Antennas at SP5BTB station.



30/40m inverted V antenna.
inverted V Once I came back to Poland from 9L in 2012 and moved to the new location, inverted 'V' antennas were my only option to be on the air quite quickly. So, firstly I built 10 meters (app. 30ft) mast, a flag pole type with a winch device, and 30/40 meters inverted V antenna fed with one cable (see photo). I used to use inverted V on 40 and 30meter bands being in 9L with good results but that time I played the so-called "DX station" role. I wondered how I will be functioning with these simple antennas in the pile-up presence whenever DX station appears. Have to say that these antennas surprised me a lot. For a short period of time (two months) I made over 120 QSOs mainly with DX stations some of them at a very long distance eg. :
just to name a few of them.
Almost all QSOs were in CW mode with IC7600 and Emtron Dx1b PA (400-500W).



Mosley TA53M antenna.
I bought the TA53M antenna from Mosley in July 2002 with in mind that I am buying "a lifetime" antenna. It was used in Africa up to the beginning of March 2012, which means for almost 10 years. Going back to Poland I decided to take this antenna with me leaving only two boom's tubes since they were oversized according to the airline rules for unaccompanied luggage. During disassembling the antenna I noticed that all block insulators for both driven elements have deep cracks so I ordered the new ones from Mosley (8pcs x 9.52USD each). Having antenna down I decided to do some cleaning and maintenance works. Opening one trap for inspection I noticed that inside there is a lot of red dust characteristic for Africa and in addition covered with cobwebs and in some places with oxidation, especially against the vent of the trap. Base on that I decided to inspect and clean up all traps. Once the trap was opened I sketched of trap wiring including a number of turns and point of connection of every coil.
You should see the surprise on my face when I saw that the Black-Green-Black trap on one side has 21 turns and on the other side 22 turns of wire (trap for 21MHz).I have consulted Mosley on that subject and was told that these coils "should have 22 turns". On my remarks that for so many years I had an antenna without a director on 15, 17, and 20 meters (and as a result of it less gain as well), Mosley answered that this difference has "no big influence on overall antenna efficiency' - they even forgot to add "We are sorry". "The warranty is two years against any defects of materials or workmanship" -it means I should open all traps for inspection once they arrived... it shows that there is no proper QC (Quality Control) system in the factory.


.... Any variation in capacity or inductance in the trap's tuned circuit will cause the resonant frequency to shift.....It is important that these coils have the correct number of turns....A trap can properly be considered the "weak link" in the chain of components that comprise a multi-band antenna. Any failure or malfunction of one of the traps will put the antenna out of operation or, at least SERIOUSLY AFFECT ITS PERFORMANCE CAPABILITY.... ..this extract was taken from Mosley web page..... NO COMMENTS

Knowing that Mosley will not help me in this matter I decided to change the coil and place a proper 22 turns. A friend of mine, Waldi SP7GXP, measured the good trap (that one with 22 turns) in order to have a base for comparison, and then he made a new coil in the faulty trap. His work was so precise that finally, I have both traps on the same resonant frequency.


Base on experience with disassembling and assembling this antenna I decided to improve the attaching point of the driven element to the block insulator. I have inserted a short aluminum tube (in red) inside the driven element in the place where attaching screw keeps the phasing line. This trick prevents from deformation of the driven elements and makes sure that elements are firmly connected.(see the sketch for details)


Another weak points are U bolt connections, aluminum bar is quite soft so I placed a big flat washer uder every nut, bigger touch area of the washer than a nut alone prevents from deformation of the driven elements bars...

Sketch of my TA53M No: 568305

for record purposes, note slight difference in dimentions between manual and real antenna (as you are aware this antenna is coming as "predrilled" so these changes are done by the factory).



Having any device, I try to find out what a principle of work of it is. Below there is a sketch of the one half of the antenna element with one trap. Arrows show how this element covers three different frequencies.


Knowing that every trap assembly consists of two resonant circuits it was quite simple to find which element is responsible for which band. See the sketch for director.



"Steps" started when we are talking about driving elements. Both have the same mechanical construction the only diference is the length and number of turns. Since there was no info in the antenna manual how the bands are placed in both driven elements, I asked Mosley, the answer was enigmatic: "BLUE radiator is for 10-15-20 meters, RED one for 12 and 17meters". Once more question was sent to Mosley: "How comes that the same mechanical assembly of trap covers three bands for BLUE and only two bands for the RED radiator. What the additional mystery role plays this Red element in the whole antenna ?" Mosley answered that the Red element is working as follows: "to the first coil is 12 meters, the second coil to the end tip is 17 meters." Since the only way to confirm that the 17-meter band is adjusted by the second part of the trap assembly and not by the tip of the Red element, was to change one element of the resonant circuit - the easiest way was to increase capacity and see if the 17 meters band will shift or not. I added a small ring at the end of the internal tube of trap and BINGO, 17 meters band moved down once the change was done. See photo to the right.>>>>
These rings were removed after that.


Change the overall length of the Red element (moving a tip) had an influence on 20 meters band, the same way as changing the tip length of the Blue element. This technic is sometimes employed when you feed both close elements in order to make the system more broadband. I have no idea why Mosley did not mention that....

Driving elements

Similar doubts I have in regards to the reflector where the last coil is presented by the straight short wire.
Mosley sent me the following explanation:
" Each element is a summation as you go lower in frequency. Let me start with the Reflector. So you have the first trap 15 turn coil is 10, 19 turn coil is 12, the dimension between the trap to the second trap 35 turn coil is 15, to the 0 turns is 17, and 20 is the end tip. It is a summation."



Adding 6m band to the Mosley TA53M antenna.
Mosley designed the TA63M antenna, upgrading TA53M to the six bands version by adding two elements. The ORANGE element named the director and the YELLOW one as a reflector. Dimensions and placement of the Yellow element on the boom make clear that we are talking about "a real" reflector. But, the so-called "DIRECTOR" placed very close to the active radiators making it a radiator for 50 MHz. Knowing the length of both elements (Orange - 2.4m and Yellow - 3.6m) and their coordinates, I fixed them to the boom and started tests. Testing the antenna, I found the minimum SWR (1.1:1) at 54.9MHz ! Based on test results, I calculated the required length of the Orange element for 51MHz.
The formula is as follows:
2.4 x 54.9= X x 51 so the required length X, is 131.76/51 = 2.58m = 258 cm.
With 2.58m Orange element antenna shows a very low SWR from 1.1:1 to 1.2:1 across 50MHz to 52 MHz.

Here you are, upgraded TA53M+6 meters band.

TA53M with 6m kit installed
The only change of TA53M parameters I noticed on 10 meters band - SWR at the beginning of the band rose from 1.4:1 to 1.7:1, but the built-in Icome's tuner had no problem working out this.

Simple drawing of my modified antenna

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