MTT4BT Installation on ATV/Motorcycle
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Ha, yeah, arguably the mini DIN 6 was the worst choice for a device intended to go mobile.
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I've had good results putting the unit in a good Tupperware container. I zip tie the mini DIN cable to the TT box. Consider foam etc to pack the TT, and how to grommet the cables going out of the plastic box. Cliff K6CLS CM87 On September 16, 2021 3:29:51 PM PDT, toy4trax@... wrote:
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On 9/16/2021 5:29 PM, toy4trax@... wrote:
Looking to do an install on my ATV and/or Motorcycle. While the unit itself is going to be in a waterproof location, I'm looking for cabling thru to the battery which will be exposed to water. I'm not having much luck with finding waterproof mini-din 6 connectors.A LONG boring list of ideas and techniques follow (you've been warned!): I like the idea of a water-tight box in a central location to split off the various signals and power leads. I've used a former style of plastic Kodak 35mm film "cans" for the "box," the kind with the black plastic "can" and the grey plastic lid. I drilled multiple undersized holes for individual cables in the soft plastic lid, stuffed the unstripped cables through the holes, slipped pieces of unshrunk heatshrink tubing over the parts to be spliced, stripped and soldered the required connections, shrunk the tubing over the connections, pushed the bundles of connections together and either shrunk some much larger heatshrink over the whole bundle or tied the bundles together with waxed nylon lacing tape, pulled the slack out of the cables through the lid of the can, filled the lid with silicone rubber and after everything was set up, snapped the lid on the "can." But, in case that's not feasible for you, here are some other considerations that you may try... First of all, I'm not very familiar with the MTT4BT, but if by "mini-DIN 6" you're referring to the "mini" line of cylindrical DIN connectors commonly used in Europe (especially Germany) for primarily consumer AUDIO and/or video connections, I think "Coax-Seal" and black electrical tape could be your answer. I bought a Grundig portable 3-inch reel-to-reel audio tape recorder in the 1960s and also made some MIDI cables a couple of decades ago that used them, although in both cases it was the full-sized versions. I've also used the "mini" sized versions as well but can't recall where or when. The insulation covering most electrical cabling is completely water-tight if undamaged, so it is only between pieces of cabling joined together that's the problem where the original overall insulation is broken. First of all, if you can, make the connection somewhat rigid to minimize bending, and especially stretching or compression of the connection. Ordinary heat-shrink tubing and maybe some waxed nylon lacing tape can usually do that (there are web pages that describe how to tie lacing tape - It's very useful stuff -- you may give up nylon tie-wraps). Then cover the whole connection with electrical tape from overlapping the original cable insulation on all ends and overlapping each turn of the electrical tape with itself. The electrical tape is not for waterproofing, but just to make it easier to remove the next layer should that become necessary in the future. This next layer could be the Coax-Seal mentioned earlier (just because they call it "Coax-Seal" doesn't mean you can't use it for sealing other things than coax!). This is best done in a warm environment because you want the warmth of your hands and fingers to soften the Coax-Seal to let you form it into a smooth conformal seal and have it stick together. Just like the electrical tape, overlap the ends of the electrical tape with the Coax-Seal and the original cable insulation and each turn of the Coax-Seal with itself, and push it into the crevices so that it won't look much like "tape" any more, but just a smooth unbroken covering. This isn't a good solution if you need a way to frequently disconnect the connections, and the seal to a chassis-mounted receptacle may be unreliable, depending on the configuration of the receptacle and how well the receptacle itself is sealed against the chassis or box. If you do sometimes need to remove the whole mess to disconnect the various parts, just dig through the Coax-Seal until you reach the electrical tape, then unwind the electrical tape taking the Coax-Seal with it. The Coax-Seal will protect the electrical tape through the ages, and it should remain pretty fresh, pliable and easy to unwind. It shouldn't be nearly as tenacious as the Coax-Seal would be if applied directly to the cabling and connectors, especially the connectors. I understand there is a heat-shrink-able TAPE available now, but I haven't yet had a occasion to try it, and I have no idea how hard it is to remove. You should also consider the application of liberal amounts of silicone rubber sealant (Loctite Clear Household Silicone Adhesive/Sealant, P/N 30808 several years ago or Plasi-Dip [plastidip.com]). Be sure to allow these materials access to air so they can set up before sealing the air away with other materials. Plasti-Dip can be dipped or brushed on, in multiple coats, and provides a slightly cushiony but tough surface, BUT it comes in a large can like a beer can where the entire top comes off to allow dipping tool handles, but is impossible to tightly seal the can closed, so it'll likely be hardened the next time you want to use it. The snap-on thin plastic lid isn't even remotely air-tight and the beer can shape leaves a large volume of air in the container to dry out its contents. It's a good product packaged poorly, although I can't think of a better way. Multiple coatings are needed to provide substantial protection, and the stuff in the can will usually stay flowable and brushable long enough to coat a few things multiple times if done quickly, but you'll probably end up throwing most of the can's contents away. Too bad, otherwise it's good stuff. By the way, Plasti-Dip comes in several different fairly high-visibility colors, if that's of any interest. I bought the red color. It makes my pliers and wire-cutters easier to spot in my jumble of hand tools. It primarily made the ends of the elements of my PVC pipe & steel tape Yagi antennas easier to see and avoid poking myself and others in the eye. The electrical tape layer MAY be useful with these coatings as well. The silicone rubber brand & style mentioned above produces a more durable coating than the typical GE window & tub caulk that comes in caulking gun refills and produces a thick rubbery-soft coating, but it doesn't seem to be as capable of being applied as smoothly as the Plasti-Dip. Both may be useful in this kind of application: a first coating of the thin GE silicone to get into the cracks and crevices followed by a coating of the Loctite stuff or Plasti-Dip on the outside for durability (and maybe all of it preceded by a layer of electrical tape for removeability). I'm also unsure of the "contact" compatibility of these various products. YMMV. It might be that you simply can't "paint" one over the other. You might have to spend a few dollars and try it yourself. If you do, please report back the results. There's also another product from the PlastiDip people called Liquid Tape that might be worth a try. I don't know anything about it. THE END! Barry N4MSJ |
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Allen,
I don't know if your statement was intended to dispute parts of my post or just to add an additional suggestion, but to clarify, I NEVER SUGGESTED THAT ANYONE SEAL THE MTT4BT CASE. And, unless a connector is designed and manufactured to be sealed with gaskets, o-rings or similar, "sticky goop," as you call it, is almost always the only way to seal most water out, and, to address the "stickyness" issue, I also specifically provided suggestions of how to make it easier to get that "sticky goop" off of the connectors and wiring later. I think many people don't know about the "electrical tape layer" trick with Coax-Seal. I didn't know about it the first time I used Coax-Seal in a C-Band antenna installation I did for myself in the early 1980s. Also, "somewhat splash-resistant" installation is usually the best one can hope for in the consumer/ham world. If I remember correctly, the OP said the MTT4BT was in a dry place, so why would you think I'd suggest sealing it with "sticky goop" (if that was indeed your purpose). I was addressing the considerations one should keep in mind when attempting to make connectors and splices water-resistant, IN A GENERIC WAY. By the way, if the MTT4BT was NOT in a dry place, would overheating it be any worse than allowing the ingress of water, especially water that would likely be contaminated and possibly conductive (seawater maybe)? Most electronic components can withstand a surprising degree of overheating with little harm, and many ICs, including micro-controllers and voltage/power regulators for example, have circuitry included to self-protect by throttling the clock rate or shutting down entirely when the junction temperatures get dangerously high. I've spent most of my career designing electronic systems for military and space applications, and many of the cases in which most such equipment is enclosed, is sealed, either entirely or at least ventilated through hydrophobic membranes and also have desiccant chambers with visible moisture indicators, yet there ARE ways of getting heat out of otherwise sealed containers, very elaborate ways like you wouldn't believe. Of course such extreme measures just aren't practical in consumer or most ham gear. As you said, it's a low duty cycle device (at least for the transmitter part of it), it's a relatively inexpensive device, and hams are supposed to recognize risky usage and make appropriate judgement. "Engineering is the art of design with intelligent compromise." My post wasn't intended to identify WHAT needed to be sealed, it was simply intended to suggest HOW to seal them. The OP had his own ideas of what was needed. I suggested techniques for sealing only those water-sensitive places where you absolutely need to keep water out and where water would be present or likely to be present, but I didn't even try to define where those places might be, other than to mention that I liked the idea of a container in the middle to split out wiring going to different places, mostly so I could suggest how I'd once or twice dealt with that option, i.e., what I'd used as the container and how I'd used it. I didn't intend to insult anyone's intelligence by attempting to provide solutions for absolutely every possible situation -- after all we're ham radio operators and we are expected to have some technical capabilities. You don't seal things that aren't exposed to water or other harmful contaminants, and you don't put unsealed things in places where they will likely be exposed to water if water will harm them. I suggested ways to seal things that the OP already stated that he thought needed sealing. I left the decision to seal or not to seal to him, and I already mentioned that I wasn't entirely familiar with the MTT4BT itself. I wasn't certain I knew where the "DIN connector" was used, but I thought it was likely to be part of the MTT4BT. I have a number of TT4s; no built-in transmitter, very little heat -- I was a beta tester for the TT4, and I've bought a couple over the years, including the display and keyboard adapter (which, coincidentally, has a mini-DIN receptacle of its own for a PS/2 keyboard). I also have the display module, the Bluetooth interface and have built several interconnecting cable assemblies for GPS and computers, not that any of that has any bearing on answering the OPs questions. I even built an adapter to connect the TT4 to my old TRGpro PDA (a Palm IIIa clone with additional capabilities) for display and control in the field (balloon chasing). I thought I'd been clear about what a mini-DIN is; I only mentioned them to be sure the readers also knew how I was using the term. I don't typically name connectors by instances in which examples of that connector is used. If I did, it might also be the "SuperVHS video connector" or the "High-8 (or Hi-8) video connector" or the "PS/2 Mouse connector" (not just the PS/2 Keyboard connector), or many others which most people have never heard of (the full-sized 5-pin variety has been used for MIDI [Musical Instrument Digital Interface] cables for several decades. DIN is a German Standards Organization, and believe me, these audio and video connectors we're talking about right now are by no means the only connectors for which DIN maintains the manufacturing, interoperability and usage standards. DIN maintains standards for all kinds of items including piping, tubing, fittings and all kinds of industrial items, not just electrical or electronic. Should we call ALL of them "DIN connectors?" Even if you limit the conversation to just the electrical or electronic items, there are DIN rails and DIN card racks with DIN card cages and DIN backplanes that have DIN connectors on them. In this case, these DIN connectors are multi-pin connectors to plug PCB cards into (the cards have mating DIN connectors on them). Those DIN connectors have little relationship to other totally different or incompatible electrical connectors that can all rightfully be called "DIN connectors." That term, "DIN connector" usage is extremely ambiguous. Frankly, I've forgotten what the non-ambiguous name should be, if there ever was one, for the connectors we've been discussing. There are other DIN connectors more similar to this particular kind of DIN connector, but still not compatible, and I thought all these things needed to be clarified in this instance, especially as I am only "somewhat familiar" with the MTT4BT. BTW, the DIN organization has been around for about a century, I believe, although I didn't encounter it until the early 1960s. Barry N4MSJ PS, I think the word you were looking for was "breathe" (the verb, ending with an "e"), not "breath" (the noun) -- Now why do I feel like Dan Quayle? No, wait, I don't feel ANYTHING like Dan Quayle; I feel like I want a bowl full of potato chips. Sorry, I just couldn't resist! On 9/19/2021 9:48 AM, vhsproducts@... wrote: Please do not seal the plastic MTT4BT enclosure with any sticky goop. These are very low mass transceivers ( The actual PCB's weigh a few ounces) with relatively high power amplifiers on board ( 10-40 Watts) and the PCB is the only heat sink. ( Keep in mind that these transmit only short packets with relatively long transmission intervals, so their duty cycle is very low) The PCB's need to "Breath". If you seal it off, your board might get too warm, and your temperature telemetry readings would be confusing. There are more "holes" in the case than just the Mini-DIN connector ( You Deutchlanders will recognize this nomenclature to be the same connector we occasionally refer to as the PS/2 keyboard connector) To call the Mini-DIN, DB-9, or PowerPole connectors on the MTT4BT's power/serial cable "Waterproof" would reach levels of sunshine-filled optimism that I am not physically, mentally, or philosophically capable of reaching. The cable and MTT4BT enclosure were designed with mobile installation in nice dry vehicles.[snipped] |
Cliff Sojourner K6CLS
Barry L. Lankford