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

[Detlef Schuecker via time-nuts]

Hi,

yes, it is self-clearing. It cycles 0 4 6 7 1 (leftmost FF MSB), 2 clears 
to 7, 3->1, 5->2. On one output you get 3/5 duty cycle, on the other two 
you get 2/5. 

Detlef Schücker




Von:"Robert LaJeunesse" 
An: time-nuts@lists.febo.com
Datum:  01.07.2020 09:30
Betreff:Re: [time-nuts] low power divide by 5
Gesendet von:   "time-nuts" 



Take a look at the "modified" shift-register like counter in the attached 
jpg file. When simulated online it behaved as expected for a divide by 5. 
I believe it also is self-clearing from illegal states, but the other 
simulator I tested that in wasn't good for documenting the design.

Bob L.

> Sent: Tuesday, June 30, 2020 at 6:47 PM
> From: "dschuecker" 
> To: time-nuts@lists.febo.com
> Subject: Re: [time-nuts] low power divide by 5
>
> Hi,
> 
> a divide by five should possible with a synchronous state-machine made 
> of 3 ( sufficiently fast-) JK-FlipFlops.
> 
> All 3 FFs are clocked with the input freq. , the outputs of the FFs are 
> fed back to the the JK-inputs,  the divided freq. is output of one of 
> the FFs.
> 
> Additional constraints: no external ANDs or ORs or NOTs, the 
> state-machine does not get stuck in the 3 unused states.
> 
> This turned out to be a very interesting problem and I do not yet come 
> up with a solution. Maybe there is none. Analytical solutions all 
> failed, I will try a brute force enumeration attack tomorrow.
> 
> lots of fun !
> 
> Cheers
> 
> Detlef
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Re: [time-nuts] 1PPS questions

[Dana Whitlow]

Dave,

I'd suggest putting about a 10-dB RF attenuator in the line between the PPS
source and
your 5372A.  That should bring the level down to about 2V.

Dana


On Wed, Jul 1, 2020 at 10:44 PM VE7HR  wrote:

> Are there any suggested method to reduce your 1 PPS signal to a safe level
> for your test equipment?
> It seems like my HP Z8316A is outputting slightly more than 5V into 50
> Ohms.
>
> Up till now I have been using a 10 MHz output from the Z3816A. But I
> understand 1PPS is a better signal to put to Channel A.
>
> My HP 5372A seems to default to 2V Max level if you hit instrument
> default.  I am starting to like it so I don’t want to trash an input
> module.
>
> I think I might try a TICC in the near future but for now I will have to
> slum with the vintage HP iron.
>
> Thanks
> Dave
> VE7HR
>
> Sent from my iPhone
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Re: [time-nuts] 30 MHz freq adjust by Hz

[jimlux]

On 7/1/20 4:59 PM, Bob kb8tq wrote:

Hi

Um …. e …..

If the phase spur is at 1.5 Hz at 10 MHz, it still will be at 1.5 Hz at 1296. 
The multiplication process
does not change the offset frequency.

What you *do* get is a change in level. If the spur is 40 db down at 10 MHz, 
then it goes up by 10 log (1296 / 10).
Net result is that your 40 db down spur is now at about 20 db down.

Bob





This is phenomenon that curses us in the deep space transponder world. 
We like to use a DDS to generate the transmit frequency for the 
downlink, but we really, really don't want spurs close in (say, within 
30 kHz) because that's where the data subcarrier is.


At low, low SNR and low, low data rate, we modulate the data at, say, 10 
bps, on a subcarrier using BPSK, then we phase modulate the subcarrier 
on the main carrier with a max deviation of say, 70 degrees, so there's 
a fair amount of residual carrier for the DSN station to lock onto.






On Jul 1, 2020, at 7:54 PM, glenlist  wrote:

RRR

Stability over about a 2 minute period, preferably within a Hz at 1296 MHz , IE 
about 1e-09 is all that is required. I'll make it and figure out what I missed 
:-). The unwanted sideband (and some of the original will of course leak 
through depending on the DBM balance) will generate spurs on the output. And 
the few Hz spurs will multiply up 100 times ot being 150Hz instead of 1.5Hz 
spurs at a gig . I also thought of downconverting (with any XO) by  
aliasing and then using a 455kc or 10.7  or 4.5 5.5 MHz etc IF filter (and then 
chopping and aliasing back up) .  Hmm or a crystal. al la cheap crystal lattice 
filter single xtal.. But now its getting a bit more complex than a 74HC4316 
pair  (as 2 x DBM)  and a microcontroller although HC4316s etc start to 
leak through a bit at 30 MHz. remember the SSB difficulty was as much as the 
(wideband) polyphase quadrature filter (the mass of R and C) performance, and 
design of the day limiting attainable long term carrier suppression.  in this 
case, it is just single freq quadrature at 30 Mhz I need to generate. We will 
see !

cheers



On 02/07/2020 09:40, Bob kb8tq wrote:

Hi

The same “small fraction of a degree” and “small fraction of a db” issues that 
plagued the analog SSB
generation process still get into this approach. For “good” ADEV you need spurs 
down below the
-130 dbc range (and likely much lower). This only gets you to 60 db or so ….

Bob


On Jul 1, 2020, at 5:38 PM, glen english LIST  
 wrote:

Hi Bob

I imagine in physics there are times when you want an oscillator to move a few 
Hz for offset, and the oscillator is fixed due to some physical / atomic 
property.

yes, the whole thing will be phase locked, so no issue with freq error. For a 
fixed frequency operation , +45 and -45 deg networks for the HF will be 
accurate enough.I'll actually look at generating it out of the micro that 
is already on the board (as it loads the PLL and also indicates to the user 
presence of 10 MHz and input level) . see what the jitter calculates to be.

Anyway, thats one way to do it I guess if you have a source that is not quite 
where you want it but otherwise good.

hi hi , an SSB generator ha ha who'd thought I would be back in analog SSB 
generators after my years in SDR...

g

On 2/07/2020 12:14 am, Bob kb8tq wrote:

Hi

There is a NIST paper (somewhere) that has an example of doing this. Like any 
image
reject mixer approach, it only does just so well. It’s no different than 
generating SSB
the same way. You get a spur that is 40 to 60 db down at the “image” frequency. 
You can
tweak this or that to get it to the 60 db point, how long it will stay there …. 
that depends … :)

Since you are summing a very low frequency signal with a very high frequency 
one, the
accuracy of the low frequency signal does not need to be very good. A 1% 
accurate
5 Hz will be off by 0.05 Hz. Your combo also will only be off by 0.05Hz. For a 
lot of
Ham sort of stuff, that’s plenty good enough.

Indeed, the noise of the 5Hz and the mixer setup does get into the act. That may
rule out a simple R/C oscillator as the source of the 5 Hz “tone”…..

Bob


On Jun 30, 2020, at 9:36 PM, glen english LIST  
 wrote:

Hello group

I have an idea that might work, and I wanted to discuss  with likeminded that 
might already have experience with the problem.

Shifting a fixed oscillator a few Hz using a image reject mixer.

background : From time to time I (and others) make lock boards for ham gear, 
pulling the internal VCXO (vary from 11 to 55 MHz ish - which are out by a few 
Hz ) in against a 10 MHz input. Frequency accuracy is required for narrow band 
modes, and low phase noise 10kHz-200kHz is required as not to desense your ham 
neighbours.

I use fast LVDS diff receivers to square stuff up and ADF4157 high res fract 
and about 10Hz BW. That's all fine.  That aside, there are a bunch of radio 
that have on

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

[jimlux]

On 7/1/20 11:21 PM, Gerhard Hoffmann wrote:


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.


Certainly, but when wire wrapping that big panel, and using a different 
color of wire for the V+ and V-, it sure makes it easier. 




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!


I'm surprised nobody has suggested using the 12AX7 or 6J6 dual triodes.

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[time-nuts] Price for HP5371A Sought

[Peter Worrall]

I shall shortly be selling my 5371A.
All working two channel pods and a battery change about 5 years ago.

What would be a suitable asking price?

Peter Worrall
G4GJL
Staines, UK
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Re: [time-nuts] low power divide by 5

[ew via time-nuts]

161 and 163 are candidates. Back in the early 70's my favorite for my counter 
work  was the 74S112 dual JK. So I went to DigiKey to check on CD74AC112 they 
have in stock so with two of those along with an AND gate you can make as many 
divide as 5 as you need.  Just like the S112 it clocks over 100 MHz!
Bert Kehren
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Re: [time-nuts] 1PPS questions

[Bob kb8tq]

Hi

Probably the easiest approach is an L pad at the input to the measurement 
device. 
Something like a 470 ohm in series and a 120 ohm to ground. A 50 ohm pad 
may not make the line driver in the source device very happy ….

Something more exotic would be to do a distribution amp. Use a NC7SZ125 at the 
input so it’s 5V tolerant. Run however many of them you need to drive the 
desired
number of outputs.  Power it all off of 2V and you have 2V p-p output(s).

Keep in mind that 2V p-p “logic” signals may or may not trigger CMOS level 
stuff 
powered off of 3.3V. CMOS running on 5V gets into the “not going to happen” 
area. 

Bob



> On Jul 1, 2020, at 9:37 PM, VE7HR  wrote:
> 
> Are there any suggested method to reduce your 1 PPS signal to a safe level 
> for your test equipment?
> It seems like my HP Z8316A is outputting slightly more than 5V into 50 Ohms. 
> 
> Up till now I have been using a 10 MHz output from the Z3816A. But I 
> understand 1PPS is a better signal to put to Channel A. 
> 
> My HP 5372A seems to default to 2V Max level if you hit instrument default.  
> I am starting to like it so I don’t want to trash an input module.  
> 
> I think I might try a TICC in the near future but for now I will have to slum 
> with the vintage HP iron. 
> 
> Thanks
> Dave
> VE7HR 
> 
> Sent from my iPhone
> ___
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Re: [time-nuts] low power divide by 5

[Bob kb8tq]

Hi

For vacuum tube divide by 5 / 10 circuits, take a look at the schematics of the 
Beckman EPUT meters…..

Bob

> On Jul 2, 2020, at 9:48 AM, Tom Van Baak  wrote:
> 
> > I'm surprised nobody has suggested using the 12AX7 or 6J6 dual triodes.
> 
> Jim,
> 
> Funny, just yesterday I was looking at the design of a laboratory cesium beam 
> standard from 1963. Sorry, there's no divide-by-5 example in there. But the 
> attached images show the 108x multiplier (8.5 MHz to 9180 MHz). Sure enough, 
> spot the 12AX7 and 6J6 tubes in use...
> 
> /tvb
> 
> <1963-cesium-1.jpg><1963-cesium-2.jpg><1963-cesium-3.jpg>___
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Re: [time-nuts] low power divide by 5

[John Ackermann]

That's a very early use of "MHz" rather than "Mc"!

On Jul 2, 2020, 9:50 AM, at 9:50 AM, Tom Van Baak  wrote:
>> I'm surprised nobody has suggested using the 12AX7 or 6J6 dual
>triodes.
>
>Jim,
>
>Funny, just yesterday I was looking at the design of a laboratory
>cesium 
>beam standard from 1963. Sorry, there's no divide-by-5 example in
>there. 
>But the attached images show the 108x multiplier (8.5 MHz to 9180 MHz).
>
>Sure enough, spot the 12AX7 and 6J6 tubes in use...
>
>/tvb
>
>
>
>
>
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Re: [time-nuts] low power divide by 5

[Richard (Rick) Karlquist]

The sum of propagation delay (~15 ns) and setup time (~5 ns)
in the 74AC161 gives just enough time to operate at 50 MHz,
based on the data sheet.  Of course, at room temp, the chip
will beat the data sheet by an undetermined margin.

The fact that the clock frequency is specified at 103 MHz
applies only to a free running configuration (divide by
2, 4, 8, or 16 only) and is irrelevant to dividing by 5.
If only there were a 74HC160 version.  Actually, you
can get them from Rochester Electronics ... but you have
to buy $250 worth minimum.

As noted, my favorite trick of connecting pin 11 to pin 9
is no help in this logic family because they finally did
the carry out correctly.

Rick N6RK

On 7/2/2020 7:03 AM, ew via time-nuts wrote:

161 and 163 are candidates. Back in the early 70's my favorite for my counter 
work  was the 74S112 dual JK. So I went to DigiKey to check on CD74AC112 they 
have in stock so with two of those along with an AND gate you can make as many 
divide as 5 as you need.  Just like the S112 it clocks over 100 MHz!
Bert Kehren
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Re: [time-nuts] Price for HP5371A Sought

[Mike Ingle]

HI Peter,

Ebay.de just sold one with OCXO for 350 euro
HP 5371A Frequency & Time Interval Analyzer, frequency counter OCXO calling
up the original offer

[image: HP-5371A-Frequency-amp-Time-Interval-Analyzer-Frequency
Counter-OCXO]
[image: Item ended]

Item condition:
Second hand
Completed:
Jun 29, 2020 5:45 p.m. CEST
Price:
EUR 350,00
Shipping:
EUR 25,00 Standard shipping
Item location:
Wuppertal, Germany
Seller:
topsound1  ( 3825

 )
|
Seller's Other Items


On Thu, Jul 2, 2020 at 4:20 PM Peter Worrall  wrote:

> I shall shortly be selling my 5371A.
> All working two channel pods and a battery change about 5 years ago.
>
> What would be a suitable asking price?
>
> Peter Worrall
> G4GJL
> Staines, UK
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Re: [time-nuts] low power divide by 5

[Robert LaJeunesse]

Makes me think one could use the input signal edge to synchronize a 2N6027 
based programmable unijunction oscillator, thus effecting a divide by 5. 
Unlikely the 6027 would be fast enough for 50 MHz, but maybe a 2 transistor 
equivalent using RF transistors? Output would be nowhere near the 40%-60% 
range, though. Might just have to build one for fun.

> Sent: Thursday, July 02, 2020 at 8:37 AM
> From: "jimlux" 
> To: time-nuts@lists.febo.com
> Subject: Re: [time-nuts] low power divide by 5
...
> I'm surprised nobody has suggested using the 12AX7 or 6J6 dual triodes.


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Re: [time-nuts] 1PPS questions

[Dana Whitlow]

I like Bob's suggestion about using an L-pad.  Even if the line driver *is*
happy driving
50 ohm line (which I was admittedly assuming), the L-pad approach will keep
the
driver cooler which will likely reduce warmup drift of its propagation
delay as well as
extend its lifetime.

Dana


On Thu, Jul 2, 2020 at 9:20 AM Bob kb8tq  wrote:

> Hi
>
> Probably the easiest approach is an L pad at the input to the measurement
> device.
> Something like a 470 ohm in series and a 120 ohm to ground. A 50 ohm pad
> may not make the line driver in the source device very happy ….
>
> Something more exotic would be to do a distribution amp. Use a NC7SZ125 at
> the
> input so it’s 5V tolerant. Run however many of them you need to drive the
> desired
> number of outputs.  Power it all off of 2V and you have 2V p-p output(s).
>
> Keep in mind that 2V p-p “logic” signals may or may not trigger CMOS level
> stuff
> powered off of 3.3V. CMOS running on 5V gets into the “not going to
> happen”
> area.
>
> Bob
>
>
>
> > On Jul 1, 2020, at 9:37 PM, VE7HR  wrote:
> >
> > Are there any suggested method to reduce your 1 PPS signal to a safe
> level for your test equipment?
> > It seems like my HP Z8316A is outputting slightly more than 5V into 50
> Ohms.
> >
> > Up till now I have been using a 10 MHz output from the Z3816A. But I
> understand 1PPS is a better signal to put to Channel A.
> >
> > My HP 5372A seems to default to 2V Max level if you hit instrument
> default.  I am starting to like it so I don’t want to trash an input
> module.
> >
> > I think I might try a TICC in the near future but for now I will have to
> slum with the vintage HP iron.
> >
> > Thanks
> > Dave
> > VE7HR
> >
> > Sent from my iPhone
> > ___
> > 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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[time-nuts] Incorrect date on Thunderbolt

[Keith E. Brandt, MD, MPH]

Apologies if this equine has been flagellated, but I wasn't pulling up 
anything in searches.


I pulled my Thunderbolt out of mothballs this week. It initialized and 
started tracking satellites very nicely, but the date is showing 
'16Nov00'. The day has incremented at UTC midnight the past 2 days and 
the time is accurate.


Is this a known issue? Suggestions on correcting?

Thanks,
Keith


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

[ed breya]

It's been fun reminiscing about all these dividers and techniques, but 
getting back to the OP, the original search was for a divide by 5 with 
"low power" and operation from 5 to possibly 3.3V, and clocking properly 
at 50 MHz. One would assume also minimal size and complexity, and low cost.


One piece of info that is missing, is how many of these are needed. If 
it's a one-off situation, that's way different from mass production and 
assured parts availability. If only one or a few are needed, then I'd 
contend that the 74AC390 is the way to go. It definitely will work at 
the lower end of the supply range, and is the simplest in parts count - 
one piece, and no doubts about external prop delays that would be 
associated with getting other types to divide by 5.


If there are truly lots of NOS ones out there, it should possible to 
just buy a bunch for all anticipated needs. I can't imagine they would 
be very expensive, except for the issues of volume versus transaction 
cost. I've never tried to buy old parts from these kinds of 
distributors, but I would imagine there would be minimum order 
requirements or fixed cost. So, getting one piece might cost $100, while 
getting a hundred pieces may be $110, and so on. There's no harm in 
asking and negotiating.


Ed


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

[jimlux]

On 7/2/20 6:48 AM, Tom Van Baak wrote:

 > I'm surprised nobody has suggested using the 12AX7 or 6J6 dual triodes.

Jim,

Funny, just yesterday I was looking at the design of a laboratory cesium 
beam standard from 1963. Sorry, there's no divide-by-5 example in there. 
But the attached images show the 108x multiplier (8.5 MHz to 9180 MHz). 
Sure enough, spot the 12AX7 and 6J6 tubes in use...


/tvb




Yeah, but I think those are multipliers, not dividers.


So then, what shall we call it. PICDIV draws from the PIC.  Next thing 
from TAPR,  catering to the retropunk style, will be a TUBEDIV or EJDIV 
(Eccles-Jordan homage) - what better to drive your nixie (or stacked 
neon bulb) display than a 19" rack full of modules.


I'm sure if one looks at pictures from WW 2 era, there's plenty of this 
around.


If I didn't have many other projects going, that might be a cool one. 
Lots of folks have binary clocks on their desks at work, but they're LED 
and solid state.  A few have Nixie clocks, but solid state driven.


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

[Hal Murray]

> Funny, just yesterday I was looking at the design of a laboratory cesium
> beam standard from 1963. Sorry, there's no divide-by-5 example in there.  But
> the attached images show the 108x multiplier (8.5 MHz to 9180 MHz).  Sure
> enough, spot the 12AX7 and 6J6 tubes in use... 

Neat.  Thanks.

Interesting.  I'd expect transistors to be in use by 1963.

When did tubes die out?

How fast were transistors back then?  How fast could you toggle a 12AX7?

Wikipedia says the first 7090 was installed Dec 1959.  The core memory cycled 
at 2 microseconds.

Was 9180 MHz fast enough that it required a tube so it was simpler to use 
tubes on the rest of the logic?

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

[Gary Woods]

On Thu, 2 Jul 2020 19:23:03 +0200, you wrote:

>Makes me think one could use the input signal edge to synchronize a 2N6027 
>based programmable unijunction oscillator, thus effecting a divide by 5. 
>Unlikely the 6027 would be fast enough for 50 MHz, but maybe a 2 transistor 
>equivalent using RF transistors? Output would be nowhere near the 40%-60% 
>range, though. Might just have to build one for fun.

And _that_ makes me think of an early Navy airborne Loran set that
used step counters to make the time base.  Adjustments were through
holes in the side of the case, because some poor soul would have to
tweak them now and again.
-- 
Gary Woods O- K2AHC   Public keys at home.earthlink.net/~garygarlic, or get 
0x1D64A93D via keyserver
fingerprint =  E2 6F 50 93 7B C7 F3 CA  1F 8B 3C C0 B0 28 68 

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Re: [time-nuts] Incorrect date on Thunderbolt

[Taka Kamiya via time-nuts]

I'm sure it's a ROLL-OVER issue where date string buffer for date isn't long 
enough.  Only thing we can do is to correct it in software.  Most "stuff" such 
as Lady Heather knows about this and if date is unreasonable, it will correct 
it when displaying date.  No fundamental fix at GPS level, as far as I know.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, July 2, 2020, 1:53:27 PM EDT, Keith E. Brandt, MD, MPH 
 wrote:  
 
 Apologies if this equine has been flagellated, but I wasn't pulling up 
anything in searches.

I pulled my Thunderbolt out of mothballs this week. It initialized and 
started tracking satellites very nicely, but the date is showing 
'16Nov00'. The day has incremented at UTC midnight the past 2 days and 
the time is accurate.

Is this a known issue? Suggestions on correcting?

Thanks,
Keith


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

[Peter McCollum]

Another way to achieve divide-by-N is with a non-retriggerable one-shot,
adjusted to the appropriate time value.
Back in the 40's/50's, the common tube circuit was called a Phantastron
(really, look it up!).
Phantastron dividers were used in several of the early HP counters (i.e.
HP524B), because you could achieve (for example) a decade divider with a
single tube, whereas a 'binary' solution requires 4 tubes (like in the HP
AC-4A decades).

If a 50% duty cycle is needed, then do a divide by N/2 with a Phantastron,
then a single flip-flop gives you 'N' with a 50% duty.

Note that the Phantastron type divider only works if the input freq is
known and fixed, because the one-shot delay has to be adjusted to a
specific value.

Pete


On Thu, Jul 2, 2020 at 2:29 PM Gary Woods  wrote:

> On Thu, 2 Jul 2020 19:23:03 +0200, you wrote:
>
> >Makes me think one could use the input signal edge to synchronize a
> 2N6027 based programmable unijunction oscillator, thus effecting a divide
> by 5. Unlikely the 6027 would be fast enough for 50 MHz, but maybe a 2
> transistor equivalent using RF transistors? Output would be nowhere near
> the 40%-60% range, though. Might just have to build one for fun.
>
> And _that_ makes me think of an early Navy airborne Loran set that
> used step counters to make the time base.  Adjustments were through
> holes in the side of the case, because some poor soul would have to
> tweak them now and again.
> --
> Gary Woods O- K2AHC   Public keys at home.earthlink.net/~garygarlic, or
> get 0x1D64A93D via keyserver
> fingerprint =  E2 6F 50 93 7B C7 F3 CA  1F 8B 3C C0 B0 28 68
>
> --
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
>
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Re: [time-nuts] low power divide by 5

[Bob kb8tq]

Hi

> On Jul 2, 2020, at 2:34 PM, Hal Murray  wrote:
> 
> 
>> Funny, just yesterday I was looking at the design of a laboratory cesium
>> beam standard from 1963. Sorry, there's no divide-by-5 example in there.  But
>> the attached images show the 108x multiplier (8.5 MHz to 9180 MHz).  Sure
>> enough, spot the 12AX7 and 6J6 tubes in use... 
> 
> Neat.  Thanks.
> 
> Interesting.  I'd expect transistors to be in use by 1963.

Some at low frequency, not a lot for high speed in production gear. A bit 
faster in 
terms of one of a kind lab devices. 

> 
> When did tubes die out?

They have yet to die out ….. :)

> 
> How fast were transistors back then?

The typical germanium transistor of the day was lucky to have an Ft rated in 
MHz 
(yes a slight exaggeration)

>  How fast could you toggle a 12AX7?

Depends on how fancy you wanted to get …. 10 MHz to 100 MHz.

Bob

> 
> Wikipedia says the first 7090 was installed Dec 1959.  The core memory cycled 
> at 2 microseconds.
> 
> Was 9180 MHz fast enough that it required a tube so it was simpler to use 
> tubes on the rest of the logic?
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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Re: [time-nuts] low power divide by 5

[jimlux]

On 7/2/20 11:37 AM, ed breya wrote:
It's been fun reminiscing about all these dividers and techniques, but 
getting back to the OP, the original search was for a divide by 5 with 
"low power" and operation from 5 to possibly 3.3V, and clocking properly 
at 50 MHz. One would assume also minimal size and complexity, and low cost.


You forgot to add rad-hard.. I was the OP - This has been a fascinating 
thing - we have a breadboard that uses a fancy clock distribution chip 
that consumes close to a watt (and has too much jitter, as well)..




I was thinking on the long commute to (tele)work from downstairs to 
upstairs (or maybe on the commute home going the other way).. You know, 
we don't need all that functionality in the clock chip, there must be a 
way to do a divide by 5, and that has good noise properties - 2 and 4 
are trivially easy (I thought), there's probably some easy way to hook 
up 3 (or 4) flipflops and get a nice divide by 5, and maybe even 50/50 
duty cycle out.


So I posted the question - because I've seen discussion of good divider 
designs here, and I was sure that someone would come with a novel 
suggestion.


What I have learned is that

1) All those clever handbook designs and data sheets that I grew up with 
in the 70s,80s, and 90s are just the ticket, but you can't actually get 
the SSI MSI parts any more.


2) One can brute force design simple functions by just trying all 
possible connections and see if it works. What a clever idea!  All that 
work with Karnaugh maps, etc. trying to come up with minimalist designs, 
and you can let your idiot savant assistant (the computer) just grind 
through all possible designs.   Of course, now that you have that clever 
efficient design, because of #1, you can't build it.


3) It's hard to even find programmable logic that is simple and small. 
All the mfrs tout their latest tiny parts with *only half a million 
gates* (I exaggerate, but you get the picture)


4) What I'd be happy to do for a room temperature breadboard probably 
won't work over temperature - and an "existence proof" that it can be 
done at room temp doesn't mean you can find parts to build it to work 
over temp (See #1, again)







One piece of info that is missing, is how many of these are needed. If 
it's a one-off situation, that's way different from mass production and 
assured parts availability. If only one or a few are needed, then I'd 
contend that the 74AC390 is the way to go. It definitely will work at 
the lower end of the supply range, and is the simplest in parts count - 
one piece, and no doubts about external prop delays that would be 
associated with getting other types to divide by 5.






If there are truly lots of NOS ones out there, it should possible to 
just buy a bunch for all anticipated needs. I can't imagine they would 
be very expensive, except for the issues of volume versus transaction 
cost. I've never tried to buy old parts from these kinds of 
distributors, but I would imagine there would be minimum order 
requirements or fixed cost. So, getting one piece might cost $100, while 
getting a hundred pieces may be $110, and so on. There's no harm in 
asking and negotiating.


We *are* building the eventual system to fly, and yeah, we've got tubes 
and tubes of old ICs at work (JPL) or, as Rick mentioned, there's always 
Rochester Electronics, who have a warehouse full of old wafers and dice. 
But I'd rather not.


For those who come after me, and are perusing the archives (thank you 
google) - here's some reasons why old parts are a pain (and a curse).


1) Reliability people freak out about packages that have not been kept 
in absolutely pristine conditions with a full paperwork trail of 
certifications. The humidity might have gone up. Oxygen or Helium might 
have leaked in. There might have been latent ESD damage.  So you'd have 
a tube of parts with date codes from the 80s or 90s that *work* (over 
temp, etc.), but the mission assurance folks will want a bunch of them 
to do destructive analysis. Making sure there's no latent degradation, 
etc.  That can cost a lot.


2) You CAN get parts from Rochester, and they're freshly packaged, from 
known good dice, etc. That's not cheap either.  But, is probably cheaper 
than #1.


3) the biggest reason - There are innumerable cases where someone used 
"end of life" or "flight spare" parts, just this once.  And then, the 
next mission comes along and wants to do a "build to print" to claim 
heritage - and you spend a lot of time trying to track down NOS parts, 
or in design reviews trying to say "well even though all the parts are 
different, except the resistors, it really isn't a new design".


We used the Xilinx Virtex II in several of our radios that have flown to 
Mars (in the Electra UHF radio on all the rovers since 2003, for 
instance).   I think we have the largest stock of flight qualified 
Virtex IIs in the world, because people still want to use Electra 
radios, as a "build to print".

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

[Bob kb8tq]

Hi

> On Jul 2, 2020, at 5:30 PM, jimlux  wrote:
> 
> On 7/2/20 11:37 AM, ed breya wrote:
>> It's been fun reminiscing about all these dividers and techniques, but 
>> getting back to the OP, the original search was for a divide by 5 with "low 
>> power" and operation from 5 to possibly 3.3V, and clocking properly at 50 
>> MHz. One would assume also minimal size and complexity, and low cost.
> 
> You forgot to add rad-hard.. I was the OP - This has been a fascinating thing 
> - we have a breadboard that uses a fancy clock distribution chip that 
> consumes close to a watt (and has too much jitter, as well)..
> 
> 
> 
> I was thinking on the long commute to (tele)work from downstairs to upstairs 
> (or maybe on the commute home going the other way).. You know, we don't need 
> all that functionality in the clock chip, there must be a way to do a divide 
> by 5, and that has good noise properties - 2 and 4 are trivially easy (I 
> thought), there's probably some easy way to hook up 3 (or 4) flipflops and 
> get a nice divide by 5, and maybe even 50/50 duty cycle out.
> 
> So I posted the question - because I've seen discussion of good divider 
> designs here, and I was sure that someone would come with a novel suggestion.
> 
> What I have learned is that
> 
> 1) All those clever handbook designs and data sheets that I grew up with in 
> the 70s,80s, and 90s are just the ticket, but you can't actually get the SSI 
> MSI parts any more.
> 
> 2) One can brute force design simple functions by just trying all possible 
> connections and see if it works. What a clever idea!  All that work with 
> Karnaugh maps, etc. trying to come up with minimalist designs, and you can 
> let your idiot savant assistant (the computer) just grind through all 
> possible designs.   Of course, now that you have that clever efficient 
> design, because of #1, you can't build it.
> 
> 3) It's hard to even find programmable logic that is simple and small. All 
> the mfrs tout their latest tiny parts with *only half a million gates* (I 
> exaggerate, but you get the picture)

If they want to sell you a fully self contained "million gate" device for a 
couple bucks, is that really
a bad thing?  Sure, if it’s in a thousand pin BGA, it’s a bad thing. If it’s in 
a < 40 pin package that 
you can get on a small board …. maybe not so much.

Bob


> 
> 4) What I'd be happy to do for a room temperature breadboard probably won't 
> work over temperature - and an "existence proof" that it can be done at room 
> temp doesn't mean you can find parts to build it to work over temp (See #1, 
> again)
> 
> 
> 
> 
>> One piece of info that is missing, is how many of these are needed. If it's 
>> a one-off situation, that's way different from mass production and assured 
>> parts availability. If only one or a few are needed, then I'd contend that 
>> the 74AC390 is the way to go. It definitely will work at the lower end of 
>> the supply range, and is the simplest in parts count - one piece, and no 
>> doubts about external prop delays that would be associated with getting 
>> other types to divide by 5.
> 
> 
> 
>> If there are truly lots of NOS ones out there, it should possible to just 
>> buy a bunch for all anticipated needs. I can't imagine they would be very 
>> expensive, except for the issues of volume versus transaction cost. I've 
>> never tried to buy old parts from these kinds of distributors, but I would 
>> imagine there would be minimum order requirements or fixed cost. So, getting 
>> one piece might cost $100, while getting a hundred pieces may be $110, and 
>> so on. There's no harm in asking and negotiating.
> 
> We *are* building the eventual system to fly, and yeah, we've got tubes and 
> tubes of old ICs at work (JPL) or, as Rick mentioned, there's always 
> Rochester Electronics, who have a warehouse full of old wafers and dice. But 
> I'd rather not.
> 
> For those who come after me, and are perusing the archives (thank you google) 
> - here's some reasons why old parts are a pain (and a curse).
> 
> 1) Reliability people freak out about packages that have not been kept in 
> absolutely pristine conditions with a full paperwork trail of certifications. 
> The humidity might have gone up. Oxygen or Helium might have leaked in. There 
> might have been latent ESD damage.  So you'd have a tube of parts with date 
> codes from the 80s or 90s that *work* (over temp, etc.), but the mission 
> assurance folks will want a bunch of them to do destructive analysis. Making 
> sure there's no latent degradation, etc.  That can cost a lot.
> 
> 2) You CAN get parts from Rochester, and they're freshly packaged, from known 
> good dice, etc. That's not cheap either.  But, is probably cheaper than #1.
> 
> 3) the biggest reason - There are innumerable cases where someone used "end 
> of life" or "flight spare" parts, just this once.  And then, the next mission 
> comes along and wants to do a "build to print" to claim heritage - and you 
> spe

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

[jimlux]

On 7/2/20 2:13 PM, Peter McCollum wrote:

Another way to achieve divide-by-N is with a non-retriggerable one-shot,
adjusted to the appropriate time value.
Back in the 40's/50's, the common tube circuit was called a Phantastron
(really, look it up!).
Phantastron dividers were used in several of the early HP counters (i.e.
HP524B), because you could achieve (for example) a decade divider with a
single tube, whereas a 'binary' solution requires 4 tubes (like in the HP
AC-4A decades).

If a 50% duty cycle is needed, then do a divide by N/2 with a Phantastron,
then a single flip-flop gives you 'N' with a 50% duty.

Note that the Phantastron type divider only works if the input freq is
known and fixed, because the one-shot delay has to be adjusted to a
specific value.

Pete



And you can be clever if you can trigger on both rising and falling 
edges, so you get basically a x2 and a divide by 5 in the same circuit, 
followed by the divide by 2 to make the duty cycle 50/50.



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

[jimlux]

On 7/2/20 2:50 PM, Bob kb8tq wrote:

Hi


On Jul 2, 2020, at 5:30 PM, jimlux  wrote:

On 7/2/20 11:37 AM, ed breya wrote:

It's been fun reminiscing about all these dividers and techniques, but getting back to 
the OP, the original search was for a divide by 5 with "low power" and 
operation from 5 to possibly 3.3V, and clocking properly at 50 MHz. One would assume also 
minimal size and complexity, and low cost.


You forgot to add rad-hard.. I was the OP - This has been a fascinating thing - 
we have a breadboard that uses a fancy clock distribution chip that consumes 
close to a watt (and has too much jitter, as well)..



3) It's hard to even find programmable logic that is simple and small. All the 
mfrs tout their latest tiny parts with *only half a million gates* (I 
exaggerate, but you get the picture)


If they want to sell you a fully self contained "million gate" device for a 
couple bucks, is that really
a bad thing?  Sure, if it’s in a thousand pin BGA, it’s a bad thing. If it’s in a 
< 40 pin package that
you can get on a small board …. maybe not so much.


yes, if it's in a small pinout package. One other peculiarity that I've 
been burned by is that a lot of the modern devices with large logic and 
few I/O pins have power dissipations that are clock rate independent 
for the internal logic - it's the leakage current that dominates and 
that's VERY dependent on die temp.



I think though, that the marketplace is driving towards increased 
functionality on one chip, with bigger die size. Those of us who want 50 
gates at medium or low speed are distinctly in the minority.



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

[Bob kb8tq]

Hi

> On Jul 2, 2020, at 6:38 PM, jimlux  wrote:
> 
> On 7/2/20 2:50 PM, Bob kb8tq wrote:
>> Hi
>>> On Jul 2, 2020, at 5:30 PM, jimlux  wrote:
>>> 
>>> On 7/2/20 11:37 AM, ed breya wrote:
 It's been fun reminiscing about all these dividers and techniques, but 
 getting back to the OP, the original search was for a divide by 5 with 
 "low power" and operation from 5 to possibly 3.3V, and clocking properly 
 at 50 MHz. One would assume also minimal size and complexity, and low cost.
>>> 
>>> You forgot to add rad-hard.. I was the OP - This has been a fascinating 
>>> thing - we have a breadboard that uses a fancy clock distribution chip that 
>>> consumes close to a watt (and has too much jitter, as well)..
>> 
>>> 3) It's hard to even find programmable logic that is simple and small. All 
>>> the mfrs tout their latest tiny parts with *only half a million gates* (I 
>>> exaggerate, but you get the picture)
>> If they want to sell you a fully self contained "million gate" device for a 
>> couple bucks, is that really
>> a bad thing?  Sure, if it’s in a thousand pin BGA, it’s a bad thing. If it’s 
>> in a < 40 pin package that
>> you can get on a small board …. maybe not so much.
> 
> yes, if it's in a small pinout package. One other peculiarity that I've been 
> burned by is that a lot of the modern devices with large logic and few I/O 
> pins have power dissipations that are clock rate independent for the internal 
> logic - it's the leakage current that dominates and that's VERY dependent on 
> die temp.
> 
> 
> I think though, that the marketplace is driving towards increased 
> functionality on one chip, with bigger die size. Those of us who want 50 
> gates at medium or low speed are distinctly in the minority.

There are very few applications that require that sort of device. Volume
matters ( a lot !!)

Bob


> 
> 
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Re: [time-nuts] 1PPS questions

[VE7HR]

Hi Dana,
I will look closer at the 1 PPS.  
I found I had the scope setup wrong and the 1 PPS is 3.84V when terminated in 
50 Ohms.  
And about 5V with overshoot when terminates in a higher impedance.  I will take 
some measurements and determine the output impedance of the GPSDO 1PPS and 
design a suitable pad.  Since the pods of the 5372A are always terminated in 50 
Ohms the risk of damage is much less.  

I will also look at how HP did the 2.5:1 attenuator in the pod.  It might be a 
good place to start on an external attenuator design. 

Thanks for suggestions.  

Dave
VE7HR 

Sent from my iPhone

> On Jul 2, 2020, at 10:53 AM, Dana Whitlow  wrote:
> 
> I like Bob's suggestion about using an L-pad.  Even if the line driver *is*
> happy driving
> 50 ohm line (which I was admittedly assuming), the L-pad approach will keep
> the
> driver cooler which will likely reduce warmup drift of its propagation
> delay as well as
> extend its lifetime.
> 
> Dana
> 
> 
>> On Thu, Jul 2, 2020 at 9:20 AM Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> Probably the easiest approach is an L pad at the input to the measurement
>> device.
>> Something like a 470 ohm in series and a 120 ohm to ground. A 50 ohm pad
>> may not make the line driver in the source device very happy ….
>> 
>> Something more exotic would be to do a distribution amp. Use a NC7SZ125 at
>> the
>> input so it’s 5V tolerant. Run however many of them you need to drive the
>> desired
>> number of outputs.  Power it all off of 2V and you have 2V p-p output(s).
>> 
>> Keep in mind that 2V p-p “logic” signals may or may not trigger CMOS level
>> stuff
>> powered off of 3.3V. CMOS running on 5V gets into the “not going to
>> happen”
>> area.
>> 
>> Bob
>> 
>> 
>> 
 On Jul 1, 2020, at 9:37 PM, VE7HR  wrote:
>>> 
>>> Are there any suggested method to reduce your 1 PPS signal to a safe
>> level for your test equipment?
>>> It seems like my HP Z8316A is outputting slightly more than 5V into 50
>> Ohms.
>>> 
>>> Up till now I have been using a 10 MHz output from the Z3816A. But I
>> understand 1PPS is a better signal to put to Channel A.
>>> 
>>> My HP 5372A seems to default to 2V Max level if you hit instrument
>> default.  I am starting to like it so I don’t want to trash an input
>> module.
>>> 
>>> I think I might try a TICC in the near future but for now I will have to
>> slum with the vintage HP iron.
>>> 
>>> Thanks
>>> Dave
>>> VE7HR
>>> 
>>> Sent from my iPhone
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Re: [time-nuts] low power divide by 5

[Bruce Griffiths]

For fixed frequency operation there's always Wenzel's divider using a D FF with 
LC feedback:
http://www.wenzel.com/wp-content/uploads/dividers.pdf
At least the power consumption is low.

Bruce
> On 03 July 2020 at 12:35 Bob kb8tq  wrote:
> 
> 
> Hi
> 
> > On Jul 2, 2020, at 6:38 PM, jimlux  wrote:
> > 
> > On 7/2/20 2:50 PM, Bob kb8tq wrote:
> >> Hi
> >>> On Jul 2, 2020, at 5:30 PM, jimlux  wrote:
> >>> 
> >>> On 7/2/20 11:37 AM, ed breya wrote:
>  It's been fun reminiscing about all these dividers and techniques, but 
>  getting back to the OP, the original search was for a divide by 5 with 
>  "low power" and operation from 5 to possibly 3.3V, and clocking properly 
>  at 50 MHz. One would assume also minimal size and complexity, and low 
>  cost.
> >>> 
> >>> You forgot to add rad-hard.. I was the OP - This has been a fascinating 
> >>> thing - we have a breadboard that uses a fancy clock distribution chip 
> >>> that consumes close to a watt (and has too much jitter, as well)..
> >> 
> >>> 3) It's hard to even find programmable logic that is simple and small. 
> >>> All the mfrs tout their latest tiny parts with *only half a million 
> >>> gates* (I exaggerate, but you get the picture)
> >> If they want to sell you a fully self contained "million gate" device for 
> >> a couple bucks, is that really
> >> a bad thing?  Sure, if it’s in a thousand pin BGA, it’s a bad thing. If 
> >> it’s in a < 40 pin package that
> >> you can get on a small board …. maybe not so much.
> > 
> > yes, if it's in a small pinout package. One other peculiarity that I've 
> > been burned by is that a lot of the modern devices with large logic and few 
> > I/O pins have power dissipations that are clock rate independent for the 
> > internal logic - it's the leakage current that dominates and that's VERY 
> > dependent on die temp.
> > 
> > 
> > I think though, that the marketplace is driving towards increased 
> > functionality on one chip, with bigger die size. Those of us who want 50 
> > gates at medium or low speed are distinctly in the minority.
> 
> There are very few applications that require that sort of device. Volume
> matters ( a lot !!)
> 
> Bob
> 
> 
> > 
> > 
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Re: [time-nuts] low power divide by 5

[Hal Murray]

jim...@earthlink.net said:
> 1) All those clever handbook designs and data sheets that I grew up with in
> the 70s,80s, and 90s are just the ticket, but you can't actually get the SSI
> MSI parts any more. 

Are families like AC OK to your Reliability people?  Any projections on how 
long they will be around?

The MSI parts you want may not be available, but the basic SSI chips probably 
are.  That complicates the design and may take another chip or two, but I 
think there is still a good chance of finding a design that works.

What sort of temperature range do you design for?  Is data sheet timing OK or 
do you need reserves on top of that?



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

[ed breya]

Jim,

At the risk of knocking over another bucket of worms, if your definition 
of "low power" can be extended to just beating the needs of the current 
part (circa 1W?), then you can look at ECL and its more modern 
derivatives, which are quite extensive. The classic bi-quinary ECL 
counter is the 10138 - another of my favorites. It's also long obsolete, 
along with a lot of others, and 10H series too. But, a lot of more 
modern ECL parts exist in a number of families, even going down to 3.3V 
and below, and with fairly low power requirements.


I used to be familiar with a lot of the choices, but always forget if 
not revisited often enough. I've seen all sorts of parts in the 100E and 
10Exx families. The fixed-decade counter may be long gone, but there are 
programmable counters in these families that are so fast that it should 
be no sweat to do a divide by 5, with little concern for external prop 
delays in a 50 MHz system. The problem then may be finding something 
small (preferably 4 bits if such exist) enough and slow enough (family 
dependent) to minimize the power, and fast enough to get the job done.


One example is the 10/100E016, which is a power hog because it's 8-bits, 
but can run below 1W at 5V.. I don't know or recall if there are a lot 
more counters (probably not many) to choose from, or which may be at 
risk of going extinct (everything does ultimately). If there are no 
4-bit counters, one trick that may help a little with power is to leave 
off the terminators/loads of all unused outputs, as long as it doesn't 
upset things internally. Also, running as low a supply as possible 
helps, so a 3.3V family should be better, for a given speed class. As 
you can see, it's about ten times as fast as you need, so if any slower 
families can be found, you can save some power. Especially in the "10" 
series, I think the one or two letters that follow, are indicative of 
both brand and speed class - it's a bit confusing to me. Look for the 
base part numbers first, then figure out the letters. A 10EP016 is much 
faster than a 10E016. A 10KP016 is just another brand, as far as I know.


Here's a data sheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/sy10-100e016.pdf

Ed

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Re: [time-nuts] Incorrect date on Thunderbolt

[Hal Murray]

keith.bra...@gmail.com said:
> I pulled my Thunderbolt out of mothballs this week. It initialized and
> started tracking satellites very nicely, but the date is showing  '16Nov00'.
> The day has incremented at UTC midnight the past 2 days and  the time is
> accurate.

The buzzword is WNRO - Week Number Roll Over.
  https://en.wikipedia.org/wiki/GPS_Week_Number_Rollover

There is a 10 bit field for the week number in the GPS data format.  That's 
about 20 years.  GPS has been running for over 40 years now.  It's rolled over 
twice.

You can fix it in software by adding 1024*7 days until you get something that 
is reasonable.  One simple test for reasonable is the date/time the software 
package was compiled.

Some GPS units allow you to give them a starting date/time.  I don't know if 
the TBolt does that.  The HP Z3801A does.



-- 
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Re: [time-nuts] Price for HP5371A Sought

[Rodger via time-nuts]

To provide some perspective.  I paid $180 for an HP-5372a 2 years ago.  All
it needed was the battery replacement and a bit of work on the OCXO.  I
picked it up at a hamfest so there was no shipping cost.  Still working
perfectly 2 years later and stays on almost 24 hrs/day.

Rodger


-Original Message-
From: time-nuts  On Behalf Of Peter
Worrall
Sent: Thursday, July 2, 2020 10:00 AM
To: time-nuts@lists.febo.com
Subject: [time-nuts] Price for HP5371A Sought

I shall shortly be selling my 5371A.
All working two channel pods and a battery change about 5 years ago.

What would be a suitable asking price?

Peter Worrall
G4GJL
Staines, UK
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