Sure they are.  You just have to ask.
http://www.digikey.com/product-detail/en/abracon-llc/ABLSG-4.9152MHZ-D2Y-T/=
535-10597-2-ND/2344537

There are similar packages available from companies like ECS with four lead=
s, two are ground.


-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of=
 Justin Richards
Sent: Monday, January 30, 2017 8:12 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Grounding the Xtal's metal cans

It seems odd to me that they are not manufactured as standard with three pi=
ns knowing that it may be an issue and may be required to ground the case i=
n certain applications.



On 30 January 2017 at 22:52, Van Horn, David < david.vanhorn@backcountryacc=
ess.com> wrote:

> You frequently see grounded cans in radio receiver and transmitter=20
> circuits.
> It is easy to order them with leads to ground the can, I have several=20
> custom crystals in my current project with that feature.
>
> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On=20
> Behalf Of Sean Breheny
> Sent: Saturday, January 28, 2017 11:09 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Grounding the Xtal's metal cans
>
> If you don't ground the can then the stability and repeatability of=20
> the crystal frequency will not be as good as it can be. With the can=20
> ungrounded, if you listen to the crystal signal on a shortwave=20
> receiver in CW or SSB modes you can hear it jump around as you touch=20
> the can. Properly grounded, you can barely hear any tone pitch change whe=
n you touch the can.
>
> Sean
>
>
> --
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