Friday, January 19, 2018

Chameleon MPAS Practical Testing

Note: Updated 4/18/2020, see summary.
Today (1/19/2018) was a simple trek to a peak near my house that I use as a proving ground to test new configurations and get a little exercise.  W6/SC-338 is only a 4 mi round trip from the base so it’s quick and easy and is a representative test area for my SOTA missions.  Today’s primary objective was to do some practical testing of the CHA MPAS with spike and additional MIL mast. I’m getting ready to use it this weekend and really would like to know if it’s going to work.  The secondary objective was to test to see if I’ve worked out the bugs for the automated APRS beaconing, and if I could post a SOTA spot with APRS (I’ve done a dry run at home but this will be a first live-fire).

When I got my MPAS unit from DX Engineering, I took it out to a hilltop park to do some initial testing because I was too lazy to hike to the mountain and I wanted to see what the performance was on a tripod.  I’m not going to hump the tripod to the top of a mountain.  I published my experience and an extensive number of SWR readings HERE.  That test gave me a basis for an analytic view but as we all know, the numbers are just half of the equation. No matter how good the modeling on the computer, you gotta get out there and see if the thing works.  On the initial test, I was able to get a couple of QSOs with it so I got a some testing but not nearly enough practical tests to be statistically valid to my liking.  I was able to skip into Puerto Rico and Nevada with it so it wasn’t totally lame.  I have full confidence with my dipole from Packtenna in an inverted V and that is my standard by which I measure everything else.  I needed to do some real testing with the MPAS on the mountain like I would on a new activation.  More testing was needed before I was willing to chance blowing an activation after climbing up to a peak I don’t want to return to.

Executive Summary:

(For those of you than don’t want to read the ramblings to get to the punchline)
     I tested the CHA MPAS, raised up 7 feet, hooked directly to a FT-891 running 100 watts.
     SWR readings weree ~1.1 to 1.
     The CHA MPAS works a lot better being up off the ground 7 feet. 
I had solid QSOs from Japan to Illinois.
     The antenna is easier to setup than the dipole on a mountain with no supports.
     I “self spotted” using APRS.
     APRS auto beacon on the FT-2DR worked going up but for some reason, not on the way down.
     This antenna rocks!

A few weeks ago I tested the CHA MPAS on just the spike up at W6/SC-338 and it failed.  I think I got one contact.  A second test wasn’t much better.  Julian over at OH8STN had pretty good luck with it in the videos and review that I read but he pounded it into a snow covered area, possibly giving him much better ground plane (not sure).  Everything that I’ve read says it works a lot better having it up off the ground a bit so, the best way to do that for my SOTA activity was get another MIL extension from Chameleon.  Now that it’s up 7 feet, I need to use guys to keep it steady.  The Chameleon gear is overpriced and I started goofing around to build my own extension but caved and picked one up.

I tried the new configuration on an extension in my neighbor's backyard.  Her yard has enough room for the counterpoise and I can setup near a drop off to simulate a SOTA peak.  It failed big time. I got one very strong report from Texas that day but I felt 1 just wasn’t enough.  I did setup the dipole right after the failure and continued to get absolutely nothing.  I packed my stuff in that day and chalked it up to the shit conditions as reported on the web.  If my control antenna wasn’t working then it wasn’t a valid test.

Today’s configuration was to use the MPAS on a 7 foot mast, with the Yaesu FT-891D HF Radio.  It’s definitely faster to setup the MPAS over the dipole but I had to first spend 15 minutes untangling my guy lines. 
NOTE: String theory.... When two strings touch, they become an  infuriating knot... better than anything that I could tie myself.

The wind was blowing about 10 knots but it didn’t pose a real problem except while I was in untangle mode.  OK... on to the test. 

The first task was to hook the antenna analyzer up and see what I get.  I got some good news, the conditions came together and it showed a really low SWR, so no tuner needed today.  I didn’t get an exact reading, but as you can see on the image to the right, SWR was about 1.1 to 1.  Awesome!  The 40m band was under two, usable without an antenna tuner.  (update: I've used this antenna a lot and most of the time I could get away without a tuner, staying under 2:1.  There have been terrain conditions and setup that really needed a tuner and I did pack one.  I've used this antenna from 10m through 80 m.  It won't always tune up on 80 but the MFJ will tune it.  

As I was looking for an open frequency to camp on and post to the SOTA spot,  I heard what sounded like someone in Japan calling CQ.  OK, why not give that a try.  And... BINGO.  We connected and had a nice chat.  My signal report wasn’t super but he wasn’t much better.  At this point you might call it quits after going 5,577 miles and mark it as good but I really like to have a lot more data... Besides, I need to check off using APRS on my FT2DR to spot myself on SOTA. 

I fired out a message using APRS from my Yaesu FT-2DR HT and it lit up my spot on the SOTA web site right away (I used SOTA goat on my phone to monitor it).   I can check this off my test list since I’ve posted a couple of other test messages prior. 

As you can see by the contacts in the table below, the first contact to Japan wasn’t a fluke, I landed a second one as well.  I was able to hit the mid-west and Illinois, and I blew out the guys to the north.  This configuration is a keeper.  I was pushing 100 watts into it so it could be the case of brute force won the day but I definitely had better luck than in the past and the band conditions were fading to the east but I was still able to get through.

BTWThis is the third SOTA activation that I’ve been able to contact stations in Japan, so that was pretty cool.  Getting to Japan is mainly due to time of day. I can hit the ocean easily from here and I’ve found that one hour before sunset is the sweet spot.

I’ll continue testing, but I’m confident enough to take the MPAS on full mission and gather more data.  In general, I think the dipole will do better but on a bare mountain top, it’s going to be a lot easier to setup.  Someday, I’d really like to have an A/B switch and then get some signal reports as I jump back and forth, but that will have to wait.  

I tested auto beacon on the way up and it continued to update the APRS tracking site without a problem.  I checked that off as good to go until I realized that it didn’t work on the way down.  One thing that I’ve noticed during my testing is that I the radio config for the auto-beacon seems a little fussy.  I’m not sure what happened on the return trip.  I thought I could hear it sending out but ... more testing is in order.  I’ll mark it down as a partial win but not conclusive.  It will have to do for now.  I know the manual position report works so I'll do that when I think I need to.

As an added bonus, I got to see a nice sunset.  When I arrived on the mountain, I was in heavy fog but it cleared and the wind died down. 

One of the things I like most about the MPAS is the quick setup.  I can be up and running in 15 minutes by myself after dropping my pack.  The reason for the easy setup is all of the elements unfold just like tent poles.  I'm using their MPAS kit plus a CHA MIL extension (6.5 feet) to get the matching unit off the ground, think of it as the "mast".  I then mount the CHA Hybrid-micro matching unit (5 inches) on the mast and attach a second CHA MIL extension and the CHA MIL whip section (thinner tent pole) (10.8 feet) to that.  I use the small guy strings that came with the Packtenna and guy the whole thing to the matching unit. All of this is screwed into a spike in the ground if needed.  When setup, the total length is about 24 feet.  The last thing I do is  attach the 60 foot counterpoise wire to the base and run it out, which takes about 1 minute if you wind it up in a figure 8.

      I've been in high winds with the top section bent over pretty good with no damage.  Trying to setup the packtenna with a mast in high winds is just a huge pain!  The entire setup collapses down to 2.5 feet and easily attaches to my pack with rubber bungees.  I've been able to get my setup time to 15 minutes because I've marked the guy lines so all I need to do is attach them to the base, pull them out and anchor them and they are ready to be attached to the mid section.

This antenna is heavy however.  It weights almost 5 pounds when using two MIL extensions (1 lb ea.) which is my config (I want the matching unit off the ground).  The other option is to go with an end-fed with a push-up pole,  which will save you at least 1 lb.  


In summary, the CHA MPAS test was a success.  The MPAS works and is a lot easier to setup than the dipole.  In high winds it's a dream.  A simple 3 point guy to stakes to the matching unit will hold it up in very high winds no problem.   I've been on peaks where the top section was leaning over from high winds and it worked like a charm.  Even better, in a no wind situation, I just screw it onto the stake that was beat into the ground with no guys.

Although I got away with not having a tuner, there were a couple of times given the setup and terrain I needed one on 40.  I started taking a small tuner with me for my FT891 and never had an issue.

What I like most about this antenna is that the CHA HYBRID-MICRO can handle 100 watts, and is a seamless multi-band antenna with quick setup and take-down.  The MFJ tuner can tune it up on 80 m, something that I rarely do but it works.  I used 80 m during a local ARES HF test this weekend and it worked fine.  The antenna can also be used as an end-fed wire, just ditch the collapsing poles.  Lastly, this thing is rugged.  It's been on tons of peaks, dropped and I don't know what else.  I had a second unit setup in my back yard for over a year continuously while I played with all kinds of antenna configurations.  I always went back to this due to it's compact size and multi-band performance.  After over a year outside mounted on a fiberglass pole with the "CHA Jaw, the matching unit looks almost new.  I've since replaced the outside antenna with a Cuscraft R8 but I had to get this antenna out of a ARES drill because I needed 80 m capability.

The downsides are weight and cost. Because I felt it worked better with the matching unit off the ground, I carried an extra 1 lb extension pole to rais it, which brings the entire system with the stake to almost 5 lbs.

As of April 2020, the cost of their kit with a little backpack is $550!  This is a bit over the top cost wise.  I don't think I spent quite that much but probably close to it because I bought an extra cha-mil extension.  The CHA HYBRID-MICRO with some wire currently sells for $211.  If you want rugged combat ready gear this fits the bill.  I did look at a similar competitor but it wasn't made nearly as well.  The only failure I've had is with a the large nut fitting, replace for about $1, and the shock cord snapped but easily replaceable.  When I purchased this I was a new ham and new to SOTA, it fit my needs, and is rugged.

I still do SOTA sometimes with the 100 watt Yaesu with this or another antenna, and it's a lot of fun during contests.

At the other end of the scale is my QRP antenna.  In 2020 I've started using a Elecraft KX2 at 10 watts and I carry a custom ultra-light multi-band antenna from K6ARK that weighs 2 oz. but it needs a push-up pole.

Would I still recommend this antenna after over 2 years of usage, HELL YES!.  I used it during a SSB contest from a mountain top and just killed it.  My first 5 contacts were all DX into New Zealand, Japan, Asiatic Russia, Brazil and more.  A few weeks ago I helped an extra-class get on HF for the first time.  I grabbed this guy and we went up to the  park.  It's easy to use.  One of his contacts was Brazil and he was hooked.  (His wife probably isn't happy because he's now going for HF gear).  I got it out for an local ARES HF drill and it worked like a charm.  It's still in use as of this update and part of my kit but because of the weight, it doesn't get to do SOTA too often.

Contacts on this outing:

Japan, with a 3X3 to 3X5
Oaklahoma 4X4
Japan, with a 3X3 signal
Texas with a 5X5 signal report
Washington with a 5X9 booming
Washington with a 5X9 booming
Canada with a 5X9

Loadout today:

     Yaesu FT-891D HF Radio at 100 watts
     Yaesu FT-2DR HT
     Yaesu FT-70D HT.
     DDT Ops Anti-Venom field pack with food
     3 L of water
     SOTA Dog
     iPhone with and MotionX GPS and sota goat
     Hiking pole...


      My Typical SOTA Loadout
      For more info on SOTA, rules, etc, go to the homepage HERE.
      Ham Terminology
      SOTA Specific Links


-- Chris Claborne, N1CLC


  1. Another good write up, just found this one after reading your SWR test one. Thanks Chris!

  2. I have been happy with mine and it continues to provide excellent service.