X-CHECKer Crystal Grinding OSC/FC kitPrice: $50.00
Due to all the latest interest in FT-243 crystals for vintage rigs and *spy* radios and such...and crystal grinding, I decided to update the workshop that was presented by myself, W1REX, Darell Brehm WA3OPY, and Ron Hale AC5UR at the Ozarkcon 2006 QRP convention. We held a hands on workshop where everyone ripped open an out of band surplus FT-243 crystal, removed the quartz blank and re-ground it to a QRP friendly frequency. That workshop was focused on the crystal grinding but I did build a few custom oscillator boards and rounded up matching frequency counters to enable the grinding session.
Original FDIM 2017 Buildathon kit
The X-CHECKer kit contains all board & parts to build the Crystal Oscillator/Frequency Counter kit a *RIST* calibration crystal and a one of my FT-243 40m crystal blanks. The *RIST* standard is an FT-243 crystal measured in my calibrated Oscillator circuit using a very accurate HP frequency counter. Measure the crystal in your oscillator circuit and adjust the trimmer cap for the microprocessor clock for a close match to the calibration frequency. You should be good to go. Round up the stuff for grinding: Plate glass, wet/dry paper, FT-243 crystals and have some fun. You wont be able to move a useless 6025 crystal to 40m! You need to be fairly close so your hand grinding is not a significant portion of the crystal frequency. Crystals over 6900Khz are moveable to 40m. I search the bins for 6950s or 6975s that are excellent candidates to move to 40m...but even those are getting harder to find. People are selling absolutely worthless WAY out of band FT-243s on Ebay as *vintage* crystals and asking $15-$20! Dont buy those... Stick to Hamfests and keep a sharp eye out. That is why I talked a crystal company to making me blanks. I had some cut & lapped at 7.015Mhz. To get them affordable to sell, I specified them at +/- 1000ppm which puts them in a range of 7.008 to 7.022Mhz...which are both excellent starting points. I measured the 1st two crystals at roughly 7.002 & 7.003Mhz bare blank on the plate. I easily moved them to 7.035 & 7.038. Grinding supplies linked below.