Introducing… the MSI Pole!!!

[First of all, I would like to excuse myself for having not updated this blog in a loooot of time… this has been due to my “free moments” being very restricted because of the time I had to invest in studying for successfully completing my second year of Aviation Maintenance studies. Now that I’ve started my summer holidays I’ll try to get the blog active and update it as regularly as it is possible to me with new content. I don’t forget the ARISSat-1 series of posts of which for the moment there’s only Part 1; I’ll continue them in between the rest of entries]

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Now let’s go to what’s of interest to us in this entry of the blog… 🙂

The MSI Pole in a storage configuration on my provisional workbench.

The origins of the MSI Pole go back to the very first months in which I owned my trusty Icom IC-R5 scanner (almost 2 years ago now!). As it always uses to happen, and although during some time I felt satisfied with just the scanner’s default rubber duck antenna (Icom FA-S270C), I rapidly felt myself in need of a better antenna so as to improve the reception in ground frequencies in the air band, and also in the 2m amateur, or ham, radio band which by that time I was starting to discover. After some tries with a “rabbit ears” telescopic TV dipole (with which I got a signal improvement), and as by then I was already avidly exploring the net in search of information about radio -my new interest- I came across a great antenna: the MSI (link in Spanish). Being a  simple quarterwave GP or Ground Plane antenna, what makes it special is its unsurpassable simplicity of construction (I’ll expand the details on this antenna and its construction in a dedicated entry later on the blog). This is what gives the antenna its name: MSI for “More Simple Impossible” (or “Más Simple Imposible” in Spanish). For the moment, it didn’t attract a lot my attention as I was already satisfied with a new acquisition: a Hoxin/Diamond SG7900 2m/70cm ham antenna in a mag-mount (which, although it is a mobile antenna, works, and worked, well, even at receiving satellites such as the ISS or ARISSat-1 with the antenna installed at home). However, when ARISSat-1 reentered and my interest moved on to trying to pick up AO-27, one of the so-called “Easy Sats” (another great ham satellite and the first I would try to receive in the UHF band) I soon discovered the limitations of the SG7900 as an antenna for satellite work. Being a high-gain whip with a low lobe, close to the ground, and lacking the help of a proper ground plane (the outerskin of a car), I barely could sense a change in the static noise in the background of the frequency as AO-27 made its pass. The weak signal from the sat, the worse propagation of radio waves in UHF (in comparison with VHF, which is where the downlinks of the ISS and ARISSat-1 were located), and living in a ground floor, also didn’t help. So I started to look for a better antenna, in order to have success at receiving AO-27. The MSI came to my mind… and although by then I knew that there were some better suited antennas for satellites (e.g. the Turnstile), as the MSI was extremely simple and fast to build I chose it. It was with this antenna that I was finally able to copy AO-27 (for some seconds and with not enough signal to “excite” my IC-R5’s S-meter…), hanging it and the coax cable in a wire in the front porch of the house with clothespins…

The MSI antenna as I placed it before having the idea of the MSI pole, in the house's front porch.

However, as it can be seen, the antenna was surrounded by walls in 2 directions, which led me to think that if I placed the antenna higher to avoid, at least partially, the obstacle the walls represented, I could exponentially improve its reception and general performance, improving also this way the reception of AO-27. And this is how I came up with the MSI Pole idea…

As it can be deducted, I’ve named it the “MSI Pole” because of the antenna for which I’ve intended it (however, this doesn’t mean the impossibility of attaching other antennas to it; in fact, in my plans is to use it with a future Turnstile, which looks easy to build and will perform better than the MSI at receiving all kinds of ham satellites, and to also attach to it an also future Yagi directional antenna), and because it is physically MSI, this is, there won’t be a lot of easier (and cheaper!) ways to have an antenna mast… 🙂

At first, I started using a metallic broomstick as a pole, inserting the antenna in the upper end of it (the end which normally fitted into the plastic piece which provides a good grip to our hand when holding the stick), where its edges came closer, making a good fit with the PL male-to-male adapter I’ve attached to the SO-239 conector in the base of the MSI. But some days later, I remembered something: a video I watched in YouTube, made by a great ham, David, KF7ETX, “USNERDOC” (who, some years ago, made some amazing ISS radio contacts or QSOs with who also is a great ham, and an amazing astronaut: Doug “AstroWheels” Wheelock), in which he showed his portable antenna support system. So I decided to try to do a similar thing:

My MSI Pole is what I like to call a “free version” of KF7ETX’s painter’s pole antenna mast. What I did, basically, was to acquire a painter’s pole (which is composed of two sections measuring approx. 2m when fully extended) in a local commercial center. I then cut off the threaded plastic part in one end of the pole and gave the new end the same rounded shape that the upper end of the broomstick had, so as to accommodate well the MSI antenna. Then, I covered this end with adhesive tape for protection, to increase the friction with the PL male-to-male adapter so that the antenna was held well (however with that friction the tape has started to peel off so I’ll have to find a better solution) and to electrically separate the antenna from the pole. At first, I planned to make the coax go all the way down the pole, and inside it, from the top to the bottom (where the hand gripping section is located), where the cable would go outside. However, I discovered that the bottom of the extensible section of the pole was covered with a piece which would be difficult to remove, so it wasn’t possible. The solution was the opening of a hole big enough for the PL female connector, installed in the end of the coax, to go through it. The coax would go down inside the extensible section, from the antenna connection point in the top, to the bottom of the section, where it would go outside across the hole, and would continue going down externally and attached to the main section of the pole by means of elastic rubber cord rings. I also found some cord at home, which I would use to secure the pole in case of wind, but as in the location in which I’ve always placed it it sits firmly enough, I still haven’t needed this.

The MSI Pole in a storage configuration in my provisional workbench.

The female PL connector where the antenna is connected, attached to 12m of Aircell 5 coax cable.

The MSI Pole in the front porch of the house.

The cord used to secure the pole, if necessary.

But the MSI Pole is not only the painter’s pole itself… As both the broomstick I tried first and the painter’s pole I definitively use now are relatively short, I provided them with “the extension”: nothing more than a wooden stick I found unused at home. On one end of it I manually drilled (with a gimlet) a hole in which I placed a rawlplug. Then, and with an appropiate screw found in the toolbox, I screwed into the rawplug the small handle included in the hand gripping end of the pole, which I happily found to be a detachable piece. This makes possible to use only the painter’s pole, or to attach it to the wooden extension, should I need it to place the antenna at the desired height (or to clear some possible obstacles in order to get the best reception possible). The only drawback of this configuration is that, attaching the painter’s pole to the extension in a single point, it is difficult for the pole to stay in a vertical position; the combination has a tendence to twist in the point where the pole and the extension attach, specially when the antenna is on the pole. So this is something I’ll have to improve…

The wooden extension stick, with the painter's pole detachable handle screwed on it.

The complete combination assembled together, with the MSI Pole fully extended.

The measures for the painter’s pole, once modified to accept the MSI antenna, are: 1.21 m when retracted for stowage and/or transport; and 1.93 m when extended. When combining the fully extended pole with the extension, the total length builds up to 3.57 m. Not a lot, but enough for my needs at the moment… 🙂

The location in the house in which I currently always install the pole (using it without the extension), is the top of the front entrance structure, in the front porch. There is what once served as a plant pot: a narrow, rectangular section, deeper than the rest of the entrance’s upper surface, which covers the majority of its width. As it can be seen in the pictures which follow, I’ve placed there a pair of pierced bricks and one solid brick. One of the pierced bricks is used as a base for the painter’s pole (inserting the pole in one of its holes); with the other I can “control” the horizontality of the “base brick” so that not only the pole is maintained in a perfect verticality, but the MSI antenna maintains a perfect vertical polarization… 🙂 The “control brick” is needed because the base of the “plant pot” is not perfectly flat, it is a bit irregular and without it I couldn’t achieve a perfect vertical position of the pole.

The MSI Pole and MSI antenna in their position up on the house's entrance.

The MSI Pole and MSI antenna in their position up on the house's entrance.

The MSI antenna atop the MSI Pole.

Another view of the MSI Pole + MSI antenna combination placed up on the house's entrance.

The base where the MSI Pole inserts, up on my house's front entrance structure.

Finally, and last but not least, how well the MSI Pole performs? Well, I’ve still not used it a lot of times, but I’ve tried to receive AO-27 on some passes, using the MSI antenna and in the above mentioned location of the house, and I still cannot make any conclusion as I didn’t hear anything… However, that was not a fault of the pole nor of the place where it was installed; I didn’t receive AO-27 for sure because of the 6m of RG-58 which I used to connect the antenna to my IC-R5 scanner. The losses at this lengths surely were entirely attenuating the weak UHF signal coming from the sat. After that, I replaced this coax with some 8m of low-loss Aircell 5 I already had, so that, although being more rigid and a bit more difficult to handle, I could have a better signal delivered from the antenna to the scanner. For the moment, however, I’ve still not had any opportunity to test the Aircell 5 cable in any good pass of AO-27. As far as terrestrial communications are concerned, and always using the MSI antenna (in the configuration of ¼λ in VHF, which also happens to be resonant in UHF as ¾λ), although there have been no major changes in the reception of ham stations involved in local QSOs as most of them came equally strong before (even when using the scanner’s default Icom FA-S270C rubber duck antenna!), I’ve been able to notice a substantial improvement in the strength of the signals coming from a pair of Echolink nodes, specially from one in 144.850 which transmits from Sabadell (approx. 19km away from Barcelona, where I live, and with the Collserola mountain chain in between) which was particularly difficult for me to pick with a good signal. In the air band, I’ve been able to hear some communications between GA (general aviation) aircraft and the tower of LELL (Sabadell Airport) which I never had received from Barcelona.

This summer I’ll also be able to test the pole in our summer residence in Arén (Aragón, Spain), which is located in an area with a huge amount of free space around. This way I’ll be able to really see the performance the MSI antenna + MSI Pole combination can achieve 🙂 Also, in my immediate projects is to build a Yagi antenna (using the discarded broomstick as the boom) and a Turnstile this summer, and to test them too in the MSI Pole. Boredom won’t be something to worry about! 😀

So all in all, and as it can be seen, I’ve been able to find, in the MSI Pole, a cheap and easy solution for supporting my antennas, placing them higher and improving their reception and the strength and quality of the signals I want to listen to. And it works!

raptor22stealth 🙂

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About raptor22stealth

Aviation, space and radio listening enthusiast!!!
This entry was posted in General radio-related projects. Bookmark the permalink.

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