Filter Test Jig: I made a little test jig for testing QRP Labs filters. I am not an engineer so my idea may be flawed. It seems to work though. Basically you, insert a filter (the right way around), connect the output to the input of a spectrum analyzer, and the input to the tracking generator of the spectrum analyzer. It's pretty simple. I suppose you could also use it with a sig gen and oscilloscope.?
Here's a link to the Test Jig on Osh Park:??It's not the cheapest board house out there but it's easy to get a prototype made, quality is high, and they do 3 board runs. I've also attached the Eagle files and other documentation (zipped).?
Crystal Tester (Colpitts Oscillator): I always use this with my oscilloscope but I suppose it would work with a frequency counter. Again, boards are available from Osh Park:??and Eagle files are attached. I also included a PDF with the schematic and board layout so you don't have to guess at component values. Thru hole components. Don't put too much voltage on it. Be mindful of your test equipments limits
Power supply. Up to 48V in - adjustable output Low Dropout DC-DC converter. People that know power supplies are going to look at the output capacitance and wonder what I was thinking. Well... I was thinking, dammit... I only have one 10?F and a pile of 220?F surface mount electrolytic caps. Good enough. Another 10?F would be fine (per the spec sheet of the regulator).? If nothing else the output should be smooth. If I remember right the output footprint is a 0810 sized cap. Relatively HUGE compare to the input cap (0605). However, the pads will accommodate the smaller cap. The LED is an optional power indicator. I made it through hole in case I decided to put a 3mm LED in the front panel. I didn't make the supply adjustable for a few reasons. Bigger board - more cost. A VR can be accidentally moved. This way, I just swap a few resistors and I have a fixed, stable output voltage. If I operate the PA at higher voltage I use two supplies. The 5V supply is wired to right side switch and then wired to the main board. The xxV supply is wired to the left side switch in case I want to operate with no PA (testing, gives me something to accidentally forget to turn on... things like that). It just occured to me that the left side switch could be wired for Hi/Lo power operation if I add a wired to the 5V supply. I wonder how much that would affect the biasing.
Osh Park:???I also included a PDF with the schematic and board layout so you don't have to guess at component values (zip file). Surface mount components. The regulator is a D2PAK package so it's easy to solder. The resistors are all 1206 package. I think those are easy. 0402 and smaller are the spawn of Satan but I can even solder those now. It just takes more of them to finish a project...
All of this stuff is creative commons, etc, etc, blah, blah. In other words, if you want to change something, go ahead.?
