Re: [time-nuts] SI532X Chips Close In Spurs (Somewhat Long)

[Hal Murray]

marklgoldb...@gmail.com said:
> I was hoping someone who knows these devices might have some insight into
> what the issue is and how to determine which plans will not provide close in
> spurs, without requiring testing. Any suggestions are appreciated. 

If you look at the binary of the word that goes into a DDS adder, the ones 
with more low order bits have closer in spurs.  Think of that word as a 
fraction, binary point on the left rather than right.

If your adder word is 0.001 (binary) it will divide by 8, no spurs.
If you have 0.0011, it will divide by a little less than 8 and have spurs.



-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] AM vs PM noise of signal sources

[Bill Hawkins]

Thank you, Charles.

What a clever way to minimize the power dissipation in Q4 with the
components of the day.

A switching regulator without the steep (and noisy) transients of
today's switchers.

Bill Hawkins 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles
Steinmetz
Sent: Monday, January 08, 2018 10:21 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] AM vs PM noise of signal sources

Bill wrote:

> What does the unijunction 2N2646 do in the oven controller?

For the following discussion, you need to refer to the *corrected*
schematic I mentioned in my last post.  If you are looking at the HP
schematic, you will wonder how the hell it works (and it wouldn't, if HP
actually built them as they drew it).

The 10544 oven control circuit uses pulse-width modulation to control
the heater in a "bang-bang" manner rather than a smooth proportional
manner.  UJT A3Q3 forms a relaxation oscillator (along with A3C1 and
A3R10), with a period of ~250uS (frequency ~4kHz) and a voltage span
from ~0v to ~8v.

This positive-going ramp is applied to the base of Darlington A3Q2
(MPSA12), which is 1/2 of a differential pair current switch along with
A3Q1 (2N3904).

The thermistor and associated op-amp circuitry set a threshold voltage
between ground and about 7v at the base of Q1.  After the relaxation
oscillator resets to ~0v, current flows through A3Q1 and A3R8, pulling
the base of Darlington A3Q4 negative and turning it on to saturation. 
The collector of A3Q4 therefore applies essentially the full oven heater
supply voltage from Pin 14 (nominally 24v) to the high side of the
heater.

The oscillator voltage ramps positive toward its ~8v maximum (the
trigger point of UJT A3Q3).  When the emitter of A3Q2, which is two
diode drops below the ramp voltage, exceeds the voltage at the emitter
of Q1 (as set by the thermistor and A3U1), Q2 steals the current that
has been flowing in A3Q1 and turns Darlington switch A3Q4 off, which
interrupts the current flowing through the heater.  Some time later
(about 250uS after the previous reset), the oscillator voltage reaches
the trigger point of the UJT and it resets the voltage on A3C1 to ~0v
and the cycle begins again.

Thus, every ~250uS the heater is on for a time (set by the thermistor
circuitry) and off for the remainder of the ~250uS.  This switching
action can be seen at the "Oven Monitor", Pin 11 (but note that the
instrument may have a capacitor to ground on the mother card side of the
oven monitor, to integrate the switching waveform for use by the
instrument's health monitor).

Best regards,

Charles


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[time-nuts] SI532X Chips Close In Spurs (Somewhat Long)

[Mark Goldberg]

I am using the Leo Bodnar Single output Mini GPSDO to generate 38.4 MHz as
an input to a Wenzel Oscillator that locks to it and produces a low phase
noise 80 MHz to drive my Perseus SDR. The Wenzel has a low loop bandwidth
so the phase noise from the Bodnar above the 10-100 Hz range does not seem
to get through.

The issue is that there are sometimes some close in spurs from the Bodnar
that do get through, about 31 and 62 Hz on either side of the 38.4 MHz
output. I believe the GPSDO is based on a SI532X chip, as reported for the
two output version. The spurs are only about 70 dB down, maybe 15-20 dB
above the phase noise in the area.

I tried several frequency plans as the SI532X can generate the same output
with several different sets of dividers. I did find one that worked very
well, with phase noise results and Allan Deviation that appear better than
the reported phase noise for the two output version. I basically used the
Bodnar software, SI's DSPLLSIM, some spreadsheet calculations and trial and
error to determine the working frequency plan.

I was hoping someone who knows these devices might have some insight into
what the issue is and how to determine which plans will not provide close
in spurs, without requiring testing. Any suggestions are appreciated.

Below is the long part. I have listed the frequency plans I tried and the
results below. Maybe someone can see a pattern.

Thanks

Mark


*My First Try Plan *


GPS 2,560,000
N31 1
N2_HS 7
N2_LS 300
N1_HS 7
NC1_LS 20
BW 15


F3 2,560,000
Fosc 5,376,000,000


Fout 38,400,000
Fout/F3 15


*No Spurs, F3 above data sheet spec*






*My Plan with in spec F3*


GPS 2,560,000
N31 2
N2_HS 7
N2_LS 600
N1_HS 7
NC1_LS 20
BW 15


F3 1,280,000
Fosc 5,376,000,000


Fout 38,400,000
Fout/F3 30


*Spurs*






*Another Plan*


GPS 2,560,000
N31 1
N2_HS 11
N2_LS 150
N1_HS 11
NC1_LS 10
BW 15


F3 2,560,000
Fosc 4,224,000,000


Fout 38,400,000
Fout/F3 15


*No Spurs, F3 above data sheet spec*






*DSPLLSIMs Plan*


GPS 2,560,000
N31 2
N2_HS 10
N2_LS 396
N1_HS 11
NC1_LS 12
BW 15


F3 1,280,000
Fosc 5,068,800,000


Fout 38,400,000
Fout/F3 30


*Spurs*






*DSPLLSIMs Plan 2*


GPS 1,920,000
N31 1
N2_HS 5
N2_LS 576
N1_HS 8
NC1_LS 18
BW 15


F3 1,920,000
Fosc 5,529,600,000


Fout 38,400,000
Fout/F3 20


*Bad Spurs*






*DSPLLSIMs Plan 3 Using This One*


GPS 176
N31 1
N2_HS 9
N2_LS 320
N1_HS 6
NC1_LS 22
BW 15


F3 1,760,000
Fosc 5,068,800,000


Fout 38,400,000
Fout/F3 21.8181818181818


*No Spurs*
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Re: [time-nuts] hp 5245L counters with 10544 and 10811 OCXOs

[Tom Van Baak]

Loney,

You'll find the schematic for the 05245-60033 adapter board at the bottom of:

http://leapsecond.com/museum/10544/

/tvb

- Original Message - 
From: "Loney Duncan" 
To: 
Sent: Monday, January 08, 2018 8:08 PM
Subject: [time-nuts] hp 5245L counters with 10544 and 10811 OCXOs


Gentlemen:

I have two 5245L counters which appear to have had a field mod where the 
original 1 MHz cylindrical oven standard has been replaced by the 10544 and 
10811 10 MHz ones.  Both counters have late 4-digit serial prefixes.  Both of 
the standards plug into an interface circuit board that, among other things, 
appears to have a divide by 10 circuit to produce a 1 MHz output to the 
counter’s oscillator card as the old cylindrical oven standard did.  This card 
for both has an hp p/n 5245-60033.

My 10811 counter works well, but the 10544 unit has a troublesome intermittent 
problem that appears to be on the board.  I cannot find a schematic and parts 
list for this board to troubleshoot and repair it.  These probably were on a 
change insert into the counter Service Manual, but I’ve yet to find one.  Have 
checked on Keysight’s website with no success.

Would anyone in this group possibly have these, or point me to an archive that 
would?  I very much would like to have the 544 unit function.  I have observed 
that after many decades of aging, a lot of the old original oven standards are 
out of adjustment range, while my 544 and 811 OCXOs can still be adjusted.  

Thanks very much for your advice.

Loney Duncan  W0GZV


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[time-nuts] hp 5245L counters with 10544 and 10811 OCXOs

[Loney Duncan]

Gentlemen:

I have two 5245L counters which appear to have had a field mod where the 
original 1 MHz cylindrical oven standard has been replaced by the 10544 and 
10811 10 MHz ones.  Both counters have late 4-digit serial prefixes.  Both of 
the standards plug into an interface circuit board that, among other things, 
appears to have a divide by 10 circuit to produce a 1 MHz output to the 
counter’s oscillator card as the old cylindrical oven standard did.  This card 
for both has an hp p/n 5245-60033.

My 10811 counter works well, but the 10544 unit has a troublesome intermittent 
problem that appears to be on the board.  I cannot find a schematic and parts 
list for this board to troubleshoot and repair it.  These probably were on a 
change insert into the counter Service Manual, but I’ve yet to find one.  Have 
checked on Keysight’s website with no success.

Would anyone in this group possibly have these, or point me to an archive that 
would?  I very much would like to have the 544 unit function.  I have observed 
that after many decades of aging, a lot of the old original oven standards are 
out of adjustment range, while my 544 and 811 OCXOs can still be adjusted.  

Thanks very much for your advice.

Loney Duncan  W0GZV
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Re: [time-nuts] AM vs PM noise of signal sources

[Charles Steinmetz]

Bill wrote:


What does the unijunction 2N2646 do in the oven controller?


For the following discussion, you need to refer to the *corrected* 
schematic I mentioned in my last post.  If you are looking at the HP 
schematic, you will wonder how the hell it works (and it wouldn't, if HP 
actually built them as they drew it).


The 10544 oven control circuit uses pulse-width modulation to control 
the heater in a "bang-bang" manner rather than a smooth proportional 
manner.  UJT A3Q3 forms a relaxation oscillator (along with A3C1 and 
A3R10), with a period of ~250uS (frequency ~4kHz) and a voltage span 
from ~0v to ~8v.


This positive-going ramp is applied to the base of Darlington A3Q2 
(MPSA12), which is 1/2 of a differential pair current switch along with 
A3Q1 (2N3904).


The thermistor and associated op-amp circuitry set a threshold voltage 
between ground and about 7v at the base of Q1.  After the relaxation 
oscillator resets to ~0v, current flows through A3Q1 and A3R8, pulling 
the base of Darlington A3Q4 negative and turning it on to saturation. 
The collector of A3Q4 therefore applies essentially the full oven heater 
supply voltage from Pin 14 (nominally 24v) to the high side of the heater.


The oscillator voltage ramps positive toward its ~8v maximum (the 
trigger point of UJT A3Q3).  When the emitter of A3Q2, which is two 
diode drops below the ramp voltage, exceeds the voltage at the emitter 
of Q1 (as set by the thermistor and A3U1), Q2 steals the current that 
has been flowing in A3Q1 and turns Darlington switch A3Q4 off, which 
interrupts the current flowing through the heater.  Some time later 
(about 250uS after the previous reset), the oscillator voltage reaches 
the trigger point of the UJT and it resets the voltage on A3C1 to ~0v 
and the cycle begins again.


Thus, every ~250uS the heater is on for a time (set by the thermistor 
circuitry) and off for the remainder of the ~250uS.  This switching 
action can be seen at the "Oven Monitor", Pin 11 (but note that the 
instrument may have a capacitor to ground on the mother card side of the 
oven monitor, to integrate the switching waveform for use by the 
instrument's health monitor).


Best regards,

Charles


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[time-nuts] Outdoor GPS Antenna Selection

[Mark Sims]

I have a bunch of small, cheap antennas that look like this one.  I bought them 
for testing some Glonass capable receivers:

https://www.ebay.com/itm/NEW-GPS-GLONASS-Antenna-car-navigation-dvd-C-receiver-Waterproof-gps-antenna-SMA/262621649740?hash=item3d25785b4c:g:OHkAAOSwglZZcC8~

They seem to work rather well.   I can track GPS/GLONASS/BEIDOU/GALILEO 
indoors.   I also have one outside in Texas weather for a couple of years 
feeding another 50 feet of RG6 television coax. It's still working...   
unexpectedly.  It probably has crappy multi-path, etc specs... but what can you 
expect for $7.
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Re: [time-nuts] Antenna Supply voltage

[Alberto di Bene]

On 1/8/2018 11:12 PM, Neville Michie wrote:

I have just scanned through the Thunderbolt manual and found no information
on the supply of power to the antenna.
Is there a standard for the supply of power to the antenna?
Are there 3.3v , 5v and 12v antennae?
Will any antenna work safely on any GPS receiver?
It is just a question that I had never thought of before.


I found this sentence :

"The antenna connector center conductor supplies +5 Volts to the antenna so should NOT be used to power the newer 3.3 
Volt GPS antennas."


in a document that I saved about the Thunderbolt, written by Brooke Clarke in 
2008, whose title is:

"Trimble ThunderBolt Timing GPS Receiver GPSDO"

73  Alberto  I2PHD


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Re: [time-nuts] Antenna Supply voltage

[Bob kb8tq]

Hi

The normal TBolt supplies 5V to the antenna. There *are* some 3.3V only antennas
out there. You could blow one up with a TBolt. There are also survey oriented 
receivers (and antennas) that work at 12V. Most 5V (but not all) antennas will 
fry
if hooked to a 12V receiver. 

Current wise, you probably are ok with any antenna out there. If you start 
cascading
things like inline amplifiers, you can get past the current available. That 
generally is 
not a fatal error. The receiver simply yells at you about “antenna short” or 
something 
like that.

Bob

> On Jan 8, 2018, at 5:12 PM, Neville Michie  wrote:
> 
> I have just scanned through the Thunderbolt manual and found no information 
> on the supply of power to the antenna.
> Is there a standard for the supply of power to the antenna?
> Are there 3.3v , 5v and 12v antennae?
> Will any antenna work safely on any GPS receiver?
> It is just a question that I had never thought of before.
> Cheers,
> Neville Michie
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[time-nuts] Antenna Supply voltage

[Neville Michie]

I have just scanned through the Thunderbolt manual and found no information 
on the supply of power to the antenna.
Is there a standard for the supply of power to the antenna?
Are there 3.3v , 5v and 12v antennae?
Will any antenna work safely on any GPS receiver?
It is just a question that I had never thought of before.
Cheers,
Neville Michie
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Re: [time-nuts] Outdoor GPS Antenna Selection

[Martin VE3OAT]

Hi, Duane,

I am actually using a small commercial GPS antenna with the small 
(lossy!!) coax and getting good results.


It is either a Garmin or Gilsson "puck" style antenna with 15 feet of 
that terrible coax, mounted on a 3 foot wooden pole at the peak of the 
roof.  The antenna sits on a cast-off 10 inch aluminum pizza plate 
(turned upside down for drainage) for ground-plane, covered by a large 
plastic funnel to keep off some of the snow.  The coax is just long 
enough to reach my Thunderbolt receiver in the room below the peak. 
Lady Heather shows that there are almost always at least 7 birds in 
view at any time and the setup seems to work fine.


You can engineer your solution for optimum results but I would guess 
that, as long as you are above a certain minimum level of signal for 
the receiver, you will get reasonably good performance.


... MartinVE3OAT


- - - - - - - - - - - - - - - -
Duane Wheaton wrote :

I'm selecting an outdoors antenna for a Jupiter Pico T Timing GPS 
(TU36-D400-020) but don't clearly understand what "dB" rating of 
amplified antenna to use. From web references, it looks like the 
degree of amplification required is dependent on 1.) The length of run 
of coax lead-in, combined with the characteristic loss of the type of 
coax used 2.) The amount of amplification needed to increase the very 
weak GPS signal to the range the receiver requires it. If I'm running 
20 feet of RG-58, would a 26dB antenna be sufficient?


The datasheet for the receiver family states, "1575.42 MHz at a level 
between –115 dBm and –133 dBm into a 50 Ω impedance." So the receiver 
needs at max a -115 dBm signal. The typical received signal power from 
a GPS satellite is −127.5 dBm. So it looks like I need to amplify the 
RF signal for the GPS receiver requirements + compensate for the high 
loss of the GHz signal traveling through ordinary RG-58 coax. Am I on 
track, here? Recommendations?


- - - - - - - - - - - - - - - - -


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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[Bob kb8tq]

Hi

Depending on the noise floor of the phase detector (which probably is not super
duper), even the noise *inside* the PLL bandwidth may not be all that great.

Bob

> On Jan 8, 2018, at 2:23 PM, Bruce Griffiths  
> wrote:
> 
> Yes, but the PN noise (outside the PLL bandwidth) will be much higher than 
> with a classical multiplier.
> 
> Bruce
> 
>> 
>>On 09 January 2018 at 02:14 Chris Wilson  wrote:
>> 
>>Hello Bruce, Sorry, this went to you direct as well, in error.
>> 
>>Thanks for the very fast reply! Would it be possible to use one of
>>these frequency multiplier IC's? Sounds simpler, but maybe there are
>>down sides?
>> 
>>
>> http://uk.farnell.com/on-semiconductor/nb3n502dg/pll-clock-multiplier-8soic/dp/2101849
>> 
>>on 08/01/2018 13:11 you wrote:
>> 
 
>>>Divide the 10MHz by 2 and use a filter to extract the fifth
>>>harmonic from the 5MHz square wave output.
>>> 
>>>Amplify the 25MHz output from the filter if required...
>>> 
>>>Bruce
>>> 
>>>On 09 January 2018 at 00:31 Chris Wilson  
>>> wrote:
>>> 
>>>08/01/2018 11:28
>>> 
>>>Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt
>>>as a reference clock at 1v P to P square wave for a Si5351a
>>>synthesizer chip please? I have the David Partridge divider board 
>>> from
>>>way back that is still going strong, but 25 MHz is not an option as 
>>> it
>>>divides only. Thanks, please keep replies to the level an idiot might
>>>comprehend :)
>>> 
>>>--
>>>Best Regards,
>>>Chris Wilson.
>>>mailto: ch...@chriswilson.tv
>>> 
 
>>--
>>Best Regards,
>>Chris Wilson.
>> 
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>> 
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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[Bruce Griffiths]

Yes, but the PN noise (outside the PLL bandwidth) will be much higher than with 
a classical multiplier.

Bruce

> 
> On 09 January 2018 at 02:14 Chris Wilson  wrote:
> 
> Hello Bruce, Sorry, this went to you direct as well, in error.
> 
> Thanks for the very fast reply! Would it be possible to use one of
> these frequency multiplier IC's? Sounds simpler, but maybe there are
> down sides?
> 
> 
> http://uk.farnell.com/on-semiconductor/nb3n502dg/pll-clock-multiplier-8soic/dp/2101849
> 
> on 08/01/2018 13:11 you wrote:
> 
> > > 
> > Divide the 10MHz by 2 and use a filter to extract the fifth
> > harmonic from the 5MHz square wave output.
> > 
> > Amplify the 25MHz output from the filter if required...
> > 
> > Bruce
> > 
> > On 09 January 2018 at 00:31 Chris Wilson  
> > wrote:
> > 
> > 08/01/2018 11:28
> > 
> > Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt
> > as a reference clock at 1v P to P square wave for a Si5351a
> > synthesizer chip please? I have the David Partridge divider board 
> > from
> > way back that is still going strong, but 25 MHz is not an option as 
> > it
> > divides only. Thanks, please keep replies to the level an idiot 
> > might
> > comprehend :)
> > 
> > --
> > Best Regards,
> > Chris Wilson.
> > mailto: ch...@chriswilson.tv
> > 
> > > 
> --
> Best Regards,
> Chris Wilson.
> 
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> 
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Re: [time-nuts] Outdoor GPS Antenna Selection

[Duane Wheaton]

Thanks for all the responses. So even a $13 active hockey puck antenna should 
work: https://www.adafruit.com/product/960 I'll get an antenna on order.
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Re: [time-nuts] AM vs PM noise of signal sources

[Bill Hawkins]

Charles,

What does the unijunction 2N2646 do in the oven controller?

Bill Hawkins
 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles
Steinmetz
Sent: Monday, January 08, 2018 7:50 AM

Also, note that the HP schematics of the 10544 have some errors that
were (as far as I can tell) never corrected by HP.  I posted a corrected
and annotated schematic to Didier's site (ko4bb.com).  Here's a link:



Best regards,

Charles


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Re: [time-nuts] AM vs PM noise of signal sources

[Ulrich Rohde via time-nuts]

Hi from Florida (it is atypical cool),ly 
 
`
Ref 1 is really  only good for an insight but to use it makes no sens and the 
names in ref 2 are out of order, that makes no difference.
 
Ulrich 
 
 
In a message dated 1/8/2018 9:02:47 AM Eastern Standard Time, att...@kinali.ch 
writes:
 Moin

Disclaimer: I am by far not an expert in oscillators. Please correct me if
I am wrong.

I am putting my replies to a few mails together into one, as not to clutter
the mailinglist too much.

On Sat, 6 Jan 2018 19:53:20 +1300
donald collie  wrote:

> So to be lowest noise, an oscillator should have the highest Q resonator
> possible in its feedback loop, operate in class "A" [for maximum
> linearity], and utilise active amplifier device(s) that contribute the
> least noise [both amplitude, or 1/f], and phase. 

Actually, it shouldn't. At least not if you want low phase noise.
The sensitivity of the output phase noise to the internal noise sources
changes during the period of the oscillator. AFAIK this has been first
noted by Hajimiri and Lee in [1], you can also find it mentioned in [2].
The small problem with that is, that it will lead to an increase of AM
noise, which in turn is turned into 1/f^2 and 1/f^3 PM noise through
the oscillator.

Also, you might want to back down a bit on the loaded Q, if you can
significantly improve the noise performance of the sustaining amplifier,
by better matching. (Gregory Weaver mentioned this during a discussion)

> Resistors in the oscillator carrying DC make 1/f noise - the best in this
> respect are the metal type, I think - so use metal resistors or WW.

The 1/f noise of resistors is lower than that of the semiconductors
involved, unless you are using carbon resistors. Hence most people
just simply ignore it. The commonly accepted theory is, that the 1/f
noise in resistors comes from the electron traps at material faults.
In carbon resistors, these are formed by the edges of the carbon particles.
In other these are formed by the way how the resistive material is deposited.
Hence thin-film and metal-foil have the lowest 1/f noise.

On Sat, 6 Jan 2018 20:12:16 -0600
Dana Whitlow  wrote:

> I've long wondered if a very slow AGC might avoid the nonlinear mechanisms
> issue except, of course, for things happening within the AGC loop's
> bandwidth.
> Is anybody reading this aware of what the truth really is?

The truth is complicated. There are so many effects that one has to
analyse and keep track that it's hard to say which one dominates in
a design, without doing extensive calculations or simulations.
At least that's my impressen, when I read papers on noise in electronics.

On Mon, 8 Jan 2018 01:02:11 +1300
donald collie  wrote:

> Does any limiter, soft or hard, [and perhaps any nonlinearity of power
> term 3 or greater in the amplifier of an oscillator] cause the "baseband
> 1/f noise to translate up to the resonator frequency [a form of
> crossmodulation]?.

The upconversion happens regardless of the limiting circuit. It stems from
the sustaining amplifier being non-linear. Even running a transistor completely
in a class A configuration will lead to upconversion, because not all the noise
sources are at places where the transfer function through the transistor to the
output is linear.

> I wonder this because
> phase noise vs freq plots look a bit like the 1/f plots of a resistor, or
> active device, or power supply. 

I do not understand this question. Noise looks "the same" for all devices.
Their only difference is the relative levels of 1/f^a noise. As such, it is
hard (impossible?) to say which device causes the noise at the output of
an oscillator by just looking at its output.

> Ceramic caps, and resonators [I`m thinking
> of quartz crystals] don`t pass much DC, and as I understand it, 1/f noise
> is associated with dc passing through resistors, or semiconductors.

1/f noise is generally associatiated with semiconductors and (carbon)
resistors, yes. But the crystal itself has its own 1/f noise and depending
on your circuit that might be actually the limiting factor and not the
electronic circuit.

Also keep in mind that a lot of electronic components are electro-mechanical
in nature. Ie they convert mechanical noise (aka vibrations) into electrical
noise. A prime culprit of this behaviour are capacitors and inductors, but
also semiconductors are known for this.

> So the
> best way to go might be to have a very linear amplifier, which exhibits
> very low noise [perhaps 150dB below the operating level], with an AGC loop,
> that sets the operating levela little below the level at which the amp
> starts to clip - this could be done with a thermistor to avoid the AGC loop
> altering the [optimised] operating conditions of the amp. Alternatively you
> might be able to use a tetrode device like a dual gate MOSFET, and apply
> the AGC to the second gate. Thus you could keep the extremely linear amp
> extremely linear. [150dB below 1Volt RMS is 0.032uV RMS].

If you google for R

Re: [time-nuts] Outdoor GPS Antenna Selection

[Richard Solomon]

Just being curious, I took 100' of RG-174 and connected one of those

"Hockey Puck" antennas to one of my Trimble Thunderbolts. Stuck the

antenna on a south facing window and had no trouble getting a lock.


I did not do any fine measurements, just looked at TBoltMon.


73, Dick, W1KSZ


Sent from Outlook

From: time-nuts  on behalf of Tom Miller 

Sent: Sunday, January 7, 2018 11:55:25 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Outdoor GPS Antenna Selection

Good quality RG6 has less loss and the mismatch is small. You see a lot of
GPS receivers and antennas with F connectors even though they generally are
50 ohms. 26 dB of gain should work fine for 20 feet of RG6. Probably also
good for good RG58.





- Original Message -
From: "Duane Wheaton" 
To: 
Sent: Sunday, January 07, 2018 10:59 PM
Subject: [time-nuts] Outdoor GPS Antenna Selection


I'm selecting an outdoors antenna for a Jupiter Pico T Timing GPS
(TU36-D400-020) but don't clearly understand what "dB" rating of amplified
antenna to use. From web references, it looks like the degree of
amplification required is dependent on 1.) The length of run of coax
lead-in, combined with the characteristic loss of the type of coax used 2.)
The amount of amplification needed to increase the very weak GPS signal to
the range the receiver requires it. If I'm running 20 feet of RG-58, would a
26dB antenna be sufficient?

The datasheet for the receiver family states, "1575.42 MHz at a level
between –115 dBm and –133 dBm into a 50 Ω impedance." So the receiver needs
at max a -115 dBm signal. The typical received signal power from a GPS
satellite is −127.5 dBm. So it looks like I need to amplify the RF signal
for the GPS receiver requirements + compensate for the high loss of the GHz
signal traveling through ordinary RG-58 coax. Am I on track, here?
Recommendations?

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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[Attila Kinali]

On Mon, 8 Jan 2018 13:14:16 +
Chris Wilson  wrote:

> Thanks for the very fast reply! Would it be possible to use one of
> these frequency multiplier IC's? Sounds simpler, but maybe there are
> down sides?
> 
> http://uk.farnell.com/on-semiconductor/nb3n502dg/pll-clock-multiplier-8soic/dp/2101849

Bruce's idea is much lower noise. The NB3N502 datasheet states
an typical output jitter of 15ps. That's HUGE for a normal VCXO
output that is usually below 1ps. The low-noise OCXOs have something
in the order of 100fs. Alternatively, you can use something like
an ADF4002 and an VCXO with 25/27MHz. That should give you a much
better performance, mostly limited by the VCXO. But you will need
to have a sine-to-square conversion of the 10MHz output of the
Thunderbolt first, as the ADF4002 has a slew-rate limit on its
reference input.

BTW: stay away from any VCXO that mentiones "programable" in its datasheet.
These are XO + fractional PLL combinations where the PLL allows quick
and cheap realization of odd frequencies. But their spurs and noise floor
is much worse than normal XOs.

Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] AM vs PM noise of signal sources

[Attila Kinali]

Moin

Disclaimer: I am by far not an expert in oscillators. Please correct me if
I am wrong.

I am putting my replies to a few mails together into one, as not to clutter
the mailinglist too much.

On Sat, 6 Jan 2018 19:53:20 +1300
donald collie  wrote:

> So to be lowest noise, an oscillator should have the highest Q resonator
> possible in its feedback loop, operate in class "A" [for maximum
> linearity], and utilise active amplifier device(s) that contribute the
> least noise [both amplitude, or 1/f], and phase. 

Actually, it shouldn't. At least not if you want low phase noise.
The sensitivity of the output phase noise to the internal noise sources
changes during the period of the oscillator. AFAIK this has been first
noted by Hajimiri and Lee in [1], you can also find it mentioned in [2].
The small problem with that is, that it will lead to an increase of AM
noise, which in turn is turned into 1/f^2 and 1/f^3 PM noise through
the oscillator.

Also, you might want to back down a bit on the loaded Q, if you can
significantly improve the noise performance of the sustaining amplifier,
by better matching. (Gregory Weaver mentioned this during a discussion)

> Resistors in the oscillator carrying DC make 1/f noise - the best in this
> respect are the metal type, I think - so use metal resistors or WW.

The 1/f noise of resistors is lower than that of the semiconductors
involved, unless you are using carbon resistors. Hence most people
just simply ignore it. The commonly accepted theory is, that the 1/f
noise in resistors comes from the electron traps at material faults.
In carbon resistors, these are formed by the edges of the carbon particles.
In other these are formed by the way how the resistive material is deposited.
Hence thin-film and metal-foil have the lowest 1/f noise.

On Sat, 6 Jan 2018 20:12:16 -0600
Dana Whitlow  wrote:

> I've long wondered if a very slow AGC might avoid the nonlinear mechanisms
> issue except, of course, for things happening within the AGC loop's
> bandwidth.
> Is anybody reading this aware of what the truth really is?

The truth is complicated. There are so many effects that one has to
analyse and keep track that it's hard to say which one dominates in
a design, without doing extensive calculations or simulations.
At least that's my impressen, when I read papers on noise in electronics.

On Mon, 8 Jan 2018 01:02:11 +1300
donald collie  wrote:

> Does any limiter, soft or hard, [and perhaps any nonlinearity  of power
> term 3 or greater in the amplifier of an oscillator] cause the "baseband
> 1/f noise to translate up to the resonator frequency [a form of
> crossmodulation]?.

The upconversion happens regardless of the limiting circuit. It stems from
the sustaining amplifier being non-linear. Even running a transistor completely
in a class A configuration will lead to upconversion, because not all the noise
sources are at places where the transfer function through the transistor to the
output is linear.

> I wonder this because
> phase noise vs freq plots look a bit like the 1/f plots of a resistor, or
> active device, or power supply. 

I do not understand this question. Noise looks "the same" for all devices.
Their only difference is the relative levels of 1/f^a noise. As such, it is
hard (impossible?) to say which device causes the noise at the output of
an oscillator by just looking at its output.

> Ceramic caps, and resonators [I`m thinking
> of quartz crystals] don`t pass much DC, and as I understand it, 1/f noise
> is associated with dc passing through resistors, or semiconductors.

1/f noise is generally associatiated with semiconductors and (carbon)
resistors, yes. But the crystal itself has its own 1/f noise and depending
on your circuit that might be actually the limiting factor and not the
electronic circuit.

Also keep in mind that a lot of electronic components are electro-mechanical
in nature. Ie they convert mechanical noise (aka vibrations) into electrical
noise. A prime culprit of this behaviour are capacitors and inductors, but
also semiconductors are known for this.

> So the
> best way to go might be to have a very linear amplifier, which exhibits
> very low noise [perhaps 150dB below the operating level], with an AGC loop,
> that sets the operating levela little below the level at which the amp
> starts to clip - this could be done with a thermistor to avoid the AGC loop
> altering the [optimised] operating conditions of the amp. Alternatively you
> might be able to use a tetrode device like a dual gate MOSFET, and apply
> the AGC to the second gate. Thus you could keep the extremely linear amp
> extremely linear. [150dB below 1Volt RMS is 0.032uV RMS].

If you google for Rohde/Poddar and noise/oscillator, you will find quite
a few papers and articles on how to build low-noise oscillators that are
only limited by the thermal noise in the 50Ω source resistance, Ie oscillators
that have a white noise floor at almost -174dBm (note: dBm not dBc).

It is "kno

Re: [time-nuts] AM vs PM noise of signal sources

[Charles Steinmetz]

Don wrote:


I`m looking at the circuit of an HP10544 oscillator - can anybody confirm,
please, if the HP transistor types 53-20, and 54-215 have commercial
equivalents?


54-215 (full HP part number 1854-0215) is the ubiquitous 2N3904.

53-20 (full HP part number 1853-0020) is 2N3702.  2N4403 is an 
equivalent if 3702 is hard to find.


Also, note that the HP schematics of the 10544 have some errors that 
were (as far as I can tell) never corrected by HP.  I posted a corrected 
and annotated schematic to Didier's site (ko4bb.com).  Here's a link:




Best regards,

Charles


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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[Chris Wilson]

Hello Bruce, Sorry, this went to you direct as well, in error.

Thanks for the very fast reply! Would it be possible to use one of
these frequency multiplier IC's? Sounds simpler, but maybe there are
down sides?

http://uk.farnell.com/on-semiconductor/nb3n502dg/pll-clock-multiplier-8soic/dp/2101849



on 08/01/2018 13:11  you wrote:


>  Divide the 10MHz by 2 and use a filter to extract the fifth
> harmonic from the 5MHz square wave output.

> Amplify the 25MHz output from the filter if required...

> Bruce

> On 09 January 2018 at 00:31 Chris Wilson  wrote:

> 08/01/2018 11:28

> Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt
> as a reference clock at 1v P to P square wave for a Si5351a
> synthesizer chip please? I have the David Partridge divider board from
> way back that is still going strong, but 25 MHz is not an option as it
> divides only. Thanks, please keep replies to the level an idiot might
> comprehend :)

> --
>  Best Regards,
>  Chris Wilson.
> mailto: ch...@chriswilson.tv








-- 
   Best Regards,
   Chris Wilson.

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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[Bruce Griffiths]

Divide the 10MHz by 2 and use a filter to extract the fifth harmonic from the 
5MHz square wave output.

Amplify the 25MHz output from the filter if required...

Bruce

> 
> On 09 January 2018 at 00:31 Chris Wilson  wrote:
> 
> 08/01/2018 11:28
> 
> Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt
> as a reference clock at 1v P to P square wave for a Si5351a
> synthesizer chip please? I have the David Partridge divider board from
> way back that is still going strong, but 25 MHz is not an option as it
> divides only. Thanks, please keep replies to the level an idiot might
> comprehend :)
> 
> --
> Best Regards,
> Chris Wilson.
> mailto: ch...@chriswilson.tv
> 
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> time-nuts mailing list -- time-nuts@febo.com
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[time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[Chris Wilson]

  08/01/2018 11:28

Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt
as a reference clock at 1v P to P square wave for a Si5351a
synthesizer chip please? I have the David Partridge divider board from
way back that is still going strong, but 25 MHz is not an option as it
divides  only. Thanks, please keep replies to the level an idiot might
comprehend :) 

-- 
   Best Regards,
   Chris Wilson.
mailto: ch...@chriswilson.tv

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