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 NEW X-CHECKer kit has an updated circuit board from the earlier Buildathon version and contains all board & parts to build the crystal oscillator/frequency Counter kit a *RIST* calibration crystal and a surplus FT-243 crystal to use as practice in order to get *the knack*. The *RIST* standard is an HC-49 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 the closest match to the calibration frequency. You should then 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! Cheap out of band FT-243s are good for practicing the art of hand lapping. You need a crystal 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. They are available on my miscellaneous parts page. I am currently out of the blank crystals, due to the surge in sales generated by the QST review, but will have more around Dec. 18th. I have easily moved them to 7.035 & 7.038 and one blank I successfully moved to 7218!. A Grinding supplies accessory kit is also available.....
All part values are specified right on the pcb silk screen so building the kit should be pretty easy. The latest version schematics are at the top of the documentation list. The Builders Guide is from the Buildathon kit so it does NOT accurately convey the parts in the NEW version X-CHECKer kit. It is a very good guide to all the rest of the kit so read it before starting to build...but note that you cannot follow it exactly as a couple of sections on the board have been changed. The overall procedure is the same with a few additions. I extended the board and added battery clips ON the board, changed the signal conditioning circuit to the MOD version in the docs and added an HC-49 crystal socket in the oscillator section to conveniently hold a HC-49 crystal for measurement.
SPECIAL LIMITED TIME OFFER ON FT-243 crystal blanks in THREE pack
HC-49, FT-243 crystals and sockets
Grinding Accessory Pack