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Author Topic: etching crystals-increasing the frequency on your ft-243s  (Read 12721 times)

Offline moof

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I learned today you can buy dilute hydrofluoric acid (Whink brand fabric rust remover) to eat a bit off your nonfunctional or crappy frequency crystals to make them operate where you want.  Seems to eat away and increase the frequency somewhere in the neighborhood of 1 khz per 10 minutes with fresh stuff.  Got to get me down to the Crap-mart and get some with a pair of autopsy gloves.  Don't do it without a pair of breaking bad gloves.
Scroll down a bit to the whink thread
http://www.qth.net/pipermail/arc5/2014-November/subject.html#20177

Offline moof

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #1 on: March 31, 2016, 2135 UTC »
Even better get a plate of glass, some Dremel polish and/or Wright's copper cream, and manually go to it for a while first.  I can see learning something new in the coming weekends.  The innernet says the more you change the fundamental frequency, the bigger chance you have on turning that crystal into a tiny brick.  Too bad.

Offline Josh

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #2 on: March 31, 2016, 2143 UTC »
Some grinders have brought dead rocks back to life by grinding a tiny bit on an edge.
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Offline Pigmeat

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #3 on: April 01, 2016, 0200 UTC »
Even better get a plate of glass, some Dremel polish and/or Wright's copper cream, and manually go to it for a while first.  I can see learning something new in the coming weekends.  The innernet says the more you change the fundamental frequency, the bigger chance you have on turning that crystal into a tiny brick.  Too bad.

I know a guy who recommends a combo of toothpaste and mineral oil instead of the polish or copper cream. He says it takes awhile longer to get the first couple of kHz off the xtal but there's less chance of a wild overshoot or ruining the crystal. I've never tried it but I know a number of people who have with success.

You can pencil them down with a Sharpie marker easily, too. Just alternate your marks on either side of xtal so they match up. I've taken them down as far as 14 kHz from the fundamental frequency, but they tend to get unstable beyond an 8-10 kHz. cut. You can't screw one up this way, if it stops oscillating, wipe the marker ink off the xtal with alcohol and start again.

Don't get impatient trying to raise the frequency. A fella I knew once got frustrated and went at one with a whetstone and honing oil. He was trying to bring it up a few kHz. He got it to the top of the 41 meter broadcast band in just a few strokes. He was one dumb Bunny.

Offline Oliver

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #4 on: April 01, 2016, 1117 UTC »
I got to admit that I am a novice on this topic as well.
Looks like I will never stop learning new things related to our obsession.
This video explains the procedure very well in my opinion.
It looks like a neat way to get the job accomplished.

https://youtu.be/j7CS4A8wB1E
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Please send eqsl to: oliverinusa[at]yahoo.de

Offline AntiRecoveryUnit

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #5 on: April 01, 2016, 1931 UTC »
You can do that with normal HC-49 crystals too, desolder or cut it open.

More use for these old computer xtals
Your local junkyard dude

Offline moof

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #6 on: April 02, 2016, 0006 UTC »
Yeah that was a good youtube.  The most informative comparison of compounds to use I found was this http://home.netcom.com/~wa4qal/crystal.htm
Have chemicals, ready to rub one out. huuhhhmmmhuhuhuhhmm.

Offline moof

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #7 on: April 04, 2016, 2055 UTC »
Here are my initial findings.
I have Wright's Copper cream, Whink 2% HF acid, Dremel polishing compound, and a couple 5x7 panes of glass.
I initially tried to make a slurry of Dremel compound but the stuff is so hydrophobic I got nothing usable.  It was like pushing putty or boogers that wouldn't dissolve.  I even tried adding dishwashing liquid to no help.
The copper cream dependably increased the frequency, so did the Whink.
Test 1-about 75 figure 8s with copper cream increased frequency from 6825 to 6835.
Test 2-soak overnight in the Whink cap in about 1ml using plastic pen holder apparatus as seen in youtube video 6835 to 6868. Awesome and easy.
Test 3- 75 figure 8s using copper cream- 6868 to 6875
Test 4 - 100 figure 8s using copper cream- 6875 to 6883
I then tried to find something to use as a vehicle for the Dremel paste.  Water with or without dishwashing liquid was no good.  91% rubbing alcohol was no good.  I then tried adhesive remover liquid-YES. It made a nice smooth light red slurry.  So did mineral spirits.  Lovely.  But next to no increase in frequency.  WTF?  Dremel compound is supposed to be the bomb.  I did 50 figure 8s and got an increase of 2 then 1 khz.  It also got stuck tight to the glass several times like when you slept in you contacts.  Tight.
Did another 150 figure 8s with copper cream -increase 6 khz to 6892.
I'm going to do another overnight soak in the Whink cap and bet I will be close to the goal.  I'm not telling final freq.  Wheeeee.
So don't bother with Dremel polishing crap.  Get Wright's copper cream and Whink.

The last overnight soak in Whink made it go from 6892 to approximately 6939.

So figure 8s in copper cream caused a change of 1 KHz with 7-25 figure 8s (about four inches overall) with an apparent diminishing return.  I'm not sure if that's real or coincidence.
Overnight in Whink increased 33 and 47 KHz.

I did get the Dremel polish to make a slurry by using a pencil eraser size bit, a few drops of water, and even more Dawn after sticking it in the microwave 10 seconds with a shot glass of water to keep it company.  I got quite warm and broke right down and I added more water.  It was quite gritty like 220 sandpaper.  I didn't have a good feeling about that and promptly bricked a 6725 crystal with 200 small figure 8s.  I have done a few additional 50 figure 8s with copper cream and a few half hour baths in Whink but it will not oscillate now.
« Last Edit: April 05, 2016, 1540 UTC by moof »

Offline moof

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #8 on: April 08, 2016, 2159 UTC »
Now if you do brick your crystal grinding to harshly or unevenly, there is hope.  Take that copper cream and do X (maybe 10-25) number of figure 8s one direction, do in the opposite direction, then rotate 90 degrees and repeat.  Then flip it over and repeat the whole process.  I got one to come back from the dead twice after doing this.  May need to repeat.  One crystal that was F'd by dremel compound needed the process 4 times to smooth it out and by the time it oscillated again it was >7100! It started at 6725 so dremel compound tore it up just using it once.  I would not recommend it.
I'd stick with overnights in HF solution to get a big change with no work and doing figure 8s on glass for changes up to 10 khz at a time.  By the way, putting a heat lamp on it overnight doubled or tripled the change to just over 100 khz for me using a couple mls in a very small prescription bottle.  That was the only one I had to mess with later twice to get to oscillate again.  Took it from 6700 to around 6940 and worked out fine in the end.

Offline moof

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #9 on: April 09, 2016, 1946 UTC »
I think I'm getting pretty good at this and have increased frequency on half a dozen crystals 5-700 khz.  I know the innertubes says to mark one side and grind only on one side but I disagree.  I have done the technique where you do X number of figure 8s in one direction with copper cream, then do X in the opposite direction, then rotate 90 degrees and repeat, then flip the crystal over and repeat the whole process and not once did it fail to oscillate when doing this.  The only fails occurred with dremel paste and when doing extreme Whink soaks overnight with a light bulb heating a shoebox up and shifting the frequency up 100+ khz.  All crystals were recoverable using the technique too.  I only have NOT done this technique when zeroing in on the target frequency last 10 khz.
I have also done the Sharpie frequency lowering deal.  It is pretty imprecise but you can salvage your crystal.  Start by doing a single line across the face on each side and letting it dry a half hour.  Just that may knock it down up to 5 khz.  You can use an alcohol swab and do a single quick swab on one or both sides to try to fine tune but it is really difficult. You can Sharpie out a large portion of each side to really decrease frequency but run the risk of no oscillation.  Alcohol it and start over maybe with a few figure 8s if you want to totally remove all Sharpie.

Offline Pigmeat

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #10 on: April 10, 2016, 1458 UTC »
Good stuff, Moof! Especially for us fellas that have some FT-243's that aren't quite where we would want them to resonate.

Offline moof

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #11 on: April 10, 2016, 1813 UTC »
Glad you enjoy.  I have a few more pearls to pass along for the week.  I'm just doing it because I had such a hard time starting out with questions on extremely specific stuff, not having a background in the area.  So few people to ask that will give specific and accurate info.
Listen to your crystal in a circuit with a dummy load lsb, usb, and am, don't just trust that $20 ebay oscillator with the green led.  It is accurate to within 0.5 khz and is perfect as far as telling you if the crystal will oscillate, but will not tell you if your audio will be warbly.  I'm reworking two crystals.  One was somewhat warbly, one was really bad.  I'm thinking this can be minimized going easy on the last 10-20 khz doing frequent small grindings in many directions and orientations toward the end.  That's all I did to recover them.  So have a plan B , C, and even D for final frequency!
I also did beveling several swipes each edge at about 45degrees and am not sure how much it had to do with recovering Fd or warbly crystals.  It sure didn't hurt.  
If the ONLY thing you do is take the crystal out, bevel gently 3-4 times each direction each edge in copper cream at 45 degrees, you will decrease oscillation frequency 4-8 khz!  You can then try one last time for your A frequency doing a few real gentle 8s....
« Last Edit: April 10, 2016, 1820 UTC by moof »

Offline ff

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #12 on: April 11, 2016, 1138 UTC »
Good stuff, Moof! Especially for us fellas that have some FT-243's that aren't quite where we would want them to resonate.
Goodonya moof!  I've also been following you through your crystal grinding odyssey and learning a lot about it in the process.  Thanks for sharing!  :)
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Offline moof

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #13 on: April 17, 2016, 2050 UTC »
I'm rethinking poo-pooing on Dremel compound.  I have been able to make a usable slurry using 4-5 micro drops of Dawn to every 1 drop water plus microwaving a small blob of Dremel compound.  It still feels too gritty, but if you use it only to do a gross increase in frequency on a crap crystal to get it within 50 khz of target it may be usable.  I took a 6550, knocked it up 70 khz with gently figure 8s, then repeated bringing up another 100.  Still had audio.  The next 2 increases up to 6880 had a bit of carrier but no audio really.  I'm processing with a few rounds of copper cream in every direction to bring it back to life and have brought the audio back at 6910.  All this in just over an hour and a couple drinks.  So it may have some use.

Offline moof

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Re: etching crystals-increasing the frequency on your ft-243s
« Reply #14 on: April 20, 2016, 2247 UTC »
OK Dremel compound, I'm sorry.  I just didn't know how you liked to get all lubed up and hot.
I'm experimenting taking a mid-5000s crystal up 1500 khz just to see if possible.
So here's how Dremel compound likes it before you go a-fingering.
Small wad on pane of glass smaller than pencil eraser sitting in 10 drops Dawn, couple drops water.  Stick in microwave 10 seconds with a shot glass of water because the Dremel stuff will want to absorb all the radiation.  It will come out flat and semi dry so add a few more drops of Dawn and water and go to town mixing all the stuff stuck to the glass and make a smooth slurry, adding a few drops of water as needed.  Start thick, end thin.  It will feel slightly gritty but there should be no visible particulate matter.  At least to old guy eyes.  Once it is all unstuck off the bottom, you can add a few more drops water if needed and start with your figure 8s in different directions.  It will have plenty of soap at this point so only add water to wet it down.
In one hour I brought it up 500 khz and the audio started to go, over 600 and it also had iffy oscillation.
I know I can bring you around with copper cream within a half hour.  Then maybe we go at it again.

Yep, cream, Dremel, Dremel, cream just once and good audio at 6815.  Up about 1300.  Now to go slow.  It can be done.
Yes, 2 more 30-45 minute sessions and we are done.  0.2khz away from target with good audio.
« Last Edit: April 23, 2016, 1836 UTC by moof »

 


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