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):
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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.
My answers are probably dumb, but you should be used to them by now.
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.
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.
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?
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 jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
ter way to distribute power to little modules like this without having to r esort to hand soldering stripped wire to the feed-thru.
ules can attach to. Test the whole thing, and only then pop the whole asse mbly into the build.
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".
upid idea in the first place. But, nobody asked me.
I've put them on RF things. The hope was that they kept all the nasty RF inside... I never tested them.
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
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com
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
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
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
https://hobbs-eo.com
Bare wire would be slightly faster than stripped wire if you don't need the insulation.
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).
I recall a special clip for starting model glow-plug engines the contacts were stamped from phosphor bronze sheet IIRC.
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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.
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