FDIM 2017 Buildathon kit mailed to your QTH

Price: $44.00
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Picture of FDIM 2017 Buildathon kit mailed to your QTH


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 WA4OPY, 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.

The FDIM 2017 Buildathon kit is essentially the same oscillator design added to an updated version of the frequency counter project we built in 2015. An integrated crystal oscillator and frequency counter is an essential piece of equipment when playing with crystals and the Buildathon kit is specifically designed to facilitate the grinding process. The new frequency counter/crystal oscillator kit is powered by either a 9 volt battery and displays the frequency on an integrated LCD display. The counter circuit has a gate time of .1second so the count is multiplied by 10 to obtain the frequency. The LCD screen displays 8 digits but the last digit is always a 0. Unfortunately, the build ran long, as usual, and the grinding part was done in the group demonstration mode. I had a batch of FT-243 crystal blanks ground to 6970Khz in my personal stash so everyone got a blank to grind at home.

As usual, the Buildathon also included a time out for a complementary pizza party so that builders didn't miss dinner while we built. Directly after the Buildathon, the now sated builders only needed to take a short walk around the lobby in order to enjoy the FDIM Club night being held in the adjacent ballroom.


Buildathon attendees were:
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JILL COMBS..................KD8QGA
JOE EISENBERG...............K0NEB
MARTHA AUCHARD..............W0ERI
GARY AUCHARD................W0MNA
DAVE WILCOX.................K8WPE
DEAN SANDERS................WB0P
MIKE DOOLEY.................N5BGZ
JOHN DEMUTH.................K8CQA
KARL DEMUTH.................N8PKB
STEVE DEMUTH................KC8YBV
DAVE PALMGREN...............N8DP
RED WILLOUGHBY..............KC4LE
GARY MORTON.................M1GRY
DON SZENINA.................N8HDT
JOHN KUNZ...................N8MCA
RICHARD SCHWENKE............N8GBA
MARTIN BOROFF...............WD9GYM
JIM EKLUND..................KD8QCS
PAULETTE QUICK..............WB9VHF
PETER AYEARST...............VE3POA
DAVE RAJNAUTH...............VE3OOI
ERIC GUNTER.................KC2TXO
DAVID WENDT.................VE3EAC
THOMAS DICKMAN..............N8TD
HIROKI KATO.................AH6CY
JONATHAN BRANDENBURG........KF5IDY
JOHN COVINGTON..............W4CC
DENNIS TERRIBILE............WR4I
DAVID DOSTIE................AE9Q
BRETT KNUDSON...............N0BAK
SEAN ADKINS.................
SCOTT McDONALD..............KA9P
AUTHOR JOHNSON..............WB0JMG
DON SZENINA.................N8HDT
DON SZENINA.................N8HDT
BILL KOSONEN................KD8ZEG
BILL OLSON..................W8SQ
ROGER STEIN.................K7SJ
AL PETER....................AC8GY
CHARLEI BROWN...............W3CHP
HOWARD SILVERWATER..........4X1ZZ
DAN WILSON..................KF7Z
CHRIS WALDRUP...............KD4PBJ
GARY O'NEIL.................N3GO
CHUCK OHRSTEDT..............WB8YUM
KEN MITCHELL................KD2KW
JON POLAND..................N0WL
JACK PURDHAM................W8TEE


So you can see that we had a pretty full house but we could have fit a few more builders in the room. I think a good time was had by all and everyone finished their builds before they left. After returning home and cleaning up a microprocessor problem, I sent care packages out to all the builders that included all the necessary stuff to get their kits calibrated and ready to grind FT-243 crystals.

The Buildathon kit contains all board & parts to build the Crystal Oscillator/Frequency Counter kit and a 'RIST' calibration crystal. 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 won't 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. Somebody is selling absolutely worthless way out of band FT-243s on Ebay as 'vintage' crystals and asking $15-$20! Don't 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 spec'ed 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.

Rex W1REX









Documentation
  • X-CHECKer Builders Overview
  • 2017 Buildathon parts list
  • FDIM2017 Counter Pg1
  • FDIM2017 Counter Pg2
  • FDIM2017 Counter Pg3
  • FDIM2017 CRYSTAL GRINDING KIT layout error
  • X-CHECKer Mods

    Related Links
  • VIDEO: Modding the LCD module to light the LED backlight
  • VIDEO: Intro Calibration & Use of the FDIM2017 BUILDATHION X-CHECKer Kit!
  • VIDEO: A complete build of the FDIM2017 bUILDATHON kit!
  • VIDEO: A complete grinding session for making a new FT-243 crystal!


  • ACCESSORIES: FT-243 SOCKETS & CRYSTAL BLANKS from QRPme

  • VIDEO: An ARRL video with scenes from FDIM 2012's Buildathon.