Re: [time-nuts] TNS-BUF update

[Gerhard Hoffmann]

Am 19.08.2018 um 10:22 schrieb Bruce Griffiths:

Rick

I devised the bias circuit for the TNS-BUF.
It exploits the fact that for a RED LED at least the difference between the LED 
forward voltage and the transistor Vbe is ~ 1V and has a fairly low tempco and 
has low noise (at  least for RED LEDs).
(Most of the LTSpice LED models do not correctly predict LED forward voltage 
drop tempco.)

Most classical  schemes for biasing BJTs use a resistive voltage divider which 
inevitably couples power supply noise into the BJT collector current.

John Miles changed the bias circuit of some classical series shunt amp buffers 
to one similar to this and the buffer flicker phase noise was significantly 
reduced.

In principle an LED could be used to directly set the dc bias at the base of 
the amplifier transistors, however inductors may be required to shunt part of 
the emitter series resistance at dc to allow the desired dc collector current 
to be established. A pair of series connected LEDs buffered by an npn emitter 
follower would allow the bias voltage to be shared by all stages and allow the 
inductor to be replaced by a capacitor bypassing part of the emitter to ground 
resistance required to establish the desired collector current whilst achieving 
the required resistance from RF to ground for RF.

Not all red LEDs are created equal. For noise, by far the best I have found
is the HLMP6000 by HP / Avago / Whoever_owns_it_today.

< 
https://www.flickr.com/photos/137684711@N07/24354944411/in/album-72157662535945536/ 
  >


0 dB is 1nV/rtHz, +20 dB is 10 nV/rtHz and so on.
LEDs are ineffective photo cells, probably because of the large band gap and
their built-in color filter. I have given up to apply the blob of black 
laquer,

I have never seen a difference.

What I find impressive is the noise performance of low voltage Z-Diodes.
We are always told that Zeners are noisy. No. Avalanche breakdown is noisy.
Take a look at these NXP BZX84C2V7 and C3V3. Admire the low 1/f corner
and note how things turn bad when we approach 5V.

< 
https://www.flickr.com/photos/137684711@N07/24411798996/in/album-72157662535945536/ 
 >


The precious 7V LM399 reference is a complete joke in comparison.
Its oven is no help here.


Classical bias schemes are usually much noisier especially at low frequencies. 
Even regulators like the LT3042 are quite noisy at frequencies below the the 
pole of the reference circuit low pass filter.
That does no justice to the LT3042. It features 2nV/rtHz to _very_ low 
frequencies.
It is very easy to bypass a constant current source while it is very 
costly to filter
a low impedance LED. The LT3042 even has a startup circuit so that it 
does not
take forever to get to the right voltage. Most LEDs are much worse, and 
especially

at low frequencies.

The LT3042 is a piece of art. It leaves the rest of the regulators that 
we know

in the dust, by 40 dB or better.

Most of the noise < 50 Hz or so goes on my 89441A and the too-small input
coupling capacitor of my preamp. (20 ADA4898 op amps in par, 220 pV/rtHz)
The preamp has been fixed with a costly :-( wet slug tantalum in the 
meantime.


regards,
Gerhard

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Re: [time-nuts] TNS-BUF update

[Gerhard Hoffmann]

Am 19.08.2018 um 14:43 schrieb Bruce Griffiths:

Yes, I looked at the plots and I see exactly what I described.
2nV/rtHz at frequencies somewhat above the reference current source output RC 
filter, rising to a high value at frequencies below the current source output 
filter pole.
This is an inherent property of the architecture.


I really don't know how you come to that conclusion. Even the HLMP-6000 
needs more than
100 Hz to be better than the 3042 in its standard data sheet circuit, 
without extra filtering

provided, and the LED delivers only half the DC voltage, another 6 dB.

'Ordinary' LEDs from Toshiba or Osram(ex Siemens) are 20 to 30 db worse, 
and they are

quality parts, not unknown junk box parts.
Their 1/f corner is - OMG!!!11! -  the plot goes only to 1 MHz!

Postulating superior LED  performance at 1Hz from that is quite venturesome.
LEDs are good in comparison to el cheapo bandgaps and high voltage "Zeners",
but they cannot do magic.


And please don't say, it's the light. The measurements are made in a box 
in a box in a box
to handle the pV noise densities. My preamps are now at 70 pV/rtHz and 
there is a
chopper in statu nascendi at 100 pV sub- 0.1 Hz. Yes, I see the noise 
of  the 0.6 Ohm switches.


But I need a better FFT analyzer now. A working SPI driver @ 
1Mtransfers/sec for the

BeagleBoneBlack would do.

cheers, Gerhard


ps. I'm also interested in that time travel movie.


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Re: [time-nuts] Naked 4046 PLL chip

[Gerhard Hoffmann]

Could it be that the reflector drops messages?

I did not get Ulrich's  NO-Message and also not that from msimon6808.

It has become quite silent since the move to the new server.

Subjectively -6 dB.

Cheers, Gerhard



Am 23.07.2018 um 02:32 schrieb Ulrich Rohde via time-nuts:

That is a different better beast !
  
In a message dated 7/22/2018 1:45:19 PM Eastern Standard Time, msimon6...@yahoo.com writes:


  
The 9046 handles ant-backlash
  
https://assets.nexperia.com/documents/data-sheet/74HCT9046A.pdf
  
Engineering is the art of making what you want from what you can get at a profit.


I like Polywell Fusion.

  
  
On Saturday, July 21, 2018, 4:54:28 PM UTC, Ulrich Rohde via time-nuts  wrote:
  
  
NO
  
  
  
  
In a message dated 7/21/2018 12:51:59 PM Eastern Standard Time, k8yumdoo...@gmail.com writes:


  
  Did the original '4046 include the anti-backlash fix? Dana On Saturday, July 21, 2018, Dr. Ulrich L. Rohde via time-nuts < time-nuts@lists.febo.com> wrote: > Obsolet by today’s standard > > Sent from my iPhone > > > On Jul 21, 2018, at 10:44 AM, Poul-Henning Kamp  > wrote: > > > > Clearly not your average chip: > > > > https://zeptobars.com/en/read/Ti-CD4046BE-CMOS-PLL- > Oscillator-VCO-zener > > > > -- > > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > > p...@freebsd.org | TCP/IP since RFC 956 > > FreeBSD committer | BSD since 4.3-tahoe > > Never attribute to malice what can adequately be explained by > incompetence. > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to http://lists.febo.com/mailman/ > listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/ > listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.


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Re: [time-nuts] Effects of Simple GPS jamming on GPSDO's ?

[Gerhard Hoffmann]

Am 31.08.2018 um 19:39 schrieb jimlux:

On 8/31/18 10:15 AM, Bob kb8tq wrote:

Hi

Having spent a lot of my life designing GPSDO’s it’s a “that depends” 
sort of thing.
For a simple noise jammer, yes, they pretty much all will go into 
holdover. When the
jammer goes away, they come out of holdover. There are a few older 
units that may not
do quite as well with various sorts of broadband jamming.  With a 
spoofing jammer that is flying
around overhead and simulating an entire constellation … you could 
see any of them do odd
things. An airborne jammer flying over this or that city likely gets 
you into a “act of war” sort of issue.

It’s something you build if you are a nation state.

The performance with noise jammers is not a guess. It’s based on 
field experience and

all those never ending meetings I keep referring to …..

IIRC, there was a truck driver who successfully jammed all those 
airworthy GPS systems
at SF airport trying to hide his private detours, just by passing on the 
highway with

El Cheapo hardware.



In effect, a broadband jammer (or, probably, a tone jammer that 
overwhelms the 1 bit ADC receiver) is the same as a "loss of signal" - 
the receiver probably doesn't know the difference - it just drops sync 
and tries to unsuccessfully reacquire.


I think that Holmes wrote somewhere that the easiest way to jam was a 
carrier quite close
to the frequency where the suppressed carrier of the BPSK would be. It 
could be weak because
it would have some processing gain, even if not completely sync to the 
rest of the signals.

The typical 1 or 2 Bit ADC has no chance to see it separated from the rest.



So you can test your hold over behavior with aluminum foil (or your 
hand) over your antenna



OMG, I first read "with aluminium foil hat over your head"

Cheers,
Gerhard


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Re: [time-nuts] NIST

[Gerhard Hoffmann]

Am 31.08.2018 um 20:17 schrieb Hal Murray:

att...@kinali.ch said:

I have somewhere a paper (which i cannot find currently, sorry) that used a
dish trained at one of the EGNOS satellites and used it as the only source
for timing. IIRC the results were promising, but not spectacular. The problem
being that all the ionospheric and tropospheric ...

There is another problem in that area.  How accurately is the location of the
satellite known?  published?

Geo-sync satellites actually wander around their nominal positions.  How much
does that effect timing?  I've seen figure-8 pictures of the pattern, but I
don't remember any data on elevation changes.


Geo-stat sats usually do their navigation via their linear transponders,
the rest is in some ground stations, so the added cost for flight hardware
is essentially nil.

The operators know the position of their sats quite precisely since,
for a phone sat as an example, the ground station transmission timing
must be aligned quite carefully to avoid both overlapping and idle time
of the channel. They switch both between cities and to give the phone
user the illusion of a continuous 2 way connection without too much delay.

The absolute position is less important as long as it is known.

Small countries like Luxembourg have just one geostationary parking lot
but operate several sats. They may have a more pronounced need to
keep the positions precise.

Overly precise position shortens the lifetime of a sat since it eats up 
fuel.


The navigation is simply made by PN streams say > 20 dB below the
MPEG data.

I have made the PN generators,  bit / frame generators /synchronizers,
correlators, de/modulators for some of them.

I don't think that the exact position data is published. It is a closed
system, after all.

But a bunch of hams with enough criminal energy could probably
measure it for themselves. The down link is already there in every
household with a SAT TV.  Oh, no, I do not promote that!

best regards,
Gerhard




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Re: [time-nuts] WWV and legal issues

[Gerhard Hoffmann]

Am 01.09.2018 um 20:40 schrieb Magnus Danielson:

One should first know that there is a lot of papers now on frequency
transfer over fiber. The stability achieved on the best ones so far
greatly below that of the optical clocks that they want to compare.


Please, in a nutshell: what are the worst offenders:

- tranceivers (mechanical, temp, other misfeatures)
- cables ( bending, temp, mechanical stress)
- others?

In the case of transceivers: are there desirable modifications
that would alleviate the problems?

best regards, Gerhard



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Re: [time-nuts] RF Isolation Amplifier ...

[Gerhard Hoffmann]

Am 14.10.2018 um 22:14 schrieb Richard (Rick) Karlquist:



On 10/14/2018 11:20 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
Actually the BFT is out of production since quite a while there are 
more stable and higher Ft devices on the market.


73 de N1UL



How is a higher Ft device more stable?  Those attributes
would seem to be mutually exclusive.


Every mm has a nH all for itself. With 1.6mm for the board thickness,
2 mm for the transistor leads, 0.5 mm for the bond wires, we have
> 3 nH in base, emitter and collector, and they are coupled.
That can annoy the most well behaved RF transistor.   [1]


For time nuts purposes, I would submit this is a bad trend.
What we want is higher DC beta, not higher Ft.  The higher
Ft just makes the device want to oscillate.  For any designs
I do, I put a 100 ohm resistor in series with the collector
as an oscillation killer.

There is a similar problem with gain block amplifiers having
bandwidths into the double digit GHz.  I routinely put a
10 pF capacitor directly from input to ground to kill high
frequencies.

A related problem is that newer devices have lower base
spreading resistance.  This does help with noise figure
but again risks HF oscillations.


I do love those Zetex BJTs with extra low base spreading resistance.
We just discussed this in the usenet sci.electronics.design newsgroup.

In "Art of Electronics edition 3 " by Horowitz? and Winfield Hill, there 
is a base

band amplifier featuring 70 pV/rtHz voltage noise.
I have verified that. One of the Zetexes was not enough, it took 16 in par
to get Rbb low enough,  just like demonstrated by Horowitz

<
 
https://www.flickr.com/photos/137684711@N07/31348447748/in/album-72157662535945536/
 >

anf the pictures to the right.

( the pics to the left are off-topic, but some of them nevertheless nice.)

regards,
Gerhard

[1]  analog to  < 
http://gunkies.org/wiki/Vonada%27s_Engineering_Maxims    >


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Re: [time-nuts] RF Isolation Amplifier ...

[Gerhard Hoffmann]

Am 14.10.2018 um 18:47 schrieb Dana Whitlow:

Corby,

Now that I learn that the BFT66 is a "wild one", I'd remark that stability
is
indeed the likely issue.  I was puzzled by the presence of that capacitor in
the first place, as this circuit is clearly neither tuned nor of especially
high frequency capability.

If the circuit really has a stability problem, one could try first to
harvest the low-hanging fruit and change the base resistors from
2R5 to 22R, maybe even more.

That won't damage the noise behavior, that has already been done by
the 180R in the input. The only possible reason I see for the 12 pF is
to kill the gain of the first stage at VHF+.  It may be a disservice to
the 2nd stage, depending on the isolation performance of the R
between the upper emitter and the lower Collector.

Also, the 100nF+10nF caps in the base divider will parallel resonate
at +/-10 MHz, depending on layout; and that means "no real decoupling" 
there.


All in all, the circuit is somewhat weird; the BFT66 was a boutique part
even in it's heyday: low noise, high gain, high ft, high price and a 
package
that was not really RF-ish. The second stage is abt. as low cost as you 
could get.

With all-3904/3906 that would be a text book AF amplifier.

Have a nice Sunday evening,

Gerhard, DK4XP





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Re: [time-nuts] HP 58503B PSU replacement

[Gerhard Hoffmann]

Am 14.11.18 um 18:41 schrieb Dr. David Kirkby:

On Thu, 8 Nov 2018 at 21:43, Dr. David Kirkby <
drkir...@kirkbymicrowave.co.uk> wrote:
On Thu, 8 Nov 2018, 14:53 George Atkinson via time-nuts <
time-nuts@lists.febo.com wrote:

Last month I was at the UK “National” hamfest and in the flea market area
a seller had a HP 58503B for sale. It was missing the cover and power
supply (AC mains version)including mounting. However it was only £3 (<5$)
so it was a no-brainer to buy it. Research shows that PSU failure is fairly
common on these units.

I had the PSU fail in my 58503A. It keeps trying to start, then stops. I
have checked capacitors with an ESR meter, but could not fix it.

Three is a good chance your unit takes the same PSU. If so


https://www.ebay.co.uk/itm/BEL-POWER-MAP55-4003-55W-Quad-Output-Embedded-Switch-Mode-Power-Supply-SMPS/132833037734

may be of interest. I had an offer of £45 accepted yesterday.

Dave.

Well, the bad news is the PSU I received was faulty (no output whatsoever),
and the seller has checked another, and that too is dead, so it looks like
he has rejects. He has refunded me and does not want the one he sent back.
So now I have two non-working supplies. The new one does not power up at
all. The old one does, but cycles on/off.


If more than one replacement unit does not work, then it is not

improbable that the switcher needs a minimum load to start.


Also, a shorted capacitor can show excellent ESR.


I once had a cycling power supply in a W TSA-2 spectrum analyzer.

It delivered power for some seconds, and that was enough to trace

a voltage to a faulty feedthrough capacitor. A DVM with enough digits

helps a lot. Towards the short, the voltage sinks mV by mV.


regards, Gerhard



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Re: [time-nuts] 10 MHz -> 16 MHz

[Gerhard Hoffmann]

Am 01.10.2018 um 03:01 schrieb Arthur Dent:

Oops, I meant divide by 5 to get 2 followed by 8x NB3N511 work?
___


That should work, also for the 12 MHz case with 6x instead of 8x.

But it still needs a second divider chip like the solution I built
this afternoon. Somewhere, there must exist a single chip SO-8 solution.

:-)

cheers, Gerhard



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Re: [time-nuts] 10 MHz -> 16 MHz

[Gerhard Hoffmann]

Am 30.09.2018 um 15:44 schrieb Pete Lancashire:

Same question 10 to 12:-)




Same Answer.

Select pins = (1, 1, 0) for 12 instead of (1, 1, 1) for 16.

\Gerhard



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Re: [time-nuts] 10 MHz -> 16 MHz

[Gerhard Hoffmann]

Am 30.09.2018 um 06:15 schrieb Hal Murray:

What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out of 10
MHz? Low phase noise isn't a big requirement and jitter doesn't need to be
sub-nanosecond. The main requirement is perfect cycle count accuracy. This is
for driving a 16 MHz microcontroller from a 10 MHz Rb/Cs/GPSDO. 10 MHz input
is likely sine; 16 MHz output is 3v3 or 5v CMOS.

There should be a PLL chip that includes the M and N dividers, but I'm not
familiar with that area.


Use this for f * 16:

< 
https://www.digikey.de/product-detail/de/on-semiconductor/NB3N3020DTG/NB3N3020DTGOS-ND/2003319 
  >


and a 74LVC for / 10.

The NB3N3020 could do *1.6 directly, but only for input frequency > 25 MHz.

regards,
Gerhard

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Re: [time-nuts] 10 MHz -> 16 MHz

[Gerhard Hoffmann]

Ingrid clicked through the "you might find that useful too" - list

and stumbled across this:

< 
https://www.digikey.de/product-detail/de/adafruit-industries-llc/2045/1528-1206-ND/5353666 
   >


\Gerhard

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Re: [time-nuts] new op amp for distribution amplifiers

[Gerhard Hoffmann]

Am 17.12.18 um 16:22 schrieb Anders Wallin:

Stylish dead-bug! ;)
On my board I increased Rf/Rg to 4k7, to get rid of the gain-peaking.
With 4k7 resistors I see +20 dBc/Hz worse phase-noise with the THS3491
compared to LMH6702 :(  (image attached)
If noise power scales with the resistors then it explains about 4k7/200R =
14 dB, for one amp, and perhaps 17 dB for two amps. Still missing 3dB
somewhere in that reasoning...

John: would you say if one can use the suggested 976R Rf/Rg resistors then
below -160dBc/Hz for a 10MHz carrier is possible for a gain of +2?

At least we can say THS3491 is much more tricky to work with than LMH6702
so far... (?)


I can't claim any personal experience with the THS3491. They are on

my next DigiKey order, but the data sheet calls for Rf=976 Ohms

(chipscale package)  and for 2K1 in the SO-8 package. And the SO-8

still has at least 2 dB peaking in the data sheet. The huge difference

of 976 Ohms versus 2100  Ohms just for the package (and still close

to fail) makes it clear that the SO-8 is not made for low-gain 
applications,


and that with a board that's made for it. (GND removal under the input)


Already at 5V/V it seems to be well-behaved to 600 MHz and then

dropping without a peak, and that without outrageous resistors.

Maybe it's possible to augment Rfdbk with ferrite beads @>200 MHz

but they are pretty good Hi-Q inductors at low frequencies.


BTW already the LMH6702 can be somewhat picky  with regard to

decoupling; a cap directly from VCC to VEE is much more

important than anything to GND, esp. for distortion.

Op amps don't care much about the concept of GND; they are happy

when their inputs are equal.


Has anybody succeeded to massage the Spice model so that it fits

LTspice?


A distribution amplifier that can be used today for 5V 1PPS into 50 Ohms

and tomorrow for 18 dBm at 100 MHz should be quite usable if one gets

the noise down.


regards, Gerhard




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Re: [time-nuts] Modern signal generators

[Gerhard Hoffmann]

Am 11.12.18 um 20:30 schrieb jimlux:

On 12/11/18 10:23 AM, Richard (Rick) Karlquist wrote:



On 12/11/2018 9:13 AM, djl wrote:
Rick: I've spent some time with the dds blocks. We found them to 
generate lots of low level spurs, making lots of "birdies" when used 
as local oscillators in receivers.

We had better results using:
https://www.silabs.com/products/timing/oscillators.



I was talking about making a programmable frequency synthesizer
with a DDS, to use as a general purpose signal generator.

A silabs part functions exactly the same as a crystal oscillator
once it receives its one-time programming at the factory, AFAIK.



Most of the Silabs parts are available in an  I2C programmable version 
rather than the factory programmed flavor.



Yes, but they all have in common that their oh! so good jitter values

exclude the first 12 or even 50 KHz from the carrier. With enough DSP

you can shove a lot of dirt towards the first 12 KHz: look, ma, no birdies.

Those without an E5052B or FSUP won't notice, and the OC-48 or OC-192

or other telecom target market won't care anyway. But the birdies are not

magically gone, they were squashed under the DSP steam roller.


The nagging DDS birdies happen when you are close, but not exactly on

a subharmonic of the clock frequency. In an avionics com transceiver I got

easily rid of them by using 2 clock frequencies and switching as best

for the channel. With this DO-178? stuff you are punished for oscillator

birdies when you try to make the receiver more sensitive. :-(


Ulrich and DJ7VY and some others have shown us >40 years ago how to

do shortwave/VHF receivers (hey, I was still in school then, and it gave me

the kick towards RF engineering) and ring mixers still have their place, but

not in the input of a ham rig. There should be a 16 bit 150MHz+ ADC after

the tuned preselector, and the rest is digital. I have published a

synthesiseable sine / cos table on opencores.org a decade ago. The test

bed is a DDS. just fill in the resolution you want and buy an el cheapo 
Xilinx


Spartan FPGA to give it a home, and then filter & decimate the hell out of

your ADC data. No more analog LO. We now have things like AD9172,

ADC12J4000 and AD9625 to play with. That's the new frontier.


Now that I have your attention I'm currently interested into 1/f noise,

or, more precisely, in how to avoid it. Is there anything known on 1/f

in FETs as used in switches, such as choppers? Is there more than thermal

noise of the channel? There is a paper of the Univ of Twente that 
suggests there


is some time delay when fets are turned on until the trap locations turn 
active.


That could be a nice by-effect.

Even van der Ziel and Cobbold are silent about that.


cheers,

Gerhard, DK4XP











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Re: [time-nuts] Minicircuits SYPD-1

[Gerhard Hoffmann]

Hi,

matching in the sense of selecting 4 equal ones won't help much with BJTs.

Take them from the same tape, that's enough. Also, the transformer ratio

does not matter much. Once VBE = 0.7V, the transistors switch on. The 
authors


write that thy use the BE junction as diodes, but that is not true. The 
transistors


are operated as switches. That's probably the reason why they are so good.

A different transformer ratio only shifts the level where the 0.7V Vbe 
is reached;


a dB more or less, not a big thing.


The power required for optimum return loss seems to be quite precise.

If you do not have enough for Vbe=0.7V, the switches will sit there 
idle, giving


bad return loss; having too much pumps a lot of current through the ring and

the mismatch will be to the short circuit side.

You could also drive them somewhat into saturation which would make

them slow. That's why I used a fast-ish transistor from the start.


In my case, 8 or 10 dBm made quite a difference from the 9dBm for 
optimum BW.


I have some MCL T1-6 and could check them over the weekend.


If you have more signal power, it's probably wise to split it to more PDs

and add the IF outputs.  This here seems to be an interesting Wilkinson:

<   https://www.digikey.de/products/de?keywords=1465-1815-1-nd    >

So it all boils down to el cheapo coils and Schnaps or beta-blockers for 
soldering.



In the case of JFETs as switches, your curve tracer could probably help 
a lot.


JFETs are all individuals, see Ic over Vgs for IF3601 / IF3602

< 
https://www.flickr.com/photos/137684711@N07/37321004540/in/album-72157662535945536/ 
   >



The IF3601 is a large geometry JFET with huge gm, that can deliver 0.3 
nV/rtHz voltage noise.


Four of them in parallel yield 160 pV/rt Hz; I could verify that but 
they were not


completely stable for inductive signal source impedance. If you want to 
simply parallel them,


one of them might happily sink 1A while the other is still completely 
cut-off.


They also seem to need more drain current than promised and the IF3602 duals

are not pairs in the closer sense. But no opposite outliers, OK.   
(avail. @ Mouser)



My newest creation uses a bootstrapped cascode to effectively remove the 
LARGE


input capacitance; that also seems to make it unconditionally stable, at 
least in simulation.


The new boards are spending this week in the Leipzig, DE customs office 
since someone


does not believe that PCBWAY in China can deliver 10 proto boards for 
$5.  :-[



Having such an amplifier after a ring mixer is probably overkill; a RF 
Schottky diode


may have easily a ohmic 50 Ohms component in series and two of them 
active in a ring


mixer guarantee 1.3 nV/rtHz thermal noise alone. (and that is NOT the 
half-thermal slope


resistance of the diode effect itself)


High power type3 ring mixers have additional resistors in series to the 
diodes to create


some back-bias. Those also create noise and so it should not come as a 
surprise that


high power mixers may be kings of IP3 but lose big time at the noise end 
of the scale.


< 
http://home.deib.polimi.it/svelto/didattica/materiale_didattico/materiale%20didattico_MRF/appnote/wj_Mixers_part_2.pdf 
   >



regards, Gerhard


Am 20.12.18 um 03:16 schrieb Jerry Hancock:

Gerhard, would there be any advantage to matching the transistors?  I have a 
pretty accurate curve tracer.

thanks,

Jerry




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[time-nuts] new op amp for distribution amplifiers

[Gerhard Hoffmann]

Have you seen the new THS3491 ? LMH6702 on steroids.


This one begs to be designed into new distribution amplifiers:

Everything from DC / 1pps to a few 100 MHz into 50 Ohms, without any 
changes.


(the usual gain = 2,    50R/50R out design)

rise / fall 1.3 ns for 10V step

slew rate 8V / ns

BW 320 MHz for 10Vpp at gain of 5

Volt. noise 1.7 nV/rt Hz

supply max +/- 16V,  drives up to 420 mA

SO-8 with thermal pad  or leadless

<     http://www.ti.com/lit/ds/symlink/ths3491.pdf    >


regards,

Gerhard


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Re: [time-nuts] Misuse of word "decimate" (was Re: Short term 10MHz source)

[Gerhard Hoffmann]

Am 10.01.19 um 17:33 schrieb Bob Martin:



Back in those same seventies, I was working for an army lab (Harry
Diamond Labs) as a summer student. I saw a picture in a lab supply 
catalog of a (ein) stein of beer. I tore it out and taped it over a 
picture off Albert Einstein that a German physicist, Howard Brandt, 
had on the wall over his desk.  This was a bad idea. Howard was so 
incensed that he called the whole department together, hauled out the 
Websters Unabridged Dictionary, and forced me to read the definition 
of the word philistine in front of the group. Fortunately, there were 
many entries under the word and I chose "a native of Philistia" to 
read out loud. The moral is words can have many meanings and, more 
importantly, don't make fun of Einstein

around German Physicists.


I wonder if Howard even understood the intended pun.


Stein means stone, nothing else. I have seen/heard it used in the

sense of a "mug for beer" only by Americans. The closest

German word would be Steinkrug, but only if you want to

emphasize that the Krug is made of ceramics and not of glass.


Decimation apart of the Roman sense for me is  only throwing away samples,

and the need for filtering goes with it even without explicitly saying.


Cheers, Gerhard




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Re: [time-nuts] Programmable clock for BFO use....noise

[Gerhard Hoffmann]

Am 16.09.2018 um 23:11 schrieb Attila Kinali:

On Sun, 16 Sep 2018 22:08:19 +0200
Gerhard Hoffmann  wrote:


I'm also not a fan of using slowish, slew-rate challenged  logic as a
replacement
for a low pass. When I want a low pass, I make it from nice,
time-invariant RLC.

Unfortunately, using a low pass after the divider will not
prevent the down-mixing. The down-mixing happens as an inherent
property of digital circuits. Any filtering you do afterwards
will be too late. If you want to have low noise, then the only
way is to produce a non-square wave signal. Or in other words:
use a divider built from harmonic mixers*.

Why do you assume that slew-rate limited mixers are any
better than mixers with an ultra-short analog time window
for doing mess?

We should sort that out offline, we are just 20 miles apart?
I propose the Zwickel pub in Dudweiler; I'm there with the
mostly emerited Fraunhofer people on Friday evenings
now & then.        :-)  :-)  :-)

* That is, if you don't like Λ-dividers or DDS

I do like DDS, and I don't see  a reason for the D/A converters
in front of the mixers. D/A converters remove the fun when you
can just instantiate a multiplier.

Cheers,

Gerhard



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Re: [time-nuts] Programmable clock for BFO use....noise

[Gerhard Hoffmann]

Am 16.09.2018 um 20:00 schrub Mark Goldberg:

For a radio BFO you want something with low phase noise (low jitter). The
SI5351 is not designed for that, and it's jitter spec is 70 ps, which is
pretty noisy. It even has a spread spectrum mode that would be even worse.
They do have other parts designed for low jitter (< 1ps). Leo Bodnar's
GPSDOs with variable output clock frequencies are based on  those chips and
they provide low phase noise, certainly enough for a radio


Oh, a half of a 12AX7 has always been good enough for my needs as a BFO,
xtal controlled or LC free running. 30 dB above the noise is S5, what more
do you want? The real problems of a receiver are IP3 and that you have
a preselector and a mixer that simply work without producing mess.
LO jitter is probably > 100 times more important than the BFO, that is just
for conversion of IF to audio.

cheers,
Gerhard, DK4XP

(I do not use many 12AX7 any more, in real life that is just a down 
converter

block in a corner of of a Virtex FPGA. )


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Re: [time-nuts] Programmable clock for BFO use....noise

[Gerhard Hoffmann]

Am 15.09.2018 um 17:38 schrieb Richard (Rick) Karlquist:


If you divide by something that is not a power of 2, then it is 
important
that each stage produces an output waveform with a 50% duty cycle. 
Otherwise
flicker noise which has been up-mixed by a previous stage, will be 
down-mixed

into the signal band, increasing the close-in phase-noise.


Wow, another thing I never knew.  The conventional wisdom was to
divide by any number (even or odd) and then follow that divider
with a divide by 2 flip flop to get 50%.  Now, that is in question.
The now correct answer is to us a variable modulus prescaler to
divide by P and P+1, controlled by a toggle flip flop to make
half the divisions at P and half at P+1.


Resynchronize the output of the divider to the undivided clock with 
another D-FF
and everything but that last D-FF will fall out of the equation for 
phase noise.


I'm also not a fan of using slowish, slew-rate challenged  logic as a 
replacement
for a low pass. When I want a low pass, I make it from nice, 
time-invariant RLC.


regards, Gerhard.



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Re: [time-nuts] HP Stories: An architectural view of the HP 5060/5061 and awkward oscillator adjustments.

[Gerhard Hoffmann]

Am 24.02.19 um 14:39 schrieb Richard (Rick) Karlquist:


yet they got a pass and became SOP.  The R lab manager
at Santa Clara Division famously said "no customer chooses
HP products because they have great power supplies."


G..  My HP16500C has a defective PS and my 4274A RLC bridge

had a major explosion inside. OMG, WHAT A MESS! All that black magic smoke!

I re-caped the bridge, it took me a day on the DIgikey site to find 
replacements.


I had to use substantially larger voltages to make them fit mechanically.

But that is a good thing.

cheers, Gerhard



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Re: [time-nuts] injection locking crystal oscillator

[Gerhard Hoffmann]

Am 02.03.19 um 17:02 schrieb jimlux:


Also, since injection locking is a case of coupled oscillators.. you 
might be interested in this (freely downloadable):




Ulrich has a discussion of n promiscously coupled oscillators in [1].

In real life probably a debugging nightmare.

I'd like to couple a bunch of MTI-260 oscillators  slooowly to a common 
incoming


reference and then Wilkinson the outputs together. A somewhat more

"disciplined" approach. I see them shiver with anticipation in the drawer.

Need more free time.

:-)  Gerhard


[1] Rohde, Poddar, Böck: The Design of Modern Microwave Oscillators For 
Microwave Applications, Wiley


< 
https://www.amazon.de/Design-Microwave-Oscillators-Wireless-Applications/dp/0471723428/ref=sr_1_1?ie=UTF8=1551547636=8-1=The+Design+of+modern+Microwave+Oscillators++For+Microwave+Applications. 
    >




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[time-nuts] Lady Heather treats me badly.

[Gerhard Hoffmann]

Hi,

yesterday I did install LH on my Linux system: got the zip file, 
unpacked it, compiled LH


and after the usual ado I was able to connect to my Lucent KS-24361 pair.

But somehow it looks like she's slowly dying: first the azimuth/strength 
display


disappears; later the clock , the info in the upper left; then the 
traces of the


DAC etc become boring: after some hours just one green line.


Increasing the display size  leads to crash. F11 immediately and each 
time I tried.


The message then is "Stack thrashing detected - heather terminated".


The compiler adds some known constants around the allocated variables

and when they do not stay constant it assumes that the program writes

outside of its allocated data area.

Did that happen somewhere else? Any Ideas?

best regards, Gerhard


(But the singing Monk fits Ash Wednesday. :-)  )

--

I called it with:

gerhard@silver:~/work/heather$ heather  -rx -b2 -tz=1CET -ta -vh 
-id=/dev/ttyUSB0


This is the system:

gerhard@silver:~$ inxi -v7
System:    Host: silver Kernel: 4.10.0-38-generic x86_64 (64 bit gcc: 5.4.0)
   Desktop: Cinnamon 3.6.7 (Gtk 3.18.9-1ubuntu3.3) dm: lightdm
   Distro: Linux Mint 18.3 Sylvia
Machine:   Mobo: ASUSTeK model: P8Z68-V PRO GEN3 v: Rev 1.xx
   Bios: American Megatrends v: 0402 date: 11/16/2011
CPU:   Quad core Intel Core i7-2600K (-HT-MCP-) cache: 8192 KB
   flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 
27289
   clock speeds: min/max: 1600/3800 MHz 1: 1600 MHz 2: 1599 MHz 
3: 1615 MHz 4: 1599 MHz

   5: 1753 MHz 6: 1648 MHz 7: 1599 MHz 8: 1599 MHz
Memory:    No dmidecode memory data: try newer kernel.

(16 GB RAM)

Graphics:  Card: NVIDIA GF110 [GeForce GTX 570] bus-ID: 01:00.0 chip-ID: 
10de:1081
   Display Server: X.Org 1.18.4 drivers: nvidia (unloaded: 
fbdev,vesa,nouveau)

   Resolution: 2560x1440@59.95hz
   GLX Renderer: GeForce GTX 570/PCIe/SSE2
   GLX Version: 4.5.0 NVIDIA 384.130 Direct Rendering: Yes
Audio: Card-1 NVIDIA GF110 High Definition Audio Controller .

There is no other load than Firefox and Thunderbird.



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Re: [time-nuts] Distribution amplifier for 10MHz and 1 pps

[Gerhard Hoffmann]

Yes :-) another one of mine:

<    http://www.hoffmann-hochfrequenz.de/downloads/iso_amp.pdf     >

It is based on a NIST design and made from discrete transistors.

Unfortunately it also needs RF PNP transistors that are slowly going the 
way of the Dodo.


Luckily, I still have a reel of BFG31.


regards, Gerhard



Am 17.03.19 um 19:00 schrieb Anders Wallin:

I've tried to collect links to frequency/pulse distributor designs over
here:
https://www.ohwr.org/project/pda-8ch-fda-8ch/wikis/Similar-Projects
if something good is missing let me know!

AW




  > But how do I do this
  on 10MHz side?  I'd like to have minimal distortion
  (sine wave) and high isolation.  I acquired a few signal
  splitter and monolithic amplifiers.  Split first and
  amplify?  Amplify first and split?  Remember it's only
  2 to 3 channels.  Amplifier module has too much gain, so
  I'll probably have to use attenuators.
  >




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Re: [time-nuts] Power supply for OCXO using "USB power blocks"

[Gerhard Hoffmann]

Am 10.03.19 um 15:54 schrieb jimlux:

True.. but there are a plethora of the USB 5V power blocks around - in 
general, there are lots of USB 5V (noisy, I'm sure), e.g. Cars now 
have 5V USB jacks, so I was thinking about designing with that in mind.


The question is really more one of "how much filtering do I need to 
design into the downstream power supply circuits"


It should not be too hard since there are no ground loops involved.




< 
https://www.flickr.com/photos/137684711@N07/39972841815/in/album-72157662535945536/ 
 >


The squares on the paper are 5mm.


Noise density is better than 1nV / rtHz above 100 Hz. You definitely 
need a fuse.  Ishort is >> 30A.


BTW, the next picture to the left is the noise of 2 cells = 8Vdc.

14 dB below 1 nV. The steep rise below 30Hz is the too small coupling 
capacitor.



for all practical purposes any legitimate 18650 sized Li-ion cell is 
around 3.5 Ah.

yes. the really good ones.

(who thinks about using a dozen of these for portable EME tests on 
432 :-) )


You're going to run your kilowatt amp off 36 cells in series? Why not..


No, 100W from a GaN FET at 48V and <= 10 element antenna is more than 
enough.


The rest is mostly a Dell XPS13 notebook and a Red Pitaya + up/down 
converter.  Lunchbox size.


< https://www.redpitaya.com/   >


It is easy when your partner station looks like this:


< http://dl7apv.darc.de/Neue%20Antennen/Neue%20Antennen.htm   >



To be more on-topic, two Red Pitayas can be synced and should easily

provide the hardware for a Timepod work-alike. That would be 4 125 MSPS 
14 Bit ADC channels,


two FPGAs and ARMs with Linux and web server.

(and with dual use as VNA, Bode plotter, signal generator...)


regards, Gerhard




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Re: [time-nuts] Power supply for OCXO using "USB power blocks"

[Gerhard Hoffmann]

Am 10.03.19 um 01:38 schrieb jimlux:
Has anyone tried a +5V to +15V DC/DC to run an OCXO, getting the 5V 
from one of those rechargeable USB power bricks.  I was thinking about 
portable operation.


In my case, the OCXO is something like a Wenzel streamline. I would 
think that the DC/DC probably has some noise, but maybe DC/DC to a 
higher voltage, then a good linear regulator to clean it up (or would 
the radiated noise just leak around).


How quiet is the output from those USB battery things..I've used one 
to run a RTL-SDR, but that's hardly a ultimate low noise receiver.


That's impossible to predict. These boxes normally contain one Lithium 
cell and a DC/DC converter to 5V.


Its output noise depends on the skill of the designer and the mood of 
the bean counter. It is probably


not a high priority. Also, there my be "effects" from the interaction of 
their switcher and your's.


And the efficiencies multiply.

BUT:

3 of these Li cells deliver 12V in ultimate quality:

< 
https://www.flickr.com/photos/137684711@N07/39972841815/in/album-72157662535945536/ 
>


The squares on the paper are 5mm.


Noise density is better than 1nV / rtHz above 100 Hz. You definitely 
need a fuse.  Ishort is >> 30A.


This Panasonic type is OK. There are lots of others on the market that 
claim twice the power capacity


but it's a blatant lie.


regards, Gerhard

(who thinks about using a dozen of these for portable EME tests on 432 :-) )


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Re: [time-nuts] inexpensive fiber optic distribution

[Gerhard Hoffmann]

Am 21.03.19 um 07:27 schrieb Hal Murray:

jim...@earthlink.net said:

It seems like you could probably figure out how to interface to these  things
and use them to distribute timing signals.


The document is the "SFP MSA".  I still have the XFP version somewhere here.


I don't know how well they will work for something like a PPS.  Somebody
should try it.  The signal pattern is mostly trying to be friendly to the PLL
that does clock recovery and/or the AGC that sets up the switching level.

If I wanted to send a PPS, I'd use something simple like Manchester encoding.
That assumes you can line your transmit clock up with the PPS.  It won't work
if you just want a link-extender for a PPS.



Manchester should work. Simply trying to transmit a differential CML 
level 1pps won't do.


The signals are ac-coupled typically 100nF/50 Ohm right at the module 
border.


I was one of the ~5 people who did the electronics of the 10 GBPS XFP 
modules


at Infineon Fiber Optics (RIP, sold) and someone decreased the coupling

capacitors to 10n for a very minor advantage. It's 10 GBPS, pure RF 
after all.


No. That gave us 1 bit error per day (complete show stopper) and a month 
of delay.



I'm puzzled that it works so far off-frequency with these SFPs. In our 
10 GBPS XFPs


it would definitely not work. The eye opener at the input to the 
transmitter would


go nuts, and the receiver clock recovery would not work.


BTW our modules for Cisco had special contents in some registers to make 
sure


that nobody could use alien modules. There must have happened some

social engineering if I read the post above :-)


regards,

Gerhard


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Re: [time-nuts] Lucent RFTGm-II-XO / Lucent RFTGm-II-Rb / NT BW50AA

[Gerhard Hoffmann]

Am 12.02.19 um 03:57 schrieb Jeff Blaine:
I have these 3 systems operational here and wonder what is the "best" 
of the sources?


The local use for the reference is as a time base for test equipment.  
Nothing hyper critical in the way of end-use requirements - but after 
running the NT GPSDO for a few years and watching the Lucent box 
collect dust, I wonder if I have got that backward?


The lucent has a 10 Mhz output on the front panel of the RB but the XO 
would need a tiny bit of modification to have 10 Mhz instead of the 
current 15 Mhz.


If it is similar to the Lucent RFTG-u REF1, then it has a 5 MHz MTI-260 
oven.


I have modded my REF1 to deliver 10 MHz  on 4 SMA outputs plus 1 PPS 
LVCMOS in 50 Ohms on another SMA.


The recipe is here:

<   http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf     >


73,

Gerhard, DK4XP


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Re: [time-nuts] AD9912 DDS frequency resolution measurement (and OT LTC6957)

[Gerhard Hoffmann]

Am 19.02.19 um 12:29 schrieb Bo Hansen:

Hi

I have experience with the AD9912 in this H/W and S/W implementation: 


But I must admit that I personally haven't measured the minimum frequency step size. 
Poul-Henning Kamp, among others, is using one of the AD9912 DDS units and observed a 
similar error, I think, that he has solved in this S/W: 


Whatever applies list the FTW values and calculate back to the real frequency 
and see if the frequency change is correct.

A friend of mine has a x96 multiplier from 108 MHz to 10 GHz but we don't have 
access to any counters capable if measuring the difference.



Actually, you can measure that with a voltmeter.

Force the frequency tuning word to 0x   and verify that the 
sine output stays at 0


or wherever it was if you already have a phase offset.


Then set the f-word to 0x  0001 and check after 19.5 hours if 
the sine has crept by 90°.




BTW I've opened a case in AD's engineering zone this weekend about the 
LTC6957 sine-to-square chip.


< 
https://ez.analog.com/clock_and_timing/f/q-a/107463/ltc6957-ims-3-output-oscillations 
    >



When it has no load at all, then connecting an inch of wire to one of 
the outputs makes the other


output show some oscillations. Maybe the data sheet needs a minimum rise 
time or minimum


input frequency spec. 1 MHz at 2Vpp  is already slow.

Not a show stopper, but that does not build confidence. Impressive 
output rise time for CMOS, nevertheless.



And the AD9901 phase comparator I mentioned there at EZ was not a real 
one from AD. :-)


It was a tiny corner in a $2  64-FlipFlop Coolrunner CPLD and half a 
page of added VHDL.



best regards,

Gerhard






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Re: [time-nuts] GPS 1PPS, phase lock vs frequency lock, design

[Gerhard Hoffmann]

Am 25.05.19 um 02:51 schrieb life speed via time-nuts:

Hi all, it's been a while since I visited.  I am venturing into an unfamiliar 
area from my usual low phase noise PLL, OCXO and microwave synthesizer design 
endeavors.
I recall there are some knowledgeable, well, time nuts on this list and hope 
you'll indulge some questions and maybe direct me to some appropriate white 
papers and share insights.
I want to discipline a 10 MHz OCXO with 1PPS from GPS.  Obviously not an 
unusual application, but I need to understand the methodology as I will not be 
buying a module but rather implementing the design with an FPGA, off-the-shelf 
GPS chip and a high-quality 10MHz DOCXO.
One of the first questions I have:  is it possible to implement phase-lock with 
a narrow digital PLL and DSP integrator/filter in the FPGA?  I suspect some 
1PPS disiplined OCXO implementations are merely controlled to the same 
frequency, but not necessarily the same phase, depending on the details of the 
implementation.
I need the output of two of these units I design to have to be phase coherent 
relative to each other.  Your knowledge, experience and scholarly references 
are welcome.
Thanks,
Lifespeed


Hi,

I have a new release of my OCXO support board on the backburner.

it will provide

-a home for HP10811A, MTI-260, Morion MV89, a 100 MHz SC cut oven 
(Digikey XC2265-ND) and some others.


- Locking on incoming 10 MHz,

- Locking on incoming 1pps

- free running adjusted from 10 turn pot

- generation of 1pps from onboard oscillator

- frequency doubler 5 to 10 MHz (or undoubled, or other frequencies)

- dBm measurement of incoming reference frequency


Gone from version 1 are:

- some voltage regulators

- ring mixer as phase detector, driver amplifiers etc.

- Picdiv ( there were complaints that I didn't have it, but when I put 
it on the board, nobody was interested. )


- the "Wenzel" style squarers ( I have seen that in a previous life in a 
frequency counter by HEB when 74S was bleeding edge, and in every other 
text book.) The LT6??? does that in 5*5 mm.


The phase comparator is now a 3 states FlipFlop comparator in a Xilinx 
Coolrunner II CPLD. That also makes the 1pps from most common oscillator 
frequencies. Freq and OCXO tuning direction are jumper selectable. The 
integrator is a JFET op amp and a foil capacitor.


VHDL sources are abt. 4 pages; 64 FlipFlops max. make sure that it won't 
grow without limit. Sources & layout will be open in BSD license style 
(basically: do with it what you want but don't bite the feeding hand).


Pics of the status quo:  old board with rucksack for the alternative 
oscillators and patches, new layout in statu nascendi. Flickr has some 
problems because they are moving to a new server farm, so I  leave it in 
the upload stream.


https://www.flickr.com/photos/137684711@N07/47929260287/in/dateposted-public/ 




Has anybody out there more information about this oscillator?

Its data sheet is thinner than a cookbook from the Sahel zone.

No phase noise data @ 100 MHz??? I've got one of them last week.

https://www.digikey.de/products/de?keywords=xc2265-nd


regards, Gerhard




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Re: [time-nuts] Excellent equipment rack + time nuts at HamRadio 2019 ??

[Gerhard Hoffmann]

Am 11.06.19 um 13:36 schrieb John Ackermann. N8UR:

Star Case (https:www.starcase.com) is  U.S. company (in Indiana)  that sells 
similar open-frame rack kits for very reasonable prices.  I have several and 
have been very pleased.  They are available whatever height you want, with 
depths of 20 to 30 inches.  They have lots of accessories to trick out your 
rack.



It seems that IKEA "Lack" attracts more and more people to house their 
19" devices.


They happen to fit and can easily be stapled.

< 
https://www.google.de/search?tbm=isch=1=TKf_XJ_hOPWX1fAPuumb0Ao=ikea+19+rack+Lack=ikea+19+rack+Lack_l=img.3...1413445.1415147..1415721...0.0..0.123.586.0j5..01..gws-wiz-img...0i30j0i8i30.sA8Vs2Zj4nM 
   >




I have also built a table/rack combination from Ikea material.

The working table is 2 pcs. Ikea Pronomen wood, 60*200 cm each.

It has 8 legs and is 120 cm deep.


The 1st and 2nd story are also  1 Ikea Pronomen each, with shorter legs.

The rack to the right is standard Schroff/Hofman stuff. It can be rolled 
to the right


to the mechanics section to get it it out of the way.


The biggest thing since last week is the hanging mount of the 
microscope. :-)  :-)  :-)


Finally, no more clumsy, heavy microscope foot  that used to be always 
in the way.


< 
https://www.flickr.com/photos/137684711@N07/48043564871/in/dateposted-public/lightbox/ 
  >



While I'm at it:

Are there any time nuts at the HAM Radio in Friedrichshafen, the weekend 
around 21.June?


I'll be there to visit the SDR subconference.

<    http://2019.sdra.io/pages/programme.html  >


regards,

Gerhard, DK4XP




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Re: [time-nuts] Aerial coax downlead placement

[Gerhard Hoffmann]

Am 04.07.19 um 22:43 schrieb Peter Vince:

Hello all,

  A new contact, whose background is in computer programming rather than
RF, is getting into accurate GPS positioning, and has been tapping me for
any knowledge I might have.  I persuaded him to get the new Ublox F9P
receiver and also a "proper" dual-band antenna - albeit from China, so
affordable!  This seems to be going quite well, and he sent a photo today.
He has mounted said aerial on what looks like a six-foot pole which is
good, but currently the coax down-lead is just hanging - flopping about in
the breeze.  Now that is bad for so many reasons :-)


I cannot think of a single good reason against putting the coax line

into the pole. In fact, my rocket-shaped Datum antenna leaves me no

other choice. Its plastic case has a ~ 1 1/4" thread that happily fits on a

water pipe and the N connector is concentric to that; so the cable MUST

go through the pole, at least initially. I think that is good also in 
case of


a thunderbolt hit; the tube will carry most of the current and lead it 
to earth.


That won't help the antenna, but maybe me in the lab.

And it is the only true symmetrical solution.

That rocket-shaped antenna spawns a lot of interest amongst my neighbors.

:-) Gerhard


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Re: [time-nuts] Aerial coax downlead placement

[Gerhard Hoffmann]

Am 05.07.19 um 23:26 schrieb Poul-Henning Kamp:


In message <28f942e8-b61d-4fa5-929d-923184828...@n1k.org>, Bob kb8tq writes:


Energy flow is indeed inside the cable if things are set up and operating 
correctly.

Please note in this context that *nothing* about lightning strikes
works the way you would assume it does.


A friend of mine got his ham radio station pulverized by a lightning

hit in the garden. He had written his PHD thesis on the breakdown

mechanism when charge powers its way through gases.

I call that an a posteriori field research addendum. ;-)


Cables run inside steel tubes protect the steel tube from lightning
current because copper is a better conductor than steel - in
particular when the leading flank is measured in kV/uS and the
current in kA.

Likewise, a 90 degree bend or a loop on the cable is a huge
inductance to get all that high frequency energy through, so
lightning tend to jump from bends and loops, to less inductive
paths if possible

Be careful with EMI/EMC clam-on ferrites, they can explode in
lightning strikes.


Then I look upon my pole as a 2 meter long clamp-on ferrite.

That 7 mm Aircell cable won't conduct much better than the pole,

and the outside of the pole will look quite, eh, attractive, given that

king size common mode choke.

And then, at the 90° cable corner to my lab, the lightning bolt may 
continue


downwards through earth on its highway to hell..


cheers, Gerhard

(Unix V6  on 1 of the 5 PDP 11/40E that ever existed)



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Re: [time-nuts] 60 Hz frequency and phase measurement

[Gerhard Hoffmann]

Am 03.07.19 um 01:25 schrieb Tim Shoppa:

Jim, most of us are satisfied to use a 6.3VAC filament transformer to step down 
from 120VAC and isolate from the power line.


Exactly. I used an old 6 or 9V AC wall wart and a resistive 1:3 divider 
last year when the European grid frequency was low because of some 
trouble in the distant south-east. That gave a really stable reading.


< 
https://www.flickr.com/photos/137684711@N07/38870750440/in/dateposted-public/ 
  >



regards, Gerhard





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Re: [time-nuts] Building a DMTD/phase noise set in the 21st century

[Gerhard Hoffmann]

Am 24.08.19 um 23:49 schrieb Jan-Derk Bakker:

there may be some flicker noise present, I've not personally seen the poor
DC performance in many S/D audio converters either (apart as artefacts from
the front-end electrolytic coupling capacitors).



Yes, these electrolytic capacitors can produce ugly effects.


purple = DigiKey 493-4582-1-ND organic polymer Alus 4700u/2.5V

blue    = Digikey 1189-2962-ND  2200u/25V

green  = DigiKey 1189-1056-ND 3300u/10V Rubycon, cheap


The winner is clearly the cheap

< https://www.digikey.de/products/de?keywords=1189-1056-ND  >


The test circuit is an Interfet IF3602 based low noise baseband amplifier.

I definitely wanted no bias loop via the gate and also for some reasons no

feedback into the source, so I enforced the drain current with a current 
mirror.


That is ugly, because the source must be AC-grounded with huge 
electrolytics.


In the test setup, there were 4 in parallel. There is only 500 mV across 
the capacitors.


Even the 2V5 organic polymer is not challenged voltage-wise.


The traces are the own input voltage noise of the amplifier. The 
horizontal part


of the traces is about 250 pV/rtHz noise density. The bad capacitors 
both show a 1/f**3 rise,


in textbook quality. At 1Hz is the lower passband corner of the 
following stages.


I wonder what process  produces that. Generation/recombination and most 
others do only 1/f**2.



A 4700u/25V wet slug tantal showed no weakness. But at $100 a pop I like 
to avoid them.


Vishay costs even 3 dB more than AVX.  :-(


regards, Gerhard

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Re: [time-nuts] Building a DMTD/phase noise set in the 21st century

[Gerhard Hoffmann]

Am 25.08.19 um 10:52 schrieb Hal Murray:

att...@kinali.ch said:

As you have always two channels, I would recommend to use two mixers fed with
an LO that is 90°C out of phase to get I and Q components.

How does that compare with running a single channel twice as fast?




At low enough frequencies, the two ways are identical in performance

and linked by the Hilbert transform.


At high enough frequencies, ADC performance starts to suffer. One gets

a smaller "effective number of bits"  ENOB  as sample rate and/or input

frequency rise.


In that region one may gain an advantage by halving the sample rate

at the cost of doubling the hardware and needing a Hilbert transformer,

also known as a wideband 90° phase shifter.  The phase shift

might come cheap, depending on the upstream processing.


One could also time-interleave 2 ADCs or even more. Some ADC chips

do that internally, and some scopes, too.

regards, Gerhard.


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Re: [time-nuts] Building a DMTD/phase noise set in the 21st century

[Gerhard Hoffmann]

Am 26.08.19 um 04:47 schrieb Bruce Griffiths:

I've only used an ultra low esr 33F supercap made in Korea in the source 
circuit of the input JFET on a preamp.
Down to 10Hz at least it didn't appear to add significant noise to the 4nV/rtHz 
@10Hz preamp.


I had bought some at DK, but 30 Ohms or worse at AC in the source 
produce >700pV/rtHz alone.


That would add (geometrically) to the 300 pV/rtHz of one Interfet 
IF3601/3602


and spoil the pot, so I stayed with the multiple electrolytics with 
milliOhms.


regards,

Gerhard



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Re: [time-nuts] Hp10811 parts ref

[Gerhard Hoffmann]

Am 11.09.19 um 08:33 schrieb Club Internet:

Luciano,
References of the manual is the following:
MANUAL PART NUMBER 10811-90002 Microfiche Part Number 10811-90003
Dated August 1980.

Thanks very much for your reply (indeed npn and Q6...!)
Looking for a replacement for UA208 (obsolete) hard to find, as well as LM208 
=> would NTE928 or ECG928 be ok ?


You can also search for LM108 (premium version) and LM308.

The LM308 is the base version, worse offset/temp. specc'ed etc, but may 
be good enough


and from same production, just not cherry-picked.

regards, Gerhard





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Re: [time-nuts] HP5370A vs B version

[Gerhard Hoffmann]

Am 20.07.19 um 10:21 schrieb Frank Stellmach:
the B version has a 500MHz front end, copied from the HP5345A, with a 
matched pair of amplifier / Schmitt trigger hybrids.

The A version has separate amplifier and Schmitt trigger ICs.

There were also changes on the trigger circuit.

Then the B version has a simplified µP board, has the OCXO 
(10811-60111), which is a must for absolute T.I. and frequency 
measurements.



My 5370A came with a 10811-60111 time base.

It also came with LOTS of intermittent contacts, but it was nearly for 
free, so I can't complain.


I solved the contact problem by buying a SR620 that was still under cal. :-)

Gerhard


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[time-nuts] FEI 405B oscillators

[Gerhard Hoffmann]

Hi,

I have one of these FEI405 oscillators from this list auction 4 years ago.

While it dives nicely down deep into E-13 land over some seconds, it 
only delivers -2.5 dBm output power


and has a lot of phase noise and spurs far out. That does not look healthy.

Is there a real data sheet out there in the wild, or has someone even 
re-engineered this thing?


If you google for it, you get links to Fender guitar bags, fertilizers 
and electron microscopes,


but nothing on oscillators apart of the time nuts thread from 4 years ago.

If the data sheet really says -2 dBm, then I could get rid of the spurii 
and life would be OK.


Yes, I have found the Frequency Electronics web site, but it seems they 
deny parenthood.


Gerhard


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Re: [time-nuts] Using the LT3042

[Gerhard Hoffmann]

Am 10.07.19 um 11:27 schrieb Bruce Griffiths:

Like virtually all low dropout regulator ICs the LT3042 is quite noisy at 
frequencies below its reference low pass filter high frequency cutoff. Some 
zener based references are considerably quieter in this region.


We had that already last year.

I have delivered measured curves that show that it's not true.

The trick of the LT3042 is that it's reference is not very noisy,

and there is NO VOLTAGE GAIN after the reference. Zener-based

reference diodes are _much_ worse, and the LT3042 can hold

the candle even to 2V7-Zeners and most LEDs.

You can filter the LT3042 reference quite heavily, and there is

a startup circuit so you do not have to wait too long for the output voltage

to become stable.


common Regulators:

< 
https://www.flickr.com/photos/137684711@N07/24070698809/in/album-72157662535945536/ 
    >



Zeners: (Look at that awful super-precision ovenized LM399!)

< 
https://www.flickr.com/photos/137684711@N07/24411798996/in/album-72157662535945536/ 
    >



LEDs:

< 
https://www.flickr.com/photos/137684711@N07/24354944411/in/album-72157662535945536/ 
    >



King of the LEDs is hp/Avago/Broadcom HLMP6600, if it is still alive.


I plan to repeat these measurements in the close future with a new 
FET-based amplifier that


is not challenged by that stronger-than-1/f low frequency noise and that 
can use cross correlation


additionally because of its missing noise current.


regards, Gerhard.


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Re: [time-nuts] Difference in antennas

[Gerhard Hoffmann]

Am 22.11.19 um 23:29 schrieb Hal Murray:

j...@febo.com said:

I like the idea of inserting attenuation until the SNR or Cn values start to
go down.  That may be the most practical solution.

Inserting attenuation is a good trick for the tool box.  It is also used to
measure error rates on fiber links.

With a reasonable fiber setup, the error rate is so low that it is hard to
measure.  At low error rates, there is a simple relation between signal/noise
and error rate.  So insert enough attenuation until you can easily measure the
error rate, then compute what it would be without the attenuation.

Unfortunately, in real life it's not so simple. There are more 
contributors than just SNR. In fact, when we were building 10 GBPS XFP 
fiber optic tranceivers, we got no bit errors at all. Just in one test, 
there was 1 failing bit per day or so. It turned out that the polynomial 
used to generate the data for that test had unusual long and unluckily 
grouped runlengths of the same polarity.


Someone had decided that 10 nF coupling capacitors on the differential 
CML lines were large enough for 10 GBPS and they did fit better onto the 
microstrips than the usual 100nF ones.


That did cost us a lot of time and money.

regards, Gerhard



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Re: [time-nuts] 100 MHz decade Divider II

[Gerhard Hoffmann]

Am 01.12.19 um 23:40 schrieb Bob via time-nuts:

 From Gerhard's and other list comments I'd never choose Morion oscillators.


I did not want to belittle Morion. In fact, their current crop is top notch.

But an oscillator that has spent 20 years on a cell phone tower

and that has cooked it's innards at 80°C for this time may have

drifted away or fail some specs.

Esp. when it looks like having been removed from its old home

with hammer and sickle.


regards, Gerhard



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Re: [time-nuts] Phase Detectors/Mixers for DMTD and PN measurements

[Gerhard Hoffmann]

Am 12.12.19 um 07:19 schrieb Bruce Griffiths:

Cross Correlation methods are commonly used with analog mixers.
Most of the high end commercial offerings use it (Holzworth, Anapico, Rhohde & 
Schwarz, etc.)



"High End"  is a contradiction to "Commonly Used" somehow.


In the published timenuts world, aka NIST or the usual suspects, there 
is only


deafening silence. I have seen the marketing blurbs and have even 
limited access


to the really good stuff.


Yes, there is the all-digital solution of Andrew Holme based on a

Spartan-6 demo board, some ADCs and Verilog but that's it. (And I like it!)


In the published analog area, there is pure joy when a 2N mixer pushes

the state of the art a few dB at 5 MHz.


While I'm at it, is there a _tested_ open C/C++/Fortran/whatever 
implementation of


fft/xcorr that I could cut & paste into a BeagleBone black?


Gerhard, DK4XP




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Re: [time-nuts] Phase Detectors/Mixers for DMTD and PN measurements

[Gerhard Hoffmann]

It seems the mixer noise cannot be ignored.


I wonder then  why nobody  takes the mixer to cross correlation land, 
and maybe even the driver amplifier.


The FFT analyzer can do it anyway, a second AF pre amp costs nothing,  
and other than that


there are only another mixer and 2 power dividers on the BOM.

In addition, each mixer gets 3 dB less power which helps the survival rate.

One can always crank it up for bragging rights.


Also, high level mixers (type 2 and 3 in [1] ) have resistors in series 
to each diode for biasing


so their lower efficiency should not come as a surprise.  And, the 
resistors in the ring generate


AF noise. With DC across them also 1/f, esp. for thick film.

The usual 1nV/rt Hz op amps (LT1028, AD797, ADA4898) have the voltage 
noise of a 60 Ohm resistor.


That probably brings them to the point of diminishing return.

The diodes in the ring themselves create only half-thermal noise.


Methinks one would be better off with many low level mixers and power 
dividers,


adding up the demodulated AF voltages. There is no point in power 
matching the AF side.


Maybe for RF with a RC high pass.

SMD Wilkinson dividers are $2.50 or so now from Macom, MCL or Pulse and

low level mixers are also cheap, or even 2 1:4 SMD transformers + diode 
ring.


Easily done when one does not have to wind the coils.


When verifying my links below, I stumbled across M9H  for $333.

The price for two of them is the number of the beast.  =8-) )


[1]

< 
https://www.jlab.org/uspas11/Reading/RF/Mixers%20-%20phase%20detectors.pdf >



< 
https://www.google.de/url?sa=t=j==s=web=1=2ahUKEwiu8Zi7pa_mAhUKQUEAHb1pAyAQFjAAegQIAxAJ=http%3A%2F%2Fwww.rfcafe.com%2Freferences%2Farticles%2Fwj-tech-notes%2Fmixers-theory-technology-p2-v8-3.pdf=AOvVaw3fc3OZgN2H5jzPx6jXDBh9 
   >



Also interesting:

< 
https://www.google.de/url?sa=t=j==s=web=1=rja=8=2ahUKEwiFuqCvpq_mAhVTh1wKHcc2ALQQFjAAegQIAxAJ=http%3A%2F%2Fliterature.cdn.keysight.com%2Flitweb%2Fpdf%2F5989-8999EN.pdf=AOvVaw3RFawCNg543QEv1hUsscbY 
  >



regards,

Gerhard,  DK4XP




Am 11.12.19 um 20:29 schrieb Bob kb8tq:

Hi

There are some famous name papers showing data taken on the 3048. When
asked about the levels involved, the next question inevitably was - “How many
mixers did you fry running the test?”.

Bob


On Dec 11, 2019, at 10:54 AM, Richard (Rick) Karlquist  
wrote:


The HP 3048A phase noise system has a phase
detector in the HP 11848A chassis that was
originally a Watkins-Johnson (the original
company) M9H.  The M9H lives on now sold by
MaCom Technology Solutions.  "Someone" (unknown)
established that the Mini-Circuits JMS-5H
is an acceptable substitute, although not
an exact replacement.

The tradeoff in picking a mixer is the LO
level.  A high LO drive level such as the above
mixer have, gives higher performance, provided
you have a driving amplifier that has both the
necessary output power is itself low phase noise.
Depending on the test set up, some of the driver
amplifier phase noise will common mode out.

Also, high drive level mixers have a narrow window
between high enough drive to operate vs the damage
level.  So a third requirement on the driver
amplifier is that it's maximum output level is
less than the damage level.  (Don't ask how I
know this :-).  You can always put a pad between the
drive amplifier and the LO input of the mixer used
as phase detector to adjust the maximum possible
drive.

Rick N6RK



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Re: [time-nuts] Using commercial video amplifier for 10MHz clock distribution.

[Gerhard Hoffmann]

Am 19.10.19 um 10:30 schrieb Bryan _:

There is a schematic here on the Extron uploaded by a TN member. The schematic 
for the Extron looks looks dead simple that one could really just make a simple 
3 channel with the included mods in the writeup, only problem is I don't see a 
source for a CLC409 any longer, and I don't have the experience or knowledge to 
use a substitute ADA800x ??




It seems that LMH6702 should fit, at least electrically.
Check for the right package b4 buying. Current feedback op amps have a
preferred value for the feedback resistor. The existing 240 Ohms fit
for the LMH6702. No wonder, it's intended as the replacement.

regards, Gerhard

< https://www.digikey.de/products/de?keywords=lmh6702 >



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Re: [time-nuts] A simple sampling DMTD

[Gerhard Hoffmann]

Am 29.11.19 um 11:45 schrieb Jan-Derk Bakker:

In general: as much as I like having it in my toolbox, I don't see how
using an FFT would be the best tool for the job in a zero-crossing detector
for a DMTD, let alone this particular sampling DMTD. For one, this 8-bit
processor doesn't have the spare cycles to run FFTs on the 32-bit data I
get from my CIC^2 decimator; besides that, I would only be interested in a
single bin (the beat frequency), where it would be more efficient to simply
I/Q-demodulate the samples in software (O(N) vs O(N log N)). While I admit
that in the latter case windowing would help, at this point I/Q
demodulating (effectively calculating only a single bin of the DFT) does
not appear to have advantages over least squares fitting the arcsine of the
incoming samples. Am I missing something here?


I admit that I did not follow this thread closely, but the Goerzel filter

is the single output line DFT , with O(n).

< 
https://www.mathworks.com/help/signal/ref/goertzel.html;jsessionid=8816f77eb76ad7dd1913c7021698 
>


<   https://en.wikipedia.org/wiki/Goertzel_algorithm     >

If you need to simulate floats, fractional integers are easiest.

I/Q demodulation probably requires to recreate a clean carrier if you want

absolute phase and not only relative jumps. That sounds more like FPGA

than 8051, or whatever the 8 bit processor of the day may be.

regards, Gerhard



OK, in a previous life I did build a system for geophysics, where they fed

dangerous amounts of AC into the soil and measured the potential at

some 50 nodes. Rubber boots required.

Each node had a 8951 to control some switches and communicate setups.

They were most exited when I gave them the sources so they could

implement FFT pre-processing locally on each node themselves.

That required willingness to suffer.




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Re: [time-nuts] 100 MHz decade divider advice needed

[Gerhard Hoffmann]

Am 30.11.19 um 02:10 schrieb Gerhard Hoffmann:


Auto-follow-up:

Why do you want crystal ovens in each stage when you  lock it to 
something else anyway?


Then something cheaper like these should do:

< 
https://www.digikey.de/product-detail/de/crystek-corporation/CVHD-950-100.000/744-1213-ND/1644128 
>


My score on Morions from China was not so pleasant.


.. and while I'm at it:

< 
https://www.digikey.de/product-detail/de/nexperia-usa-inc/74LVC163PW118/1727-3097-1-ND/946754 
 >


150 MHz min @3V3,  200 MHz typ.

Sorry, no DIL.  74ACT, 74F, 74AS are also dying. 74HCT is still there.


regards, Gerhard


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Re: [time-nuts] 100 MHz decade divider advice needed

[Gerhard Hoffmann]

Am 30.11.19 um 00:50 schrieb Perry Sandeen via time-nuts:

Yo Bubba Dudes!,
I'm considering attempting  making a 10 MHz frequency difference meter sort of 
based on the Ticor 527.
The design calls for using 100 MHz OCXO's and using the PLL difference to steer 
the EFC and then mix it with a PLL 90 MHz locked to the reference 10 MHz.  Then 
that 10MHz difference is fed into the next stage PLL and the process repeated 
in the following stages.
Hy problem is this.  The only generally available 100MHz decade divider I've 
found is the 74LS196N.
The problem arises that on the TI website it's advertised as going to 100 MHz 
BUT when one reads the data sheet it says that it only works to 85 MHz or so.
I found on ebay the MC12080 100 MHz to 1.1GHz chip that can be configured to 
divide by 10.
Now the ON units carried by the big name distributers are about $6.  The Chicom 
no-brand-name units on ebay are less that $2 each.
I'd really like to use the LS296 chip as it is a dip type and *genuine* ones 
sell for less than $2 on ebay.
Since I need one OCXO for each decade stage plus one for the 90 MHz reference, 
at $50 each used on ebay this starts to get very expensive quickly.
I did find some obscure 100 MHz decade counters on some design circuit on the 
net but I'd never heard of them and expect they will be unobtainum.  The same 
seems to be true for the 74S and 74AC series.


74ls, 74s and mostly 74AC are all obscure now. 5V is mega-out, 3.3V is

still standard but the trend goes to even less. 74LVC is mainstream.

Not all chips of the old 74 series have been ported to 74lvc because nobody

designs system around MSI function blocks any more. There are just the

essentials: octal bus drivers, gates, flipflops (mostly only 1 gate/ff 
per pop in a tiny


SO-8 or sot-23-5). There is still the 74LVC163 counter. I think there is 
no LVC191


whose precursor I have used a lot. These SSI/MSI chips only save as glue 
logic to make


LSI ICs to fit together or to connect them to IO.  Heavy functions that 
do not


justify a full custom chip go to FPGAs or at least to CPLDs.

I personally like the Xilinx Coolrunner-2 CPLDs as garbage collectors, 
but they


are getting old also.


The 74LVC163 + inverter should work for you, up to 200 MHz at least.

But remember: with the speed come problems, too. Your output may be

only 10 MHz, but rise and fall times are easily as fast as 500 ps.

Good rf engineering is absolutely required.


The lower-left quarter of the picture should work for you.


There are more fast families, like Fairchild NC7SZ04P5X  (04 = one 
inverter in sc70-5)


or TI SN74LVC1G04DCKR (mostly the same)

or ON Semiconductor NL17SZ74USG  (D-type FF), Fairchild NV7SV74K8x

or NXP 74LVC163PW ( counter )

as search strings for your google-foo, as typed from the anti-static bags

in my drawer. If you find one of the family, the brothers are easy.


local bed time now,   Gerhard  :-)




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Re: [time-nuts] Are there SC-crystals out there in the wild that are not Overtone?

[Gerhard Hoffmann]

Am 27.02.20 um 17:45 schrieb Richard (Rick) Karlquist:

OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.

Any time nut should be up for that.


5.000 MHz. That was easy. It used to be in something Colpitts-like

for 30 years, but did not age to its advantage like good Scotch.

I was just puzzled because I could not find the fundamental.

When the subharmonic is so far off as Bernd has said, then I could

well have searched a day with the network analyzer at 1 Hz receiver

bandwidth without finding it. I'll postpone that to the weekend.


Someone has reverse-engineered the whole oscillator:

< https://www.bartelsos.de/dk7jb.php/ocxo-morion-mv89a?download=118 >

Jörn seems to read the timenut list, HI!


cheers, Gerhard

(now I'll have to shovel some snow, first time for this winter!)







Rick N6RK

On 2/27/2020 5:35 AM, Bob kb8tq wrote:

Hi

Ok, so just to run the math:

5 MHz / 2.9 = 1.724 MHz

If the Q at the fundamental is 500K (a wild guess) then 1.724 MHz / 
500,000 = 3.4 Hz


In a world where a synthesized sweeper *might* be stepping in 10Hz 
steps, that’s an

easy one to miss.

Bob



On Feb 26, 2020, at 11:40 PM, Bernd Neubig  wrote:

Hi Gerhard,
I am rather sure that it is a 5 MHz 3rd overtone crystal.
the resistance should be in the 80 to 110 Ohm range and Q about 1.5 
million. You can see the resonance without ringing in a span of 100 
Hz or smaller with a sweep time of 10 sec minimum.

See attached the response of a 5 MHz SC3 crystal in HC-40/U package.
Indeed the 5.45 MHz is the B-mode which has a temperature 
coefficient of -30 ppm/K
Because the crystal blank  has  a plano-convex shape. The overtones 
are quite far away from 3 times or 5 times the fundamental mode. 3rd 
overtone is about (rough guess) 2.9 time of fundamental mode.
To find them you must really carefully sweep around a few 10 to 100 
kHz span with slow sweep time a narrow bandwidth


Regards
Bernd
DK1AG

-Ursprüngliche Nachricht-
Von: time-nuts [mailto:time-nuts-boun...@lists.febo.com] Im Auftrag 
von Gerhard Hoffmann via time-nuts

Gesendet: Mittwoch, 26. Februar 2020 01:42

To get a first impression, I soldered the crystal to an SMA plug and 
put it on an
R ZVB-8 network analyzer and measured S11. I could see the 5 MHz 
resonance
as a 15 dB dip.  There was also a resonance at 5.45 and a smaller 
one another 90 KHz

higher. the +10% suggest that it is an SC cut.
But I could not see anything at 1 or 1. MHz, so it should be a 
fundamental crystal?

Is that common?
I made most measurements at room temperature. I can turn the hot air 
solder

station down to 91°C which is not far away from the crystal's 87.7°C
inflection point, and I could see some variation on the 5.45 MHz 
resonance vs. temp.
I must build a fixture for the hot air because the sweep time at 1 
Hz bandwidth

is close to eternal.
Is the un-harmonicity (???) between fundamental and overtones 
stronger with SC-cuts
than normal AT? I also could not see anything at 15 MHz. Next I'll 
make a board
for the PI fixture as described by Bernd Neubig in his crystal 
cookbook.
BTW I could see some more dips with >= 10 Hz resolution. I hope that 
does not mean

that the ZVB needs service.




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Re: [time-nuts] Are there SC-crystals out there in the wild that are not Overtone?

[Gerhard Hoffmann]

Am 28.02.20 um 11:34 schrieb Attila Kinali:

Yes, but how many of us can build a time-nuts quality oscillator?
I'm still lacking that paper/book that teaches me how to build
a high stability oscillator.


Especially if you see THIS in a tutorial and 5 cm below the OOOH

so precise phase noise simulation results of this circuit:

- < short.png  > -

That builds confidence.


But Bernd was very precise with his prediction where the fundamental

of the SC crystal was to be expected. The sweep took abt. 25 minutes @ 
1Hz RBW.



The step on the left side is where the next measurement happens.

The crystal laid openly on the end of the port cable on the table at 
room temperature.


--- <  fundamental.png > ---


I have a couple of 5MHz 3rd OT SC cut crystals in HC-37 case sitting
in a box, waiting to be used as some oscillator, I just lack the knowledge
to make good use of them.



regards, Gerhard



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Re: [time-nuts] Are there SC-crystals out there in the wild that are not Overtone?

[Gerhard Hoffmann]

Am 26.02.20 um 15:22 schrieb Attila Kinali via time-nuts:

Do you know what the two coils/transformers that were glued to the
outside of the inner oven were for?


I guess they are part of the 5 -> 10 MHz doubler



Bernd Neubig has written a few documents on how to measure crystals
properly, which should be available from Axtal's website, if I'm not
mistaken.


Yes, I mentionend the Quarzkochbuch above. There was a nonstandard

solution proposed by Detleff Burchard in UKW-Berichte / VHF Communications

4/92 but I can't find my copy. I had built the head some 20 years ago

and it seemed to work. The drawback was that one had to compensate C0,

at least at 100 MHz.

regards, Gerhard


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Re: [time-nuts] was: Odd-order multi Now: fft analyzer woes

[Gerhard Hoffmann]

Yes, that spill-over to neighbor bins is a known thing; when I wrote 
software


for mixed signal wafer testers we sometimes used no windows at all and

instead made sure that all frequencies involved were proper submultiples

of the sample rate. In my current situation I'm limited to what the 89441A

has to offer, and that is not too much. IIRC the manual proposes flat top

for sines and Hanning for noise. While there is no such thing as a Hanning

window. That Guy was Justus von Hann, from Austria.


Carriers are also not of prime interest at the moment; I'm more focused

on the noise itself. Maybe 1/f of oscillator transistors or the noise of

GaN fets in a pV/rtHz chopper amplifier where the GaN have some appeal

for low charge injection. When I used my URV-35 with the Z51 thermal

head to measure the noise, the result would be dominated by the 1/f,

even though the Z51 collects everything to 18 GHz.

And when I measure phase noise, the carrier has already been

carefully and lovingly removed.


With all that TCP/IP and GPIB programming and C library feature

flavor macros I feel already quite deep in the wrong rabbit hole.


My test carrier is not off by milliBels but by 50 dB and correcting that

won't probably work without some lying where the carrier hits the noise 
floor.



Cheers,

Gerhard, DK4XP


Am 24.01.20 um 01:59 schrieb jimlux:

On 1/23/20 4:20 PM, Magnus Danielson wrote:


.

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Re: [time-nuts] Symmetricom 023-63008-07 5MHz Crystal Oscillators

[Gerhard Hoffmann]

Am 23.01.20 um 19:12 schrieb Bob kb8tq:

Hi

If you do try it, double balanced mixers seem like the way to go.

Two 5’s into one mixer gives you 10, a low level spur at 5 and some crud at DC.
Duplicate that with another mixer and you have a second 10. Maybe go into a
low Q filter to clean it up a little. Since you have loss in the mixers you 
will need
some gain. At this point you have 4 OCXO’s running.

I had the idea to phaselock a bunch of MTI-260 very slwly to a common
master and then simply to Wilkinson-combine the outputs.  That won't help
long-time adev but phase noise. This was the original idea behind my 
carrier board.
I still have some GPS-less Lucents from that guy in FLA from some years 
ago. :-)


But the 260s are not good enough to justify the effort, simply buying
an ULN would be less ado.

At least two MTI-260 and also MV-89A on their carrier boards don't seem
to show a tendency to injection lock as far as I can tell  when I use them
as independent Timepod references, each just with 10-turn-pot tuning.

Gerhard, DK4XP



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Re: [time-nuts] was: Odd-order multi Now: fft analyzer woes

[Gerhard Hoffmann]

Hi, Abdul!

Am 21.01.20 um 19:10 schrieb Prologix:

Prologix controllers pass data as is from the instrument to PC. It does not add 
any termination characters.


But then there is the ++eot command just to set up this.


++eos command controls how termination is handled for data going the other way 
-- from PC to instrument.
Please consult instrument manual about how it terminates output.
I also could not see what the timeout does. When I try to read a 
character and
none is available it still hangs forever, even with the timeout set to 2 
seconds.


We should take that offline probably.



In the meantime, the LAN connection to the FFT analyzer works again.
Ansi C requires some re-synchronisation when switching the direction of 
the data

flow in a TCP/IP connection or you may get old messages a second time.
An otherwise empty fseek() is enough, per side effect.
A year ago, the connection to the analyzer was solid, then it would hang 
now & then

and in retrospect, since I have the current V5 Linux kernel it is unusable.
The fseek() has healed that.

There is still the minor? problem, that from low to high frequencies, 
many new decades
start with elevated noise, but I correct for the increased noise 
bandwidth. Maybe discrete
spurii are then over-represented? I'm unsure how to handle that. When I 
add a carrier
from a signal generator for CAL reasons, that carrier level should not 
be changed by noise BW

correction, assuming that all of the carrier power hits the same bin?

The amplitude of the carrier in the picture has been corrected for 5 
decades = -50 dB,
and that's obviously wrong, the 3325B is not that bad. When I do a 
narrowband sweep, it

looks OK on the FFT analyzer screen.

Even when I go through the spectrum and decide that this or that is a 
carrier and it should
not be downscaled, how do I handle its sidebands? There is no pure black 
and white.


Cheers, Gerhard


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Re: [time-nuts] Low Phase Noise Amplifiers

[Gerhard Hoffmann]

Am 11.01.20 um 15:36 schrieb Charles Clark:
I wonder if adding active bias feedback around the RF transistor to 
reduce the low frequency current variations would help.  This is the 
classic PNP bias scheme which can be applied to BJT's or FET's.  I 
have used it to successfully improve the phase noise on oscillators.  
Details from T.T. Ha, or Gonzales books on Amplifiers.



... and available as cheap SOT343 chip from Infineon:  BCR400W

< 
https://www.infineon.com/dgdl/Infineon-BCR400W-DS-v01_01-en.pdf?fileId=db3a30431400ef68011407e93d8601a1 
 >


I vaguely remember that its use in an oscillator has been patented.    =8-()

cheers, Gerhard


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Re: [time-nuts] Norton amplifiers

[Gerhard Hoffmann]

Am 13.01.20 um 19:29 schrieb Alexander Pummer:
there was one "zwischen basis-Schaltung" which has good noise 
properties basically the basis and the emitter of a bipolar transistor 
is connected to the two ends of a transformer's secondary winding ,a a 
tap on said winding is grounded Ulrich Rohde may could tell more about 
it, I have seen articles written by him on that subject long time ego 
perhaps in German.


Here in Germany it was popularized in the ham community by Michael 
Martin, DJ7VY with


several articles in the Club newspaper CQ-DL and in UKW-Berichte /VHF 
communications.


I just have found one article of his neatly recycled on the web:

< 
https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/ukw-berichte/1977/page194/index.html 
   >


The website seems to collect a lot of stuff.

Gerhard





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Re: [time-nuts] Horowitz & Hill - "The X Chapters" - shipping now

[Gerhard Hoffmann]

The extra material that did not make it into The Art Of Electronics 3rd 
ed. because


that book weighs already 2.3 Kg. It filleth the community with bliss and is

the current bestseller, just 3 days available.


< 
https://www.amazon.de/Art-Electronics-x-Chapters/dp/1108499945/ref=sr_1_2?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91=x+chapters=1579717926=8-2 
  >



cheers, Gerhard



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Re: [time-nuts] Odd-order multiplication of CMOS-output OCXO

[Gerhard Hoffmann]

Link does not work, but

https://www.digikey.de/product-detail/de/ecs-inc/ECOC-2522-100.000-3FC/XC2265-ND/6578492


Sorry, Gerhard


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Re: [time-nuts] Odd-order multiplication of CMOS-output OCXO

[Gerhard Hoffmann]

Am 20.01.20 um 22:57 schrieb Attila Kinali:

On Mon, 20 Jan 2020 12:50:09 -0800
Mark Haun  wrote:


True enough, but remember that my motivation for using the OCXO in the
first place was to combine the required phase-noise spec with
OCXO-class frequency stability (this is for narrowband coherent
modulation schemes on the shortwave bands where short-term stability of
~ 10^-10 is nice to have).  The alternative is what Attila said,
VCXO phase locked to an OCXO.  The advantage of doing it this way is
that I [potentially] reduce complexity, board space, and power.

For an SDR application, the ABLNO allone would be the best option, IMHO.
It's low power and low noise. Even for narrowband SW applications.
If you look at the data, you see that the cross-over between the
ABLNO is lower noise to the OCXO is lower noise is around 100Hz.
Unless you are operating at much lower than 100baud, the ABLNO
is going to be enough. If you are using something like AFSK31/PSK31
it's probably borderline which one is better and I would go with
the ABLNO only for simpler construction and easier sourcing.

If you are thinking about trpoposcatter, EME or similar things
with really low baud rates, then I would go for the VCXO+PLL
approach for one simple reason: Flexibility. With a PLL you
have a choice what kind of reference you want to use.

For a back burner project, motorcycle based portable 432 MHz EME,
(i.e. collecting squares with a friend of mine who has a _huge_ antenna),
I decided to use one of these

< https://www.digikey.de/de/product-highlight/e/ecs/ecoc-2522-smd-ocxo   >

and call it a day.

432 - (4*100) = 32 MHz = somewhere in the middle of the Red Pitaya passband.
And the Red Pitaya could also run on the 100 MHz. There happen to exist nice
SAW-Filters for both 400 and 432 MHz. No tuning.

There is no Baud rate on EME, just a 600 Hz side tone. :-) Or WSJE.

regards, Gerhard, DK4XP





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Re: [time-nuts] low phase noise, noise floor and noise figure amplifier at 400MHz

[Gerhard Hoffmann]

Am 10.01.20 um 03:01 schrieb jimlux:

On 1/9/20 5:38 PM, Lifespeed wrote:

Hi Time Nuts,


I have a need for a low phase noise, noise floor and noise figure 
amplifier
at 400MHz.  I have tried some off-the-shelf 50 ohm amplifiers, the 
best of
which degrades phase noise by a couple dB.  I'm working with a signal 
with
-172dBc/Hz PN, so not much tolerance for degradation here.  The input 
signal
level is only 3dBm, so noise figure still matters as well.  I'm 
looking for
15dB gain, 16dBm P1.  The residual phase noise would have to be 
better than
-180dBc/Hz, and I would probably operate the amplifier slightly 
compressed.


A friend of mine measured my SKY 75150 demo board at F= 0.35 dB last weekend

on 432 MHz for EME purposes. More careful measurements to follow.

chip    = < https://www.digikey.de/products/de?keywords=863-1559-1-nd     >

board = < https://www.digikey.de/products/de?keywords=863-1562     >

When I ever get it back  :-) , I might characterize it for added phase 
noise at 400 MHz,


but he should have his fair share of time to play with it.

Given the extra tiny SMD input inductor, an even better F must be possible.


The Mini Circuits SAV-551+ has a Fmin of  ~ 0.08 dB at 450 MHz according 
to the


data sheet IIRC. When I add 0.1 dB of losses, that is still outstanding.

Does anybody know of an ADS design kit for these parts? Spice is 
probably hopeless.


ADS and MCL do not seem to go together well.


If you want to allow compression, there will be 1/f up conversion. 1/f 
is completely


unspecified for these parts.

If you need lower than that, I can ask around about discrete designs. 
There's some group in Norway that is using FETs from Switzerland and 
getting L band noise temps in the single digit Kelvin range. (without 
cryocooling).  I don't know if it would go down to UHF and hold that 
performance



Interesting. What are these FETs from Switzerland? Any pointers?




Any suggestions on topologies, transistors, white papers, etc? I'm
considering the NXP BFU590Q silicon bipolar transistor, which I have 
used in
a transformer feedback configuration at 100MHz with less than 
-180dBc/Hz PN.
But this topology doesn't appear practical for 400MHz due to the 
difficulty
maintaining a high collector impedance at that frequency with a 
transformer.


Have you tried Infineon BFQ19S ? I just have bought quite a lot of them.



Nor do I need to control the gain, which is one of the features of the
transformer-feedback topology.  I was thinking about common emitter with
inductive emitter degeneration.  Not sure cascode is right for this UHF
application.


Cascodes do not add noise in real life. p-HEMTs have ridiculously low output

impedance, so cascoding with SiGe BJT might be a good thing. The output

could be a low-Q tuned tank if the impedance needs to be high.


regards, Gerhard





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[time-nuts] Now is the time for all good dogs

[Gerhard Hoffmann]

to jump over the lazy fox.

Oh, not really.


But if you always wanted to experiment with harmonic balance,

nonlinear noise and other things that your LTspice cannot do, then

Keysight currently offers 3 month trial licenses for ADS for home office use

for free.

< 
https://www.keysight.com/de/de/cmp/promotions/innovate-anywhere.html?elq_cid=1083495=7012L00tzyG 
    >



cheers, Gerhard.


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Re: [time-nuts] Now is the time for all good dogs

[Gerhard Hoffmann]

Am 07.04.20 um 19:27 schrieb Brent:

Saw this the other day regarding training but it looks like its only the
Pathway stuff.  I don't see anything for ADS...


It seems they have renamed it.


< 
https://www.keysight.com/de/de/products/software/pathwave-design-software/pathwave-advanced-design-system.html 
   >


My exposure to ADS is growing old already.


Gerhard





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Re: [time-nuts] Phase measurement of my GPSDO

[Gerhard Hoffmann]

Am 03.04.20 um 23:08 schrieb Bruce Griffiths:

One can merely add diodes to the opamp feedback network form a feedback limiter 
and maintain the opamp outputs within the range for which the opamp is well 
behaved whilst maintaining the increase in slew rate for the output.


Has anybody here  ever tried the OPA698 / OPA699 limiting op amps?

http://www.ti.com/lit/ds/symlink/opa698.pdf

A lower 1/f corner would be appreciated, and slightly less noise.


On 04 April 2020 at 04:26 Tobias Pluess  wrote:


Jup, some of them even have phase reversal when they are overloaded, so it
is perhaps not a good idea in general, but I think there are opamps which
are specified for this.


That phase reversal thing is a misfeature of old JFET-OpAmps when

overdriven at the input. It created weird behavior of feedback loops.

Newer ones have that corrected.


Cheers, Gerhard





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Re: [time-nuts] power supplies

[Gerhard Hoffmann]

I love my R NGT20, I have several of them.
Reasonably clean, analog, uA741 technology, no switcher, knobs for 
everything.

3 independent, unconnected outputs:

2* 0-20V@1A for op amps etc

1*0-6V@5A for the digital stuff

for example:
< 
https://www.ebay.de/itm/Rohde-Schwarz-DC-Power-Supply-Stromversorgungsgerat-Typ-NGT-20/193258127587?hash=item2cff1500e3:g:v6wAAOSwlnVd9j7J 
  >



I have measured some of the devices I have here to see how much there

was to filter for my analog toys:


< 
http://www.hoffmann-hochfrequenz.de/downloads/Noise_Measurements_On_Some_Laboratory_Power_Supplies.pdf 
   >


For the NGT20 that was not much.

The HP6633B: OMG!!!

Cheers, Gerhard




Am 01.05.20 um 20:51 schrieb jimlux:
What with telework, I'm doing more timenuts-ey stuff at home, and the 
power supply conundrum has come up.


There's a plethora of interesting widgets scattered across my bench 
requiring variously, 5V, 8V, 12V, and 15V.


I've got a box full of various fixed voltage supplies, mostly linear, 
picked up over the years.
I suppose I can package a bunch of those up in a bigger box with 
banana jacks or binding posts.



And then there's some things where you'd like current limiting and/or 
variable voltage.


So I've started looking at inexpensive bench power supplies - there 
appear to be dozens, if not hundreds, of these available. There must 
be dozens that are all very similar - They're switchers for the most 
part, displays, etc. for $50-100, from different vendors, all similar.


Are they essentially commodity? Or are there particular brands that 
are good or bad?


Are they all noisy?

Weird UI problems (7 menu layers with a single knob)?



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Re: [time-nuts] GPS antenna splitter recommendation?

[Gerhard Hoffmann]

Am 30.04.20 um 03:01 schrieb Bob kb8tq:

Here’s a few:

... lots of ebay offers snipped


The problem is, they will do their Job at RF, but the GPS receiver

usually has to feed the antenna pre-amplifier with DC through the cable.

The 4 RX candidates should not have to fight for the right / duty to do 
this,


with their possibly conflicting offers. Given that DC makes it through the

transformers (or whatever) of the splitter of choice at all.

So, probably a bias tee is needed also, and some replacement dc power

source, which is the easy part.

Also, the 4 receivers should not see each other DC-wise, although there

is usually a protection against catastrophic abuse.


Cheers, Gerhard




On Apr 29, 2020, at 8:18 PM, Frank O'Donnell  wrote:

I'm looking for a splitter to allow three or four GPSDO's to share my 
roof-mounted Lucent PCTEL KS24019L112C 26db GPS twist antenna.

I understand from scanning past threads that inexpensive splitters by companies 
like Mini-Circuits often turn up on eBay, but I'm having trouble narrowing down 
to one that will work for my situation. Can anyone recommend a specific 
splitter that wouldn't be too expensive?


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Re: [time-nuts] Bourns for fine frequency tuning

[Gerhard Hoffmann]

Am 12.05.20 um 11:03 schrieb tim...@timeok.it:

  Bourns 3700S-196-1004


A short search leads to

< 
https://www.mouser.de/ProductDetail/Bourns/3700S-1-103?qs=Ce8Nk3DxA0Ci0Gcap53qHg== 
    >


which says that that the base type is EOL-ed (end of product life).

The data sheet has no 100K version. Also the type number is probably a typo.

1004 would mean 100  which would be 1 Meg, practically impossible to

do produce from NiCr wire or similar.


If all it has to do is selecting a voltage between 0 and some reference 
voltage,


10K is probably just OK.

regards,

Gerhard


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Re: [time-nuts] f-multipliers from VHF to 10 GHz

[Gerhard Hoffmann]

No, no, no, it's not that bad :-)  I should not post here in the middle 
of the night. Sorry to cause that confusion.


Minimum  is -90 dBc @ 50 Hz, or let's say @100 Hz @ 10 GHz.
that would equal -110 dBc@1 GHz,   or -130 dBc @100 MHz, BTDT.

And then, the ~4 MHz difference between TX and RX frequency could be
done by a SSB mixer with a non-multiplied crystal. We would have some
common mode noise, but the RX-TX difference would be fairly constant.
It would not de-correlate over the 10 mm run length, not at low
offsets where it counts.

The -110 was only meant for "Don't care about multiplied white noise
floor", not in the sense of a spec but in the sense of "guaranteed
harmless". It's not such a great relaxation after all, it could be
20 dB looser.

The question was really only about a _simple_ multiplier chain. The
style used in ham radio 10 GHz transverters has too many stages,
GaAS-Fets with 1/f and pipe cap filters. Too complicated.

Macom still make a SRD diode, but probably it is easiest to phaselock
a ceramic puck or an on-chip VCO to a 100+ MHz crystal. The offset-
mixing removes the need for a low reference frequency or fractional
voodoo.

cheers, Gerhard


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[time-nuts] f-multipliers from VHF to 10 GHz

[Gerhard Hoffmann]

I have a potential project in the electron spin spectroscopy sector and 
I need
one or two clean signal sources in the 10 GHz range. Phase noise at, 
say, 50 Hz offset

is important, but anything below 110 dBc  does not care.
That probably calls for a multiplied crystal. These Hittite PLLs from AD 
seem to be

just not good enough, maybe they'd work if pushed, but no reserve left.
Are there any known proven multipliers chains from VHF to 10 GHz?

Cheers, Gerhard

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Re: [time-nuts] OCXO Support Board

[Gerhard Hoffmann]

Am 15.05.20 um 01:25 schrieb John Ackermann N8UR:

On 5/14/20 5:07 PM, Bob kb8tq wrote:


No, the cheap board houses don’t check for this stuff. They just build and send 
it
back. If there’s a gotcha, you get it on the board.

I was pleasantly surprised last week when Seeed Fusion contacted me to
point out a problem where two vias were too close together (by a couple
of thousandths).  They asked if they could reduce the hole diameters

I had the same good experience with PCBway.

I used these 0.9 * 0.9 mm GaN FETs, and that does not mean 0.9mm gate 
length:

https://www.digikey.de/product-detail/de/epc/EPC2038/917-1138-1-ND/5774048

and used the proposed Altium footprints from EPC. These pull the
solder mask onto the pad which is unusual but maybe essential for
a smooth soldering experience. I'm sure that EPC have experimented with 
that.


PCBway emailed me directly and we cleared that up that it was intentional.
They still produced the board on the same day, and soldering was easy.
Very satisfied customer.

Nevertheless I'll try JLCpcb next week. They now have a proxy man somewhere
here in .de who gets one box from China a day and forwards the contents
to the different customers after the customs work is done, via normal 
local registered mail.

The import VAT is then already done and billed by JLCpcb.
DHL Express is a royal pain to deal with.

Cheers, Gerhard


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Re: [time-nuts] OCXO Support Board

[Gerhard Hoffmann]

Am 13.05.20 um 13:35 schrieb Bill Notfaded:

I've been trying to find a base PCB design to use too.  In the interim I
bought some boards from Gerry Sweeney that sells them for HP5313x frequency
counter OCXO upgrades and supports different footprints.  Open source
design is even better.  OSHpark is great.  Please post it!


Here it is:

< http://www.hoffmann-hochfrequenz.de/downloads/ocxo_carrierV2_pack.zip    >

These are the Gerber files as used by PCBway to produce my boards.

2 buglets:

- the 2 mounting screws for the 10811 should be slightly bigger.

  Drill as needed

- Unless the oscillator delivers only a small signal, the 2 emitter 
capacitors should


  each get 22 Ohms in series to adjust gain.

This will be addressed in V3. Circuits are included, comments and small 
change


requests are welcome, could be done shortly thanks COV19.


cheers, Gerhard







Bill E.


On Tue, May 12, 2020, 11:59 PM Matthias Welwarsky 
wrote:


On Dienstag, 12. Mai 2020 20:53:25 CEST Gerhard Hoffmann wrote:


Ten boards did cost $5 at PCBway, DHL wanted $25 for transport. :-<
I can publish the Altium Designer project or the Gerber files when the
1st ten are used up
and there has been somewhat more testing. The number of possible
combinations
is quite large.

If you publish the Gerber files, People in the US can use OSHPark for
having
the boards made, in EU Aisler.net is probably the best option.

BR,
Matthias


Cheers, Gerhard

Am 12.05.20 um 19:52 schrieb Wes:

Does anyone know of a ready made board that will allow me to mount and
at the least, minimally support the operation of an MV89A oscillator.
I have one which I've powered up deadbug style and would like to clean
up the mess a little.

Thanks

Wes N7WS


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Re: [time-nuts] Noise Floor

[Gerhard Hoffmann]

Am 24.03.20 um 20:06 schrieb Attila Kinali:


If you want an SDR like system to play with, try the


Red Pitaya?

You get 2 ADC channels 125MHz/14Bit or 128.x MHz/16 Bit,
2 DAC channels, 2 ARM CPUs, Network etc and it boots Linux when
you plug in an USB power supply. It has existing apps such as scope,
vector network analyzer, Bode plotter, ham radio etc - and the
software as well as the web server that presents the results to
your browser is open.
It's fun to watch tuning S21 of a filter in Firefox. :-)


With 2 boards one could do the whole cross correlation thing,
with at least the 2 ADC pairs completely isolated.
<  https://www.redpitaya.com/Catalog   >
Prices are reasonable.





While I'm at it:

Is there a _done_ solution to expand a Timepod to
~ 100 MHz, narrow-bandish is OK. I'm willing to solder,
but I'm not ready for yet another development project.
Not now.

When I've flushed my project pipeline, I might consider
something serious with JESD-204B ADCs and such.
That would require a larger FPGA with GTX transceivers
and maybe a Beaglebone as a controller.


cheers, Gerhard



 The bad part of Zurich is where the degenerates
throw DARK chocolate at you.

Does Zuerich have a good part? That's news! No one threw
chocolate at me. Driving in the inner city of Berlin in
the rushhour is the pure relaxation in comparison.
Never ever again!  =8-(   )







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Re: [time-nuts] book could be interesting 4 you

[Gerhard Hoffmann]

OOOhps, that was not intended for here. :-)

Looks like Thunderbird has messed up the address data base.

But at least it's on-topic.

Gerhard




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[time-nuts] book could be interesting 4 you

[Gerhard Hoffmann]

< 
https://epdf.pub/discrete-oscillator-design-linear-nonlinear-transient-and-noise-domains.html 
>



And there is more!


cheers, Gerhard


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Re: [time-nuts] 1pps signal measurement

[Gerhard Hoffmann]

Am 29.06.20 um 20:48 schrieb Gerhard Hoffmann:


eternity, with CMOS being so slow that interoperability with CMOS was 
not an advantage.


ooohps, sorry:    substitute / interoperability with CMOS / 
interoperability with TTL /


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Re: [time-nuts] low power divide by 5

[Gerhard Hoffmann]

Am 29.06.20 um 18:43 schrieb jimlux:
What logic family might be appropriate for a divide by 5 from 50 to 
10MHz, low power, running off 3.3 or 5V? 


In the picture is probably what you need, and maybe more.
The left third is a comparator that generates valid CMOS levels from a 
vaguely defined sine signal.
The right third determines if there is a valid reference and tells the 
PLL (not in the picture) to use

or ignore it.
If you have a valid CMOS signal, the middle is all that is needed. 
LVC163 + LVC04. Good enough for
150 MHz+.  On terminal count, the inverter forces the counter to load 
the P0..3 pins on the next
clock.  The value on P0..3 determines the division ratio, from 2 to 16. 
Large numbers  = few clocks
until the next terminal count. The example is divide by 5, which happens 
to fit your problem.


IIRC, the 74AC191 could have done that without the external inverter, 
but it did not make it

into the 74LVC series.

That's what I used to lock my DG8SAQ vector network analyzer V2+  to an 
external 10 MHz reference

before  that was available in V3. The PLL chip was a 74lvc4046.

https://www.digikey.de/product-detail/de/nexperia-usa-inc/74LVC163PW-118/1727-3097-2-ND/946683

Cheers, Gerhard
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Re: [time-nuts] low power divide by 5

[Gerhard Hoffmann]

Am 02.07.20 um 00:35 schrieb jimlux:

On 7/1/20 1:41 PM, ed breya wrote:

Yeah, I know. I was just lamenting the lack of nice medium-density 
count functions in 74AC. It's hard to beat the simplicity of a '390 
when you 


16 bore holes just to deploy 4 flip flops is not what I'd call 
simplicity. And Fairchild
recognized that as well. The 390 did not make it into the 1987 Fairchild 
Advanced CMOS

(FACT) data book.
They expected other chips to sell better, like the 74ACT488 GPIB / HPIB 
/ IEEE488 bus
interface. Ever used one? The market for Nixie clocks with one counter + 
one decoder

per digit must have been smaller, even back then.



Anyway, I've always liked having a wide assortment of MSI logic 
devices available in all families, that you just hook up and it goes 
- no setup, no programming. I've saved lots of counter types for 
possible use. One obscure one is the MC14566, with divide 6 counters 
for clock time readout and generation, in the old days.


That's sort of the design goal for the 22V10 and earlier PAL devices - 
keep them in familiar DIP packages, power on the corners like the IC 
gods intended, and you can program it to replicate a whole variety of 
MSI functionality, often with the same pinout.



Corner pinning for Vcc and GND is not what any gods intended. In FACT, 
(pun intended)
it's evil. Remember ground bounce? The corners are the worst locations 
on a DIL chip
you can find for that job. And fig leaf capacitors across the chip are 
just that.
At 100 MHz, they simply are not there. The optical illusion helps only 
to hide that.
The 3  ACT chips on the experiment board posted yesterday reminded me of 
the

last pages of this:

< 
http://www.hoffmann-hochfrequenz.de/downloads/experiments_with_decoupling_capacitors.pdf 
>


The golden times of logic design are now, not then!

Gerhard

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Re: [time-nuts] low power divide by 5

[Gerhard Hoffmann]

Am 01.07.20 um 03:04 schrieb Hal Murray:

What logic family might be appropriate for a divide by 5 from 50 to 10MHz,
low power, running off 3.3 or 5V?

How important is the "low" power?  Do you have other logic/CPU around?

Do you need 50/50 duty cycle (or close) or is 20/80 OK?

How about a CPU with a counter/timer block setup to divide by 5 and the CPU
sleeping (if it doesn't have anything else to do)?

What is available in the small FPGA or PAL space?

In the divide-by-81 thread I have proposed a Xilinx Coolrunner, with
VHDL code, and a link to a prefabricated Chinese board. Just replace
the 81 by 5 and choose the new On/Off ratio.

< 
https://www.digikey.de/product-detail/de/xilinx-inc/XC2C64A-5VQG44C/122-1420-ND/966601 
    >



Prices are slowly rising, that's Xilinx' way of saying: we don't like it 
anymore,

but we usually don't obsolete anything.
I'm just doing a custom reciprocal frequency counter with SPI interface 
in one,
and my crystal oven infrastructure board uses such a 2C64 for its 1pps 
generator
and switchable direction 2FF phase detector. You can do a lot of things 
with just 64


flipflops. It's weird, but Coolrunner Flipflops can act on both rising 
and falling


clock edge if required.


Much modern logic is aimed at the high speed market which usually means thin
oxide which leaks.  I'm pretty sure I've seen some FPGA/PAL families that are
old but still very active just because their idle power is very low - the last
family before things started to leak.

When it was new, Xilinx demonstrated the Coolrunner with a battery
made from 3 apples or oranges and some wire.





How about a shift register?  It needs a reset signal to get started.




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Re: [time-nuts] Frequency division by 81

[Gerhard Hoffmann]

Why don't you simply divide by 81 with a normal CMOS divider and 
synchronize its output with a 7474-like flipflop to the original clock? 
The phase noise would be determined only by this last flipflop.


regards, Gerhard


Am 18.06.20 um 13:58 schrieb Gilles Clement:

Hi
I need to divide the output of an OCXO by a factor D=81 for testing purposes. 
So with minimum added phase noise.


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Re: [time-nuts] Vibration isolation of quartz oscillators

[Gerhard Hoffmann]

Am 27.06.20 um 14:02 schrieb Michael Wouters:


What do other people do with their quartzes ? I thought I should ask
for some advice before attempting measurements.


A sand box? Literally? Some bags filled with sand really helped

with my turntable. Make sure that it stays in the bags.


Gerhard




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Re: [time-nuts] 1pps signal measurement

[Gerhard Hoffmann]

Am 29.06.20 um 19:35 schrieb Mark Spencer:

I am also wondering a bit about the possible impact of my 5370B's having a 
maximum trigger setting of approx 2.18 volts vis a vis the typical specs for 5 
volt TTL signals that typically define a logic 1 as having a slightly higher 
voltage ?  Would enabling the 10:1 attenuator on the input to the 5370B make 
sense ?

TTL has nothing to do with 5V, other than that 5V is the intended supply
voltage. An input at less than 0.8V is guaranteed to be low, anything
higher than 2.4V is guaranteed high, the nominal switching level is
about 1V8. The difference between 1V8 and 0V8/2V4 is to provide
a minimum noise immunity.

It's different for CMOS. CMOS outputs are close to either VDD or GND,
and the inputs switch nominally at 1/2 VDD. That went on for a little
eternity, with CMOS being so slow that interoperability with CMOS
was not an advantage. So people used pullup resistors and were happy.

I still hear the voice of the professor saying "Ladies & Gents, now you
understand why CMOS will never be fast!". Oh, he was wrong!
Then the CMOS steamroller accelerated. Nobody escapes the CMOS 
steamroller, as they used to say.  The 74HC series was as fast as

74LS and switched at 1/2 VDD. The functions were like the TTL
series. Then there was the 74HCT series with a switching threshold
at 1V8, like TTL. That was implemented by massaging the width/length
ratio of the FETs and the intention was to get 74LS sockets.

Replacements were a no-brainer, only open inputs
would no longer default to "High". With CMOS, they have to be
definitely driven to a valid value, bad things happen if not.

74AC / 74ACT is like 74HC/HCT on steroids. Faster but essentially the same.

3.3V CMOS came later with a switching threshold at 1/2 * 3V3, so
it is TTL compatible by coincidence.  74LV, 74LVC... etc, depending on
who makes them. 74LVC may operate at less than 3V3, then the
switching thresholds are lower in proportion. These chips may not like
input voltages higher than their 2V5 or 3V3 supply, such as 5V.
Some families are designed to accept that abuse, some will die.
Caveat emptor.


To make it short, you have no problem with your counter.
The magic voltage for TTL is 1.8V.

Cheers, Gerhard







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Re: [time-nuts] Frequency division by 81

[Gerhard Hoffmann]

Am 19.06.20 um 11:42 schrieb Clint Jay:
12F675 is specified for clock input of 20MHz and (without digging too 
deep into the way the code works) I think the PICDiv code works with 
clock input rather than input to a timer or counter peripheral so 
20MHz would be fine. While I'd not recommend it for use I have seen 
them run (experimentally) at 27MHz and I've seen anecdotal reports of 
over 30MHz. 

Burn the attachment into something like this:

< 
https://www.ebay.de/itm/Coolrunner-rev-C-fur-Jasper-Trinity-Corona-Phat-Slim-Kabelpuls-IC-Xbox-36-tp/353110312086?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20200520130048%26meid%3D477f5b9f172e4c9b92d885140d5a8df0%26pid%3D15%26rk%3D1%26rkt%3D2%26mehot%3Dco%26sd%3D402298757019%26itm%3D353110312086%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWebWithBBEV2bDemotion%26brand%3DMarkenlos&_trksid=p2047675.c15.m1851 
 >


and you're done.

Add sine/square converter in front if neededand output precision 
flipflop if standard CMOS is not good enough.


I have my own stamp-sized Coolrunner II board, never tested this one. 
One could also program a phase comparator and/or 1pps generation from 
100 MHz into it. BTDT. I might provide the Gerbers for JLCPCB.


regards, Gerhard

-

library IEEE;
use     IEEE.STD_LOGIC_1164.ALL;
use     ieee.numeric_std.all;

entity div81 is
    Port(
        clk:  in   std_logic;   -- CMOS clock to > 200 MHz in
        q:    out  std_logic    -- divided output
    )
end div81;

architecture beehive of div81 is

    signal tctr:  integer range 0 to 80;

    attribute LOC: string;
    attribute IOSTANDARD: string;
    attribute LOC of clk: signal is "P1";  -- in put is pad 1
    attribute IOSTANDARD of clk:  signal is "LVCMOS33";
    attribute LOC of q:   signal is "p31"; -- output is pad 31
    attribute IOSTANDARD of q:    signal is "LVCMOS33";

    -- (function boolean_to_standard_logic no more needed in more 
modern VHDL)

    function bool2sl(b : boolean) return std_logic is
    begin
        if b then
            return '1';
        else
            return '0';
        end if;
    end function bool2sl;

begin

u_div : process(clk) is   -- this block wakes up if something happens on 
clock pin

    begin
        if rising_edge(clk) then

            if (tctr = 80)
            then
                tctr <= 0;  -- reset if maximum count reached
            else
                tctr <= tctr + 1;   -- else just increment
            end if;

            q <= bool2sl(tctr < 40); -- set output high/low time to taste
        end if;   -- rising_edge()
    end process u_div;

end beehive;







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Re: [time-nuts] Voyager space probe question

[Gerhard Hoffmann]

Am 30.11.20 um 07:00 schrieb Mark Sims:
I once bought a spool of tungsten-rhenium alloy wire on ebay for dirt 
cheap. A few weeks later a guy contacted me and offered a lot of money 
for it. Turns out they used it to rebuild TWTs. 


1. I used to live in Ulm, Germany, where there was? Thales TWT production.
My neighbor and fellow ham worked there, so I got an invitation for their
family-open-house day. That was most interesting. One division looked so
much like a mechanical craft shop: glass blowing, milling, electrical
discharge machining, welding, all so ...retro. And then, the next room:
An array of the best and newest vector network analyzers, with ladies
moving magnets to collimate the beam and maximizing S21.
But I don't think they can survive the GaN revolution.

2. @ Jim:  Is there a canonical way to couple a varactor etc to the
DRO for locking without killing Q or without having any effect?
I have made some experiments with 3D-electromagnetics but did
not get very far. It's not for the casual user.

Mechanical vibration is probably not an issue for our electron spin
DRO.   :-)   It weighs more than 3 Kg, most of it iron to support the
DC field magnets. Looks good. I'd like to get one for the mantlepiece.
Our puck has a borehole for a tiny glass pipe through it to apply
the solution with the free radicals.  Q takes a hit but there is
still enough left. We get quite a frequency shift when changing
the uMol concentration. Can't tell numbers.

Cheers, Gerhard



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Re: [time-nuts] SMPS or conventional?

[Gerhard Hoffmann]

Am 22.12.20 um 00:43 schrieb Hal Murray:

[Old mail, context is TECs] bruce.griffi...@xtra.co.nz said:
If the drive current ripple is too high fatigue failure from cyclic 
thermomechanical stress can be significant. 
Do good data sheets say anything about that? Is there a frequency term 
in there? Can I use PWM, which is as much ripple as you can get, as 
long as the frequency is high enough? If yes, ballpark of how high? 
Physically, where is the heat/cold generated? Is it mostly at the 
junction? 


The g**gl search for "TE coolers ripple current" delivers the first 2 
hits of 3.65e6:



< 
https://www.google.de/url?sa=t=j==s=web==2ahUKEwiQ4YK0tuDtAhWKCewKHckIALoQFjAAegQIBRAC=https%3A%2F%2Fwww.ii-vi.com%2Fwp-content%2Fuploads%2F2020%2F07%2FMRLW_Working_with_Thermoelectric_Materials.pdf=AOvVaw3pbUbFp4SsfdKsBzRNf-Wi 
   >


(that looks dangerous  :-)  and


< https://www.ferrotec-nord.com/technology-of-thermoelectric-module/    >


Both agree that ripple > 1 KHz is harmless. But then the current delivered
to the TEC is quite large usually -  and It's a different question if 
you want such

large and dirty currents on your table or in your device.

The thermal resistance between the hot and cold side is not very large
and that explains part of the suboptimum efficiency.

You do not want such a thing to regulate the temperature of a crystal etc
because if you externally heat or cool one side, that will soon propagate
to the other side; delta T stays constant until your regulator takes note
and corrects it.


Oh, and the google search shows that everybody and their dogs make
TE controller chips.


Gerhard






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Re: [time-nuts] Flicker Noise Reduction

[Gerhard Hoffmann]

There is a paper from the univ of Twente in NL that
seems to indicate that it takes some time in an open
FET until the traps in the channel build up, so switching
the FET off in a regular way might be an advantage.
I stumbled across it when I was seeking input for my
ultra-low-noise chopper amplifiers.

Gerhard

Am 19.11.20 um 00:38 schrieb Attila Kinali:
On Wed, 18 Nov 2020 19:13:00 + (UTC) Bruce Hunter via time-nuts 
 wrote:
Can anyone who subscribes to these transactions report on this?  I 
dropped my subscription. In this letter, a novel 1/f noise mitigation 
technique is presented to improve the receiver 1/f noise performance 
of a 670 GHz receiver. 
The paper in question is: "A Novel 1/f Noise Mitigation Technique 
Applied to a 670 GHz Receiver", by Ogut et al. 
https://doi.org/10.1109/TTHZ.2020.3036179 The description is extremely 
vague, but I think what they are doing is modulating the gain of the 
first LNA stage in an amplifier chain to get information on the total 
gain of the chain and correct for it. Which would make it basically a 
fancy chopper-amplifier that operates on the gain instead of the 
offset voltage. Attila Kinali

"I have some vague idea that I could place behind the IEEE wall of shame.
I won't work on it in the foreseeable future, but it may give me precedence
if it turns out to be usable and I can count it as a publication, even 
if no one

will read it."

cheers, Gerhard


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Re: [time-nuts] 5065A Rb Cavity RX - Varactor repair?

[Gerhard Hoffmann]

Am 22.10.20 um 23:54 schrieb Richard (Rick) Karlquist:

I suspect that the stock 5065 chain has better
phase noise than this chip.  I know for sure
that you can get much better phase noise than
this chip by using conventional architectures.
Of course they are more complicated, etc.  Just
wanted to put this chip in perspective.

Rick N6RK


On 10/22/2020 12:12 PM, Gerhard Hoffmann wrote:


This is a ADF5356 with 2 LT3042 to clean up the supply voltage.
I measured the successor to this board yesterday on 10 GHz out
with my new 1/8 prescaler and the SR620 counter and some


As long as you can measure the noise with a 89441A vector signal

analyzer instead of a signal source analyzer, it cannot be leading edge.

Close-in, it seems quite ok. Enough to guide a 5 MHz crystal oscillator, 
and


also to guide a (in my case) 10 GHz dielectric osc with a Q of 20 to 30K.

Sorry, I must stay diffuse at this point.


My question for the phase noise in the Engineer Zone was also kinda 
"scheinheilig",


German word, (hypocritical, falsely innocent, ...lost in translation). I 
know that I could


go to a phase detector frequency of 150 MHz with this chip (instead of 
20*2), and it


would help for sure.  But I'm still struggling to make a connection between

the Windows evaluation software results and the data sheet.  My software 
driver is


1200 lines of C code (but including lots of comments.) ~400 bits to be 
set up.



And the 100th harmonic of 60 MHz won't be a phase noise wonder either, with

or without a SRD. You can see the effect in the well-known pictures of 
the old


HP spectrum analyzers that display a staircase with many a step, 
depending on


the LO harmonic.


Sky and MA/COM still make step recovery diodes, whether they fit is a 
different


question. But I cannot think of a special SRD failure mode. If you can 
do that,


solder it out and measure it with a normal Ohm meter. If it still 
behaves diode-ish,


it is very probably a working SRD. Maybe without the soldering, 
depending on the circuit.


Repairing will always be cheaper than transplanting a completely new heart.


Cheers, Gerhard





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Re: [time-nuts] Daft idea with the National Grid

[Gerhard Hoffmann]

Am 08.02.21 um 00:11 schrieb Philip Gladstone:

As an amateur radio guy, I can't help wondering whether I could use this as
a *very* low bit rate channel across the country.

I have done navigation _for_ tv and phone sats, and the spread
navigation signals are just 20 dB under the MPEG data stream via
the analog transponder. If you back down another 10 or 20 dB, I'm
sure you could disseminate encryption keys or maybe phone without
anybody taking note. And everybody has a TV dish in the right direction.
Search the right one.
Really, I can't imagine that the agencies don't do that already.

Gerhard, DK4XP

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Re: [time-nuts] AM/PM conversion on mixer, DMTD

[Gerhard Hoffmann]

Am 10.02.21 um 16:19 schrieb Lux, Jim:


There are people making triple balanced mixers.
L3Harris Miteq makes them

https://www.markimicrowave.com/home/ was started by Ferenc Marki, who 
developed triple balanced mixers at WJ



Synergy Microwave claims to make triple balanced mixers:

<   https://synergymwave.com/products/mixers/  >

but the web site is so brain damaged that you cannot search for it, short of

opening all the data sheets.


Gerhard




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[time-nuts] Re: Best frequency to start for GHz synth ?

[Gerhard Hoffmann]

OOps, the 400 MHz filter is

< 
https://www.digikey.de/product-detail/de/qualcomm-rf360-a-qualcomm-tdk-joint-venture/B39401B3742H110/495-3923-1-ND/1858979 
>


Gerhard
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[time-nuts] Re: Win 10 stuff

[Gerhard Hoffmann]

Am 15.04.21 um 10:12 schrieb Rex:

Thanks for that info (below) about Win 10 turning off auto updates.

I think I got gpedit installed on my Win 10 Home and have made these 
changes. Nice.


Does anyone know if there is a way to get Win 10 to stop nagging me 
about creating/fixing a Microsoft account?  -- "Microsoft account 
problem -- we need to fix..."
I don't want an account. To paraphrase an old movie -- Accounts... we 
ain't got no accounts. We don't need no stinking accounts.


BTW My one Win 10 PC is dual boot with Linux Mint.



I did read from converging sources that this here:
https://udse.de/reboot-blocker/
is the only solution that really works.  I did not test it. Web site is 
German only.


I no more give WIn-? control over an entire hardware machine.
I run Win in a VMware virtual machine on top of Linux Mint. The network
of the VM ends at the host computer, so even Win7 is never exposed
to the bad, bad world.
Every other week I give WIN10 internet access after saving a copy of
the virtual machine. Then it can pull updates and reboot as often as it 
likes.

Allowing/denying internet access is just two mouse clicks on VMware.
No more phoning home.
VMware is transparent for USB2/3. Even the Xilinx FPGA dongle works,
and the DG8SAQ network analyzer which has some real time requirements.
The no-cost VMware player is enough.

Gerhard

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Re: [time-nuts] AN/URQ-13 FE-15a oscillator question

[Gerhard Hoffmann]

Hi, all of y'all,

would you please snip the cited parts that are long out of 
context?!!one!eleven!!


I wonder how that reads on a cell phone.

cheers, Gerhard


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[time-nuts] Re: Testing a GPS mag mount antenna

[Gerhard Hoffmann]

Am 20.08.21 um 22:14 schrieb skipp isaham via time-nuts:


Hello to the Group,

I picked a box of used (removed from commercial radio APRS type 
service) mobile/vehicle GPS Antennas. They are mostly the classic 
square molded, black plastic magnetic mount type, about the size of a 
bar of soap when cut to square (2/3 the size of a large bar of soap). 
The coax length terminates to an SMA connector.


I'd like to use some of these unmarked (obviously also unbranded) 
antennas for a few projects. The initial goal is to first set up a 
system to test (good/bad) the antennas, then determine their operation 
voltage, I suspect them to be 3.x to 5.x Volts. They are probably not 
"new enough" to be the type to operate of 3 or 5 Volts DC.


For testing... I purchased a nice NOS Mini-Circuits bias-Tee.

The intent is to now operate the antenna through the bias-tee, in to 
an analyzer. I would initially start the bias supply off at 3 Vdc, 
while also monitoring current.  If I don't receive an adequate/valid 
GPS signal off air, I could increase the bias up to 5 Vdc (rinse/repeat).


Should I be able to "see something" on or around the GPS frequency 
other than what I suspect will be something visual looking like a 
noise/pulse source/signal?


You won't see anything interesting on the spectrum analyzer. The 
signal(s) look like noise, and they are buried in the real noise.


Deeply!  In a real receiver, there are probably just 1 bit ADCs, aka 
comparators, and the receiver  needs to know the pseudo random


polynomial that was used to blow up the bandwidth of the 50 baud message 
to some MHz in order to reverse that effect.


And you have to know which part of the polynomial is currently used. 
This is done by search & correlation tries. Sloppy wording, I know.


Only when that reversal is done you have a positive signal/noise ratio. 
GPS receivers are 95% math, the rest is electronics


and packaging.

You may see a noise molehill at the nominal frequencies, but that means 
only that the pre-amplifier and maybe some filtering works.


And there is a hefty preamplifier to make up for 5 meters of El Cheapo 
RG-174  coax. The GPS pseudo-noise is only


1 promille of that what you see.

Disclaimer: Last time I was involved in this was with the Plessey 
1010/2010 chip set in a previous life, for GPS/Glonass combined,


which was new then.


Gerhard, DK4XP





I don't yet have a GPS receiver with a signal strength indicator, else 
I could probably not have to send this post.  But, I do have access to 
an analyzer, I bought the bias-tee (was reasonable in price) and I'd 
like to test these 30 antennas to see if they work and determine if 
3.x volts is enough... or 5 volts is required.


Thank you in advance for any replies and comments.

cheers,

skipp

skipp025 at yahoo.com
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[time-nuts] Re: Affordable 160 GHz Sampler

[Gerhard Hoffmann]

Am 01.09.21 um 19:42 schrieb Mike Monett:

Conventional samplers for home brewers usually go to 1 GHz. The SD-32
sampler for the Tektronix 11801C mainframe goes to 50 GHz. The HP 110GHz
oscilloscope costs around $1.3 Million USD, with a 10-bit resolution. Very
impressive.


I have a HP54750 sampling mainframe, the sampling plug-ins up to 50 GHz 
54752A and differential TDR Agilent 54754A. Quite a lot of bang per buck 
how our military colleges would formulate it. The plug-ins do also work 
in newer mainframes.




I have invented a new sampling technology that promises 160 GHz bandwidth,
yet is affordable to home experimenters. If you can afford an IPhone or
IPad, you can afford this sampler.

This technology is not pie-in-the-sky. I made a basic 5 GHz version for the
University of Ludwigshafen, Germany, and they were very pleased with the
results. I am attaching images of the response compared to a
Tektronix 1502 TDR and the pcb as proof.

This was the first prototype, and I have made significant improvements
since then.

I have two questions for the time-nuts group:

1. where would a sampler with this bandwidth be useful?


You said it yourself: wideband scopes, TDRs, phase detectors for 
frequency synthesizers, or spectrum/network analyzers. The 5G and 
upcoming 6G cell phone world is your oyster.   :-)   And car radar @ 70 GHz.


The cost projection seems optimistic given that a female-female coax 
connector barrel for 50 GHz easily costs a few hundred $$. Have you 
ordered your recent edition of the Keysight ADS software, with the right 
options?


There is a Google sponsored prototype chip design program. Not exactly 
the newest process but you might get a 10 GHz single chip solution from it.



2. where can I find signal sources at these frequencies to check the
response?


I have made a design with a ADF5356 synthesizer chip that goes to 12 
GHz, but the chip has a frequency doubler and the fundamental 
suppression is a joke. A bad one.


< 
https://ez.analog.com/rf/f/q-a/536893/adf5356-doubts-about-bleeding-current-programming 
    >


430 views, no answers, let alone from AD.    :-[

There is a new design based on TI LMX2594 that goes to 15 GHz without 
doubler, but I'm still fighting with the eval board software. Why can't 
I just say: have 100 MHz in pristine quality and SPI, want 14 GHz from 
eval board? I don't want to know each of the 120 registers personally, 
at least not from the start. I have made a 4layer pcb @JLCPCB with 
LMX2594 + AD/Hittite HMC541 post amplifiers. Enough power to drive high 
level ring mixers. A step towards my Timepod frequency extension.


5 boards with 4 stamp sized synthesizers + 2 test structure microstrips 
each did cost €4 plus postage. You can get some, but I still have to 
solder the 1st one.


There is a 20 GHz version of the chip with doubler + tracking filter. 
Above that, your options are few without board level design or access to 
a phemt or SiGe process.


Mike, could it be that we have met on sci.electronics.design?

And, does anybody out there have a working W SNA-20 to -33 spectrum 
analyzer, or the disk contents?


cheers, Gerhard


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[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP

[Gerhard Hoffmann]

Am 08.10.21 um 15:26 schrieb CFO:

My Z3810 had begun to show Alarm on the GPS receiver.
On Coldstart it seems like it lives for 10min or so , and the enters 
alarm state.
I'm quite sure it's the GPS receiver that has gone to "heaven" , never 
got that "Coldstart" every 6 months incorporated in my routines


A span of 10 minutes from cold   points more towards the oven. Maybe it 
stays too far away


from the exact frequency so that a lock is impossible.

There would be no reason to complain as long as the oven is cold.

cheers, Gerhard


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[time-nuts] Re: Death of a Capacitor

[Gerhard Hoffmann]

Am 27.09.21 um 00:34 schrieb Bob kb8tq:

Hi

If you start dumping major current spikes into a common ground, it’s amazingly 
difficult to
get rid of the results.


First Principles know the law of the conservation of spikes:

Capacitors convert voltage spikes to current spikes.

Inductors convert current spikes to voltage spikes.

Gerhard


(who just has fun with a new  LMX2594 synthesizer board.

10 MHz to 15 GHz, 2 cm**2, 20 dBm, limited amount of empty

boards available for free. Soldering them is NOT harmless.)
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[time-nuts] Re: Death of a Capacitor

[Gerhard Hoffmann]

Am 27.09.21 um 10:16 schrieb n...@lazygranch.com:
I've only designed one LDO as a discrete chip (as opposed to a portion 
of a chip where performance just has to be good enough), so I have no 
guru status. That said, what spikes pass through a LDO if you do it 
right is simply a capacitor divider comprised of the capacitance 
across the pass device and the filter capacitor. This is a bit more 
predictable with a PFET pass than a PNP. 
FET and predictable does not go together well. FET data sheets are 
seldom more than a page and normally don't promise hard limits. And 
then, like for the IF3602 there comes V2 with reduced claims after 20 
years, much more like what we used to measure in real life, still 
slightly optimistic.


https://www.analog.com/en/products/lt3045.html You can see the PSRR 
after a point (200kHz) rolls off and appears to flatten. I assume the 
error amp is out of loop gain. It goes flat for a while. The idea here 
is the drive on the pass device is constant and just maintains the DC 
voltage. The AC rejection is mostly due to capacitance ratios. This 
being a bipolar pass device there is some secondary effect here where 
after 2MHz the rejection improves then goes flat again.
I would not call nearly 80 dB PSSR  to 2 MHz bad. And @ 2MHz it is no 
longer really needed. A simple, cheap RC/LC pole does wonders there 
given it has some decades to develop its attenuation.


Where it really counts is in the low Hz region, when even costly 1uF 
show barely any effect.


Gerhard

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[time-nuts] Re: NTP servers

[Gerhard Hoffmann]

Am 23.11.21 um 11:53 schrieb Avamander:

Speaking of Raspberry Pi's as time servers, does anyone here know of a nice
single board computer that supports both Ethernet hardware timestamping and
GPIO PPS input?


It seems the BeagleBoneBlack fits the bill.
I like it because it runs a normal Debian and it has more
I/o-Pins than competing boards, and the 2 PRU-I/O processors
that are completely time-predictable.


< 
https://forum.beagleboard.org/t/does-the-x-15-have-hardware-timestamping-ieee1588-support/30107 
>


The BB-X15 obviously has no hardware-timestamping.

Gerhard
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[time-nuts] Re: Potting compound advice needed

[Gerhard Hoffmann]

A customer of mine uses Solitane, another one Mupsil.
I just wrote down the names in case I might need it.
Probably more for coating boards in space apps, no idea
if it fits.


Am 10.11.21 um 23:40 schrieb Richard (Rick) Karlquist:

I am looking for help choosing a potting compound that
has the following properties:

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[time-nuts] Re: 1 pps

[Gerhard Hoffmann]

Am 10.11.21 um 23:56 schrieb B Riches via time-nuts:

Any ideas on how to get a useable 1 pps output sig out of a Lucent KS-24361 to 
use with SL sampling rate detector.
I am using the 1 pps output from a Jackson unit but would like to use the 
Lucent if I can since that is my gps standard.
73
Bill, WA2DVUCape May, NJ


There are some pics with red arrows herein:

<   http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf  >

The board I made was home-etched, so there are no left-overs,
but you or whoever can get the Altium or Gerber files.
Should be less than 20 bucks for 10 boards from JLCPCB,
including postage.

Cheers, Gerhard
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