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Real Hams Drill Holes

Monday, August 19th, 2013

You all know “that guy” – The one with the car or truck with the UHF/VHF antenna (or antennas) stuck to the roof or trunk lid and wires trailing off to the side that go through a trunk or door gap. The antenna maintains its death grip on the outside of the vehicle with the mysterious forces of magnetism, via a lip or edge clamp, or something that bolts to your roof rack. You wash your own car and drive a couple extra blocks to avoid parking garages. It’s all for the better you tell yourself. It is how you “suffer” for your art.  It is also why your significant other won’t let you touch their car.

I was “that guy”.  I also remember when I knew that it was time to no longer be “that guy”.

We all have that moment of clarity when we face a problem or challenge and know exactly what to do. My moment came to me right after finding dry clothes for my 10 year old.  We had just gone through a carwash and the water had run down the antenna feed wire, past the door gasket, and landed right in his lap.  Before we had entered the carwash I had tipped the mag mount antenna down and tucked it in along the roof rack so it would not get “stripped” off the roof as we went through the car wash.  This was the usual practice because to unscrew the antenna from the radio, pull the wire back under the floor mats, and through and under the roof rack rail was too much of a hassle.

I had just purchased this truck a few months ago – a nice, tuxedo black, 2010, Ford Expedition. It has a moonroof, and DVD player for the kids. The moonroof is for me as it is the closest thing I will be getting to a convertable for the foreseeable future. All that stuff on the headliner of the truck made me wonder how I was going to solve the challenge of mounting an antenna. To make matters even more complicated, many newer cars and trucks have roof pillar mounted “curtain” airbags.  So poking cables under trim panels with a screwdriver was not really an option either.  So I came up with a list of criteria.

  1. I wanted to be able to take the truck through a carwash without also washing the passengers.
  2. I wanted to be able to go into an underground parking garage.
  3. I wanted to be able to do 1 & 2 without taking the antenna off the roof.
  4. I wanted a stealthy/clean installation.  I was not looking to necessarily hide that I had a radio in the truck, but I did not want to advertise it either.
  5. I still needed it to be efficient and actually do the work of a proper antenna.

In other words, I want my cake and to be able to eat it too.

I spent the better part of a month reading articles on QST, searching forums, reading search engine hits, and speaking to my local Elmers. (Elmers are awesome.  I aspire to be one someday.)  I was able to break the solution down to the following…

  1. Choose a mount.
  2. Find an antenna that would be flexible enough to bend in a car wash or parking garage.
  3. As part of #2, possibly come to terms with putting extra holes in the shiny new truck.
  4. Install the solution without destroying my vehicle.

There are many, really great web sites that discuss all the do’s and don’ts of mounting a mobile antenna for UHF/VHF and HF.  NMO or through hole mounted antennas are typically considered the best, and everything else is a compromise. The true non-believers avoid the NMO, mag mounts, and lip or edge mounts and use glass mounts on passivated glass to achieve the goal of something is better than nothing.  None of these options were appealing. They were still going to damage the finish of the vehicle and/or be too much of a compromise on performance. So after this soul searching, it became clear that the best way to protect my vehicle and still be enjoy my hobby was to drill holes. NMO was the only option that made sense.

To find a subtable antenna I did have to look further than I thought – and it came from outside the normal amateur radio circles.  Nothing seemed to be what I wanted. I was looking at all the dual band NMO antennas. The issue was that dual band antennas were all going to be too tall and/or too stiff for my project. Spring mounts were no good. The springs added height and/or were too stiff.  Collar sprung antennas would still require me to get out of the truck, un-collar the aerial and fold it over. Motorized mounts were too much of a compromise on performance and still had wires on the outside of the vehicle to deal with.

I finally found what I was looking for from a company that markets to public safety, not the amateur radio market. Sti-Co makes an antenna called a Flexi-Whip. It is very low profile in the NMO mount, guaranteed not to break, is extremely flexible, and is tunable with a pair of diagonal cutters. The “gotcha” was it is not dual band. This is where that second NMO mount came into play.  I purchased 2 of the Flexi-Whip (ROOF-FT-NITIantennas, and a Comet duplexer (CF-4160J). By adding the duplexer I was able to take the output of the FT-8800 into the duplexer and out to the pair of 1/4 wave antennas, one for each band (2M and 440).  The flexible nature of the antenna, no dual band load coils or springs keeps the length of the 2M antenna just under 20 inches.  The 440 antenna is about 6.5 inches. It is barely even noticeable on top of the truck.

Know your limits. I knew right from the get-go that if I were to tackle the headliner in my vehicle it would have been an hours long, brutal, exercise in frustration, and potential damage, to either the headliner, the moonroof mechanism, the DVD player, or any combination of the above. I did not have the experience or the right tools to accomplish this.  So I started making some calls.  I found a really great, local, car stereo place.  With Navigation systems, DVD players, and satellite radios regularly a part of in-dash entertainment units now it is completely normal for them to go into headliners in a wide variety of vehicles to install GPS or Satellite radio antennas. For the pre-negotiated price of $100 they would install my antenna mounts. I was very pleased with the work they did. It was done in a couple of hours. The holes were lined up perfectly and centered along the top of the truck and the coax was run down the side pillars, under the flooring, and up into a space in the center console where I was going to mount the radio control unit.

To complete this project successfully I needed one more very important component… an Elmer (K7DAA) with an antenna analyzer. I had purchased a short jumper to connect the radio to the duplexer. When my Elmer put the analyzer on the antennas we discovered the jumper was a “magic length” that was resonant on 2M.  So I chopped off a couple inches, soldered on a new connector and we checked it again. To tune the antennas I read the instructions that came with the antennas and cut the 2 antennas a little longer than stated for each of the 2 bands. The analyzer was attached and I started snipping off 1/4″ at a time until the SWR was where it needed to be.

Ultimately this project came down to drill vs no drill. Making the decision to go NMO was one of the best I have made in my short ham career. Over the useful life of this vehicle I will have paint scratches, dings, and dents way worse than what was ever caused by the 3/4″ holes drilled for the 2 antennas. Every ham that has seen the install comments on how pro it looks. It has been through several car washes and there are no leaks or other problems to report. It has also been in parking garages without incident and without me having to remove them. I was able to meet all my original design criteria for roof clearance and system performance and ended up with a sharp looking vehicle to boot. If there was one regret I would have to say it was not installing a 3rd NMO at the same time I did the other 2.  I am KJ6VTP, and I am a Ham.  I drill holes.




You may call me “General”.

Friday, August 2nd, 2013

hamA big shout out goes to the SBCARES group for the recent “ham-cram” at the Community and Cultural Center.  We added 2 more technician licensees to the family, and I was able to upgrade to general class.  I may now talk to the world on the HF bands, and I am certain they are waiting for what I have to say.   I had to study over 350 questions to pass the exam. 35 questions are picked from the pool of 350.

You always knew I was a ham…

Wednesday, April 17th, 2013

ham_radio_operatorI think in my heart I have always been a ham. I had friends that were hams, and my childhood best friend’s brother was a ham. Yes, I am talking about being an Amateur Radio Operator.  I still remember my best friend brother’ radio shack and the walls covered in QSL cards from all over the world.

Fast forward 40 years and changes to the licensing requirements, and the advent of Internet based practice testing, had all but erased any remaining excuse I may have had for not taking the test and getting my “ticket”.  On 4/16/2012 I drove up to a little meeting room, in a park, in Sunnyvale, California.  With pencil in hand I completed the 35 question exam about megahertz, how to safely climb an antenna tower in a thunderstorm (you don’t), and ohm’s law, and other topical questions.  I passed and was issued the call sign KJ6VTP.

I immediately drove to the local Ham Radio Outlet and purchased my first radio, the Yaesu FT-60R.  The FT-60, as it is commonly known, is a great first HT (Handie Talkie).  It is dual-band, easy to program, and has a lot of available accessories. If there were one significant flaw in the FT-60 I would have to say it is the single mic/earphone jack. The single, 4 pole, jack needed to plug in headphones, speaker/mics, and other audio accessories has a tolerance that is to narrow and often causes the accessory to not function. More reviews to come.

Irrigation Caddy Review

Friday, August 12th, 2011

Our last sprinkler timer was not working properly.  As it turned out the timer was only part of the problem. The wiring at the valves was rotted from being in the sun and there were places the previous owners had taken shortcuts and wired multiple valves together to get all the zones to fit on a cheaper timer. Even when the last timer was working, the zones that had more than one valve wired together had too many heads running at once. This made for lower water pressure and inefficient watering.

So I repaired the wiring.  But to  break out the 9 valves to separate zones again was going to require a different timer.  Most timers have 6 or 8 zones.  Anything above 8 zones starts getting pricey anyway.  So after digging around in the local hardware stores and online I decided to check out some web based timers.  Some are crazy expensive.  Some will even check the weather for you and alter your watering schedule based on the weather.  I didn’t need that, or especially the cost of that.  I kind of accidentally stumbled on the Irrigation Caddy.  At $150, it may seem expensive, but is really a bargain as a web controllable sprinkler timer.  Since Irrigation Caddy can run up to 10 zones. So, we were able to break the valves out to individual zones again.

It took longer to set up the programs in the web interface than it did to connect the wires. Since there are no buttons, knobs, or dials on the irrigation caddy itself, I never have to stick my hand in that black widow infested corner of the garage again! The tricky part is that you have to have an Ethernet cable that can reach to the Internet Caddy. My garage does have network since that is where the services to the house come in. But definitely something to be aware of. Some users have successfully used a wireless bridge to connect their Caddy to their home network. You do not need internet or network access for the Caddy to run. You only need it to program it. So in theory, you could just bring the Irrigation Caddy in the house, plug it into your home network, program it, and then put it back wherever your sprinkler wires are (the wires have a quick disconnect thing). But then you don’t really get the full benefit of the web interface. You will definitely want the web interface when you are first setting up and testing your schedules.

Scheduling with the web interface is easy. I did have some confusion about the days, odd/even, every other, thing. But when you read the manual a little you realize how powerful and flexible the scheduling can be. It is too long a topic to get into here probably, but you can get pretty granular with the watering control.

It is also easy to manually run zones if you are just sitting in the back yard and you wanted to turn the sprinklers on for the kids to run through on a hot day. Just bring up the web interface on your laptop, tablet, or smartphone and turn on the zone! The web interface is not really optimized for the iPad or iPhone yet. But I bet there will be an interface in the future. And yes, there are regular firmware updates, or at least there have been lately.

I don’t know what else to say. If you imagined in your head what you would want a web controllable sprinkler timer to be, Irrigation Caddy would probably nail it, or be really close. It just works. And for the ultimate endorsement, it even got the “what electronic thing did you buy this time” seal of approval!

More Build Notes…

Monday, August 8th, 2011

Here are some additional build pictures.  The gimble is pretty solid now.  There is still one issue where if you turn to fast to the left the weight of the skull will cause the servo to over rotate and then the skull will try to spin around backward.  I just have to get the left/right tab and servo arm in the right combination of position to remedy the problem.  As you can see in the photos there is also a little work to do inside the skull itself.  There is a chunk of plastic that will interfere with the left/right gimble tab.  It will hit if you have the skull tilted forward, as if looking down, and then try to turn the prop left or right.  A dremel took made quick work of the plastic.

Dead As A Door Nail…

Friday, August 5th, 2011

Well…   The TrackSkull application was working great – right up until my 8 year old Microsoft Sidewinder joystick up and died.  I have no idea why.  But it just stopped working.  Poof.

Have you tried to buy a joystick lately?



  • Target  – Stab in the dark.  They used to have more computer stuff.  Clearly that has changed.
  • Staples – Another shot that might have panned out in the past.  I knew they carried some peripherals.  But the selection has dwindled.
  • Radio Shack – Huge disappointment, again.  Do they ever have what you want or need anymore?  How are they still in business?  The only people I ever see in there are “old people” arguing with the clerk (Who is typically clueless) about why they can’t get a replacement battery for their 12 year old cordless phone.
  • Game Stop – Semi disappointed.  The accessories are obviously not their bread and butter.  The displays are kind of haphazard.  So I am going to give them a pass on this one.
  • Best Buy – Home of the $99 HDMI cable that you can get other places for $10.  Came through in the end, but at an almost $10 premium.  If time wasn’t the crunch,  I could have purchased on-line with free shipping and had it in time for next weekend.

No wonder I hate shopping.

Servo Extensions Part IIIa

Wednesday, August 3rd, 2011

My extensions have arrived.  They shipped pretty quck.  I have just not had a lot of time to spend on this the last few days.  I did change the servo horn for the left/right motion of the skull.  It is smoother, and does not over extend anymore.  And the joystick input on TrackSkull from MoneyBasic.com is working great.  They are having a sale, btw, through Aug 31 (2011).

Or Maybe You Could Do This…

Friday, July 22nd, 2011

A thought occurred to me.  And I may change direction and go this route.  So I wanted to share my new alternative.

Get some servo extensions.  Go to a local RC or hobby store and get 4 6″ servo extensions.  Cut them in half.  Splice them onto the 2 ends of your 25′ of CAT5 cable.  Use the wiring guide as shown in the other extension posts.  It will reduce the number of connections you need to make.  And it doesn’t alter the existing servo cables on the servos.

Servo <—> male end of server extension <—> 25′ CAT5 <—> female end of servo extension <—> SCC 32

Extensions can be pretty cheap on-lineHere are some more cheap extensions.  There are certainly plenty of hobby stores and RC stores in the Bay Area.


Servo Extensions Part III

Wednesday, July 20th, 2011

So now that we know we want to use CAT5 cable we may as well begin hacking, cutting, and splicing.  In Part II I mentioned that stranded CAT5 is probably a better choice for this project.  Since I can repair my own cables easily, I am going use what I already have laying around my “lab”.  I have a 25′-30′ length of solid CAT5 wire.

I have also decided to not just add 25′ of wire to the skull.  I don’t want 25′ of wire in the way when I am setting up or taking down the prop.  So I am going add a new connection at the skull with a short piece of wire, and then connect the 25′ extension to that.  I will be using a DB9 serial connector.

There is a male and female connector for this.  Again, I am using what I have around the lab to put this all together.  So…

I will cut the connectors off the servos, and using a short piece of CAT5 cable, attach a male DB9 connector to the servos.  I will then take my 25′ piece of CAT5 and on one end attach a female DB9 connector, and on the other end I will splice the servo connectors back on.  Writing it makes it sound more complicated than it is.  The key is to make sure the same wires are connected on both ends when you are done.  My color scheme as shown below is simply what I came up with.  You can choose your own as long as it matches all the way through.

In the diagram below you will see that I am using both brown wires, and both green wires for the Red, and Brown servo wires.  This is from the discussion with Mr Chicken regarding having the wire able to carry enough power to the servos.  So by doubling up on the Brown and Green pairs of CAT5 to carry the ground and VS1 (or power) we should be able to get enough power to the servos based on what I have read on other 3-axis skull forums.

I will update this post with pictures from the build when I start working on the actual cable.


Servo Extension Cables Part II

Wednesday, July 20th, 2011

After some reading it looks like the best option is to go ahead and use CAT 5 cable to extend the servos to the PC.  There are lots of references to using lengths of CAT 5 that are 50′ or more with no issues, as long as the servo power supply is correctly sized.  Our kit came with a power supply that can provide up to 2 amps.  That should be plenty of power to push through 25-50′ of CAT 5 cable.

So what is CAT 5?  It is sometimes called UTP or Unshielded Twisted Pair.  It has 4 pairs of wires that are twisted together.  It is most commonly used to connect computers to networks.  The cable that runs from your home DSL modem to your computer is a CAT5 cable.

CAT 5 comes in different grades.  There is CAT5, CAT5e, and also CAT6.  E and 6 are more expensive.  You do not need the E or the 6.  Plain old CAT5 will be fine.  You can purchase a length of bulk cable from a hardware store or buy a long CAT 5 patch cable at someplace like Fry’s, or order one from Monoprice.  If you get a patch cable, you will be cutting the ends off anyway.

One more thing – CAT5 wire comes in stranded and solid.  Bulk wire is often solid.  Patch cords are usually made with stranded wire.  This makes them more flexible and the wire in the cable is less likely to break from being moved around over time.  So stranded is probably the way to go.  So if you do go to the hardware store, check if the bulk cable on the spool is solid or stranded.

So the next step is to figure out what we are going to cut and splice, nut, crimp, or solder, to what.

On to Part III…

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