[time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
Donald E. Pauly
trojancowboy at gmail.com
Fri Jun 2 17:51:22 EDT 2017
# 2 is not true. A cut has either two turning points or zero. Where
both turning points exist there are two temperatures at which the
temperature coefficient of frequency is zero. Cut 0 on figure 6 at
https://coloradocrystal.com/applications has no turnover point. It is
neither fish nor fowl. Cut 6 is the normal AT curve with extremes of
±16 ppm for -55° C thru +105° C. All curves normally intersect at 25°
C rather than the 27° C shown. 25° C is half way between -55° C thru
+105° C. Curve 6 is the Tchebychev polynomial y=4x^3-3x and curve 0
Consider the standard AT cut which has turnover points at -15° C and
65° C. The lower turnover would ordinarily not be used in ovens. A
set point error of ±1° C in the upper turnover point at 65° C results
in a frequency error of +14.875·10^-9. For cut 0, that same ±1° error
in room temperature results in a frequency error of ±31.25·10^-12.
This is an improvement of 476 to 1. You apparently have not thought
thru what improvements are possible with thermal coolers/heaters.
Among these is near instant warm up and greatly reduced power for
---------- Forwarded message ----------
From: Bob kb8tq <kb8tq at n1k.org>
Date: Fri, Jun 2, 2017 at 12:43 PM
Subject: Re: HP5061B Versus HP5071 Cesium Line Frequencies
To: "Donald E. Pauly" <trojancowboy at gmail.com>
Which statement is not true:
1) That there is a tolerance on the cut angle of a crystal?
2) That true zero temperature coefficient only happens at the turn?
3) That heater based controllers are impossible to build?
On Jun 2, 2017, at 3:40 PM, Donald E. Pauly <trojancowboy at gmail.com> wrote:
That is not true. I say that thermal coolers have made ovens
obsolete. A zero temperature coefficient at room temperature is
easier to hit than a zero temperature at the upper turnover point when
such a thing exists. See
curve 0 in Figure 6 at https://coloradocrystal.com/applications/ .
On Friday, June 2, 2017, Bob kb8tq <kb8tq at n1k.org> wrote:
> Any real crystal you buy will have a tolerance on the angle. In the case of a crystal cut for turn
> the temperature will be a bit different and you will match your oven to it. If you attempt a zero
> angle cut, you will never really hit it and there is no way to compensate for the problem.
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