[ARC5] WHINK and crystals.

[Kenneth G. Gordon]

On 26 Jun 2013 at 17:57, Dennis Monticelli wrote:

> Ken,
> 
> My experience with a buffered HF solution has been that 25KHz of
> movement is easy without loss of activity but more than that may
> impact activity.

I had wondered about that. As I remember it, edge-grinding can sometimes 
restore activity. I suspect that the etching solution etches all six sides, which 
"rounds" the edges and perhaps the corners too, reducing activity.

BTW, I have some really excellent grinding compound here. It is not the 
usual valve-grinding compound, but something far better. I understand that 
there is a grinding compound that is sold by Dremel which works 
outstandingly well too.

>  You need to insure the solution has good access to both sides without
> masking off a part of any surface.

I had also wondered about that. In this case, I have simply been plopping the 
crystal blank into the container and letting it sit.

>  That is a bit tricky to implement
> mechanically.  Providing a little bit of agitation every now and then
> helps move quartz laden solution away from the immediate surface.

I am thinking about some sort means of vibrating (safely) the container. I'll 
work on that.

> It helps to be able to quantify activity ( perhaps via osc output or
> vigorous startup) so you can determine when you are approaching the
> danger zone.  It is hard to restore activity after it is lost.

Yes. Well, I have a circuit I have been meaning to build for some time now 
that measures crystal activity. I'll get to work on that before I get to carried 
away with making crystals.
 
> Let us know how the long distance move comes out. I have moved several
> dozen rocks with HF so I'm really curious how yours turn out.  I still
> have a lot to learn about etching technique.

Boy! You ain't the only one, Dennis.

FYI, there is a digitally controlled machine out at the University of Idaho in 
the metallurgy department which "makes" crystals both mechanically and 
simultaneously by acid etching and measures their thickness in microns in 
the process. I have been assured by those who own the machine that I can 
use it any time I would like to. However, I have avoided going out there to do 
it, as I really didn't want to take the time to learn how to use it. Besides, I 
would have to take with me some means of measuring the frequency of the 
crystal while it is being "worked on". It seemed to me like it was a bigger 
hassle to deal with than it was worth. However, those of you who live near a 
large state university may find that it is something you can use.

I'll go out there and find out what the name of this machine is and will post it 
here.

My goal is to make crystals for every few KHz from the bottom of chosen 
bands. I thought a collection of such crystals beginning at the bottom of 80, 
40, and 30 meters would be a good start. Doubling and tripling the crystal 
frequencies would result in crystals for 20, 15, and 10, and even for 17, and 
12 meters.

I bought a couple of hundred old FT-243s some time ago in frequency 
ranges that were outside and below the various ham bands with the idea of 
grinding and/or etching them up to chosen frequencies.

As I have time and the inclination to do so, I'll carry on.

Ken W7EKB