the two wires whose solder joints are completely in the picture? To this      Which, in turn, led to this later that evening. The moral of the story for me? Always check the two terminal component first because they’re the easiest to fix.     

 KO6BTY took over debug implementation last night. She wired the RF out from the Rockmite directly to Project TouCans antenna out and... Nothing. Looking at the schematic , that leaves a few choices for what's going on. My favorite for the moment, because it's easy, and because the part is actually very bent, is the T/R switch transistor: The transistor is a 2N7000  MOSFET. Wikipedia lists its maximum current as 200 mA and I can see where we could have exceed that when the Rockmite was shaking loose in TouCans (several of the nylon spacers sheered after a fall.) Also, keep in mind that the power bump has more current traveling through this part of the circuit in any event. After that, we'll be looking at whether or not the oscillator is still oscillating. But actually! Good news! If the oscillator weren't oscillating, the receive branch also wouldn't work, and it most certainly is working!

Since we returned from camping, Project TouCans has been pretty much off the air. We still have receive, a keyer, and a sidetone, but the rig just isn't transmitting. Last week I thought the issue might be the output transistor of the RockMite. It is not. I removed the original transistor, replaced it with a new one, and to no avail! Here's the before And after There was no change in the operation of the rig. No signals were spotted by the RBN or either of the Utah or Half Moon Bay SDRs.

 In electronics engineering classes at both Ohio State and Texas A&M I did homework problem after  homework problem working out radio wave propagation. One of the fundamental points was that radio waves are just another kind of light, and therefore behave like light. Radio waves however are not like visible light in one major way, their wavelenghth. The Rockmite operates on the 20 meter ham radio band. That means that the radio waves emitted  by the little ham radio have a wavelength of (about) 20 meters. Meanwhile, visible green light (as an example) has a wavelength of about 510 nanometers (that's 510 billionths of a meter.) This rather huge difference in wavelengths affects how the two different kinds of 'light' interact with their worlds and —for me —produces rather dissapointing results. While we can use the same field equations for both green light and radio waves, in a lot of cases radio waves do not (apparently) behave like the green light we're used to. For...