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dbv last won the day on April 18 2017

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About dbv

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  1. dbv

    Ham Radio Install

    All done with antenna mounting. Larsen 5/8 VHF/UHF antennas in the front two positions and MFJ-1699S HF antenna in the back. I have Diamond single band antennas for 20, 40, and 80 meters, but they aren't actually short enough to legally drive with. Good for fixed ops though. Pretty soon I'm going to drive up to one of the highest passes in Colorado, and see what I can do on the various bands.
  2. dbv

    Ham Radio Install

    It's going better than I expected. I decided to put the two forward antennas above the interior lights, which makes the back one hard to get at since I can't reach it without a stepstool, but it meant I didn't need to drop the headliner. The rear antenna is just inboard of the back hatch. The support member there comes farther forward than you'd expect. Threading the coax lines was relatively easy, and I was able to run them around the airbags on the outside, and down the drivers pillar. I'm very glad I got the RG-316 cable versions, as three RG-58 lines would have been hard to fit. The rigs are set up on an aluminum pallet which fits under the drivers seat. Remaining, to print the control head brackets in ABS, and run the power line from the battery. For now I'm using the console power outlet intended to serve the rear seats.
  3. dbv

    Ham Radio Install

    In the expedition and the Suzuki, I was able to drop an overhead console at the antenna point, and that gave me access to drill upward, and to mount the connectors. No such luck on the connect. I am worried that I won't be able to get enough access with just pulling the headliner down a bit, especially in the front. I can probably use the position above the middle dome light for the middle antenna. I haven't looked at the back position much yet. All the parts are in, and I could theoretically start this week, but the weather here is going to be snow or rain all weekend, so it looks like I will be pushing to next weekend at best. Fusing: No worries, that's one reason I choose larger gages. I want the wire to be rated significantly in excess of the fuse current. In a typical fault, the wire will have rubbed on something which shorts through the insulation into a small point of contact on the wire, with high local heating. The large gage acts as a heat sink until the fuse blows. This article by LittleFuse is excellent: http://www.littelfuse.com/~/media/automotive/catalogs/littelfuse_fuseology.pdf From the graphs, it appears that a 25 or 30A maxi fuse may be what I need. That seems wrong, but look at figure 2 which shows the time to blow for a 30A fuse at various currents. Two seconds at 100A, and basically "never" at 50A.(!) Section 6 says that I should not exceed 47A for under the hood applications with a #6. Fuses are tricky. I will of course have spares on hand and this is open to revision. Related: I had a run in with this phenomenon in my day job a couple years back, and I highly recommend a read of the article "Low Voltage, the Incompetent Ignition Source". In my case it was a PCB which had passed all applicable UL testing, but was capable of igniting and sustaining a flame under certain conditions. The brick power supply detected the fault, and was in "hiccup" mode, but the PCB couldn't quite dissipate all the heat from one pulse before the next one hit, and the temperature got high enough. Don't underestimate the ability of low voltages to cause fires. They show one case where a lithium coin cell caused ignition on a PCB. The two radios in transmit could draw as much as 38 amps. I've decided on a #6, which will probably be about 10 feet or less. Powerstream has a nice table that tells me that #6 will do 38 amps all day, (literally) and will sustain 110A for short periods. The chassis wiring rating is conservative, but does assume that the wire has air surrounding it rather than being bundled or enclosed with other wires. I will have something like 0.004 ohms in series with the battery, so IR loss is 0.15V. It's all about the I^2R losses. Assuming a 40A fuse current the I^2 term is 1600A, and the resistance is .004 for this length of wire, so 6.4 watts of heat lost in the wire over its total length. That's nicely conservative. I will at least temporarily use the chassis as the ground return until I get better info on the implications in this vehicle. I can always run a ground return if needed. If I need to run that wire it will be fused, to protect against wiring faults like open battery-ground cable which could subject my ground lead to more current than it can sustain. The likelyhood of this is near zero, but it is not zero. Depending on where the battery current sensor is, that ground would terminate either on the battery, or on the point where the battery grounds to the frame. Diamond recommended their C213 cable for the HF antennas, so it's their antenna, their mount, and I can't much argue with that. http://www.diamondantenna.net/c213.html The mounting of the two radio main bodies and the tuner will be an interesting problem. One option might be to locate the tuner in the drivers side back pocket near the jack, and save space under the seat. I've got the mounting brackets for the control heads printed in PLA now, and that all looks good. I will have to re-print them in ABS or some other high temperature filament before summer, but that's a ways off yet. One of my smaller problems is finding a home for the two microphones, but I'm not too worried about that. I'm looking for some doc that will tell me the relative safety of mounting two VHF/UHF antennas in close proximity. I worry about the receive front end in one radio being damaged by the other transmitter. I will not have a lot of options in locating the center antenna, and somewhat less on the front and back antennas.
  4. So my Suzuki unexpectedly died, and I was thinking what vehicle I might go to next. I'd looked at a number of minivans, and talked to a friend about a Chrysler that he owns. His response was "Oh HELL NO" due to tons of wierd problems. I liked the look but his comment put me off that brand. So while I was shopping, I started noticing what was on the road nearby, and I spotted a Chrysler just ahead of me on the highway, and I sort of jokingly said to myself "Look, a RUNNING Chrysler!". And at that moment, the four ways came on, and the Chrysler rolled off to the side of the highway. Amusing coincidence, but I swear I'm not making this up.
  5. Is there a doc somewhere showing how to drop (not necessarily remove) the headliner? I need access in three spots along the center of the roof for radio antenna mounts. I can wing it, but I'd prefer to know more before I attack. The airbags up there make me nervous. Installing high powered electronics next to armed explosives....
  6. Working on getting my control head brackets done, but I do, and I probably will do some custom gizmos for this rig. Printing for in-car is a challenge, it requires something like ABS for the temperatures, but ABS is very prone to warping when printed. I'm looking into other filaments that would be compatible with my printer.
  7. dbv

    Make the center console compartment useful

    I have this. I may end up 3D printing a gizmo to create the false bottom and shield the USB stick from bashing. For now I'm just not puttng the usual gear in there. The compartment is disappointingly small. That's one feature I am missing of my Suzuki XL-7. There were three large-ish compartment spaces in the center console.
  8. dbv

    Ham Radio Install

    Afternoon update: The dealer referred me to an installer, but I don't want or need anyone to do this for me. Back to the dealer, and they say they have no idea what document(s) I might be referring to.. So, I will re-engage with fleet. (sounds like a Star Trek episode)
  9. dbv

    Ham Radio Install

    I am trying to obtain info from Ford on removing and replacing the headliner, and whatever info they would provide to someone doing a police/fire/etc build. Dealer sent me to Ford Fleet, Ford Fleet referred me to the dealer.. Fleet is now telling me I need to purchase "IDS" software to access the information?? I think this has gone off the rails somewhere. Who actually has this info, and how do I get it?
  10. dbv

    Ham Radio Install

    Ok, the day is getting closer. I ordered the NMO and SO-239 mounts, and the tuner, and three single band HF antennas. The mounting brackets are here. I need to know how to delicately pull down the headliner so I can install the three antenna mounts. Is this documented somewhere? It appears the whole shelf (pictured) needs to come out for this, but I could be wrong. I see airbags up there as well. Currently printing the 7000 mounting bracket for test fit, and probably next up is running the power.
  11. dbv

    3D models?

    I am looking for a reasonably accurate 3D model of the 2017 wagon. I've found a lot of near misses, low quality or wrong year/model. Hopefully someone out there knows where one lives?
  12. dbv

    Ham Radio Install

    Pic of the 350 control head on prototype bracket. Sorry for the bad focus, I'll do better later. The shelf doesn't look like it's going to have any issue with the weight. I'm still adding details, but I wanted to ride around with it in this config before I commit.
  13. dbv

    Ham Radio Install

    Both radios will be on. The FTM-350 transmits automatically and it can be short intervals between transmissions. If I am transmitting on the 7000 it is fairly likely that the 350 will transmit at the same time. While it won't "hurt" the radios, the lower voltage will cause variation in the output power which can be audible.
  14. dbv

    Fuel efficiency

    It's all that time sitting at stoplights at 0 MPG that really sucks. Maybe someday they will find an alternative to stoplights, and arrange traffic to minimize stopped time. Even for any sort of EV, stopped time is range being eaten while going nowhere.
  15. dbv

    Ham Radio Install

    As I get more information, the install evolves. I am looking for info now on clearances between the headliner and the roof. My thinking is that the FTM-350 and IC7000 main decks will live below the drivers seat, and I will need three coax runs up into the roof. Forward position will be NMO for the FTM-350 VHF/UHF antenna. In the middle, where Ford suggests roof vent mounting will be another NMO for the IC-7000 VHF/UHF side. In the back, near the hatch, an SO-239 for the IC7000 HF side. That will work with the Diamond HF antennas on SO mounts, and also with any longwire or loop I might set up when camping. The SO-239 mount in the rear is likely to need some extra clearance, as I will probably do what I did on the Expedition, with reinforcing plates on top and under the roof. Last time it was a large washer on top, and a Ryobi weed eater blade underneath. That let me run the SG-7900 antenna without any real flexing, even though the roof metal on the Expedition was apparently reinforced tinfoil. This might be the most interesting installation of the bunch. I need find a good right angle bulkhead mount for that one. The control head mounts have made a ton of progress though I was away at a conference all weekend and I think I'm ready to print those in ABS for the final (?) version. This week while waiting for the main unit mounting brackets and the control head mount for the 7000, I will mount the 350 head, confirm the main unit mounting positions, and run the separation cables. I wasn't overkilling the power as much as I thought. The 7000 can draw 22A, and the 350 can draw another 12A. #8 would cost me half a volt with both transmitters running. #6 about 0.25V and #4 about 0.125V. I'll need to check out the path for the power wires real soon. So that's my current thinking. Attached, a view of the current version of the FTM-350 mount that will attach under the shelf and above the visor on the drivers side. It's done in OpenSCAD. I can share the files if anyone is interested. The IC-7000 version is just a different front hole pattern, but I won't know that till I have that mounting bracket in hand. It's currently clearing customs in SF. I think I have the downtilt angle on the bracket right, but I will mount it today and drive for a while like that before I commit.