John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in news: snipped-for-privacy@4ax.com:
Most are custom and follow the direction of the company who contracted us for the product.
Most HV designs are very custom as all HV load situations are very individual.
We did one for Cymer Laser that bolted to the side of the machine and the HV output lead was a spring loaded flap that made the connection once installed. It was right in the middle of the potted cavity in the device and it was only about 5 x 3 x 2.5 inches. 6kV IIRC.
We had one where we created the connection and connector and there was an HV insulation paste filled tube that a 6" long HV lead "poked through" to get to the HV output node at the bottom of the tube. Were it only air filled the six inches between the output node and the ground connection at the back panel would have arced. That one was for LANL. Not able to be mass produced and sold elsewhere. Very application specific. That one was 50kV.
If a heavy unit is cantelevered off the front panel, it will be a hazard to install and remove. As you install it, it will scrape on the unit below and scratch it up. When someone later loosens the front panel screws, all its weight will flop onto the unit below, which already had its own weight to support. The whole stack of units could collapse.
Users can't know, years later, if this will happen or if the unit below can bear the weight of both.
John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in news: snipped-for-privacy@4ax.com:
Use some common sense. AND ask the dopes you are buying that POS thin faced turd from. No matter what you think, the front panel carries all the weight of the unit, just as the specs state, and the ONLY exception is when "drawer slides" have been mounted.
For one thing, that is not even the correct term. Any rack device will be stable if only held in place by the bottom two screws, because the entire faceplate is held fast against the rack by the weight of the device itself hanging behind the faceplate.
You have obviously not spent much time populating racks, much less examining rack equipment, and obviously particularly not for a military contractor.
More bullshit. The spec also includes NOT having ANY protrusions on the top and bottom face of your product. Like screw heads on the bottom OR the top of your unit. So "sliding one out" after the front panel has been detached ALWAYS has its weight on the unit below it. If there is no unit there, one must hold the weight as the screws are removed to keep it horizontally oriented. They are specifically made to be able to be slid into place on top of an existing unit, and ALL properly designed rack mount devices have ZERO protrusions on the top or the bottom. One must use countersunk, flush or below flush fasteners in one's design. There are also not supposed to be any venting on the top or bottom of a unit.
You said you "saw" thousands of units. I INSTALLED (and uninstallled) thousands of units over several years time and those racks are in place in over 50 cities around the world. They were ALL
100% fully disassembled after the build and the cabling and rack units and the racks were shiped to the site and then fully reloaded and rewired up. Every last one... literally thousands of units Some 3U and up units do get slides installed. Some do not. Again, the specification is that the unit must be able to reside in the rack only held by the front panel with no rear attachment (slide mount points). Granted many if not most folks incorporate rear attached slides that support the weight as well, but that is a prefernce, not a requisite. The spec remains. The only exception are server chassis, which are typically many more U than a 3 or 4. They ALWAYS get slides installed.
A good example is rack mounted UPS units. They have very thick front faces. Because they follow the spec. Not every one gets installed in the bottom of the rack or gets slides added, and those that do... oh looky... nothing below to support them. There are many other heavy devices with thick front panels. Why? Because that is the spec.
No shit. And no, it does not "flop", like your argument here has. You are sporting 100% flawed logic. It sits on what is below it and if there is no unit below it, it should be sitting on the tech's hand as the front panel fasteners get removed. And it has been that way since the onset of the use of this type chassis which we all know of as racks.
Racks typically, but not always get populated from the bottom up. Been that way forever. The stack of still installed units below the one being serviced are supposed to be able to support such weight. Been that way forever. The bottom unit has no support below it. Some get slides and some do not.
More flawed, non-factual horseshit.
A tech pulling a unit from a rack will normally have access to the rear of the rack to remove cabilng AND to examine the circumstance under which they are performing the servicing. More flawed, non- factual logic on your part... for years running.
All the folks in industry that use racks who know how to spell the word competent do.
So one tech uses his hand, from the back of the rack, to support the box while another tech pushes the heavy box into the rack and fastens the front panel screws? Hire really strong techs. Or one with really long arms.
John Larkin <jlarkin@highland_atwork_technology.com> wrote in news: snipped-for-privacy@4ax.com:
Before I built all those satellite baseband gateways for all those US and Aussie cities, I built the simulator for the F-35. Several racks full of GHz level RF modules... And then another... and then a third. They were several racks of 9 units. 8 4U 16 channel units with one 5 or 6U center modules, which were the combiners for those with a back panel loaded with 64 SMA ports that resolved down to 16. I built those modules. But none of them had a behemoth like that in them. They all were Chem etched Aluminum though like that chassis. I hand built every single module and *then* installed them all into the racks.
So after months of building units and tying them all together using same length cables, etc. They all went into a classified lab that after I placed and wired together all the racks, including a monster inch diameter welding cable that grounded all of them together that would be placed in the field in the drop floor when it got to the Hughes Anechoic facility in Texas. After I got them all wired together, they program all of the racks for timing so that all 1024 channels were gathering signals that all then got the same timestamp, and calibrated the offsets down to microseconds (or even faster). Once we got all that done, I was no longer allowed in that lab, wired it with white noise generators over the door to the lab and was literally no longer allowed in the lab because I did not have the clearance for the final programming segment. A lab you were not even allowed to take a piece of paper into or any kind of writing instrument. It became a secret level classified lab. There was a small wooden box on the wall outside the lab for cell phones. The door had an electronic lock on it that looked like the dial on a bank vault. And a sign in / out sheet.
I literally built every module from flat panels and side panels with angled edges for rigidity. They were pretty thick Aluminum chassis. Each of the 4U modules had 16 variable phase, variable gain modules from General Microwave at first. Those were how they all got calibrated together for matched arrival times on signals. They had several tens of units (at like $800 each) that would not perform the
370 odd degree span of the electroninc phase control. Apparently the vendor's in house calibrator looked at the two ends of the spectrum and called them good to go, but in actual use they puked on wheeling the phase around the full 360 degrees much less
370. So they ALL got rejected and a new vendor used. The real PITA was having to take the rack modules all apart to replace the 16 units in each one with the new vendor's modules. They worked nice and were a lot lighter weight than the hobbed out chassis of the originals, but I had them alter the chassis design to make that rear of the rack bank of mixers and phase shift modules "serviceable". Because that replacement chore was a real pain. They agreed. So now, they could be serviced without having to disassemble practically the entire module. Two central trays instead of just one. I have probably seen and used more semi-rigid SMA cables than you have, so many that we got really good prices from the makers and then there were a huge number of sheathed SMA cables for all the back of the rack links to that the center splitter / combiner in each rack had. But inside there were a hundred small diameter "solder wetted" of the unsheathed semi-rigid variety. Various same length links. My shtuff looked like that Quantum computer they make that gets lowered down into a liquid Nitrogen tank. And the splitter combiner was a mad house of links inside. 16 sets of 8 way splitter combiners inside to make the giant 64 channel center modules. So they were timed together very good, and the phase shift / attenuator modules had less of a chore to do to get them all synched up. Making any detected event carry proper microsecond timed stamps on them for the events that were simulated in the anechoic chamber in order to calibrate the sensors on the F-35 they had hanging there in the chamber with all of my racks full of channels. Fake a missile launch radio event in the chamber and get all the sensors in the bird calibrated out correctly. I wish I had been able to go down to Hughes to seee it in place, but did not have the clearance yet.
But none of the rack devices I built that were 6+U like that had a hunk of laminated mass in them like that though! The 4 inch wide slides, right? Dang, dude.
They all used linear supplies because swtchers introduce glitches ticks and noise into the high frequency events. So bigger than a switching supply but still small potatoes compared to that monster. Your gonna need a bigger overhead lift. That looks dangerous for that amount of weight. How many did you have to make of those? And you WANT to be a power supply maker... so funny. You move from small Hi Freq devices to big PS stuff. I question your logic again. Hehehe...
The biggest we produced when I was at the power supply company weight wise on this side of the pond was one that had two 2kVA transformers sitting in the bottom of it, and it looked like a big server on casters. Like a Weeble, one could not knock it over. All the weight was down there at the bottom.
But back at the telecom place (F-35 Stimulator) every unit used slides and they were ALL suspended units that did not touch the unit above or below, even though the racks were all fully populated from top to bottom. Any unit could be pulled out and serviced at the bench easily. They were fairly light.
But when I did the satellite baseband gateway series of racks some were packed in like sardines, and all were packed with millions worth of our gear and network switching gear from Cisco and Juniper. Quadruple redundant. High speed, properly terminated Ethernet links, and high speed optical links all throughout. All tagged by a whole crew of girls that came in after I built out the racks. Then ran power to them and then the software engineers would come in and install many many sessions of boot / and run VDMs on all the items that had operating systems or firmware that operated them... quadruple redundant... oh, did I say that already? Then, the girls break all the wiring down and put it in a giant box on a pallet. Each end tagged of course. And I would the place every item back in the boxes they came in and the only thing that remained in the racks were the power strips and the big server card chassis. And any blank slot covers.
Once on site, there were two 8 meter dishes being constructed to point at the bird in the sky with. And they reset all of the racks, without their soft shipping pads, and add a couple Ka band RF racks, which we did not need in the network side series of racks I built, and put all the cables back in and fired them up for a series of startup testing... and voila! Satellite baseband gateway. 21 US cities and 17 cities in Australia, and a couple colleges in the middle east. Theirs was the most scrutinized, believe that. One rack was filled top to bottom with high speed hard drive arrays. None of ours or Australia's had that.
There are customers that do care, and test for it by full-scale vibration tests on whole cabinets to MIL-S-901. A front-cantilevered heavy components would break free and fly across the room.
Small equipment rates a 500-pound hammer, and medium rates 2000 pounds.
Yes. We tested some marine control consoles. They were installed in a barge in a pond and explosives were detonated in the water. All sorts of buttons and knobs flew off, imaged by a high speed movie camera.
They used some sort of magnesium lights for the camera, and that set some stuff on fire, but that didn't count against us.
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