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Author Topic: Are all of my ducks in a row?  (Read 5783 times)
AC5UP
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« Reply #15 on: June 16, 2012, 09:45:28 AM »

...easy for you to say.
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KJ4QYM
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« Reply #16 on: June 17, 2012, 01:45:38 AM »

Ok so one last thing I just realized I don't have is solder and a soldering iron because according to my research even when using a crimp on connector you still need to solder: k0bg.com/coax.html under "Soldering" states: "The tip should be soldered first. If you use good PL259s as I suggest, this operation takes about 10 to 15 seconds. Enough solder should be used to close the connector tip entirely to aid in keeping out moisture. Avoid slopping solder on the outside of the center pins. Let the tip cool before soldering the shield." I've never done this before. Should I purchase the soldering iron recommended on his website? I'd like to go as cheap as I can on the soldering iron for this part of the setup. Also any pictures of this step would be great as I'm still not sure from these instructions how to go about soldering the "connector tip".
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K3GM
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« Reply #17 on: June 17, 2012, 05:46:02 AM »

Yes, even with crimp-ons, there is a soldering step.  It is advisable to first solder the center pin to basically hold the connector in position for the crimp.  The iron you need should be able to provide sufficient heat. For years, I've used a Weller gun with a large tip.  Regardless of the iron, heat the pin of the connector, and not the solder itself. Touch the solder to the pin as you heat it.  When the pin is sufficiently hot, the solder will flow into the hollow pin via capillary action, meaning you won't have to force it to go where it need to go.  With a sufficient amount of solder, the hole will close up,  but this will require some regulation of heat so the solder isn't too "runny", but is more viscious in nature.  If I were you, I'd first try twisting some copper wire together and solder them to get the feel of the process.
« Last Edit: June 17, 2012, 06:45:48 AM by K3GM » Logged
AC5UP
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« Reply #18 on: June 17, 2012, 06:05:39 AM »

As I type this I'm staring at a Kings KU-5958 connector... Can't find a picture of it on the web. I suspect it's long discontinued as not even the Kings web site shows it, but I scored two bags of them on the cheap from eBay many moon ago because of this oddness. It's a semi-crimp connector as the barrel end works well with " RG-8 " style cables and the crimp tool I use with CATV connectors. Not a textbook method, but the crimp is mechanically solid and doesn't look obviously wrong. The center pin has a small shank at the tip with a hole barely large enough for the center conductor of RG-59. This makes the concept of crimping the pin a non-starter.

What to do?

The small hole is more than adequate to wick solder inside the pin, so the trick is to prep the cable so the center conductor bottoms against the tapered shank. Crimp the shield then solder the center pin. Solder will flow (draw) towards heat and a 35 watt pencil iron is more than adequate to heat the pin to the point of drawing solder. Takes only a few seconds and I usually feed solder until it stops drawing. I should also mention it's good practice to give the iron a good five minute warm up before trying this... A cool iron can make for a cold solder joint so the wait is worth it.
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K1DA
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« Reply #19 on: June 19, 2012, 07:04:36 PM »

Your Camry probably has an auxillary fuse box right behind the little coin holder drawer to the left below  steering wheel.  An adaptor  with pigtail which plugs into a fuse slot works fine there and can be found at most car parts stores.  I'm using a dual band antenna on a Larson cell phone mag mount on the trunk with my dual bander.  Works fine.  There is a reinforcement rib which runs down the middle of the Camry trunk lid, makes it difficult to install  a body mount in the center of the trunk.  My car, of course, came with a sunroof.   Embarrassed
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KJ4QYM
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« Reply #20 on: June 20, 2012, 12:23:02 AM »

Your Camry probably has an auxillary fuse box right behind the little coin holder drawer to the left below  steering wheel.  An adaptor  with pigtail which plugs into a fuse slot works fine there and can be found at most car parts stores.  I'm using a dual band antenna on a Larson cell phone mag mount on the trunk with my dual bander.  Works fine.  There is a reinforcement rib which runs down the middle of the Camry trunk lid, makes it difficult to install  a body mount in the center of the trunk.  My car, of course, came with a sunroof.   Embarrassed

Where did you mount your radio inside your car? Or do you have an HT?
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N6AJR
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« Reply #21 on: June 24, 2012, 12:43:23 PM »

I purchased a crimper kit fro the folks at high sierra ( http://www.hamcq.com/index.php?_a=viewProd&review=write&productId=473#write_review ) for something under 100 bucks and am extremely happy with it.  they also have a good tutorial on hwo to do it on the web site ( look at the "bar" on top with the different selctions of where to go on the site.) Nice folks , good stuff , great prices, and I am 1 happy customer.  I used to solder everything and now I crimp it all, pl 259's  tnc's, even N's, this makes it easy.

I have several trunk lip mounts on the car , but have drilled holes  ( using greenlee chassis punch) in the pickup, but I have also made holes with a twist drill and even a step dril. they all work..  I have 6m, 1.2 g, 220 mhz, and 900 mhz antennas punched through the roof  with larson  NMO mounts and 2 screwdriver antennas and 2 more 2m and 2m/440 antennas on the bed rails of the truck.   

most important thing is that its your vehicle, do what you want. and enjoy the hobby.
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N6AJR
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« Reply #22 on: June 24, 2012, 12:51:42 PM »

also, I have several styles of crimp connectors, some need the center soldered, and some are crimped, so either works fine for  me.   an option also is to buy yourself a matching trunk lid from a junk yard and then mount all your antennas there, i drilled mounts.  when you sell the  car, switch back to the origonal  trunk lid.  and be sure to bond any troun lid or hood mount  from the lid to the chassis with a piece of braid. the hinges on the trunk lid do not make good electrical contact,
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KA2ODP
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« Reply #23 on: July 21, 2012, 08:49:08 PM »

I work at a radio shop on a military base where we are constantly installing 2-way radios into military vehicles for use out in the missile field.  We usually install a roof-mounted VHF antenna for best performance, using a 5/8-wave Motorola “Spectrum” 3 dB gain antenna.  If the vehicle is only used on base, we install just the basic ¼-wave VHF antenna.  For special vehicles that lack an adequate ground plan we use the Maxrad ½-wave VHF antenna.

In all situations we use the Motorola NMO mount.  It is the industry standard in the Land Mobile Radio (LMR) world.  There are a vast variety of antennas available for the NMO mount.  Depending on what radio gets installed, you just screw on the appropriate antenna – VHF, UHF, etc.  If the radio gets replaced with a new radio on a different band, just replace the antenna with a different one to match the new frequency range.  The NMO mount and coaxial cable are good for the entire HF, VHF, and UHF frequency ranges.

I use NMO mounts on my personal vehicles for the same reason.  For Amateur Radio applications the Larsen NMO-2/70B and the Maxrad MDB-1444 are excellent dual band (2-meters / 70-cm) antennas available with bases that match the NMO mount.  Larsen also makes the NMO-27 antenna for the old VHF-Low business band, but it can also be tuned for either 10-meters or CB radio (11-meters) due to its frequency range of 27-31 MHz.

Drilling the ¾-inch hole required by the NMO mount is best done using a specially designed hole saw made by Antenex.  The Antenex model HS34 hole saw comes with a pilot drill already installed.  The special design has a shoulder around the outside of the saw blade that limits the depth of cut to 1/8-inch.  This means you can cut through the vehicle roof without fear of going too far and damaging the vehicle headliner below.  A regular ¾- hole saw will cut through the thin metal roof and keep going!  An added bonus with the shoulder design comes into play after you have finished cutting the hole and have removed the resulting metal disc from inside the hole saw.  Place the hole saw back into the hole and spin it with the drill while applying light pressure.  This lets the shoulder of the hole saw wear down the paint on the vehicle roof until the bare metal is visible.  When you install the NMO-mount brass locking ring with the O-ring gasket, it will contact the bare metal and get a good ground connection. 

Most vehicle roof panels are painted with primer on the underside, preventing the two tabs on the bottom half of the NMO mount from making a good ground connection.  If you have small fingers you might be able to stick a strip of sandpaper down the hole and use your finger to sand away the primer on the inside, but it is far easier to just let the hole saw remove the paint on the outside of the roof panel with only 15-30 seconds of spinning.  The small ring of bare metal created around the hole is just wide enough so it is covered by the brass locking ring when it is tightened down.  There is no bare metal visible once the NMO mount installation is complete, even before the desired antenna is screwed on.

The center portion of the NMO mount has two small round holes on either side of the center contact.  Motorola sells a special wrench that fits into the holes, so you can keep the mount from rotating while you tighten the outer locking ring with a wrench.  However, a small pair of needle-nose pliers with tips small enough to fit into the holes works almost as well.  Stick the needle-nose pliers into the holes so they form an “X”.  Use the palm of your hand between the handles to apply down pressure to keep the tips in the holes.  Use your fingers and thumb to keep the pliers from rotating while your other hand tightens the outer locking ring.

The Antenex HS34 hole saw can be expensive if purchased at retail prices.  I have seen it priced at $60 retail, but less than $40 when purchased through a parts wholesaler such as Tessco.  If you are going to be installing a lot of antennas on vehicles, it is a wise investment.  It makes installing NMO antenna mounts sooo much easier.  Replacement blades are available, but in general use the original blade will last a long, long time.  At the base radio shop, with constant use, we are getting 5-years out of the blades before we even think about replacing them.  The Antenex HS34 hole saw is probably too expensive for the average ham radio operator to justify if you only install a NMO mount once every few years.  However, it would be an excellent item for a radio club to purchase for use by its club members on a temporary loan-out basis.  That way everyone gets to benefit from the professional results without purchasing a specialized tool that only gets used infrequently.
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KA2ODP
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« Reply #24 on: July 21, 2012, 08:50:53 PM »

Besides drilling the ¾-inch hole required by the NMO mount, the other big challenge is routing the coaxial cable from the roof to where the radio is mounted.  For a roof-mounted antenna installation, the best location to drill the hole is usually somewhere above where a dome light is installed on the interior of the vehicle.  Remove the entire dome light assembly and look for a clear spot on the vehicle roof either just in front of or just behind the opening in the ceiling headliner.  Avoid reinforcement beams, roof stiffeners, or any location that is not a single layer of metal.  Using the dome light hole for access to the roof underside allows the use of a “fish tape” to pull the cable from the mount location over to the side of the vehicle and down the A or B pillar.  From there run the cable underneath the door sill plates to the dash board and over to the back of the radio.  Many new vehicles use a rubber gasket that runs all around the door opening on the vehicle body.  Pull the gasket down from the top of the door opening to gain access to the edge of the ceiling headliner.  Gently pull the headliner down slightly and see if you can insert a fish tape all the way to the dome light opening.  If you can find a path to the dome light opening, then you know you can pull the coaxial cable from the NMO mount location over to the side of the vehicle roof.  Ensure a clear pathway is available BEFORE you drill the hole in the vehicle roof!  If you cannot find a clear route for the cable, then perhaps a roof mounted antenna is not the best choice for your particular vehicle.

On pickup trucks, a favorite roof-mount location is towards the back of the truck cab.  Remove the third brake light from the back of the cab and look inside the opening for access to the vehicle roof.  Usually you will see a second opening inside that passes through a second layer of sheet metal that curves up to reinforce the roof panel along the back edge of the truck cab.  Past that inner opening you should be able to see where the interior headliner curves up to meet the roof.  In the space between the second opening and where the headliner contacts the roof, there is just enough room to drill a ¾-inch hole and install a NMO mount.  This is usually around 6 to 7 inches in from the outer opening where you removed the brake light assembly.  The goal is to install the antenna mount as far forward as possible from the brake light.  This allows adequate space in case a tall metal topper is installed later.  An antenna that mounted too close to a tall metal topper will have SWR problems.

Some pickup trucks have a flat roof all the way to the back of the cab, which is great.  But other truck cabs have a roof that slants down towards the back edge of the cab and the third brake light.  Installing an antenna mount on this sloping roof surface will result in an antenna that will tilt backwards at an angle.  With a short ¼-wave VHF antenna installed, the tilt might be slightly noticeable.  But with a longer 5/8-wave VHF antenna installed, the tilt angle will be much more obvious!  Check this out before deciding to install your antenna near the back of the truck cab.  Perhaps a spot in the center of the cab roof would be a better location.  Again, the availability of access up through the vehicle headliner, and a clear pathway for the coaxial cable to be run, is a big factor in deciding where to install an antenna mount.

This is definitely a situation where you need to measure very carefully before drilling the hole!  The coaxial cable will follow the same path as the brake light wiring – just above the headliner over to the back corner of the truck cab and down to the bottom corner of the cab.  Often the brake light wiring runs over to cab corner on the passenger side of the vehicle.  From there route the cable underneath the door sill plates towards the dashboard as before.  If the truck has coat hooks or screws installed on the headliner along the back of the cab, removing them will allow the back edge of the headliner to be pulled slightly down, giving you just enough room to stick your fingers up behind the headliner and grab the coaxial cable that you fished in through the inner opening towards the cab corner.  On standard cab pickup trucks with a rear mounted dome light, removing the dome light will often give you access up behind the headliner.  Look for access holes in the inner sheet metal where the wiring for the dome light and/or brake light pass through.  Again, confirm a clear pathway for the coaxial cable exists BEFORE you drill the hole in the vehicle roof.

On a crew-cab (4-door) pickup truck, installing a NMO antenna mount along the back edge of the cab using the brake light opening usually leaves enough room for a second antenna mount to be installed in the center of the roof above a dome light located in the middle of the cab interior.  This can be handy if you are running multiple radios and need more than one antenna.  If you have a dual-band radio, a single dual-band antenna may be all you need.  Otherwise you can install separate antennas for each band if you wish.  Another option for the second antenna location is the Larsen NMO-150450800 antenna, which is a tri-band antenna for 150/450/800 MHz intended for use with a radio scanner (check your local laws concerning use of a radio scanner in a vehicle).

Most NMO antenna mounts come with approximately 17-feet of RG-58 coaxial cable.  This is just enough to reach from the back of the cab, over to the back corner, down and forward to the dashboard.  Sometimes in order to have enough cable with the longer crew cabs you have to run the cable along the door sills to just beside the front passenger seat, then go under the floor mat at a diagonal path under the seat and over to the center console if that is where your radio will be installed.  On a standard (2-door) cab there is usually plenty of cable to run all the way from the back of the cab, up underneath the dashboard, and over to the center console.  Where the antenna mount is installed, and where the radio will be installed, has a big influence on how the coaxial cable is routed between the two locations.

A final word of caution is needed regarding vehicles with side-window curtain air bags installed.  These curtain air bags vastly complicate the installation of an antenna mount in the roof of a vehicle.  When you pull down the door opening gasket, you can often see the rolled-up white curtain air bag installed just above the headliner.  Beware of the yellow wiring that runs to the curtain air bags.  The antenna coaxial cable must not interfere with the deployment of the curtain air bags!  Route the cable far away from the curtain air bag and associated yellow wiring to avoid ensnaring the air bag during deployment.  Many pickup trucks with side-window curtain air bags do not have one across the back window.  This leaves a clear path for the coaxial cable to run above the headliner, across the back of the cab above the back window, over to the back corner of the cab, and then down to the bottom corner of the truck cab.  This is why installing the antenna mount from the third brake light opening is so popular for pickup trucks equipped with side window curtain air bags but no rear window curtain air bags.  Consult your owner’s manual to find out the location of all the air bags in your particular vehicle. 

Obviously, you cannot mount any radio equipment or microphone clips in the deployment zone of a dashboard air bag.  Likewise, if your vehicle has side-window curtain air bags AND a rear window curtain air bag installed, a roof-mounted antenna might not be the best choice.  We inspected the current model of the Chevy Suburban and found they had curtain air bags installed along both sides and across the back as well.  The greatly increased difficulty of installing a roof mounted antenna in such a vehicle caused us to change our strategy.  For Suburbans and similar SUV’s we now install the 2-way radio antenna on a simple L-bracket along the fender/hood gap on the driver’s side, opposite the AM/FM antenna.

The typical mobile radio installation at our base involves a 50-watt Motorola VHF radio and a 3-dB gain antenna mounted on the roof of vehicle.  On Chevy Suburbans and similar SUV’s we install a ½-wave antenna with a L-bracket along the fender/hood gap.  We always route the coaxial cable away from and at right angles to any yellow air bag wiring.  We have never had any air bag activated by RF signals in all the years we have been installing 2-way radios.  But if the roof of the car, mini-van, SUV, etc is loaded with air bags, we skip the roof mounted antenna and find some other place to install a bracket and antenna.  Better to be safe than sorry.

It can be a simple task or a complicated task to install a roof mounted antenna.  It all depends on the vehicle.  If you like the idea of a roof mounted antenna, but not the labor involved, consider taking your vehicle to a local 2-way radio shop to have the NMO mount installed.  For $50 or less the mount will be installed with the connector of your choice on the radio end of the cable.  When you get home, finish the radio installation and attach the desired antenna onto the NMO mount.  Purchase or borrow an SWR meter to verify the antenna is properly tuned, and you are ready to go!  No more magnetic-mount antennas scratching the paint, falling over at highway speeds, or getting the coax smashed flat in the door.  A black plastic rain cap (Larsen P/N: “NMOCAPB”) is available to screw on to a NMO mount in place of the antenna for when you want to run your car through the car wash.
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KA2ODP
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« Reply #25 on: July 21, 2012, 09:00:34 PM »

As a side note for those not familiar with the NMO mount, it installs from the outside of the vehicle.  You pass the coaxial cable in through the hole in the roof from outside the vehicle.  Once you have pulled all the excess cable through, tilt the NMO mount to one side and slip one mounting tab in through the hole, then the opposite tab.  The center portion of the NMO mount is slightly larger than ¾-inch, so you cannot simply stick it up through the hole from inside the vehicle.
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K7RBW
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« Reply #26 on: July 22, 2012, 09:04:26 AM »

As a side note for those not familiar with the NMO mount, it installs from the outside of the vehicle.

This is probably worth repeating! It sure looks like you could stuff the mount up through the hole from the inside...until you try it! (don't ask Smiley )

Thanks for the detailed description of the process! (I could have used this 6 months ago Smiley )

Also, I'd argue that even if you only install one antenna in your life, the $40-ish spent on the Antennex hole saw is money well spent. Just compare that cost to what it would cost if you slip and damage the paint on the outside or tear up the headliner and any wiring on the inside. Those potential costs make the $40 cost of the hole saw seem trivial (to me, anyway). That said, I agree that they'd make a good addition to any Ham club's inventory of goodies.
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KF4HOQ
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« Reply #27 on: July 22, 2012, 10:01:11 PM »

I'll second what KA2ODP said.  I also used to install radios in police cars, and all of the advice he gave is spot on.  I'd also like to reiterate the mounting of your radio.  Make sure that you NEVER mount the radio or the control head in the airbag deploy zone.  It WILL become a missile in the event of airbag deployment.  Also, make sure that whatever you use to mount your radio will not come off in the event of an accident.  Again, missile during an accident.  It took an officer getting 9 stitches to his forehead before the department brass said that no laptop computer screens were to be raised while driving.  He got in a wreck, and the airbag ripped the screen right off the hinge, and it hit him in the head!
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