Changing the clock frequency slightly (PDP-11)?

[Nico de Jong]

----- Original Message ----- 
From: "Roger Merchberger" <zmerch at 30below.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Thursday, December 29, 2005 7:15 PM
Subject: Re: Changing the clock frequency slightly (PDP-11)?


> Rumor has it that Charles may have mentioned these words:
> >After pulling out my hair for a while trying to get my PDP-11 to
> >talk to me, I finally discovered that the master clock (26.667 MHz
> >crystal oscillator) is dead. (KDF-11BA CPU board).
> >
> >Those metal-package oscillators are very common and inexpensive
> >(around $2), but I can't find one in that exact frequency. 25,
> >25.175 and 27 MHz units are available.
>
The 27 MHZ unit is only 333 Hz off, which is 0.00125%, if I have my decimal
point correct.
A common trick to change the frequence of a crystal, is to put a capacitor
in parallel with it.
Nico