If you look back at my post about the MFJ unun that I am using to help match my Hamsticks, you might see that I got a couple different bits of feedback.  The basic question I had asked is this:  When matching an antenna is it better to start at lowest SWR or Resonance?  The method I ended up using that I described in that post was starting from Resonance - mainly because that seems to be the suggestion from K0BG on his website - plus it had some other advantages that made me lean towards that method.
     Like many things, there is a lot of back forth when questions like these come up.  There are things like questions about how much it really matters when you consider how compromised a mobile antenna is, where is the matching device located, how long is the coax, etc.  With that in mind, I'm considering a small experiment:

     Because the Hamsticks use the whip at the top for tuning, the matching I did, starting from resonance, is a combination of the setting on the matching unit, and the length of the whip.  I could unscrew the whip part, and set it aside, and screw in a separate whip, and do the whole matching process again, but starting from low SWR.  Doing this would give me a way to compare the two methods because I could quickly swap the Antenna back and forth between one matched starting from resonance, and one matched starting from low SWR.  I have an inexpensive meter that I can use to measure field strength - it doesn't give absolute values, but I could set it based on the first antenna arrangement, and then compare the second antenna.  The process would go like this:

1. Put in the whip matched from resonance, and set the MFJ matching unit to the appropriate setting.
2. Put the field strength meter some set distance from the antenna (15 feet?)
3. Transmit a carrier on low power - maybe 5 or 10 watts
4. Calibrate the field strength meter to mid-scale
5. Switch to the second whip, matched from low SWR, and set the MFJ matching unit to the appropriate setting.
6. Transmit a carrier on the same low power setting as step 3
7. Compare the reading on the field strength meter

     Does this sound like it would be a reasonable comparative test, or am I missing anything important?  I think by following these steps I'll have a "controlled" experiment, and I'll have a fairly objective way to measure the results, other than just asking someone "how do I sound now?"  Thoughts?  Comments?  Should I go for it?

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    Some call it CB.  Some call it 11 meters - tomato tomáto.  I know that for some amateur operators, CB radio is something you look down your nose at - and there are some pretty big noses to look down out there!  In reality though, many hams got started in CB, and for those of us that have jobs that required a lot of time on the road, a CB is a nice accessory.  There are times where you can find out what's up with traffic faster with the CB than with any other method.  Also, while some hams may choose not to believe it, truckers are people too, so sometimes it is just as fun to chat with them as it is to chat with hams!
     With all that being said, this is part one of my project to get my CB installed in my car.  If you have read my past posts, you may recall that I mentioned in passing that I had installed another NMO mount (this one), in anticipation of an additional antenna.  That mount is for the Browning CB antenna that I purchased from Amazon recently.  This antenna will be located on the front passenger side quarter panel.  To orient you, the NMO mount you see in the picutre is just in front of the passenger side rear view mirror.  I routed the coax through a factory grommet located just behind this point, that ends up behind the passenger side kick panel.  For a while, the coax was just coiled up there, waiting for me to have time to get on with the rest of the project.
     The next several steps happened over the course of a couple weeks, when I was able to steal an hour here and there to work.  I decided to use the center console as the location to mount the CB (I hinted at this in a post back in November when I first got the car.) Because I don't use the CB nearly as often as my Amateur radio, I wanted it somewhere that was out of the way, but was still easily accessible when I did want to use it.  To keep it clean looking, and to have a spot to mount a couple future items (like maybe a screwdriver controller....) I decided to make a panel to fit the console, to mount the radio, and any future equipment into.  
     Step one was going to be brackets to hold the panel.  I have all kinds of stuff in my metal scrap/recycling pile, so I dug through and found this, and figured I could make it work:

     After measuring the inside of the center console, I cut 2 pieces of this to length.  I then double checked where the other end of the screws would go, and screwed the two brackets into place, to act as supports for the panel that will drop in place on top of them.

     Because the space in the center console isn't square, and I needed to be able to do some test fitting, I made a template.  I started by using strips of stiff cardboard.  I cut them to length, trimmed, and fit them into place temporarily, and when they looked like a good fit, I taped them together so that I would have an outline of the console, to trace onto the next piece.

     Next, I traced this outline onto a solid piece of cardboard, and test fit that into place.

     

     Ultimately, this pattern will be cut out of the same plastic sheet material that I used to make the mounting location for the remote head for my Yeasu 857d.  For now though, I traced this cardboard template, onto a piece of scrap OSB plywood that I had, which was the same thickness as the plastic I'll be using.
​

     I actually ended up cutting several of these as I did test fits, trimmed, test fits, etc.  Once I had the basic shape the way I wanted it, it was time to decide how the radio would mount.  

As it turned out, the dimensions on the web site, didn't include the connectors on the back of the radio.  In order for it to fit, the radio was going to have to get installed at an angle.  I cut the opening for the face of the radio, and used a couple pieces of angle bracket to attach the radio body mount to the bottom of the panel.  The idea is that with everything attached to the panel, I should be able to lift the panel, and everything attached, in and out to have access to the back of the radio, and any future stuff that gets installed here.
     But there was a problem!  The brackets I cut (the first couple pictures in the post) were wide enough that they actually got in the way of the thumb screws (more like knobs) that hold the radio body to it's bracket.  I ended up taking those brackets out, and cutting new brackets from a fresh piece of aluminum angle stock that I picked up at Lowes.  I put them in place, a little more strategically this time.

     With some better, more properly arranged brackets, everything seems to be starting to fit nicely.

     With this part of the template process done, I connected the mic cord and opened and closed the console, to make sure there was proper clearance for everything.  Luckily, center console lids are designed knowing that people are probably going to have phones, iPods, and other electronic devices in them, so there is purpose built clearance for cords to be able to exit with the console lid closed.  In my case that works perfectly for the mic cord.
     The next thing I did was to pop off the outer trim that covers the center console, so that I could drill two holes for the power and coax to enter the compartment.  With the holes drilled, I routed the coax that I mentioned in the beginning of this post, and the power wire that I mentioned several posts back.  These wires had been coiled up behind a body panel, patiently waiting for a place to go.  Now they have home!
     

     I had to stop there, because it was time to move on to other family things.  With any luck I'll have some early mornings before everyone wakes up, or some evenings after everyone heads to bed, to finish up.  Basically, all that's left is to:

1. Put a PL259 on the end of the coax so that it can get connected to the radio
2. Put Powerpole connectors on the wiring that will power the radio, and on the radio's power leads
3. Connect up the power so the radio will actually work (that helps!)
4. Install the antenna onto the NMO mount, and tune it up
5. Connect the antenna to the radio
6. Do a short road test so that I can verify that I like the location and operation of the controls with the radio in this location.
7. unhook everything, take it out, and transfer the panel from the plywood to the black plastic HDPE sheet that will make up the final product (Luckily, I have plenty left over from the other project!)
8. Re-install everything, and call it a day!

     Depending on the timing of when I can get this stuff accomplished, part 2 may include all of these steps, or it may get broken into part 2, 3, 4...... time for stuff like this can be unpredictable when there is both a 4 year old and a 7 week old in the house.  Even though I said at the beginning of this post that I enjoy talking to the truckers on the highway, I enjoy my kids more, so time for this project plays second fiddle at the end of the day!

     Do you do any talking on Citizen's Band, or are you strictly a ham radio operator?

     Its finally March!  For me that's exciting because it's generally the last month where we get cold weather here in central PA, and there are usually more nice days than cold days.  This post will be a short one, so I apologize if you were looking for a long soliloquy on the merits of antennas.  I did however, want to fill everyone in on a my recent shopping trip to HRO.  I was at my company's New Castle DE location conducting a training session on the the 24th and 25th, so I had to stop by the candy store.
     I didn't actually "need" anything - but then again, nothing in this hobby is about needs......  While I was there, I did however get a new dual band antenna for the roof of my car, and some powerpole connectors.  I had run out of one of the sizes I regularly use.  As far as the antenna goes, I had been using a short little jobbie, that was a 1/4 wave on 2m, and 5/8 wave on 70cm.  It worked fine for me, and being on the roof of the car, performed better than many bigger antenna's often do, when you consider how some bigger antennas often get installed.  
     I decided to "upgrade" to the standard Larsen NMO 2/70 antenna, which is basically a 1/2 wave on 2 meters and a collinear antenna on 70cm.  Here are a couple pictures of the new antenna (and my 20 meter hamstick) on the car, if you can see it.....even when antennas are tall, they can blend in pretty easily depending on the background!  

     One of the first parts of my mobile shack project that I shared was how I made the panel to fit in the space under the climate controls in my car, to give me a location to mount the control head of my radio.  It looked pretty good, but over time, I started to notice 2 things:

     The first thing I did was to pop the old part out, and clean all the adhesive off the trim where it had been mounted.  While this was off, my first order of business was to fashion a way to attach the new panel a little more firmly.  

     I decided to go hard core, and screw something fast.  I had a piece of aluminum bar left over from another project.  I cut it to length, so that I could screw the ends of it to the back of the trim on either side of the panel, and then I would be able to use the metal to attach whatever mounting arrangement I came up with for the panel.  I didn't even bother taking the bar code sticker off, because this would end up hidden behind the new panel part, so in the pictures showing the aluminum bar, you can plainly see the label proclaiming that this is, in fact, the brand of aluminum bar you can get at any of the big box home centers.  Where did we buy our random stuff before Lowes and Home Depot?  Oh wait....the hardware store!  Almost forgot about that place!

     After tracing the outline of the old panel, I drilled a hole in the upper left hand corner of the new one, for the bulkhead RJ45 connector.  After having it in the lower left on the first one, I realized that I wanted more wiggle room for my fingers on the buttons on top of the radio, so to shift the radio down, I needed to move the mic jack up.  I also decided that I would use the same screws that attach the radio head to the panel, to attach the panel to the aluminum bar.  This way all the mounting screws would be hidden from view, and I would only need 2 screws to attach both the panel and the radio head.  With this thought in mind, I drilled holes in the new panel for the screws to pass through and hold the remote head mount.  I also drilled a larger hole for the control cable to come through to the back of the radio head.  I then pressure fit the part in place, to use it as my drilling guide to transfer all the same holes to the aluminum.

     I didn't randomly pick my hole sizes.....I used a drill bit that fit my 10-24 tap, so that the screws that hold the panel and the remote head mount could just thread into this, instead of having to work with nuts, wrenches, etc. in the small tight space behind this location. After doing this, I popped the panel back in place, verified that my holes lined up, and then put the screws in.

     After doing this, it was just a simple matter of feeding the control wire through, hooking everything up, and popping the control head back onto it's mount:
​

     After a very cold Winter Field Day, the weather got mild fast, and it rained hard for a day, so our snow is almost gone, and the temperatures are back above freezing.  As promised, this means that I am now revisiting the unun that I recently installed in my vehicle, to do more antenna tuning.  In a previous post I explained the slight lack of clarity in the directions that came with the unit, and talked about my hunch about a better way to go about the process.  
     I basically decided to "start from scratch" so that I could talk you through what I did, what measurements I took, etc.  With that being said here we go.......

     The directions that come with the unit I purchased tell you start by tuning for lowest SWR without the unun in line.  Since I was working with my 40 meter Hamstick, I decided to target the center of the voice portion of the band (I don't plan on doing digital modes and such while driving!)
     The analyzer I have is the RigExpert AA-54, so I exported the charts to my computer after taking my readings - it was my first time playing around with this feature.  I didn't realize how powerful it was!  As I tune the rest of the Hamsticks I might take my laptop along out and use it in the "live" mode.  After tuning for lowest SWR at 7.212 this is what I had:

    Some interesting notes on this.  The range of the graph covers just slightly more than the 40 meter band.  The SWR at its lowest is 2.05:1 which will work, but isn't great.  The 857d doesn't like SWR levels more than 3:1 per it's manual, so that puts the 3:1 frequency range at 7.138 to 7.282 which is a bit short of covering the whole voice portion available to Extra's.  
     Also, take note of the subset box.  You can see that at the lowest SWR the impedance of the anteanna is 58.5+j38.6.  In my mind this seems like a funny place to start matching from.  My gut (Elmer's jump in if I'm wrong!) tells me that I should be starting from a point where the antenna impedance is pure resistance, i.e. starting from a resonant point, instead of a low SWR point.  I actually had two of these points "relatively" close to the low SWR point.  One of the neat things with loading the data from the analyzer onto the computer is that I can show you those two points on the same graph:

     The first resonant point, above,  is actually just below the lowest frequency on the scale.  At the very bottom of the scale, we're almost there at 7.7 +j0.2 Ohms.  This would be a 6.48 SWR at resonance.  
     The second resonant point, below, is up at about 7.261MHz (thats as close as the resolution of this graph will show anyway). At that point we've got an impedance of 125.1 +j2.2 ohms for an SWR of 2.5:1 which isn't horrible.  

    So where should I tune my antenna to, before starting my matching?  

     From an SWR standpoint - awful, but I'm still hanging my hat on the fact that it's better to start at resonance and then match from there.  This however, is where the directions that come with the unun could leave you wanting.  At this point they say just click through the setting and use the setting with the lowest SWR.  this makes it sound like one of these setting ought to get you close to to 1:1.  This isn't the case.  I ended up re-graphing on each setting, and choosing the setting that had the lowest dip, the closest to 7.212.  This was actually relatively far from where I was.  I had to graph with a really wide frequency range to find the setting with the lowest dip:

     So after doing these steps, with the unun in line, the lowest SR is 1.13:1, but all the way down at 6.972 MHz.  Time for the final Step.

     So, for the final re-tuning of the antenna - re-tuning to get that 1.13:1 SWR point up to 7.212 MHz, which meant shortening the antenna a bit.  After a number of consecutive shortening and re-measuring activities, I ended up here:

     So after all that, was my thought process sound, and is my final result a good one, or have I unknowingly made this way more complicated than it needed to be, and screwed something up without realizing it?  Hello?  Is anybody out there?
     Oh - on a final note, I re-tuned my 75 meter Hamstick too.  Resonance was very close to low SWR on that one, so the adjustment's weren't nearly as extreme, or as exiting, so I didn't bother sharing the graphs of those.