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I read the "HP-45 Crystal Modification" page with great interest. Then spent many hrs on the web trying to find a 784 kHz crystal, or resonator... of any "cut" or "mode" but it is such a weird frequency (rather low and also unusual). Does anyone know where I can get two (or even one)? I cannot find a crystal manufacturer with stock or willing to make only a few of this unusual frequency. Also, Does the "enter key modification" change the normal functionality of the calculator (I'd like to keep using it as a calc as well as a cool stopwatch!). Thanks for any help!

Quote:
Also, Does the "enter key modification" change the normal functionality of the calculator

No. It works normally except if you press the sequence RCL ENTER^.

I did find a small difference, precisely when comparing the timer on my unit with that in Dave's version of Eric's emulator. I think the modified ENTER key no longer quits the timer mode, instead it starts the timer but does not stop it, unlike CHS.

Jordi Hidalgo

HPCC #1046

You can tune a crystal:
http://www.hanssummers.com/radio/penning/index.htm

If crystals are so hard to find, maybe you should consider looking for a 55 which is a great calc although it was reported on this forum that it fails more than other classics.

Arnaud