Dave Van Horn wrote:
>
>Richard Otteson wrote:
>>A third overtone crystal on the Scenix can interfere with the oscillator
>>pins when they are used to program the SX. The inductor of the filter
>>for third overtone operation can short the programming voltage and
>>damage the SX or the programmer!
>
>So use a large value cap (0.1uF or so) in series with the inductor to
>remove the un-necessary DC short.
>

Ling wrote:
> Thanks Dan.  Found it, the Citizen part number is HC49US50.000MABJ.
> Think this is also 3rd OT from their website.
> http://www.citizencrystal.com/quartz/crystals/hc49_d.htm
>
> Manage to get some 3rd OT, will try it out and inform all later.

Steve Baldwin wrote:
>Try this link
>http://www.saronix.com/pdfs/128/128.p1.pdf
>which is a document called "miniature high frequency fundamental
>30-250MHz"
-------------------

Ling,

I did a little follow up re 50 Mhz xtals & SX. Talked with Richard
Duong, FAE from abracon.com [1-888-4ABRACON], and checked around
a bit.

As Dave and Richard O. indicate, you will need "additional" circuitry
to get a 3rd OT working with SX processors - cap & inductor, besides
the regular parallel R and 2 caps to gnd. Also, in this case, you can
have ISP problems, possible startup problems over temperature, etc.
Richard Duong is sending me a ckt for using 3rd OT with SX. You might
check with him too before trying these xtals.

Also, the 50 Mhz fund-mode xtals from Abracon, AB 9703 50.000M-F,
are apparently not a stock part, but were special order for Scenix.

However, checkout the Saronix parts. They do appear to have a stock
50Mhz fund-mode part, in std HC-49 pkg - P/N 49S500B:

http://www.saronix.com/pdfs/112/112.p1.pdf

best regards,
- Dan Michaels
Oricom Technologies
===================