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ve7kjr

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Everything posted by ve7kjr

  1. Hi Chris, I helped a friend build one years ago.I have the mechanical / electrical drawings with the equations,I hope you are really good at math ! I would have to scan the book and email it to you if you are still interested. VE7KJR (Phil)
  2. The problem I was having here in Vancouver was sync, both music and dialogue this drives me nuts like being on bad drugs I guess. The broadcasters/cable providers know this is a problem but I see and hear it again over and over.Makes me want to get my own digital delay, put it in line with the audio and re sync the dam show.VE7KJR (Phil)
  3. Hi Michael, yes that is the negative rail (or ground)you see on the bottom of the box, the yellow wire is the negative feed to the embeded leds in each switch. The imput dc feed came in from the left side of the box near the on-off-on switch (looking at the box from the back) Not shown in the photo, is a smaller hole with a rubber grommit in it. Always use a grommit anytime you are feeding wires through metal or you will have a fireworks show sometime later on down the road ! Rubber will tend to break down over time so it is a good idea to do a general inspection once a year on your electrical .The negitive feed to the rail should be connected in the middle so that the voltage is as even as possible across the entire system. "The on-off-on switch"First let me say all switches are not created equally. I chose NKK because of their quailty and reputation. The double pole/ double throw allows for redunded mechanical connection within the switch itself. Wiring the switch "ON-OFF-ON" is just another level of redundancy. Hope this helps you out.Phil (VE7KJR)
  4. Thank you all for your very kind words on my power panel. I have always enjoyed designing/modifying or building equipment to suit my needs. First, a lot thought has to go into what is needed for the job it is intended to do. Second, it has to be fail safe and never let me down. Third, I have to have the right tools to do the job. ( nothing will make me crazy faster than trying to do a job with the wrong tool) There is no way in hell I could have all those connectors lined up and spaced out evenly without first making the template, finding the exact center point of each connector then transfering that information to the box. Without the knockPunch I would not be able to maintain the alignment that I had designed. "Vin" wanted to know about this tool. Below is a picture with all the parts explained. The punch has been around for a long time and is used for cutting precise holes in metal. Once a series of pilot holes are drilled(starting small and working your way up till the draw stud fits in the hole) the punch is attached, hand tightened, next a wrench is used to tighten the nut which draws the punch threw the metal into the die making a very clean precise cut.The tool comes with different size punches and dies that fit on the same draw stud. The best ones are made in Germany but cost a bit more. I woun't say where the cheep ones are made so as to not offend anyone on this board. Hope that helps you Vin and anyone else that is interested in buying one. Phil (VE7KJR)
  5. Hi Michael, nice to hear you want to build your own, I have built two 12 volt power distribution systems for sound carts over the years and have been very happy with both. I started off with a hammond aluminum boxwww.hammondmfg.com/dwg21.htm I used a circuit breaker panel that had been build for the marine industry but would meet my needs just fine.http://bluesea.com/category/7/27/products/8271 The panel would give me 8 seperate outputs, also this panel is available with either glass fuses or push button circuit breakers. The contura switches are embedded with "on" leds in each switch. A template comes with or can be downloaded from the site to take the guess work out of the cut you will have to do in the box.BlueSea systems offer a varity of different panels, both vertical and horizontal design with outputs from 3 position to 8 position. The panels are well built and made to take a beating, (think of a boat on rough water and the pounding it will take)The cumulative rating for panel is 45 amperes (way more than any sound cart will ever see).The most difficult part of the build was designing a template for the 4 pin female chassis connectors that were to go on the side of the box and I would be mounting 8. A number of hours were spent designing the paper template that matched the side of the box exactly and where the center point of each connector would be. Once this was all worked out,I taped the template to the reference points I had on the box and used a spring loaded center punch to mark the center of where each connector would be.Now that the box was marked, a series of larger pilot holes were drilled to allow the knockout punch tool to fit in the holes. This tool does a great job! Once all 8 holes were punched out, it was a matter of putting all 8 connectors in the box, looking at the alignment and making very slight adjustments to mark where the mounting holes would be drilled. I can't stress enought the measure twice cut once rule, if you are off just a little bit in your math, the box will look like S*** and you might want to buy another box and start over again. Once all metal cutting/punching/drilling was done,it was time to put a finish on the box. A scotch brite pad was used to scrub the box followed by a cleaning in lacquer tinner to remove any grease/oil or other contaminate that might be on the surface. The box was sprayed with a self etching primer and baked in an oven fo 30 min: at about 200degs. Next a very thick coat of crinkle paint was applied and the box put back in the oven at about 400degs for about an hour. Crinkle paint need lots of even heat for best effect. I don't suggest doing spraying/cleaning or baking in your home oven as the fumes are nasty. A better and safer way to go would be to bring the box once all the cutting is done to a powder coater and have them do the finish for you.Once the box has had time to dry and harden, assembly can begin, the panel should be mounted first,the chassis connectors should have their leads sodered on before they are mounted on the box as once they are mounted there is not enought room to get a sodering iron in there, give yourself extra length on the wires as you can trim it at the connection to the switch/ground bus just befor you crimp/soder those connectors on. The first box I built had the volt meter mounted on the box, the second box had the volt meter located in an easer to see location. Both boxes had a bright green led just to remind you that power was getting to the box, or not,the master switch is an "NKK" double pole double throw wired ON-OFF-ON. Both leads comming from the gell cell have fuses in line and I used 14 gauge wire. All wiring in the box was 16 gauge except the wire going to the embeded leds in the switches. I hope this will be of some use to you, give you more ideas etc. I'm not saying this is the best power distribution box ever, but it has never failed/ blown up/ let me down or run short of a dedicated 12 volt circuit.It took three days to build and was a lot of fun, total cost for everything was around $250.00 The pictures are of the second box I build without volt meter on the panel. The pictures are also before the box was installed in the sound cart so more wiring/ cosmetic work was done once the box was in place.The white nipples (sorry can't think of a better word to describe them right now) above the contura switches are the circuit breakers (push to reset)also there is room on the panel right above the breakers to put a label to identify that circuit (mixer/radio rack/recorder etc). Phil (VE7KJR)
  6. I worked on the Canadian auditions in Vancouver last year for three days and was looking forward to working on it again this year but it was canceled do to the economy here in Canada. It was fun but at the end of the three days I concluded that there are a lot of crazy people out there. I loved her " guy holding the sound stick". VE7KJR (Phil)
  7. Hi Bernie, I remember doing the big set ups on the sporting events as an a2 as well, a day to set it all up and have it working, the game might be 2hrs and then take it all down. Never did like the take down part, what a mess of cable, camera cable, video cable,intercom cable all stacked in a big pile next to the moible.Like a big pile of spaghetti ! You would have to take your time and use caution getting the cable out so as not to pull the connectors right off.The nice part was when someone finished with their cables they would help another dept. camera helping sound lighting etc.There was a brotherhood there among the crew. I haven't done a moible in a long time, but it is like riding a bike, you never forget. I have several books on antenna design from the ham radio hobby, as I have said most of the antenna desings we use today have been around for some time, it is easy to make your own if you like building things and have the time and tools. The formulas for doing such are in the books all you have to do is the Math. In the end what is important is that you have confidence in your system and know what it can and can't do. What works at one location may not work at another location or the same location on a different day. There are so many factors to take into consideration, so a little thought might go a long way. It's not just plug and play. Phil (VE7KJR)
  8. Hi Again Aris, To answer some of your questions, The switch from c stand setup to a single pole setup was made for a faster setup/ takedown/ or a move. Remember how I said I would have to undo and redo the bnc connectors every time I would have to move the sound cart and how this causes wear and tear on the connectors. Chances are really good that you will have to move your sound cart several times a day as the set changes or you need power and the electric dept. has moved their drop to somewhere else. Then there were days where I would have perfect cart parking, not having to move all day and could cover several sets on one stage, just swing the antennas a bit to hit the set we were shooting on. I used wireless boom all the time for several reasons, faster setups/ two man crew/ rapid set changes etc. etc. Some mixers will cringe at the idea of a wireless boom but over the years the transmitters sound pretty good when setup right,,, never as good as a hard cable but still pretty good. Yagi verses Shark Fin The yagi antenna design has been around for a long time and has proven itself to be one of the best antennas for rf gain. The more elements there are the more rf gain you will have (3db per element) however they are very directional and need to be pointed or amied just right. They also offer great front to back rejection. The Shark Fin The shark Fin has been around now for a number of years and is a log periodic dipole design, it has a very wide bandwith 450 to 862 MHZ say (depends what they are cut for)and has a gain factor of 4 dbd over a dipole. Do they work, yes they do,and I use them all the time now, do they have a much gain as a yagi, no. Would I put one on a long cable run, no. However with that being said Lectrosonics now offers a "shark fin" design with an rf amplifier that is phantom powered and adjustable up tp 12db gain right at the antenna. I have not played with one yet so it is not fair for me to pass judgement on the design, but in theory would work well on a long run of cable.Nor I have not used the sennheiser a5000cp which is a (circular polar helical design), a design that has been around for a long time as well and now is beign introduced to the ET industry, offers 8dbi gain, wide bandwith 450- 960 mhz / very directional / and weight 3lbs. (A bit much) Do the work,,, sure they do ! Would I use one,,, only if the situation called for it.Seldom is the rf arriving at your your antennas in the phase that you would like it to be in, as rf travels at light speed it will bump into it own reflections, bounce of just about anything and turns itself from vertical to horizontal and back and forth many times over. What happens is a lost in rf siginal level at the recieving end. This is the beauaty of the a5000cp design, to be able to deal with this problem. The other way around is SmartDiversity, which is a microprocessor controlled technique that automatically analyzes audio content and RF levels to determine optimum timing for the switching activity. Active analog antenna phase switching techniques use both antennas at the same time, with 180 degree phase switching to help keep the received signals in phase and minimize dropouts. When the overall RF signal strength quickly drops, the phase of one antenna is switched 180 degrees. If the switch increases the RF level, it will remain latched in that position until the RF level quickly drops again. Both antennas are used at the same time, so overall operating range is also improved. As far as antennas spread apart,,, they only need to be a 1/4 wavelength apart from each other, doesn't matter if they are beside each other in a horizonal plane or one below the other in a verical plane as long as they are 1/4 wavelength apart.If you want to spread them more, go ahead if that will make you happy. I feel I'm getting too deep into this for you, The bottom line is, you will have to think about the kind of work you are about to do and what antennas will work for you. Antennas are just tools, to do the job by. Understanting what works for you and what doesn't work will be the key for you. Rf is crazy stuff, trying to understand it fully can take a lifetime. Experience will be your best teacher ! You really don't want to have to shout out "another for sound please" and then the director asks WHY and you have to say I had a drop out in the radios SIR. Sure drop outs will happen even to the best of us from time to time, remember I said rf is crazy stuff. If you are using wireless a lot, and most of us are forced to for whatever reason, having a good antenna system will save your bacon and you might get the next job the producer is working on. Antennas are the first stage of how the rf and sounds that come with it get into your cart so think about that. And yes there have been times when I just used the "rubber ducks" that came with the receivers on the bnc mounts on the cart, why,,, because I just knew it would work. You asked about a strain relief for the rf cables, well I use a piece of sash cord at both ends, top of the pole and at the cart,works just fine or you can get velcro ties that will work as well but you will have to replace them as the velcro wears out. I do hope this has helped you out, got you thinking a bit more before you start spending you cash. Phil (VE7KJR)
  9. Hi Aris, Years ago before the shark fins came along, I would have my antenna system mounted on a c stand and sand bags borrowed from the grip dept. The system consisted of a dipole(lectrosonics sna600) and a 6 element yagi for gain and distance.The arm of the c stand was horizontal with the antennas at each end, I used very low loss coax cable about 25 ft. and even mounted the comtek transmitter in the center of the c stand. The height depended on how far I was from set or how far away the actors were. I remember long shots where the actors might be 1/8 of a mile away with a very long lens. I had no problems with the rf. Putting the comtek transmitter up there solved reception problems at video village as well.If it was a panning shot my third could rotate the stand to keep the yagi on the actors, remember a yagi is very directional just like a shotgun mic. The down side to this was the amount of time it took to set up and take down each day and every time you had to do a move you had to disconnect the cables from the sound cart. Ever time you connect and disconnect an rf connector you are causing wear and tear on that connection, if you do this several times a day you will end up with less than ideal rf reception over time.I have made it a point to change to new connectors on the cables and cart once a year where connections are connected and disconnected. I inspect and listen to the rf cables to see and hear if there is any breaks in the shield, if there is you will hear a noise as you move the cable. When working in rain, I protect the connections on the antennas and the antennas themselves. Water in the coax is not a good thing and the antennas are water resistant not water proof. Ok lets jump to present day. The fastest and easyest setup are the antennas mounted on a single boom pole, an old one you don't use anymore for booming but will work well for a mast. A shark fin (log Periodic) with the ambient "quicklok" "quick release tip" mounted to the shark fin and boom pole. No fuss no muss, on and off in seconds. A lectrosonics sna600 folding diopole antenna with some sort of clamping adaptor so you can clamp it a foot or so below the shark fin on the boom pole. Both antennas should be vertical, 10 or 12 feet of low loss coax cable (9913f has a loss of 1.9db per 25 ft. at 700 mhz which is not very much) should be more than enough, tape or heat shrink the two cables every foot to keep them neat but leave enough seperation at the ends of the cables so you can connect them to the antennas and to your cart.The most important point of all is to add a strain relief at both ends of the cable, a piece of sash cord will work fine. Way too many times I have seen coax cable get pulled right out of the connectors, had there been a strain relief on the cable it wouldn't have happened.Have two sets of cables made up,one for back up.You should be able to mound the boom pole on the back of your cart on either side or the middle of your cart whatever works for you as I have not seen your cart. The beauty of this system is 1 an easy fast setup.2 when it comes time for a short move all you have to do is lower the pole and don't have to undo any connections. The boom pole will give your antennas more than enough hight to receive your transmitters and you can be some distance from the set. If working in the rain just put a plastic bag over the antennas/connectors to keep the water out.I hope this is all make sense to you, over the years I have found this to be the fastest/easyest and a very reliable setup. Phil (VE7KJR)
  10. Love the pictures Jeff, keep up the great work ! I will have to post some picture of the cart I work with, comes apart,all electronics in the top,power and storage in the bottom. Works great for loading into a small van or doing tow shots.I just posted on "who am I today so you can check me out Phil
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