[time-nuts] Re: Potting compound advice needed

[djl]

I forgot to mention that it can be removed nicely with hot air, and has 
the very nice property that you can solder things that are coated just 
in case you should make a misteak. it is soft. I did not know the 
epsilon or tand.

Don

On 2021-11-11 17:49, Lux, Jim wrote:

On 11/11/21 4:00 PM, djl wrote:
I've used, wait for it, beeswax as a potting compound. Gouda cheese 
comes coated with it (some has paraffin, get the best,) in a lovely 
red. I also found out some years ago that Catholic churches use pure 
beeswax for large (not votive) candles and may give you the stubs. 
Nice, clean white.  Or, dear ol' Amazon has a huge assortment for 
around $1.00 / oz, in various stages of "purification". For expensive 
beeswax with some unknown sticky additives, use toilet mounting 
rings... (good also for preserving dry milsurp gunstocks, according to 
Anvil.)

73, Don



Beeswax, if perfectly dry, and no carbon residue, is pretty good RF
wise - at 1 MHz, epsilon is around 2.5, tan d is around 0.01 which is
ok, but not great. You could mix it with microballoons to lower
epsilon and dissipation.

It does shrink and, of course, it's pretty soft.


Pointing back to a previous suggestion 3M DP270 - that's 3.5 epsilon
and 0.018 tan d, but at 1kHz.  The graph in the datasheet does show
pretty constant 0.020 up to 1 MHz.

http://www.emesystems.com/pdfs/parts/DP270.pdf

At least it's available in less than a gallon quantities.

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The whole world is a straight man.
--
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
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[time-nuts] Re: Potting compound advice needed

[Lux, Jim]

On 11/11/21 4:00 PM, djl wrote:
I've used, wait for it, beeswax as a potting compound. Gouda cheese 
comes coated with it (some has paraffin, get the best,) in a lovely 
red. I also found out some years ago that Catholic churches use pure 
beeswax for large (not votive) candles and may give you the stubs. 
Nice, clean white.  Or, dear ol' Amazon has a huge assortment for 
around $1.00 / oz, in various stages of "purification". For expensive 
beeswax with some unknown sticky additives, use toilet mounting 
rings... (good also for preserving dry milsurp gunstocks, according to 
Anvil.)
73, Don 



Beeswax, if perfectly dry, and no carbon residue, is pretty good RF wise 
- at 1 MHz, epsilon is around 2.5, tan d is around 0.01 which is ok, but 
not great. You could mix it with microballoons to lower epsilon and 
dissipation.


It does shrink and, of course, it's pretty soft.


Pointing back to a previous suggestion 3M DP270 - that's 3.5 epsilon and 
0.018 tan d, but at 1kHz.  The graph in the datasheet does show pretty 
constant 0.020 up to 1 MHz.


http://www.emesystems.com/pdfs/parts/DP270.pdf

At least it's available in less than a gallon quantities.

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[time-nuts] Re: Potting compound advice needed

[djl]

I've used, wait for it, beeswax as a potting compound. Gouda cheese 
comes coated with it (some has paraffin, get the best,) in a lovely red. 
I also found out some years ago that Catholic churches use pure beeswax 
for large (not votive) candles and may give you the stubs. Nice, clean 
white.  Or, dear ol' Amazon has a huge assortment for around $1.00 / oz, 
in various stages of "purification". For expensive beeswax with some 
unknown sticky additives, use toilet mounting rings... (good also for 
preserving dry milsurp gunstocks, according to Anvil.)

73, Don

On 2021-11-11 15:00, Gregory Beat via time-nuts wrote:

Rick -

Look at 3M Scotch-Weld Epoxy Potting Compound DP270.
https://www.3m.com/3M/en_US/p/d/b40066438/
I purchase from McMaster-Carr (Midwest pickup window is 2 miles from 
house).


This is what I have used, since it is rated for -65° to 350° F and
safe with copper (potting electronics, transformers, etc.)

***
Date: Wed, 10 Nov 2021 14:40:53 -0800
From: "Richard (Rick) Karlquist" 
Subject: [time-nuts] Potting compound advice needed
To: time and frequency measurement T
I am looking for help choosing a potting compound that
has the following properties:

1.  Good for 5,000VAC @ 1 MHz
2.  Low RF losses.
3.  Low permittivity is preferred
4.  Low tempco of permittivity is a want.
5.  Something I can implement in my home shop without access to a
vacuum pump etc. is a want.

Thanks in advance

Rick Karlquist N6RK
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The whole world is a straight man.
--
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
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[time-nuts] Re: Potting compound advice needed

[Gregory Beat via time-nuts]

Rick -

Look at 3M Scotch-Weld Epoxy Potting Compound DP270.
https://www.3m.com/3M/en_US/p/d/b40066438/
I purchase from McMaster-Carr (Midwest pickup window is 2 miles from house).

This is what I have used, since it is rated for -65° to 350° F and safe with 
copper (potting electronics, transformers, etc.)

***
Date: Wed, 10 Nov 2021 14:40:53 -0800
From: "Richard (Rick) Karlquist" 
Subject: [time-nuts] Potting compound advice needed
To: time and frequency measurement T
I am looking for help choosing a potting compound that
has the following properties:

1.  Good for 5,000VAC @ 1 MHz
2.  Low RF losses.
3.  Low permittivity is preferred
4.  Low tempco of permittivity is a want.
5.  Something I can implement in my home shop without access to a vacuum pump 
etc. is a want.

Thanks in advance

Rick Karlquist N6RK
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[time-nuts] Re: Potting compound advice needed

[Lux, Jim]

On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote:

I am looking for help choosing a potting compound that
has the following properties:

1.  Good for 5,000VAC @ 1 MHz
2.  Low RF losses.
3.  Low permittivity is preferred
4.  Low tempco of permittivity is a want.
5.  Something I can implement in my home shop
without access to a vacuum pump etc. is a want.

Thanks in advance

Rick Karlquist N6RK 



After consulting the experts at work, what they use for this kind of 
thing (HVPS, high power RF, etc.) is:



https://www.elantas.com/pdg/products/tooling-composites-materials/gel-encapsulants-sealants.html

Elantas EN-11 (Conap) Casting, Potting and Molding Compound.

epsilon of 2.9 @ 1 MHz

610 V/mil breakdown

tan d of 0.009 at 1 MHz

8 hour cure at 80C, more than a week at 25C. 50 min pot life


your challenge may be finding it in small quantities - a casual search 
shows gallon cans at just under $200, and I'm not sure that you don't 
need to buy a part a and a part b.

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[time-nuts] Re: 1 pps

[Darren Freeman]

On Thu, 2021-11-11 at 14:07 +, Andy Talbot wrote:
> I made a 5MHz doubler plus distribution for my HP5061. You can see
> the
> design at http://g4jnt.com/10MHzDist.pdf  The doubler is a full wave

It's worth noting that the HP5370A has a doubler on the reference
input. It will accept either 5 or 10 MHz, and in the case of 5 MHz, it
doubles.

It may not be as clean as what you need, but the full schematic is in
the service manual.

There is a reasonable chance that I could measure mine and see if it
comes close. Bear in mind that it converts to a square wave in order to
drive the counter, but also back to a sine wave for the reference
output.

Have fun,
Darren
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[time-nuts] 5/10MHz Doubler and Distribution

[Andy Talbot]

Several people have asked for the Gerbers for my  5/10MHz doubler and
distribution amp, that I've now made them available for direct download

Get the latest version of http://g4jnt.com/10MHzDist.pdf just updated
(refresh your browser if it's already in cache) and the link for the
download is given.


Andy
www.g4jnt.com
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[time-nuts] Re: Can ADEV of a frequency source be correctly determined using a continuous time-stamping frequency counter?

[Magnus Danielson via time-nuts]

Hi,

I strongly recommend the HP AN200 series of application notes. Having 
those alongside Enricos slides is a good start for those new in the field.


There is one variant of averaging which is used in the HP5328A/B 
counters that is described there that is not covered in Enrico Rubiolas 
otherwise excellent set of slides.


A more updated version exist in the Rohde, Rubiola, Whitaker "Microwave 
and Wireless Syntesizers" book. The PDEV was not published in 2012, but 
came in 2014. PDEV is now included in the IEEE 1139 draft, going through 
the voting process.


Many modern counters have used the method of charging a capactor and 
then read that charge out either as a pulse (Nutt interpolator) or 
through A/D conversion such as SR-620, Pendulum/Fluke CNT-80/81/90/91 
and Wavecrest DTS and SIAs. Modern FPGA based tapped delay was used 
already in HP5371A but is now used in FPGA and ASIC for higher 
resolution and is for sure comming along strong in commercial and 
academic counters.


Cheers,
Magnus

On 2021-11-11 16:02, Erik Kaashoek wrote:

Lewis
The interesting source you referred to contained a slide deck which 
turned out to be a gold mine for a novice like me.

http://rubiola.org/pdf-slides/2012T-IFCS-Counters.pdf
This should be on leapsecond
Many thanks
Erik.

On 10-11-2021 19:36, Lewis Masters wrote:

Hi,


Anders Wallin has details of a commercially available time stamping 
counter

that will do a proper ADEV measurement.  He also includes links to other
interesting sources.


Search for:

CONT vs RCON mode on the 53230A frequency counter
 - anderswallin.net

1604.05076.pdf (arxiv.org) 


Lew

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[time-nuts] Re: 1 pps

[DM]

Gerhard, 
May I have a copy of the Gerbers for the Doubler-Distribution amp? I started 
designing a PCB for the board myself, but if you could send me a copy of your 
files, surely would save me a ton of time and work. 
Thanks for your willingness to share your work. 

DaveM 
Hazel Green, AL, USA 


From: "Gerhard Hoffmann"  
To: time-nuts@lists.febo.com 
Sent: Wednesday, November 10, 2021 6:52:56 PM 
Subject: [time-nuts] Re: 1 pps 

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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[time-nuts] Re: Can ADEV of a frequency source be correctly determined using a continuous time-stamping frequency counter?

[Erik Kaashoek]

Lewis
The interesting source you referred to contained a slide deck which 
turned out to be a gold mine for a novice like me.

http://rubiola.org/pdf-slides/2012T-IFCS-Counters.pdf
This should be on leapsecond
Many thanks
Erik.

On 10-11-2021 19:36, Lewis Masters wrote:

Hi,

  


Anders Wallin has details of a commercially available time stamping counter
that will do a proper ADEV measurement.  He also includes links to other
interesting sources.

  


Search for:

CONT vs RCON mode on the 53230A frequency counter
 - anderswallin.net

1604.05076.pdf (arxiv.org) 

  


Lew

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[time-nuts] Re: 1 pps

[Andy Talbot]

You seem to have gone to extraordinary lengths to trap out each unwanted
product, yet  the final spectrum shows only -50dBc products.   That seems a
poor return for that effort in filter design.

I made a 5MHz doubler plus distribution for my HP5061. You can see the
design at http://g4jnt.com/10MHzDist.pdf  The doubler is a full wave
rectifier and the filter a three section top capacitor coupled LC
resonator.I achieved better than -80dBc rejection of the 5MHz
fundamental and something like  -75dB at 15MHz but this far down,
measurement is quite a challenge.

For most practical purposes these levels are more than adequate, but I do
sometimes directly multiply up to 10GHz or higher, using this 10MHz source
as the reference input to a PLL synthesizer.   I think I've seen evidence
that even -80dBc at 5MHz can introduce spurii at this level of
multiplication, so really ought to be aiming at -100dBc - but that woul dbe
impossible to measure with any test equipment I have.   Even seeing -80dBc
was a challenge.

Andy
www.g4jnt.com



On Thu, 11 Nov 2021 at 00:53, Gerhard Hoffmann 
wrote:

>
>
> 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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>
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[time-nuts] Re: 1 pps

[B Riches via time-nuts]

 
Thank you Gerhard. Great project!
Bill, WA2DVU
73,
On Wednesday, November 10, 2021, 07:53:20 PM EST, Gerhard Hoffmann 
 wrote:  
 
 

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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[time-nuts] Re: HP/Symmetricom 59551A showing wrong date

[Gregory Beat via time-nuts]

Claude -

Let’s start with the HP/Symmetricom 58503A/59551A manual (leapsecond.com)
http://www.leapsecond.com/museum/hp59551a/097-59551-02-iss-1.pdf

Use an appropriate Serial Cable for the SatStat program to access the 59551A.
The HP/Symmetricom 59551A uses SCPI commands for configuration.
==
Earlier instructions existed here on Time-Nuts for setting the current time to 
the receiver, BEFORE accessing GPS satellite data.  This worked for my 
HP/Symmetricom Reference.
==
Access your HP/Symmetricom 59551A with SatStat, 
while it is disconnected from the GPS antenna (before Satellite Acquisition).
You should be able to set your location coordinates, current date and time in 
NVRAM.
Shown in the Manual, Chapter 5 (CommandReference), page 5-7
“Facilitating Initial Tracking”
==
greg, w9gb

===
Date: Mon, 08 Nov 2021 17:01:05 -0500
From: va2...@ebox.net
Subject: [time-nuts] HP/Symmetricom 59551A showing wrong date
To: time-nuts@lists.febo.com
—
Hello to all members of the list.
I'm testing an HP/Symmetricom 59551A that powers up OK and if I connect
an antenna the "GPS LOCK" LED lights up after a while.

The receiver is tracking satellites, but the status screen shows wrong
date and time, please see attached screen capture.
Is this a case of a GPS receiver not counting week 1024 correctly ?

Thank you for your help,
Claude, VA2HDD
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[time-nuts] Re: Potting compound advice needed

[Javier Herrero]

Hello,

Probably Mupsil was a typo. Mapsil 213B is a silicone-based coating also 
approved (at least by ESA) for space applications.


Regards,

Javier

On 11/11/21 5:56, Lux, Jim wrote:

On 11/10/21 5:31 PM, Gerhard Hoffmann wrote:

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:

_



Yeah, the solithane (that's the name we use) is more used to repair 
conformal coatings, stake fasteners, stick wires down to the board, 
glue components to the board so it will survive vibe (think tall 
skinny things, with the vibe in the plane of the board).  Fairly 
fluid, cures fairly quickly, low outgassing, and most important for 
space - someone else used it and it worked without causing a 
disaster.   There probably is a potting version of it, and I'll ask 
one of the M folks at work tomorrow what they think about Rick's need.


I've not heard of Mupsil, but we use a lot of Nusil - silicone 
elastomers, often with alumina particles in it, as a thermal bonding 
material. Say you've got a box with a fairly flat surface that you 
want to clamp to another fairly flat surface. The problem is that 
tightening the fasteners deforms both surfaces (unless you've got a 
zillion of them) so the thermal contact area is just around the 
fastener, and there is a perhaps a gap everywhere else. Spaceflight 
people hate "perhaps" so they say, ok, put a thermal gasket in there 
(hey, many of us have used a mica washer and silicone grease between 
part and heat sink, right?).  You can get elastomeric thermal gaskets 
from Chomerics and similar companies, but they actually have the same 
problem with clamping force. You tighten the fasteners, but to get the 
required clamping force over the WHOLE gasket, you need a lot of 
fasteners, or a lot of force, and you're back to the deformation problem.


So the answer is "thermally conductive glue" - you slather a thin 
layer on, tighten the fasteners, which then causes the alumina 
particles to poke into the surfaces on both sides, and hey - good 
thermal conductivity.  Of course, if you need to take it off, you need 
to get in there with a wire saw and that's "not fun".


I will say the nifty-est thermal connection was a sort of velvet made 
of carbon fibers. Carbon fibers have very high thermal conductivity. 
You bond that furry velvet to both surfaces, and when you put it 
together, the fibers slide along each other and make good contact 
along their length, and there's millions of them. You aren't depending 
on clamping force - it's the springyness of the very stiff fibers that 
provides the contact force, and as you can imagine, it can tolerate a 
lot of misalignment and gaps.


The actual stuff was developed originally to make a very optically 
absorbing black coating over wide bandwidths - all those fibers bounce 
the light around. And as a laser load (instead of the proverbial stack 
of razor blades.  It was then was used to coat mannequin forms, for 
displaying lingerie for Victoria's Secret, of all places, because it 
was very rugged and didn't shed lint.  There's a whole exotic trade 
secret about how they make the velvet - there's some sort of 
electrostatic technique to making the fibers stand on end while 
they're bonded, and some other exotic trick to getting them all the 
same length, and so forth. I kept trying to use it in space (it is 
*so* much easier than glue, gaskets, or zillions of fasteners), but it 
never took -> 1) nobody else had used it before and 2) everyone was 
worried about little conductive fibers shedding and floating around 
into places they shouldn't be.  Again, in the space world, no matter 
how tedious and painful, if it worked before, we can do it again. 
thermally conductive glue may be a pain, but it's "known to work".



For those of you doing bolted joints..  thermal conductances are 
around 0.1 to 1 W/K -


You want to google a chapter called "Mountings and Interfaces" by 
Gluck and Baturkin - It's in Spacecraft Thermal Control Handbook 
Volume 1. but there's tons of copies floating around the web, and it's 
a great handbook reference for "just what is the thermal resistance 
with a 4-40 screw through that TO-220 tab onto an aluminum chassis"


It's one of those references which everyone cites.
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