HP5061B Versus HP5071 Cesium Line Frequencies
https://www.febo.com/pipermail/time-nuts/2017-May/105566.html
The lock system on the HP5071 is complex and expensive. My plan to
improve the HP5061B is to to use a pair of third overtone crystals
running at 91.9 mc and 100 mc. I have come up with the magic numbers
to lock them together. This eliminates all multipliers with the
exception of the A4 board. The 12.61 mc synthesizer input presently
wastes half the microwave power produced by the 90 mc input in the
unused lower sideband. Therefore only half the 91.9 mc drive is
required.
Eight bit ECL dividers in one package are available to perform the
necessary lock. When multiplied by 100 to the cesium resonance line,
the 91.9 mc frequency is a few cycles high so that C field currents
are reasonable. With crystal cuts for zero temperature coefficient at
25°C, it is possible to get along without an oven. Room temperature
performance at 25°C±5°C is ±15·10^-9. Oscillator warm up time would
be measured in seconds.
Square wave modulation of variable frequency and amplitude shows
promise for reducing the noise effects of the beam tube. You can
smoothly change the lock time constant, deviation and frequency. This
would avoid the big disturbance of the HP5061B when you switch from
OPR to LTC. (OPR=operate with 1 second time constant, LTC=operate with
100 second time constant)
πθ°μΩω±√·Γλ
WB0KV
Direct multiplication to 9192 MHz isn't used
by any manufacturer of any atomic clock that I
know of, due to its well known disadvantages.
I can state for a fact that it was summarily
rejected by the designers of the 5060/5061
(Cutler, et al). In the 5071, I (being the
RF designer) also summarily rejected it.
The architecture that is instead used is indeed
complex and expensive as you say. It is
also ACCURATE.
Rick
On 6/1/2017 7:04 PM, Donald E. Pauly wrote:
https://www.febo.com/pipermail/time-nuts/2017-May/105566.html
The lock system on the HP5071 is complex and expensive. My plan to
improve the HP5061B is to to use a pair of third overtone crystals
running at 91.9 mc and 100 mc. I have come up with the magic numbers
to lock them together. This eliminates all multipliers with the
exception of the A4 board. The 12.61 mc synthesizer input presently
wastes half the microwave power produced by the 90 mc input in the
unused lower sideband. Therefore only half the 91.9 mc drive is
required.
Eight bit ECL dividers in one package are available to perform the
necessary lock. When multiplied by 100 to the cesium resonance line,
the 91.9 mc frequency is a few cycles high so that C field currents
are reasonable. With crystal cuts for zero temperature coefficient at
25°C, it is possible to get along without an oven. Room temperature
performance at 25°C±5°C is ±15·10^-9. Oscillator warm up time would
be measured in seconds.
Square wave modulation of variable frequency and amplitude shows
promise for reducing the noise effects of the beam tube. You can
smoothly change the lock time constant, deviation and frequency. This
would avoid the big disturbance of the HP5061B when you switch from
OPR to LTC. (OPR=operate with 1 second time constant, LTC=operate with
100 second time constant)
πθ°μΩω±√·Γλ
WB0KV
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Hi
On Jun 1, 2017, at 10:04 PM, Donald E. Pauly trojancowboy@gmail.com wrote:
https://www.febo.com/pipermail/time-nuts/2017-May/105566.html
The lock system on the HP5071 is complex and expensive. My plan to
improve the HP5061B is to to use a pair of third overtone crystals
running at 91.9 mc and 100 mc. I have come up with the magic numbers
to lock them together. This eliminates all multipliers with the
exception of the A4 board. The 12.61 mc synthesizer input presently
wastes half the microwave power produced by the 90 mc input in the
unused lower sideband. Therefore only half the 91.9 mc drive is
required.
Eight bit ECL dividers in one package are available to perform the
necessary lock. When multiplied by 100 to the cesium resonance line,
the 91.9 mc frequency is a few cycles high so that C field currents
are reasonable. With crystal cuts for zero temperature coefficient at
25°C, it is possible to get along without an oven. Room temperature
performance at 25°C±5°C is ±15·10^-9.
I would suggest you check a few real crystals over the 20 to 40C range ….
With all the “stuff” in a 5061, it will change (rise) at least 10C after turn on.
Bob
Oscillator warm up time would
be measured in seconds.
Square wave modulation of variable frequency and amplitude shows
promise for reducing the noise effects of the beam tube. You can
smoothly change the lock time constant, deviation and frequency. This
would avoid the big disturbance of the HP5061B when you switch from
OPR to LTC. (OPR=operate with 1 second time constant, LTC=operate with
100 second time constant)
πθ°μΩω±√·Γλ
WB0KV
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
https://www.febo.com/pipermail/time-nuts/2017-May/105566.html
If we build this circuit it would be a bench model not designed to be
inside a hot chassis. It would be able to lock ± 5° C of 25° C. My
idea of an oven is to keep the crystal and oscillator at 25° C ±0.001
°C with 60 second warm up/cool down time.
πθ°μΩω±√·Γλ
WB0KVV
---------- Forwarded message ----------
From: Bob kb8tq kb8tq@n1k.org
Date: Fri, Jun 2, 2017 at 5:57 AM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Hi
I would suggest you check a few real crystals over the 20 to 40C range ….
With all the “stuff” in a 5061, it will change (rise) at least 10C
after turn on.
Bob
Hi
If you are going to use an oven, it’s better to run it at the turn temperature of
the crystal. That would put you above 50C for an AT and a bit higher still for an SC.
Bob
On Jun 2, 2017, at 2:09 PM, Donald E. Pauly trojancowboy@gmail.com wrote:
https://www.febo.com/pipermail/time-nuts/2017-May/105566.html
If we build this circuit it would be a bench model not designed to be
inside a hot chassis. It would be able to lock ± 5° C of 25° C. My
idea of an oven is to keep the crystal and oscillator at 25° C ±0.001
°C with 60 second warm up/cool down time.
πθ°μΩω±√·Γλ
WB0KVV
---------- Forwarded message ----------
From: Bob kb8tq kb8tq@n1k.org
Date: Fri, Jun 2, 2017 at 5:57 AM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Hi
I would suggest you check a few real crystals over the 20 to 40C range ….
With all the “stuff” in a 5061, it will change (rise) at least 10C
after turn on.
Bob
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and follow the instructions there.
A cut at that angle has no turn over temperature. The zero temperature
coefficient point is 25°. Its temperature coefficient everywhere else is
positive.
On Friday, June 2, 2017, Bob kb8tq kb8tq@n1k.org wrote:
Hi
If you are going to use an oven, it’s better to run it at the turn
temperature of
the crystal. That would put you above 50C for an AT and a bit higher still
for an SC.
Bob
On Jun 2, 2017, at 2:09 PM, Donald E. Pauly <trojancowboy@gmail.com
javascript:;> wrote:
https://www.febo.com/pipermail/time-nuts/2017-May/105566.html
If we build this circuit it would be a bench model not designed to be
inside a hot chassis. It would be able to lock ± 5° C of 25° C. My
idea of an oven is to keep the crystal and oscillator at 25° C ±0.001
°C with 60 second warm up/cool down time.
πθ°μΩω±√·Γλ
WB0KVV
---------- Forwarded message ----------
From: Bob kb8tq <kb8tq@n1k.org javascript:;>
Date: Fri, Jun 2, 2017 at 5:57 AM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement <
Hi
I would suggest you check a few real crystals over the 20 to 40C range ….
With all the “stuff” in a 5061, it will change (rise) at least 10C
after turn on.
Bob
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To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.