Re: [time-nuts] General Radio Model 723D Precision Oscillator (Tuning Fork)

[paul swed]

Here is the link to some fine pictures and the schematic. Its uasable.
http://worldpowersystems.com/J/instruments/GR723/
As a heads up the AC power comes in and is immediately doubled.
Loaded something like 164 VDC.
Reg tubes 107 V.
Osc draws 35 Ma at 135V B+.
Fil 1.42V@47 ma.
Distortions quite low .219% Tek AA501.
IMD 5.59% Tek AA501.
I actually used independent supplies when I fired it up the first time.
Totally did not trust the power supply.
Takes about 20 seconds to start up.
You will hear it running quite apparent.
I have a theory. Crystals were invented so you would not need to listen to
the tuning fork.
Regards
Paul
WB8TSL



On Sat, Dec 9, 2017 at 11:37 AM, paul swed  wrote:

> Well we are kicking butt on 723 oscillators. I have the 1000 hz model and
> found it at the MIT flea about June.
> Bad rectifier section. Cap was good though I carefully reformed it. Have
> to say what attracted me was the case and then the realization of what it
> was. It works very well so now I can make sure my cesium is on frequency.
> There is a schematic online but its a picture actually in the wood case. I
> copied that as I could find no real details.
> I do have the genrad article.
> The actual internals are hot. Be careful. It uses an output transformer as
> the only isolation.
> It makes sense actually. It keeps the 60 Hz magnetics out of the
> oscillator.
> I thought my tube might be bad as it didn't glow. But its a 1.5 V filament
> ohm'ed it out and it was fine.
> Lastly I have a hacked power cable. I was going to buy the right plug. But
> it actually is a bit unclear. It should be the cenetr ground and they are
> around $15 each. Its not the cost. The 3 I see are sort of unclear that
> they match my socket.
> I swear I actually have one. Some place here.
> Regards
> Paul
> WB8TSL
>
> On Sat, Dec 9, 2017 at 10:30 AM, Eric Scace  wrote:
>
>> Another fascinating tuning-fork standard was used together with a
>> Synchronome to govern the timing of pulses of Morse code on undersea
>> telegraph cables in the British empire’s globe-girdling telegraph network.
>> Timing was derived electromagnetically from incoming Morse code signals (a
>> bi-polar signal where one polarity represented a dit and the other a dah,
>> but both dit and dah were of equal length) to set the master at each
>> downstream relay/switching station on a cable route.
>>
>> In essence, brass, mahogany and electromagnetics were use to perform all
>> the functions done today on fiber optic cables: signal generation,
>> multiplexing, regeneration, and timing recovery… not to mention encoding &
>> decoding plus printing.
>>
>> One can see a working example at the Museum of Undersea Telegraphy in
>> Porth Curno, Cornwall — a museum well worth the detour to Land’s End.
>>
>> — Eric
>>
>> > On 2017 Dec 09, at 10:11 , Don  wrote:
>> >
>> > Thank you, Pete.   -Don
>> >
>> > ==
>> >
>> >
>> >
>> >
>> > On Sat, 2017-12-09 at 05:57 -0800, Pete Lancashire wrote:
>> >> Here's a look at a 723-C (1,000 cps) and how its power supply cap was
>> >> handled and a good look inside
>> >>
>> >> https://www.eevblog.com/forum/reviews/vintage-teardown-general-radio-
>> >> 723-c-vacuum-tube-tuning-fork/
>> >>
>> >>
>> >> The GR Experimenter
>> >>
>> >> http://www.americanradiohistory.com/Archive-General-Radio/GR%20Exp%20
>> >> 1941_10.pdf
>> >>
>> >> There is another Experimenter that goes into how the tuningfork was
>> >> made
>> >> but can't find it
>> >>
>> >> -pete
>> >>
>> >> On Sat, Dec 9, 2017 at 5:18 AM, Don  wrote:
>> >>
>> >>>
>> 
>>  I was fortunate to find a vintage, General Radio (GR) Model 723D
>>  Precision Oscillator (tuning fork).
>> 
>>  The exceptional wooden case is as 'exciting' to look at as is the
>>  mechanical tuning fork inside (400Hz).
>> 
>>  As it is ac powered, I'll need to recap it before I turn it on.
>>   Then, we can test for accuracy! (sic).
>> 
>>  A real class-act, 'time-nut' oscillator from the last century,
>>  predating crystals.
>> 
>>  Don
>> 
>>  Don Lewis
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
>
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Re: [time-nuts] General Radio Model 723D Precision Oscillator (Tuning Fork)

[paul swed]

Well we are kicking butt on 723 oscillators. I have the 1000 hz model and
found it at the MIT flea about June.
Bad rectifier section. Cap was good though I carefully reformed it. Have to
say what attracted me was the case and then the realization of what it was.
It works very well so now I can make sure my cesium is on frequency.
There is a schematic online but its a picture actually in the wood case. I
copied that as I could find no real details.
I do have the genrad article.
The actual internals are hot. Be careful. It uses an output transformer as
the only isolation.
It makes sense actually. It keeps the 60 Hz magnetics out of the oscillator.
I thought my tube might be bad as it didn't glow. But its a 1.5 V filament
ohm'ed it out and it was fine.
Lastly I have a hacked power cable. I was going to buy the right plug. But
it actually is a bit unclear. It should be the cenetr ground and they are
around $15 each. Its not the cost. The 3 I see are sort of unclear that
they match my socket.
I swear I actually have one. Some place here.
Regards
Paul
WB8TSL

On Sat, Dec 9, 2017 at 10:30 AM, Eric Scace  wrote:

> Another fascinating tuning-fork standard was used together with a
> Synchronome to govern the timing of pulses of Morse code on undersea
> telegraph cables in the British empire’s globe-girdling telegraph network.
> Timing was derived electromagnetically from incoming Morse code signals (a
> bi-polar signal where one polarity represented a dit and the other a dah,
> but both dit and dah were of equal length) to set the master at each
> downstream relay/switching station on a cable route.
>
> In essence, brass, mahogany and electromagnetics were use to perform all
> the functions done today on fiber optic cables: signal generation,
> multiplexing, regeneration, and timing recovery… not to mention encoding &
> decoding plus printing.
>
> One can see a working example at the Museum of Undersea Telegraphy in
> Porth Curno, Cornwall — a museum well worth the detour to Land’s End.
>
> — Eric
>
> > On 2017 Dec 09, at 10:11 , Don  wrote:
> >
> > Thank you, Pete.   -Don
> >
> > ==
> >
> >
> >
> >
> > On Sat, 2017-12-09 at 05:57 -0800, Pete Lancashire wrote:
> >> Here's a look at a 723-C (1,000 cps) and how its power supply cap was
> >> handled and a good look inside
> >>
> >> https://www.eevblog.com/forum/reviews/vintage-teardown-general-radio-
> >> 723-c-vacuum-tube-tuning-fork/
> >>
> >>
> >> The GR Experimenter
> >>
> >> http://www.americanradiohistory.com/Archive-General-Radio/GR%20Exp%20
> >> 1941_10.pdf
> >>
> >> There is another Experimenter that goes into how the tuningfork was
> >> made
> >> but can't find it
> >>
> >> -pete
> >>
> >> On Sat, Dec 9, 2017 at 5:18 AM, Don  wrote:
> >>
> >>>
> 
>  I was fortunate to find a vintage, General Radio (GR) Model 723D
>  Precision Oscillator (tuning fork).
> 
>  The exceptional wooden case is as 'exciting' to look at as is the
>  mechanical tuning fork inside (400Hz).
> 
>  As it is ac powered, I'll need to recap it before I turn it on.
>   Then, we can test for accuracy! (sic).
> 
>  A real class-act, 'time-nut' oscillator from the last century,
>  predating crystals.
> 
>  Don
> 
>  Don Lewis
> ___
> 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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Re: [time-nuts] General Radio Model 723D Precision Oscillator (Tuning Fork)

[Eric Scace]

Another fascinating tuning-fork standard was used together with a Synchronome 
to govern the timing of pulses of Morse code on undersea telegraph cables in 
the British empire’s globe-girdling telegraph network. Timing was derived 
electromagnetically from incoming Morse code signals (a bi-polar signal where 
one polarity represented a dit and the other a dah, but both dit and dah were 
of equal length) to set the master at each downstream relay/switching station 
on a cable route.

In essence, brass, mahogany and electromagnetics were use to perform all the 
functions done today on fiber optic cables: signal generation, multiplexing, 
regeneration, and timing recovery… not to mention encoding & decoding plus 
printing.

One can see a working example at the Museum of Undersea Telegraphy in Porth 
Curno, Cornwall — a museum well worth the detour to Land’s End.

— Eric

> On 2017 Dec 09, at 10:11 , Don  wrote:
> 
> Thank you, Pete.   -Don
> 
> ==
> 
> 
> 
> 
> On Sat, 2017-12-09 at 05:57 -0800, Pete Lancashire wrote:
>> Here's a look at a 723-C (1,000 cps) and how its power supply cap was
>> handled and a good look inside
>> 
>> https://www.eevblog.com/forum/reviews/vintage-teardown-general-radio-
>> 723-c-vacuum-tube-tuning-fork/
>> 
>> 
>> The GR Experimenter
>> 
>> http://www.americanradiohistory.com/Archive-General-Radio/GR%20Exp%20
>> 1941_10.pdf
>> 
>> There is another Experimenter that goes into how the tuningfork was
>> made
>> but can't find it
>> 
>> -pete
>> 
>> On Sat, Dec 9, 2017 at 5:18 AM, Don  wrote:
>> 
>>> 
 
 I was fortunate to find a vintage, General Radio (GR) Model 723D
 Precision Oscillator (tuning fork).
 
 The exceptional wooden case is as 'exciting' to look at as is the
 mechanical tuning fork inside (400Hz).
 
 As it is ac powered, I'll need to recap it before I turn it on.
  Then, we can test for accuracy! (sic).
 
 A real class-act, 'time-nut' oscillator from the last century,
 predating crystals.
 
 Don
 
 Don Lewis
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Re: [time-nuts] General Radio Model 723D Precision Oscillator (Tuning Fork)

[Don]

Thank you, Pete.   -Don

==




On Sat, 2017-12-09 at 05:57 -0800, Pete Lancashire wrote:
> Here's a look at a 723-C (1,000 cps) and how its power supply cap was
> handled and a good look inside
> 
> https://www.eevblog.com/forum/reviews/vintage-teardown-general-radio-
> 723-c-vacuum-tube-tuning-fork/
> 
> 
> The GR Experimenter
> 
> http://www.americanradiohistory.com/Archive-General-Radio/GR%20Exp%20
> 1941_10.pdf
> 
> There is another Experimenter that goes into how the tuningfork was
> made
> but can't find it
> 
> -pete
> 
> On Sat, Dec 9, 2017 at 5:18 AM, Don  wrote:
> 
> > 
> > > 
> > > I was fortunate to find a vintage, General Radio (GR) Model 723D
> > > Precision Oscillator (tuning fork).
> > > 
> > > The exceptional wooden case is as 'exciting' to look at as is the
> > > mechanical tuning fork inside (400Hz).
> > > 
> > > As it is ac powered, I'll need to recap it before I turn it on.
> > >  Then, we can test for accuracy! (sic).
> > > 
> > > A real class-act, 'time-nut' oscillator from the last century,
> > > predating crystals.
> > > 
> > > Don
> > > 
> > > Don Lewis
> > > Austin, TX
> > > N5CID
> > > 
> > > 
> > > 
> > > 
> > ___
> > 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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> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/t
> ime-nuts
> and follow the instructions there.
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Re: [time-nuts] General Radio Model 723D Precision Oscillator (Tuning Fork)

[Pete Lancashire]

Here's a look at a 723-C (1,000 cps) and how its power supply cap was
handled and a good look inside

https://www.eevblog.com/forum/reviews/vintage-teardown-general-radio-723-c-vacuum-tube-tuning-fork/


The GR Experimenter

http://www.americanradiohistory.com/Archive-General-Radio/GR%20Exp%201941_10.pdf

There is another Experimenter that goes into how the tuningfork was made
but can't find it

-pete

On Sat, Dec 9, 2017 at 5:18 AM, Don  wrote:

> > I was fortunate to find a vintage, General Radio (GR) Model 723D
> > Precision Oscillator (tuning fork).
> >
> > The exceptional wooden case is as 'exciting' to look at as is the
> > mechanical tuning fork inside (400Hz).
> >
> > As it is ac powered, I'll need to recap it before I turn it on.
> >  Then, we can test for accuracy! (sic).
> >
> > A real class-act, 'time-nut' oscillator from the last century,
> > predating crystals.
> >
> > Don
> >
> > Don Lewis
> > Austin, TX
> > N5CID
> >
> >
> >
> >
> ___
> 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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