LF: Re: TIP: modifiying X-tals

["hamilton mal" <g3kev.ham@virgin.net>]

Dick.

 

My xtals are small sealed units, some are also enclosed in glass like B7G tubes with the same base. These cannot be modified as you describe.

The old larger types with a plate that can be removed are different.

I was wondering how far they would pull with a capacitor in series etc.

mal

 

----- Original Message -----

From: Dick

To: rsgb_lf_group@blacksheep.org

Sent: Saturday, August 19, 2006 7:16 PM

Subject: LF: TIP: modifiying X-tals

For those who didn't know, use following 'trick' to tune your own X-tal.  (found it in a magazine from the VERON)

 

Remove the metalcover and place the remains in an oscillator.

Now it will oscillate on it's original frequency.

 

Take an permant marker pen ("Edding, or similar) and put a little stripe/line on the X-tal plate.

You will notice that the frequency goes down a bit.

Wait a little until the xyleen/alcohol or other stuff that's in the paint has gone.....

By adding more of the ink on the cristal, it will go lower in frequency.

However there is a limit, and there will be a point where the X-tal will not start anymore.

 

When there is to much ink/paint on the X-tal, you can remove it with alcohol or something.

 

In this way I managed to tune a 4433,619kHz X-tal down to 4406,4kHz, which, divided by 16 give 275,4, which drives my rig.

275,4 divided by 2 is 137,7kHz!

 

I think for this X-tal this is about the limit, maybe 40kHz down, but that's probably it.

 

But it works!

 

A really nice thrick to get those odd X-tal frequencies!

 

Dick, PA4VHF