Feed-Thru cap connector?

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Probably a dumb question, but let me ask it anyway.

I want to know if there is a connector for a feed-thru cap, like the one on
 this Mini-Circuit part (chosen at random):

https://www.minicircuits.com/WebStore/dashboard.html?model=ZEL-0812LN

We use parts like this in several of our products.
I'm trying to speed up production, and am wondering if there is some better
 way to distribute power to little modules like this without having to reso
rt to hand soldering stripped wire to the feed-thru.

Ideally, I'd like to distribute power via a circuit board that these module
s can attach to.  Test the whole thing, and only then pop the whole assembl
y into the build.

Got any ideas?

I'm thinking that a shaped-wire clip in just the right location/orientation
 would work.  Of course, if it's not tight enough (and it probably wont be)
, we could still solder to the "clip".  That would at least eliminate all t
he hand-routed, one-off, "wire harnesses".

Personally, I think using these feed-thru's as a power connector is a stupi
d idea in the first place.  But, nobody asked me.  


Re: Feed-Thru cap connector?
wrote:

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My answers are probably dumb, but you should be used to them by now.

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Sure.  Any wire end or PCB test point connector will make the
connection.  I tried that once and regretted it.  Production didn't
like soldering, so they want and plug in replacement.  We had an
Amp-o-lectric crimper that was used to attach wire end connectors onto
interconnect wiring, so I just found a connector in the Amp catalog
that fit the wire gauge on the Erie(?) feed throughs, did some minimal
testing and shuffled the appropriate paperwork.

Everything seemed to be ok until we started getting reports of
intermittents.  It seems the connecting wire in the feed through
capacitors were designed to be easily solderable, which at the time
meant that they were solder plated, tinned or dipped.  Shoving a tin
plated connector onto such a wire did not produce a very reliable
connection.  I changed the feed through type to use a tin plated wire
and things worked much better.

But, not good enough.  We would get warranty returns on the radios
with one or more wires having fallen off the feed throughs.  There was
no detent or retention mechanism on the wire lead to lock the wire end
connector in place.  A little tension, as conveniently supplied when
the cable hardness was installed in the radio, and the connector would
slowly slide and creep off the end of the feed through lead with
nothing to stop it until it fell off.

I'm sure that there must have been some other things wrong with the
plan, but I didn't have the opportunity to experience them. Production
went back to soldering and we lived well connected ever afterwards.

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Deja vu.


Yeah.  PCB pin connectors on the PCB with the proper spacing.  Good
luck maintaining the positioning tolerances between these connectors.
The feed throughs are probably fairly sloppy positioned in their holes
and there's nothing that moves which can take up the position error.
You'll end up stuffing the PCB pin connectors in a fixture to get them
positioned perfectly and still have a fit problem if the feed throughs
moves in their mounting holes.  It can probably be done if you get a
PCB bin receptacle that allows some sideways movement, or you use feed
throughs with fairly soft copper wires instead of hard straight pins.
As before, it can be made to work, but I wouldn't want to bet on the
long term reliability of the connection.

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If you're going to solder to the clip, you're defeating the purpose of
the exercise.  Let me guess... your instructions were to fix the
problem but don't change anything?

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I've lost track of the number of times I've been asked to so something
stupid.  In the distant past, I used to complain about being forced to
so something stupid.  I even quit one job over such an exercise in
stupidity and futility.  I eventually decided it was easier and better
to just do what they ask, demonstrate that it will fail, and move on
to something better that has some hope of working.  You can show
management with calculations and presentations that something is a bad
idea, but nothing gets their attention than a live demonstration of a
failure to function.

Good luck.

--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: Feed-Thru cap connector?
wrote:

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The RF boys love those things. They are stupid.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Feed-Thru cap connector?
On 10/11/2018 10:24 PM, John Larkin wrote:
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Great help, John.


Re: Feed-Thru cap connector?
On Thursday, October 11, 2018 at 11:24:08 PM UTC-4, John Larkin wrote:
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 on this Mini-Circuit part (chosen at random):
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ter way to distribute power to little modules like this without having to r
esort to hand soldering stripped wire to the feed-thru.
Quoted text here. Click to load it
ules can attach to.  Test the whole thing, and only then pop the whole asse
mbly into the build.
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ion would work.  Of course, if it's not tight enough (and it probably wont  
be), we could still solder to the "clip".  That would at least eliminate al
l the hand-routed, one-off, "wire harnesses".
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upid idea in the first place.  But, nobody asked me.  
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I've put them on RF things.  The hope was that they kept all the  
nasty RF inside... I never tested them.  

George H.  
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Re: Feed-Thru cap connector?
On 10/11/18 11:24 PM, John Larkin wrote:
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They're brilliant for some things.  I bought a couple of thousand  
Russian 33 nF feedthrough caps long ago, and have used them in all sorts  
of test jigs and so forth.  There are lots of situations where supply  
feedthrough is a serious nuisance, and using feedthrough caps allows you  
to do fully coaxial measurements at frequencies of interest.  The  
large-value ones I have are especially nice, and cost about 2 cents  
apiece IIRC.

In the mid-80s when I was a grad student, I built a 13-bit  
successive-approximation IF phase digitizer for a heterodyne laser  
microscope.  It was based on a 12-bit AM2504 TTL SAR chip, a Mini  
Circuits RPD-1 phase detector, and a homemade linearized phase shifter  
running at 60 MHz, because I had a really great 60 MHz bandpass filter  
in the drawer.

The phase shifter was the usual op amp/varactor thing, except  
implemented with ua592 video amps.  (The noninverting path had a gain of  
+1 and the inverting path a gain of 1/2, instead of +2 and -1 as usual.)  
  There was an extra flipflop and XOR gate that decided which of the two  
nulls to shoot for, which gave it 13 bits' precision.  Worked great at  
50 kS/s, which was about what my lab computer could cope with.  (The FF  
latched the comparator output at the beginning of the conversion, and  
with the XOR it guaranteed that the SAR's feedback loop was always stable.)

The phase shifter was nowhere near that linear, of course, so the second  
problem was how to calibrate the thing.

I built two VCXO-based synthesizers with pulse-swallowing counters,  
running at a 166.67 kHz comparison frequency (x360), so that stealing  
one pulse moved their relative phase by one degree, and kluged together  
an auto-calibration system using an HPIB-controlled relay driver to run  
the pulse swallowing buttons.  Worked great, eventually, though the  
calibrator was several times more complicated than the digitizer.  It  
was all built up from parts except the 60-MHz IF filter.

The point of this long story is that the major bugbear was signal from  
one channel getting into the other, causing a sinusoidal phase error.  
To get real 13-bit accuracy, I needed that error to be less than 1/16384  
cycle.  That's a bit under 400 urad, so the feedthrough had to be less  
than  20*log(sqrt(2)*4e-4) = -65 dB.  I could measure that by sitting on  
the pulse-swallowing button, which shifted the frequency by about 500 Hz  
so I could see the spur on a spectrum analyzer.  It was way too large.

The two sections shared a power supply, which turned out to be the major  
problem.  A couple of feedthrough caps fixed it.

There are lots of these sorts of things in RF systems.  Birdies multiply  
unless you keep them separated. ;)

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Feed-Thru cap connector?
On Fri, 12 Oct 2018 09:09:57 -0400, Phil Hobbs

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When a box is sold and used as a component, it's ugly to force people
to connect to it by soldering stranded wire to it. Production is very
different from making one-off grad-school experiments.

You'd think that Mini-Circuits and the other guys would furnish some
nice crimpable push-on connectors with each unit. I guess they don't
know of any.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Feed-Thru cap connector?
On 10/12/2018 11:01 AM, John Larkin wrote:
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There are any number of gold-plated crimp-on inserts for Molex
connectors.  One of those and a drop of solder would be a perfectly
reasonable solution.  With proper strain relief it would probably be
okay barefoot.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
We've slightly trimmed the long signature. Click to see the full one.
Re: Feed-Thru cap connector?
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Bare wire would be slightly faster than stripped wire if you don't need the
insulation.

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Turret terminals like that are intended for wrapping and soldering wires.

but with that one if you have something to mount the flange to you could
put those terminations through holes in the PCB, keyhole slots might
be a "win".

When the feedthroughs have flexible leads they can usually be bent to
go into the PCB (but that's not whjat you've got).

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I recall a special clip for starting model glow-plug engines the
contacts were stamped from phosphor bronze sheet IIRC.

https://coxengines.ca/cox-glow-plug-clip-oem-style.html

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Could be that you are not their target market. in full custom stuff
turret terminals ain't so bad.

assuming you want to bolt (etc...) these to the main board  
perhaps a piece of PCB with two keyhole (or edge) slots for the
feed-thrus that also mates with a slot*, edge connector, or header  
on the main board, it could possilby be a mostly routed press-out
piece from inside the module's footprint.

(*) probably not a slot - edge soldering seems unreliable, but
OTOH maybe it works better on boards with plated slots, I've mostly
seen it fail in single sided consumer goods.

--  
  Notsodium is mined on the banks of denial.

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