Vintage Frequency Measurement
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
Hi,
With low-pass filters, I think.
This is the simplest method: an rc filter and measure is done on the
capacitor poles.
Ilia.
On 02/12/17 06:08, Scott Stobbe wrote:
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Ilia Platone
via Ferrara 54
47841
Cattolica (RN), Italy
Cell +39 349 1075999
Back in the early sixties I worked in a lab adjusting filters for line transmission.
We had numerous oscillators, built to be boat anchors, and CROs set up for X-Y display.
The lab had 100hz, 1kHz, 10kHz standards wired in.
We were expert at recognising lisajou figures. We might have several oscillators running together,
and we could establish almost any frequency with precision.
Calibting an oscillator would not have been difficult.
Cheers, Neville Michie
On 12 Feb 2017, at 5:08 PM, Scott Stobbe scott.j.stobbe@gmail.com wrote:
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Look at (Singer) Gertsch Frequency Meter. This was standard measuring equipment in our (spectroscopy) lab in 1975.
Mike
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Neville Michie
Sent: Sunday, February 12, 2017 05:20
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Vintage Frequency Measurement
Back in the early sixties I worked in a lab adjusting filters for line transmission.
We had numerous oscillators, built to be boat anchors, and CROs set up for X-Y display.
The lab had 100hz, 1kHz, 10kHz standards wired in.
We were expert at recognising lisajou figures. We might have several oscillators running together, and we could establish almost any frequency with precision.
Calibting an oscillator would not have been difficult.
Cheers, Neville Michie
On 12 Feb 2017, at 5:08 PM, Scott Stobbe scott.j.stobbe@gmail.com wrote:
I was inspired recently coming across a Lampkin 105 frequency meter,
as to how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On 2/11/2017 10:08 PM, Scott Stobbe wrote:
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Google BC-221 and you may get some idea of how those worked. I just
wish I could find the one hidden in my garage :^)
Dan
Hi
Counters go back at least into the early 1950’s. I started out with fully vacuum
tube (except for diodes) counters obtained as surplus in the mid 1960’s. They
used some odd gas filled triodes. Everything in them could have been on the market
in 1947. They were not a common thing until the late 50’s.
Prior to that (WWII era) the standard approach was to use a heterodyne frequency
meter. They could be quite complex. I once passed up a “deal” on one that spread
out over several rack cabinets. The idea was that you produced a beat against this or that
and then beat it again against something else. Ultimately a meter or scope showed
you the phase offset.
The heterodyne approach lived on in the era of the counter using a synthesizer as
the reference. The beat note went into an analog meter based audio frequency meter.
It allowed you do do cute things like servo to a target when grinding or plating something
to frequency.
One key thing to keep in mind: in the 1930’s it is rare to find a frequency spec that is
not stated in percent (with some zeros involved). A tight spec was in the 20 ppm
(or 0.002% ) range. The idea of a heated crystal as a reference was a “national
standards” sort of thing in 1935. The crystal industry as we know it today really only dates
back to 1939. Before that the number of producers and the volume produced
was very small.
Bob
On Feb 12, 2017, at 1:08 AM, Scott Stobbe scott.j.stobbe@gmail.com wrote:
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
[Hopefully this time my post is in the required plain-text format!]
The solid-state HP-5210A and its vacuum-tube predecessors, the
HP-500A/B/C family, were analog frequency measuring instruments. The
circuitry summed the input frequency (converted into pulses) and
generated an analog voltage to display on a meter. Higher frequency
meant more pulses and thus a higher voltage. My 5210A goes up to 10 MHz
and is surprisingly accurate although the resolution, even with an
expanded-scale switch, is only three digits. A nice tool in the 5210A is
an FM discriminator with adjustable filters.
Jeremy
On 2/11/2017 10:08 PM, Scott Stobbe wrote:
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
time-nuts mailing list --time-nuts@febo.com
To unsubscribe, go tohttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
First you need a standard, a crystal oscillator. If you want serious precision, you'd have one in an oven. Zero beat that with WWV. Then make a very stable VFO and calibrate the harmonics against the crystal. Assume linear calibration on the VFO between check points.
The military LM and BC-221 were very good units. I had one. The check points in the calibration book were too far apart but there were others that weren't documented that would make for more precise calibration.
I also built a frequency meter that was amazingly accurate, from a GE Ham News project printed back in the early 1950s. It used a VFO that went between 100 kHz and 101 kHz for its full range, adjusted by a micrometer dial (military surplus). Its harmonics would be zero beat with the unknown. Using a successive number of harmonics would identify the harmonic number and the scale could be interpolated to within much less than 1 kHz over the HF range.
Of course, zero beat was hard to identify so you could use an oscilloscope lissajous pattern (if you had an oscilloscope, which I didn't). What I did was turn up the volume and listen to the beat. When it got down near zero the sound of the AGC surging would tell me the frequency of the beat and I could adjust to make it stop surging.
When I got my hands on a Beckman counter I was in heaven.
Bob
On Sunday, February 12, 2017 4:01 AM, Neville Michie <namichie@gmail.com> wrote:
Back in the early sixties I worked in a lab adjusting filters for line transmission.
We had numerous oscillators, built to be boat anchors, and CROs set up for X-Y display.
The lab had 100hz, 1kHz, 10kHz standards wired in.
We were expert at recognising lisajou figures. We might have several oscillators running together,
and we could establish almost any frequency with precision.
Calibting an oscillator would not have been difficult.
Cheers, Neville Michie
On 12 Feb 2017, at 5:08 PM, Scott Stobbe scott.j.stobbe@gmail.com wrote:
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
In a word,Wavemeters. Classic US onwas the BC221 with built in 100kHz crystal calibrator
http://radionerds.com/index.php/BC-221
British was the "Class D"http://www.royalsignals.org.uk/photos/classDno1.htm
For UHF and Microwave it was Lecher lines or cavity wavemeters.
Robert G8RPI.
From: Scott Stobbe <scott.j.stobbe@gmail.com>
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sunday, 12 February 2017, 6:08
Subject: [time-nuts] Vintage Frequency Measurement
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
There was also one generator which you could tune to beat the frequency
in question the generator was a frequency synthesizer without any
digital part that was the famous Schomandl FD! see here
SCHOMANDL-FD1-FDM1 FREQUENCY METER,
https://elektrotanya.com/schomandl-fd1-fdm1_frequency_meter.pdf/download.html
there they have the circuit diagram and a complete service manual
also, the circuit was not that complicated
a similar Dekadischer Service-Frequenzmesser
FD100http://www.radiomuseum.org/r/schomandl_dekadischer_service_frequenzmesser_fd100.html,
on which I worked to was made with solid-state components
73
KJ6UHN
Alex
[Dr. Alexander Pummer a former design engineer of Schomandl KG in Munich
Bavaria/Germany]
On 2/12/2017 6:07 AM, Bob Camp wrote:
Hi
Counters go back at least into the early 1950’s. I started out with fully vacuum
tube (except for diodes) counters obtained as surplus in the mid 1960’s. They
used some odd gas filled triodes. Everything in them could have been on the market
in 1947. They were not a common thing until the late 50’s.
Prior to that (WWII era) the standard approach was to use a heterodyne frequency
meter. They could be quite complex. I once passed up a “deal” on one that spread
out over several rack cabinets. The idea was that you produced a beat against this or that
and then beat it again against something else. Ultimately a meter or scope showed
you the phase offset.
The heterodyne approach lived on in the era of the counter using a synthesizer as
the reference. The beat note went into an analog meter based audio frequency meter.
It allowed you do do cute things like servo to a target when grinding or plating something
to frequency.
One key thing to keep in mind: in the 1930’s it is rare to find a frequency spec that is
not stated in percent (with some zeros involved). A tight spec was in the 20 ppm
(or 0.002% ) range. The idea of a heated crystal as a reference was a “national
standards” sort of thing in 1935. The crystal industry as we know it today really only dates
back to 1939. Before that the number of producers and the volume produced
was very small.
Bob
On Feb 12, 2017, at 1:08 AM, Scott Stobbe scott.j.stobbe@gmail.com wrote:
I was inspired recently coming across a Lampkin 105 frequency meter, as to
how frequency measurement was done before counters.
Certainly zero-beating a dial calibrated oscillator, would be one approach.
Is there a standout methodology or instrument predating counters?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
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