How I grind FT-171 crystals
Posted: 25 Feb 2020, 07:44
Yesterday I ground a crystal, purchased at the paraset shop and I decided to test different approach than I did last time.
This time I used 600grit paper made for wet sanding, which I positioned on a thick glass plate (an old TV stand that´s never been used becasue the TV hangs on the wall)
I position the blank on the paper, apply some water, and using my index finger, i make number 8 patterns across the paper with the crystal blank.
From previous grinds using 1200grit paper (which took forever) I quit counting the number "8's" and instead used a timer.
10 minutes of rubbing on 600grit shifted the crystal from 3380 to 3460khz, Another 8 minutes shifted us up about 60khz, settling in at around 3520khz.
from there I took it easy in 1 minute passes, until i reached the 3554khz goal.
To finish it off, I took 10 strokes on each chamfer of the crystal, cleaned it in alcohol, and reassembled it and called it good. all under 45 minutes.
Keys very well, with full output, even though I moved over 170khz.
This time I used 600grit paper made for wet sanding, which I positioned on a thick glass plate (an old TV stand that´s never been used becasue the TV hangs on the wall)
I position the blank on the paper, apply some water, and using my index finger, i make number 8 patterns across the paper with the crystal blank.
From previous grinds using 1200grit paper (which took forever) I quit counting the number "8's" and instead used a timer.
10 minutes of rubbing on 600grit shifted the crystal from 3380 to 3460khz, Another 8 minutes shifted us up about 60khz, settling in at around 3520khz.
from there I took it easy in 1 minute passes, until i reached the 3554khz goal.
To finish it off, I took 10 strokes on each chamfer of the crystal, cleaned it in alcohol, and reassembled it and called it good. all under 45 minutes.
Keys very well, with full output, even though I moved over 170khz.