Re: [time-nuts] Power connectors continued

[Van Horn, David]

I have a design rule that I've used for decades: "If it fits, it works, or it 
does no harm."


-Original Message-


Why so many connecter types?   So you don't cross stuff up.

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Re: [time-nuts] Power connectors continued

[jimlux]

On 6/22/17 4:22 PM, William H. Fite wrote:

A good friend of mine, sadly of blessed memory, was a lead engineer for
Grumman on the comm systems of the lunar lander. He spoke of small
space-rated multi-pin connectors that cost upward of $500 each.


The Micro-D is widely used in spaceflight, and is a pox on the connector 
world - not only are they expensive, the way the pins and jacks are made 
is almost asking for damage - the pin is shrouded in a hole, and the 
jack is exposed. $100 for a 9 pin wouldn't surprise me.


Lately, I've been encountering nano-D (Glenair, Omnetics) - they're not 
as delicate, they're smaller.







On Thursday, June 22, 2017, Arnold Tibus  wrote:



Hello,

I can second Magnus and want to throw in some more details.
Cannon, Deutsch, Bendix, Souriau, Matrix, Amphenol,  etc. etc. are (big)
companies manufacturing all kind of connectors and are  n o t  connector
type designations! Important are the type numbers of the manufacturer or
higher level specification numbers.
We used in the aircraft and spacecraft business naturally the military
(MS-) numbers listed in the MIL-QPL (or eg. for Spacelab with GSFC spec.
no). Most types of connectors are under these numbers available from
different manufacturers, of course with different manufacturer in house
part numbers. Attention: the 'same' connectors may be bought w/o the
Mil.-spec. sheets with somewhat lesser quality. Important details are
the max. mating number, the contact resistance (e.g. 20 mOhm) and the
max. continuous current, max. Voltage, vibration resistance and
reliability etc.  Of course, this makes good connectors somewhat
'expensive'. Hirel and non-magnetic gold plated D- subminiture type
connectors do survive e.g. the rocket launch phase (high vibrations),
vacuum and low temperatures and are still used for space projects.



AMP (and others) sell a lower cost version called the "Circular Plastic 
Connector" or CPC. A coarser screw thread than the round metal MS 
connectors.


The round connectors (called Bendix connectors by some at JPL, because, 
of course, that was the mfr for some batch of them) have a nice mil-std 
to define them.  There's a Shell, an Insert, and pins/jacks.  You can 
get shells and inserts with different keys and "clocking" to prevent 
mismates. There are coax and triax inserts, high voltage inserts, etc.


While they're pricey brand new, there are numerous surplus suppliers 
(Apex Electronics in Sun Valley, CA used to have thousands of them).


You can get them hermetic, vacuum tight, waterproof, locking, 
non-locking, every kind dielectric imaginable, etc.








 The D-sub series of connectors was introduced by Cannon in 1952. They
are still available as standard, hirel, and non-magnetic versions. The
contacts were machined contacts forcrimping or soldering connection and
made of massive copper with gold finish. (more see e.g.
https://en.wikipedia.org/wiki/D-subminiature). Example for the standard
9 pin connector designation (crimp): DEMAM-9S and DEMAM-9P. Today are a
big number of companies producing equivalent types. Cheap ones are
equipped with contacts made of sheetmetal. Nobody should expect then the
same spec. values as reliability, mating numbers, contact power rating etc.
It is up to the designer of a product to be informed and select the
right quality device for his product ...



My problem with D-sub is two fold:
1) making a chassis hole is a pain - although now, with places like 
Front Panel Express, it's less so.
2) the shroud around the plug/male gender is easy to bend if it gets 
stepped on.  Sure, for flight hardware, carefully handled under the 
watchful eye of QA, not an issue, but I have lots of these from my 
not-entirely-mis-spent youth that are bent.


They do come with removable pins/jacks, and you can get coax flavors too.
They're fairly compact in a panel.


Other connectors of interest are those made by Lemo and Hirose.  Lemo 
are locking, pretty rugged when mated, and small for the number of 
conductors.  You see them on high end video and medical gear.


There's also something about double banana plugs and mating jacks. I go 
back and forth between PP and banana plugs for preference.


BTW, there are panel mounts for PP.




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Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Brooke Clarke]

Hi Chris:

Yes.  Just looked on eBay and in under a minute found Item 231877388026.
11.1 V   6.6 AH with a label rate of 75C, but the eBay ad says 75C-150C.  So it will produce between 495 and 990 Amps.  
The stock connector is the EC5, which is needed for this kind of current. It's the connector used on the devices which 
used to be advertised as car starters, but now are sold as battery chargers.

http://www.prc68.com/I/PowerBankJumpStarter.html#Photos

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

 Original Message 

18 volt nominal 8,000 mAH LiPo battery


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Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Chris Albertson]

You are correct about 9V batteries.  A 10A short is about 90 Watts.   But
have you seen the specs on a LiPo Battery?

I have a 18 volt nominal 8,000 mAH LiPo battery that is rated "40C".  This
battery is safe and within design limits to discharge at 40 x 8,000 mA.
Yes, taking 320 amps out of the battery is acceptable, the battery is
designed for that.

The battery can continuously supply 5.7 Kilowatts over 2 times more power
then can a standard AC mains wall outlet.  Of course at that rate it runs
out of power in roughly one minute.  But you can do a LOT in one minute.

When you short the leads you get a LOT more than 320 amps

A battery like that costs only about $50 today so they are available to
almost anyone who wants one.




> (1) A common 9V (NEDA1604 style) battery should never be left where it
> might contact a metal short, and should never be left in a pocket. I
> knew better, but temporarily slipped an alkaline 9V battery into a
> trouser pocket, where it was shorted by my keys and became extremely hot
> very rapidly. The peak current might reach 10 A (depending on the
> battery chemistry and how it's shorted), so the battery heats up very
> rapidly!

-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Need advice regarding rubidium oscillator

[Bob Martin]

Roman--

You'll find a lot of information on the care and feeding of rubidiums such as 
the LPRO-101 on the list, and referenced websites.

A specific reference for the LPRO-101 is: 
http://www.ka7oei.com/10meg_rubidium1.html 

that page has links to a lot of information on rubidiums, and on the LPRO-101 
-- links to this list, the KO4BB website, manuals, and more.

In general:
   Rubidium packages have a finite operating life. The ones we get from eBay 
are usually telecoms pulls of unknown age.
   Rubidium packages need heat sinks!
   The outputs of some rubidium packages are cleaner than others

Have fun. Let us know what works and what doesn't -- that helps the next person 
to trod this path avoid the simple mistakes, and instead get right to the 
complex ones that are more interesting.

bob k6rtm

(using a rubidium reference for my Elecraft K3S for amateur radio Field Day)

> On 2017/06/23, at 9:00 , time-nuts-requ...@febo.com wrote:
> 
> Message: 13
> Date: Fri, 23 Jun 2017 12:47:59 +0400
> From: Roman >
> To: Time-nuts@febo.com 
> Subject: [time-nuts] Need advice regarding rubidium oscillator
> Message-ID:
>   

Re: [time-nuts] Need advice regarding rubidium oscillator

[Bob kb8tq]

Hi

It’s an LPRO Rb. I’ve always gotten good stuff from that seller. Like any Rb, 
the 
phase noise and spurs are not good enough for most microwave applications. If 
you
are into high dynamic range HF SDR, they will impact that as well.

Bob
> On Jun 23, 2017, at 4:47 AM, Roman  wrote:
> 
> Hi group,
> 
> Is it a good rubidium oscillator to buy?
> http://www.ebay.com/itm/292160126291
> Thank you in advance for your opinion!
> Planned use - as reference source to my SDR radio (passive radar
> application).
> 
> Regards,
> Roman
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[time-nuts] Need advice regarding rubidium oscillator

[Roman]

Hi group,

Is it a good rubidium oscillator to buy?
http://www.ebay.com/itm/292160126291
Thank you in advance for your opinion!
Planned use - as reference source to my SDR radio (passive radar
application).

Regards,
Roman
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Re: [time-nuts] GPScon running on Raspberry Pi 3b

[Chris Albertson]

I've got a Pi3 here on my desk.   I only see one UART that connects to GPIO
pins.   But it turns out if you actually need to use serial you use the USB
to serial dongles.  If you need four serial ports use four dongles.   That
is just the way the Pi3 is.

You can level the 3.3 volt serial port but then you are into a MAX chip and
some passives or maybe just a couple transistors but the =USB-Serial dingle
is easier then level shifting.

If you want a Pi-like device that is better for real-time embedded use look
at the Beagle Bone Black.  But it was limited CPU and RAM compared to Pi3
but better IO.

If you are building a NTP server, look at the Pi Zero version 1.3.  $5 each.



On Thu, Jun 22, 2017 at 7:51 PM, Orin Eman  wrote:

> On Thu, Jun 22, 2017 at 5:36 PM, Mark Sims  wrote:
>
> >
> > The PI does have a couple of logic level serial ports on the expansion
> > connector you can connect a level shifter two.  One port is normally the
> > Linux serial console which you can configure to be a general purpose

-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Power connectors continued

[Magnus Danielson]

Hi,

Either that, or make protection schemes to save the day.
If you can't come up with a protection scheme that works, then you need 
to move on to another connector. A crow-bar circuit and a diode for 
reverse-bias and a fuse could probably form sufficient protection.


There is plenty of connectors around, and you can choose unconventional 
use of them.


Cheers,
Magnus

On 06/23/2017 10:08 AM, Michael Wouters wrote:

I've been caught by that one.

Someone used 240V IEC inlets as convenient 10A DC inputs to an oven in an
ion trap. Fiddling around in the back of the racks, I made the inevitable
mistake and Poof! there went $1000 worth of isotopically separated Yb 171.
A few years later, someone else did the same thing.

So yes, follow conventions!

Michael

On Fri, 23 Jun 2017 at 7:35 am, Orin Eman  wrote:


On Thu, Jun 22, 2017 at 1:06 PM, Chris Albertson <
albertson.ch...@gmail.com>
wrote:



A really dumb idea was this guy, I heard this story secondhand.  He used
A/C extension cords for speaker cables because they work well for that
purpose, but then someone plugged a speaker into a 120vac well outlet.

 I

assume it made a load 60 Hz tone for a few cycles.Best to follow
industry conventions because that is what people expect.




 CQ magazine had an article where they did something similar and used a
120V extension cord for low voltage - 12V solar panels or some such
project.  Accidently plug the cord into 120V and you'd blow your panels and
radios up!  I didn't renew my subscription after that one.
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Re: [time-nuts] Power connectors continued

[Michael Wouters]

I've been caught by that one.

Someone used 240V IEC inlets as convenient 10A DC inputs to an oven in an
ion trap. Fiddling around in the back of the racks, I made the inevitable
mistake and Poof! there went $1000 worth of isotopically separated Yb 171.
A few years later, someone else did the same thing.

So yes, follow conventions!

Michael

On Fri, 23 Jun 2017 at 7:35 am, Orin Eman  wrote:

> On Thu, Jun 22, 2017 at 1:06 PM, Chris Albertson <
> albertson.ch...@gmail.com>
> wrote:
>
> >
> > A really dumb idea was this guy, I heard this story secondhand.  He used
> > A/C extension cords for speaker cables because they work well for that
> > purpose, but then someone plugged a speaker into a 120vac well outlet.
>  I
> > assume it made a load 60 Hz tone for a few cycles.Best to follow
> > industry conventions because that is what people expect.
> >
>
>
>  CQ magazine had an article where they did something similar and used a
> 120V extension cord for low voltage - 12V solar panels or some such
> project.  Accidently plug the cord into 120V and you'd blow your panels and
> radios up!  I didn't renew my subscription after that one.
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Re: [time-nuts] GPS splitter

[Magnus Danielson]

Hi,

I don't remember anymore. I just picked one somewhere in that range. I 
got a inductor SMD set. The main point is that the time-constant of L*R 
needs to be low enough not to cause any real harm to 1,57542 GHz, which 
makes the value relatively flexible. Sure, I did not consider the stub 
of the T-connector, but it seemed to work.


So, 68 nH could very well be it.

Cheers,
Magnus

On 06/21/2017 08:12 PM, David C. Partridge wrote:

Hi Magnus - what sort of inductor value did you use?  68nH or so?

Dave

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus 
Danielson
Sent: 17 June 2017 15:12
To: time-nuts@febo.com
Cc: mag...@rubidium.se
Subject: Re: [time-nuts] GPS splitter

Hi,

At one time I had to design a DC-load since the GPSDO did not experience enough antenna 
current due to a different antenna being used. So, a BNC-T was quickly converted with a 
SMD inductor and resistor to add 150 Ohm of more load, and that helped the telecom 
operator to get their GPS out of "no GPS antenna" warning and actually accept 
the GPS satellites it was already detecting fine.

Cheers,
Magnus

On 06/17/2017 02:40 PM, Bob kb8tq wrote:

Hi

The DC block requirement depends a lot on the design of the GPSDO’s
you are using. With some GPSDO’s a 50 ohm load on the eighth port of a
splitter will do a pretty good job of “antenna detect” signaling. In
the more general case of “I didn’t design this beast” dc blocks and dc shunts 
to ground is the best approach.
This fairly quickly gets you headed in the direction of the HP /
Symmetricom splitters.

Bob




On Jun 16, 2017, at 11:54 PM, Clay Autery  wrote:

This brings up some interesting questions:

If sharing an active GPS antenna, do you have to DC block all but one
receiver port to prevent multiple receivers trying to supply current
to the antenna?

On say a 26dB antenna (ignoring line loss, power divider insertion
loss, et al), what is the effective gain to each receiver?  (Sorry,
having a senior moment)

Should ALL unused ports have 50 ohm +/- 0j terminators on them?  I
assume so...  Thus, it would be "better" to always use the divider
with the minimum required ports?

I am assuming since this is a receive only situation, it will follow
approximately the same rules of physics that dealing with satellite
antenna installations.

I would LIKE to share one PC-TEL 26dB GPS antenna mounted at the top
of my 38 foot horiz.loop mast right  at the shack entrance, using
LMR-400-DB from antenna to Narda 2-way and thence to my current
hacked Nortel GPSDO and my soon to be complete RPi 2/3 w/ Adafruit
Ultimate GPS Hat NTP Server.  On that mast, the antenna would have a
near 360 degree view of the sky completely unobstructed.
(Eventually, I expect both of those units to be replaced with commercial units).

I'm assuming that I DC block whichever unit is capable of providing
the LEAST current at 5VDC...  I suspect the Nortel unit can supply
more current than the RPi, but that's not a guarantee...  And I guess
I could block/turn off DC delivery on BOTH units and add a voltage
adjustable, current limiting DC injection unit into the line.

Thanks.

73,

__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 6/16/2017 7:26 PM, Tim Lister wrote:

On Fri, Jun 16, 2017 at 4:40 PM, Gregory Beat  wrote:

I have reached the point that I need a 4-port splitter for my GPS antenna 
(outdoor 5 volt).  Any recommendations of models (HP/Symmertricom/Microsemi) to 
acquire OR to avoid??

As we recommended to me when I asked a similar question, the Narda
4372A-4 was a brand I had not heard of before and didn't come up in
'gps splitter' searches. I got one on ebay for $24 plus a bit extra
for DC blocks on the n-1 other ports and it seems to work well and
it was handy to have an SMA-based solution as most of the gps
receivers and the antenna pucks seem to use SMA. This meant I only
needed 1 N to SMA converter cable for an external antenna (which has
yet to be externalized...). I found it smaller in real life  than it
looks in a lot of the pictures, about the size of a modern
smartphone but about double or more the thickness (the connectors are on the 
ends).


greg
---

Cheers,
Tim
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