My Experiments

Antennas

When we have restrictions in mounting the station antennas, we start to make experiments with other alternative ways. It was what I did.

I made and test several antennas, the magnetic loops was on of them. In my research, I read many things and this kind of antennas seemed to be the solutions for my problem. They are small and in some cases very small indeed. In my research it seems that this antennas was announced as a miracle. Even inside shack we could make astonished contacts, cause the antenna works the magnetic part of the wave. Unfortunately I verified that this is not totally truth. That is truth if the shack is a really wood shack. If the building is brickwork, you beter forget the part of miracle.

Really, I made contacts that impressed me much, with the antenna inside home. I didn't expect. But were not Dx contacts. I made contacts to 200 km or a little more. The iron structure of the building have influence on that. Outside is another story, however don't expect big signal reports. With the little MagLoop in the pictures below, with a pedestrian QRP station with 2 Watts, in a cold winter saturday afternoon, I made two good contacts with a Belgium (ON4YOTA) and Spanish station (EA3BFX). For 2 Watts the report were good 5/8, 5/7, but only two contacts in a afternoon... that's the problem of 2 Watts! In this antenna I used a diferent coupling, a kind of triangle. Initial the small coupling loop was 1/5 of the diameter of the big loop, but the swr meter did not give me the expected readings, so I started with my experiments. The length that goes from the top of the loop to the coax is indeed 1/5 of the diameter of the loop and the plastified rigid wire makes 20 turns on each side as you can see in the middle picture below.

Questions about the little MagLoop

Hello Frank (N4SPP/F4WCN), thanks for your e-mail and for the wishes of a good year of 2020. I wish you as well a good 2020 with health.

As for the question about the change of direction in the turns of the coupling for the little MagLoop and if it was intended, first I must point out that who made the question was aware. Indeed the direction of turns changes in the middle, as it passes through the hole made in the wooden mast. I Have many ideas about disigns for antennas and I experiment how they work. Most of the times they do not work at the first time and I think again in the issues, trying to find the solutions. When I had the idea for this way of coupling the antenna the turns was on the same direction and the number of turns was also different. As I said, most of the time does not work at first atempt, it was the case. I experimented different ways till I get to this configuration. One of the changes was the direction of the turns at the middle.

73 from Jo Lourenço (CT1ECW)

Before this 7 - 21 Mhz MagLoop, I also had made this gorgeous classical MW / SW Loop antenna. It's really a beauty and receives very well. Normally it's usually receiving at night many broadcasts from the neighbor country, Spain, if you are in a rural environment. But receiving broadcasts from France and UK in MW, in a urban noisy environment it's very good, even with an inside loop antenna, as long the cable TV modem is switched off. That's a really noisy problem, as well the energy saving lamps. Despite we do not listen, this is a big health problem for us as well for radio receiving. If you have headaches, feel aggressive and with stress, make a simply experiment. Turn on an AM radio receiver, with the TV modem and the saving lamps off, verify the noise on the radio and after that switch on a saving lamp or the cable TV modem near the radio. Anyway, usually I use this two loops for receiving, I'm also a SW Listener as you know (CT0 1093). At this moment I'm working on a vertical fishing pole antenna, as simple as possible, without balun to use with a little wire tuner for my incursions with a QRP backpack. Nothing better than work in free space.

Baluns

Fist of all, what is a balun?

Here's an example of an 4-1air core balun to mach with an antenna with an impedance near 200 Ohm (200/50).

The black sealed box in the left side of the first picture, has a ferrite core with this thin phone wire used in ancient phone boxes centrals and is one of the baluns who give me better results. however become saturated with power, so I started to research that ones with an air core.

MY QRP ANTENNA END FED TUNER PROJECT

In my researches and experiments, I used an old balun coil to make an end-fed tuner. It seems to work at least in 40 and 20 meters band and maybe in other, but I didn’t test with correct wire length It was just an experiment, a promising one.

In internet, I also found a simple LED circuit to see when the antenna is well tuned. So decided that I intend to do by myself this little QRP antenna tuner with a LED indicator.

Here is my project:

• 1,7 cm diameter PVC pipe with 10 cm lenght;

• Two 3 mm different color insulated wire (1,5 mm without insulation), coiled 13 times side by side at the same time as shown in the folowing picture:

• Polyester variable capacitor ≤10 pF to ≥200 pF. If you find a better one use it. The good old air variable capacitors are hard to find and when you find it are expensive. For QRP purposes the polyester capacitor will do. Find one that holds at least 50V.

• It’s recommended a counterpoise wire 0,05 wavelength single wire. For 20 meters band 300/14,100x0,05=1,064mt.

• Now you need to add a circuit device that indicates when the antenna is tuned. I found the following one. It’s very simple, you just have to connect it on the output of the tuner to the antenna and certify yourself that the anode and the cathode are in the wright position. The cathode is the shorter leg:

TUNING LED INDICATOR CIRCUIT

• I already tested it. Verified that when you tune the variable capacitor and the RF can pass through the tuner circuit to the antenna, glows like this (almost like Janis Joplin song):

• A couple of days after and some more tests, I saw that this LED method of tuning the antenna to the radio was not so precise as I expected. The maximum bright it does not always overlap with minimum SWR indication. I remembered that I had in my junk box a charge meter indicator, VU meter or something like that and I had this idea of put it instead of the LED. The pointer touched hard in the end of the scale when I made the connections and experimented it. So I needed some resistor to reduce it and used a 10 kΩ resistor. It wasn’t enough, but with two 20 kOhm resistors in each side of the connections in the circuit, where before was the LED, worked good. The pointer almost enter in the red part of the scale using QRP when is tuned. So, I think it's better this way and if you have other ideas test it, be creative!

• Now you just have to put all together in a small box and enjoy it. That was what I did. A couple of weeks later, after I bought some material that I did not had in my stock, I assembled the project and it is no more a project, it's reality. It's a piece of QRP equipment that works good. Started with the box, an aluminium case at the right measurements and after some mistakes, a few unforeseen scratches and some bad words, nothing that a rasp and a little sand paper would not solve, I made the holes.

• After holes made, I disposed and fixed the components. At the left side of picture you can see the little air variable capacitor with four sections. A section of 8.5-382 pF, a section of 10.5-328 pF and two sections of 5-20 pF, a total capacity of 750 pF. At the center of the picture a lever switch, to divide the total capacity in two parts. A part to take advantage of the lower capacities, using just one of the sections, and the other to take advantage of the higher capacities, joining all sections in just one. At the right side the charge meter indicator that at the maximum indication of the pointer will tell me that the wire is tuned and at the bottom, the air coil.

• To fix the components I used a mastik glue to paste metal, plastic and other materials. I left a space between the coil and the bottom of the case as you can see in below picture.

• With wires welded and all components disposed and fixed in their places, I assembled the back part with the PL plugs, linked them to the coil wires with tin and welded the ground wire of the variable capacitor to the chassis ground on one of the PL plugs. I also welded the two capacities wires that the capacitor is divided to the connections of the lever switch. After all that connections made, I made some more tests to see if readings on the reader coil was still working well and found that the pointer returned to play the full scale. So, I had to make some changes and more experiments to find values of the resistors and I had to put also a 20 kOhm resistor between the 10pF capacitor and the diodes. With the maximum of 10 Watts power, the reading coil works good. If I want to use more power I have to increase the value of the resistor between the 10 pF capacitor and the diodes.

• All tests and experiments made, I assembled the simple circuit on his definitely place, as can be seen on the next picture. The definitely reading coil circuit diagram, can also be seen on the right side.

• After all assembled and some use of the end fed tuner, I verified that in some cases I had some difficulties on tuning. After a few more tests I introduced two more possibilities in the tuning circuit, adding another little coil with an internal diameter of 10 mm and 9 turns and a toggle on/off/on switch. One side of the coil is connected to Tx PL plug input and the other side is connected to the middle connector of the switch (the "off" one). The conectors "on" are linked to the PL antenna plug, one to the middle of the plug and the other to the chassis as you can see in the below picture:

• Here it is the final product working with a QRP radio, a Yaesu FT-817 with another homebrew device, a cw morse paddle (I show you in the next opportunity). I was amazed when I found that it can tune the 70 cm, 2 and 6 meters bands with the same wire antenna that I was using also for HF, but it can not tune the 80 and 160 meters bands. I suspect that can tune from 40 meters to 70 cm bands. After box closed the initial 10 W that was calibrated the reader coil, now can't put more than 5/6 W of power. With this reader coil system I have to memorize, for the power I'm using, where usually the pointer marks, because if the point of tuning is lower than usually it should be for that power, it means that it's not tuned, don't have the desired income, and might have some SWR.

• I still can pounce some letters and figures or a scale around the knob and will be much better. It will seems made in factory.

You can download the pdf file on the bottom of this page. Please wait for the scenes of upcoming episodes... hihi

SMALL RECTANGULAR LOOP ANTENNA

ANOTHER VERSION OF MY BALCONY ANTENNA

• After many experiments trying to decide what is best, a rectangular slinky wire, a rectangular slinky loop wire, a rectangular wire, a rectangular loop wire or whatever geometrical configuration you can try for an urban antenna with all kind of restriction, now I chose to work on a very small rectangular loop antenna. The measures are 2,80 x 1,02 Mt, the length of the wire in the rectangular shape is 7,64 Mt, some more windings in the pole where is the fed and a 40 cm for connections, in a total of 10,04 Mt of 3 twisted thin phone wires. Why these measures? That's the measures I have in the balcony and λ = 71,25/7,1 λ = 10,04 Mt, a quarter of λ in 40 Mt band and a full wave in 10 Mt band. The wire instead the slinky because is more stealthy or less flashy to the eyes of some kind of folks that, if some mobile phone operator offers them money, they would immediately accept the installation of an antenna, but not yours, that´s the really truth!

• I do not have a suitable measuring device and as you can see in the picture, I only have a 1:9 balun made with a ferrite toroid Amidon FT 240-43 with 8 windings of three color multifilar wire, that does not conform to the requirements for impedance adaptation of these kind of antennas. The characteristic resistance of a full wave loop in free space is ± 120 ohms and a half wave loop is expected to be ± 60 Ohms. This loop should be near 80 or 100 Ohm, the ratio is about 2:1, it must be a 2:1 balun. Some time later I saw in the internet an antenna for 10 Mt band very similar to this one. The shorter sides of the described antenna were to the top and bottom and is said that the input impedance is near 50 Ohm, no need a transformer device. The feed point of my balcony antenna is not in a center but at a corner, almost as a rhombic, the working position is different, the antenna is practically inside doors, which means that the building iron will influence the antenna behavior and the antenna wire has some windings in the pole on the feeding side to complete a full wave in 10 meter. I fed it just with a 50 Ohm coax and the SWR in the different bands was constant, pretty much similar to the ones achieved now with a balun, a little higher. So what to do? Experiment other connections and join a ferrite rod with some more windings. After some tests and measures I achieved a configuration that seems to result. I used a ferrite rod of an old transistorized radio receiver and a wire (blue) winding on it with 20 turns and welded from the braid connection of coax to the other wire of the loop, passing the ensemble through the Amidon hole.

• The SWR measurements made with 5 Watts gave the following results, which increase with more power but, are acceptable without a tuner in the 80 till 30 Watts, 1.15 and 10 meter band till 60 Watts, 1.12:

• The best results are achieved in 80 meter band and in the higher portion of the 10 meter band. The antenna efficiency it will be pretty much the same of the previously slinky antenna, hopefully a little more because of better coupling to the coaxial cable.

A SMALL UNNOTICEABLE IAMBIC CW KEY FOR BACKPACK MOBILE OPERATION

If you have a mobile RIG and sometimes want to use it as backpack station, probably you also want to have a small unnoticeable and lighter iambic CW key.

You have some in the market, but you can easily make a less expensive one with the satisfaction that was you who made it. You just have to acquire the following materials:

• 2 arm micro switches

• Welding glue

• 7,5 cm of a rigid plastified copper wire with a big section

• 120 cm of a shielded thin cable (two conductors and mesh)

• A 3.5 mm metalic stereo audio jack (with a plastic internal insulator)

• Tin weld and and an welding iron

• Heat shrink sleeve at measure

• Two flat polyester capacitors (doesn't matter the values, see your junk box)

With a welding glue, join the two arm micro switches back to back. Shape a "U" with the 7.5 cm of the rigid plastified copper wire and weld it in the lateral contacts of the switches. The big section of this rigid copper wire will also create a support structure on the center bottom of the "U" where should be glued the shielded cable with the welding glue. The twisted shielding mesh of the cable will be welding on one of the lateral contacts of the switches. Cut the wires of the polyester capacitors and the arms of the switches at the desired size. Glue the capacitors on the switches arms in the way they don't pass the limit line of the switches bodies, as the pictures.

With a multimeter in condutivity test, find the contact of the two bottom contacts that has no condutivity with the lateral contacts of the switch but, when you press the arm switch, will make the contact. After you find the contact, tin and weld one of the wires of the shielded cable on that contact and do the same to the other wire in the other switch on the opposite side. Open the screw capsule of the stereo audio jack and insert it back on the shielded cable together with the plastic insulator. This way, after all weldings made, you will not verify that you forget it. Twist, tin and weld the shielding mesh on the exterior contact of the stereo jack and the other two wires in each of the the remaining two contacts.

Consulting a KBPC5010 data sheet, as can be seen, the bridge rectifier suports 700 V and 50 A.

WOUXUN KG-UVD1P SOFTWARE ON WINDOWS 10

If you own an Wouxun KG-UVD1P, recently have changed your operating system (OS) to Windows 10 and advanced computing it's not your wave, you may be interested to know how I achieved a way to the manager software of this radio recognize the communication port (ComPort).

6 - Restart the computer and disconnect the cable

7 - Turn on the radio manager software, check the ComPort (probably Com1) and close the software

8 - In the computer, go to "computer management", search for "Device Manager", right click on the device with issues, uninstall it and

delete the driver software also

9 - Do the same on the port that appeared in the radio manager software, that is, uninstall device and remove software

10- Turn on the radio manager software, and then connect the data cable to the computer, then to the radio and finaly turn on the radio

11- Go to "Communications Port", select an available port (probably Com5 or 1) and read from the radio to see if it's OK

12- Always go to "Communications Port" to select the port each time you restart the radio manager software and do not upgrade the

ComPort unit.

Let me say that actually I do not use these bands often. These kind of equipments are very easy to acquire, the antennas that come with them are already built in and calibrated to the bands, do not burn the final stage, this means that persons that are not allowed (don't have a HAM licence) are also using these bands causing disturbs in the frequencies. In satellites operation and DStar that's a different story and when I decide to experience these modes maybe I'll come back, till there... I like very much HF, DX in SSB and particulary CW.

UNIHAM UNI-730A IAMBIC MORSE PADDLE

Some time far ago I acquired this uniHAM UNI-730A telegraphic key. Never liked the stereo jack plug connecting the cable to de key paddle and from a time ago, when I was playing with it, yes playing cause I still not am a proeficient CW operator but I keep trying, and than, I noticed that it had a malfunctioning. This is due to bad contacts between the female and male jack plugs in the morse paddle. So, I decided to change it this time!

When you have done all of this, joint the iambic paddle key with his base and without screwing it together, test it to verify if it is all good.

Finished the tests and it was all good, tight the top 3 screws.

Now you will verify that you have no more the contact malfunctioning.

URBAN ELECTRIC & MAGNETIC DISTURBS

You probably have already experienced some kind of eletromagnetic interference (EMI) in radio reception and for those who live in a urban areas, you have all kind of radio disturbs. The high frequencies(HF), for nature, are already noisy and the EMI are special annoyant in HF. So this time I improved the filtering in the power instalation security to my RIG, although I already have some similary kind of filters.

This time I resolved to add some more EMI filtering stages bought in the world wide web. It's like the security concept, one measure won't make it secure, but a set of different measures will made the security. In this case, the measures are very similar, the principle is the same, a serial of in line stages to wear out the EMI disturbs and some ferrite cores in the wires. It won't work for all disturbs, you will have to consider the installation of a band-pass filter, if the EMI is received by the antenna and even in these cases, you still might to experience disturbs in a particular portion of the HF band. I'm also working to install a 3.5-30Mhz band-pass filter when necessary, remember between the radio and the antenna tuner. The little electric transformers and other devices that actualy are sold in the market, for economical reasons, are deprived of some components that would do this filtering and instead of the component we can see in the circuit a space for it with a direct link. It's cheaper but, it will polute even more the frequencies spectrum. I have these problems with the box TV, router n' modem, these devices make several EMI in the frequencies spectrum and the little transformers that feed them also. The energy-save lamps as well make EMI, if you want to know if a lamp of this nature is of good quality, just try to turn on near these lamps, a little transistor radio, in the medium-wave frequencies, in amplitude modulation. Some people have complaints of headaches because these devices interfer even with the physiological frequencies 0.1 to 30Hz (delta, theta, alpha n' beta waves). Some international mandatory measures should be taken in the engineering of these devices.

LOCAL FAST ANTENNA COUPLING

With some softwares that can be downloaded from the internet, by bluetooth, you can connect to your smartphone or with a data USB cable to a computer.

SWR, impedance, capacitance, inductance can be measure with this device as you can see in these bad photos that a took, but can show the idea.

The graphs shows measurements in 40 meters band, 7.028.00 Khz for Tuesdays CQ GPCW QRS hi hi. Can be established a central frequency and have measures while tuning. Coax cables as well can be measured.

INSERTING AN INTERNAL BATTERY WITH A DIFFERENT PLUG

To have an autonumous device, you need to instal a battery inside. I do not like an inside battery, because you need to remove the screws to get it removed and in this case you'll have to glue it some how, with a little contact glue or with a sticky tape and when the battery get in the final cycle of life it can leak and mess the circuit. So, you will have to take care and at least to put down, the back face of the case device.

The device I bought did not come with a battery, I had to acquire a 3,7V 1700mAm lithium-ion polymer battery apart, as well, it's difficult to identify the reference number of the internal plug and I bought a bag of the wrong ones. Now I have a bunch of the wrong plugs, but no problem, I'll use them anyway.

Experimenting and testing a new improvised appartment antenna with a 4:1 balun

Once more I had this new idea, after another one, when I experienced an indoor big slinky loop, the last one of the never ending story of the odyssey to achieve the best HF multiband antenna to use in an appartment. This time I disposed more wire in the balcony pole.

A 4:1 balun, the other pole connected directly to ground, some measures and tests,

that provided the following results, which can be used with a tuner, and concluding that the wire size is more suitable for the WARC bands:

I will use, test it and make new experiments, till the next big new idea, in the never ending odyssey history.

Playing with and improving power supplies

Finally holidays, time for my experiments and radio transmitions.

Some time ago I do had the necessity to have a power supply to work only with the little youkits telegraphic radio.

When I come from a day of work, I´m tired and do not feel like to turn on the big radio, so I play with the youkits HB1B radio that I can turn on near the lounge and handle a iambic key paddle on 40 meters band.

The working voltage for this little radio is 9-14 VDC, and 13,80 VDC is too much close to the maximum, so I prefer to work with a battery. However, have to charge the battery every time I work with the radio is the big issue. I had this old laptop 12 VDC output adapter that I started to use. Had no problem while working with a magnetic loop antenna, the problem was when I change the antenna that also started to receive all these noises 9+20.

Initially I thought that was from all that stuff conneted to neighbors's televisions. After mid-night all that noise still there. I started to suspect and reconnected the magnetic loop again... hi there, no noise! Changed again the antenna and the noise come back, changed to battery... no noise. The bloody laptop adapter... of course, it's switched not a linear power supply, it has much ripple.

I decided to modify an old 2 A power supply that I have for a long time and, to do that, I opted for a 12 VDC output regulator circuit, the L7812. This regulator can support an 1 A current and the youkits, when in tx mode, consumes between 800-900 mA, it's in the regulator range. For a few time I worked it with no problem, nevertheless I thought that the electric current range was short, and as I had this desire to acquire a linear laboratory power supply for so long, it was the right moment.

When testing the new power supply, found that although is a laboratory power supply, my old 2 A power supply has much less ripple. Having available time with holidays, I work it out a way to improve it all, and at first consulted a datasheet of the L7812.

To avail the 2 A that the power supply can delivery, I decided to put together the two L7812 in parallel, with some availlable and preferable ceramic or mica capacitors, as long as I have them in my stock.

Tested several points in the circuit board where could provide an adquate voltage for more than 14,5 VDC and I found one, but when connected with the regulators, the voltage lowed down, probably it was no enough electric current. I tryed at the output of the transformer, where I put two diodes, that released a voltage of almoust 17 VDC, but at the output of the regulators, I only had 11,4VDC. The best I found It was even at the output of the circuit of the power supply, that I could obtain 13,5 VDV in the original front output borns, with a charge of resistors of 2 Watts wich and 60 Ohm, made with 3 resistors, and at the rear output borns, the regulators's output, 12,03 VDC.

The circuit board has a variable resistance to regulate the output voltage. The original factory value of the resistor was 2 K and in the circuit boad is marked 5K, but I made worst, I put it, in the other side of the board, for better regulation, a 25K variable resistor an works fine.

A fan has been adapted for better cooler of heat, but it's too noisy, although a 2k variable resistor for velocity control that I put it, and I probably will take it off. I also put it in parallel, several ceramic capacitors for ripple filter, two electrolytical capacitors, one for the principal and original circuit, other for the improvised regulated circuit with 12,03 VDC and two toroidal ferrite as you can see in the pictures, for better filter as well.

The ugly and old 2 A power supply is ready, next I will make known the improvements, that I think I made, or not..., in the laboratory power supply.

The new lab power supplie

Before I acquired this power supply I saw the technical characteristics, particularly the ripple noise. It was a good value for the price, but what was said to what I found, there was a difference. The old ugly changed power supply I was been using presented less noise in the youkits HB1B, so I decided to investigate.

At first glance I found a dented 63 V, 4700 µF electrolytic capacitor, as if it was getting sucked. I also have this idea that when this appens, the voltage range of the capacitor is too short, so I replaced it for one of 100 V, 4700 µF, but it didn't fit in the circuit board, I had to put it out of the circuit board, connected to it with wires. The wires must be as short as possible, otherwise you will not be able to zero the voltage and current values on the display.

The fan cooler is also too noisy and the rotations will generate frequencies that will cause circuit noise, some tantalum and polyester capacitors, and a ferrite bead in the wires will definitely solve that.

Multiple figures for half-wave lengths in a random wire antenna

Looking at the possibility of installing a long wire antenna, I have been reading about it and among the various readings taken, one was about the appropriate half-wave multiples for random wire antennas in HF.

I immediately remembered a long wire antenna, that I had many years ago, when I had free space to install them. It was about 70 and a few meters, but it wasn't the 82.14 meters of a full wave in the band 80 meters, but it worked very well and I had a QSO with an OM from the old days, in Germany, who was doing AM tests. That QSO lasted a good few hours, I have an idea that it was almost all afternoon, and in AM, I was just using about 20 W of radio output power.

In one of the readings made, I observed a table with several numbers of multiples of half-wave lengths in each band, where It was said that you shouldn't use an even half-wave number for a random wire and concluded that the half-wave length in the 40 meters band would have the best results.

I also decided to make a table with more half-wave multiples and check if there would be repeated numbers. I only found one, and it is an odd half-wave, which is good. The others half-wave numbers, are by approximation in the odd and even half-wave multiples.

Observations:

1. The repeated number is the length I used on my old long wire antenna, near 74 meters.

2. The even and odd lengths approximation numbers, are in the same amount, this is, there are the same number of "bad" and "good" half-waves for the two most possible aproximattion half-waves, the half-wave in the 40 meters band (21,11) and the half-wave in the 160 meters band (81,91).

3. The approximate odd half-wave in the 160 meters band, appears in the 17, 20 and 30 meters bands.

4. The approximate odd half-wave in the 40 meters band, appears in the 15, 17 and 40.

5. The approximate odd half-wave in 160 meters, is the exactly same number in the 20 and 30 meters bands.

Although I have not tested an antenna with the various lengths mentioned and in the same place, with the same conditions, despite read someone mentioning about 16 meters, presumably after SWR tests in all wave lengths, in the same place and same conditions, it seems to me that the most suitable length for a random HF wire antenna is 74 meters and that the length of 21.11 will be a compromise or possible length.

HANDHELD RADIO ANTENNA TESTS

Lately I have been researching the reality of antennas for portable radios, because since I bought a Yaesu FT5 handheld radio, I have seen some situations that deserve some caution regarding the use of antennas that come with them and other ones.

A few years ago, in a QSO in UHF through a repeater, the other station informed me that he was not listening to me anymore. I went to check the antenna connections and noticed that the radio was boiling. The antenna I was using was the one that came with the equipment itself (stock antenna). It was a Yaesu FT-817ND and at the time I attributed the problem to bad design of the radio. It is a QRP radio, very small for all its capabilities and very closed, with no vents.

More recently, I verified an identical situation with the Yaesu FT5. I attributed the problem to the adaptation of a battery box for battery eliminator until I noticed that it persisted. As long as the 7.2 V was present and the current was also present, the problem could not come from there. I started to research and purchase several antennas. I ended up purchasing more specific and accurate measuring equipments. My friend CT1ABE, Augusto Cebola, an OM with a lot of knowledge of the old days, told me how to test these types of antennas. Specific SWR meters for laptops and field meters.

I've been doing the measurements, learning new things and coming to interesting conclusions, which I will report as I go along.