PU1UTC – Radioescuta, DX e Telecomunicações

Electricity, the basis of our civilization

Raining is coming, summer arriving soon and with our third world infrastructure, long blackouts and electricity intermittent fail are expected in geometrical scale.

So, forget the devices sold as stabilizers and filters because it will simply not work.

Adopt UPS with at least expansible feature to install additional battery bank to improve time operation. Manageable UPS with updated software is a best choice because we can monitor its performance and status online.

Starting service for adding extra battery bank

APC is a high standard equipment and according to its specifications it could feed one more 24 Volt battery, with the only drawback of need more time to fully charge all batteries.

As a matter of fact, I used the same standard battery and configured a bank using of course a in series configuration and to input this external bank into the system I have cut a piece of its chassis to pass the new cabling and have both positive and negative wires welded in the internal DC line because they are already welded in a special place in the master board.

Welding external bank wiring into internal feed

The big deal when you do that is to check to only the specifications of the UPS, but also check if there is a trimpot to adjust the charge tension of the batteries. It may need to increase 1 Volt – depending on the original project – and use good instrument to make all applicable measures to assure the correct drain current for stationary batteries.

The battery bank is attached to the top of main chassis using professional 3M Dual Lock Velcro permanent glued over it, and another face to the batteries, so you provide a stable position for the bank to avoid risk of accidents. In case of battery substitution, just take it away from the top of UPS and use a new piece of 3M Dual Lock into the bottom of the new bank.

Please check the quality of connectors used to assure electrical isolation and mechanically firmed attached to avoid any possibility of short circuit and bad contact which could be catastrophic for your UPS and also for our office, don´t forget electricity outages may cause big troubles and put fire on your site !

Final assembly of the APC RS 1200 VA with additional battery bank

Now, another feature that must be checked is the operating temperature of rectifier diodes and power transistors, because more current drained, more power and of course more temperature. This APC model has a cooler and I have just reinstalled it very near this components, because in the original position, it were directed to the mains transformer.

Update the management software and check the performance and status of the UPS and we will see almost double time of battery operarion.

This 1400 VA UPS from TS Shara has already connector for external 24Volt battery

To expand this UPS battery bank it was not difficult, since the main concern was to find the external connectors needed to connect the external bank in the rear part of the equipment. Using and surplus UPS parts, it

UPS under operation using same assembly concept of external bank

Again, always consider security in all operations, installations and only use correct procedures for connectors, welding and isolate everything with professional products like 3M™ Scotchfil™ Electrical Insulation Putty – this black electrical grade, rubber-based, self-fusing insulating putty is supplied in tape form. It´s simple to use, last forever, and support high tension (which is not our case since we are talking about 24V DC).

Unmanaged UPS SMS 700VA – all purpose no break

Now, imagine a simple but efficient UPS that has only one internal 12V battery for general purpose use, like a desktop, a PlayStation console and other stuff that must not be turned off due to power outage to not generate not only hardware failure but software issues.

But if you connect some equipment which uses in average half of its nominal Watt output, life battery maybe not enough to even shutdown or device and then, you may have a headache.

Preparing the cooler and tools after system survey

Considering not using a large and expensive UPS for this kind of situation, you can study how to expand its battery time, but please, check if the rectifier and the AC driver is able to provide more current, otherwise, for sure we will see some component burning and you may feel a bad smell coming from it.

In this case, to avoid temperature rising in main diodes and transistors, I decided to install a simple cooler to blow cold air into the unit, and the air flow is assure naturally by the design of the whole assembly.

It’s not a simple issue to blow FRESH air into the equipment; you must assure the HOT air leave the equipment otherwise there will be no AIR FLOW, no temperature stabilization. It´s simple like that.

UPS expansion done and fully operational providing power to some gadgets

The battery used is the same standard as the internal one, and it is fixed atop the UPS using 3M Velco.

To isolate the external terminal of the batteries it’s advised to use PVC insulated tape – also from 3M or even Silver Tape from 3M depending on the physical position and shape of the equipments. This way you protect the system if some metallic part touch them and provide mechanical stabilization of the external batteries.

To protect the main board from corrosion or humidity, the super master mega plus WD-40 will solve it. Just spray its flux along the board and electrical contacts that you will extend the life of the equipment.

Enjoy your longer life UPS operating time ! But don´t forget, if you are unsure about what to do, please, ask for an electronic technician support.

Grounding, Grounding & Grounding – Good connection to Earth is mandatory for electrical devices work proper and safety, don´t forget it

As telecomunicações atualmente representam a chave para a sociedade, não só em tempos de paz como em tempo de conflitos, seja eles quais forem.

Eu tive a grata oportunidade de realizar uma atividade profissional a bordo do porta aviões NAe A12 São Paulo, referente a sistemas de comunicações embarcados.

Foto oficial no convoo do Aerodromo A12 São Paulo

Essa foto oficial tirada pela tripulação do navio mostra o indicativo do aerodromo São Paulo que está pintado na base da torre da embarcação.

Foto com a visão parcial do mastro do A12, destacando as antenas dos sitemas de comunicações

“Missão dada é missão cumprida.”

Neither electromagnetic theory nor calculations of any kind, just practical experimentation. As we know, the number one enemy of Dxers and shortwave radio listeners is man made noise.

Dirty electric power grids, low quality transmission lines, made in chinese electronic bulbs plague, and we have a chaos in the HF spectrum, also in MW.

How to chase it ?

Place antennas away from potential noise sources and use a transmission line shielded to input the signal into the receiver is a good and efficient approach.

Transformer circuit diagram for 9:1 impedance matching

To achieve this the use of a impedance match transformer is a powerful tool. Put your random wire in some safe place, install a balun to couple the wire that acts as antenna into a coaxial cabling that will be the transmission line that is supposed to not capture noise up to your receiver placed indoor.

The random wire typically presents hire impedance, depending on its weight and length, and we can estimate in average 500 Ohms, while the coaxial cable presents 50 Ohm impedance, that is the most common input impedance of tabletop receiver and also portables like Sony and Sangean.

Transformer schematic using a toroid core of ferrite for 9:1 coupling

So, to make the correct energy transference between the antenna and the receiver input, we should transform both impedances to avoid attenuation in the transmission line.

The theory of maximum energy transfer is quite simple, just think in a battery providing power, and this battery has an internal resistance value, so if the load presents the same internal resistance, maximum power transference will occur.

The same principle applies to receiving RF signals. And the so called magnetic coupling, impedance matching or transformer, will provide a ratio between the random wire impedance and the internal impedance of receiver’s front end input.

The 9:1 ratio will provide about 500 Ohm impedance of random wire be divided by 9, so the final impedance should be next 50 Ohms, the same of coaxial cable and receiver’s input.

Ferrite core in toroid shape

The use of ferrite core is mainly for increasing the inductance value of the coil, and toroid shape helps magnetic coupling of the transformer and also isolates from other magnetic fields nearby.

Using enameled wire is just an option, because in this kind of assembly the wire used is not critical, because this balun is intended just to receive signals not transmit.

This toroid is really big, and in practical terms it is not necessary this way just to receive RF signals, but I have purchased 3 units in surplus conditions, so I have not had a choice to choose a specific ferrite toroid.

In fact, it can be used larger powered iron toroids to wind inductors, however, they can also be wound on ferrite cores or be air-wound. The core size, wire gauge and type of inductor used can affect the insertion loss of the transformer (balun), however for practical receiving purposes it is not a major concern.

And that makes the hobby more interesting: use the theory, but make experimentations … always.

Balun construction using a strong alloy case used on VSAT stabilized systems offshore

The case to assembly the balun can be whatever material available, I have chosen a robust alloy case used as a modem for some VSAT systems. It’s mechanical features allow it to be installed virtually anywhere and placed to resist weather and very long wire that causes tension over the connector.

Final assembly of magnetic coupling for random wire antennas

This case will never be broken, just that simple.

This balun is also called UN-UN (unbalanced – unbalanced) because it couples a random wire and uses a coax as transmission line, and both component are unbalanced related to ground.

If we use an antenna dipole, so, the proper balun should be balanced-unbalanced in this way.

More to come, I have two toroid units available yet to test other coil configurations and ratio transforming.

Holiday, a rainy day, some enameled copper wire and here we go in another experiment with small loop antennas.

The famous RGP3, developed by Rene Passold based in an old project called “bazooka antenna”, is spread over MW dxers in Brazil, and still represents opportunities for testing several configurations, specially related to the coil.

In this experience, I checked two forms of winding the coil, with turns together and spaced by a constant distance using a common string.

And the results confirm that spacing the turns makes the tuning range wider, due to less capacitance losses. Both performance are similar, not noticed using a standard receiver like a Grundig YB400, that shows a small but reliable s-meter (not professional but adequate to fine tuning small loops).

The format of ferrite rod were kept the same as the original RGP3, but this one I got glued two sets of ferrite to check with sensibility would be better. Practical experience shows no sensible improvement doubling the number of ferrite rods aligned in the axis.

But its nulling capacity seams to be a little bit better.

Final product and the inductive coupling with the internal ferrite antenna of a portable MW receiver

Instead of using Litz Wire that requires some time and tricks to get good soldering, I adopted enameled copper wire due its rigid construction and overall quality showed for the small loops.

That´s all folks.

The complexity of telecommunications using satellite is very high, imagine now provide full telecom services for off shore operations…

Internet, voice, data communication, video and monitoring system 24 hour a day, to support oil and gas prospection and production, regarding human safety and environment protection which demands almost military class equipment and high level services.

Ocean, sea, salt water, extremely powerful winds, tide waves, electrical thunder storms, helicopter operations and so on off shore…

This is what we face all the time to apply technology to off shore operations, managing high trained teams.

Not only for defense, energy or maritime industry, but for all aspects of telecommunications where reliable communications are demanded in all sort of fields.

Let´s look at the skies and try to imagine what is around us, and what mother nature makes it possible by radio waves.

It´s electricity and RF – Radio Frequency – that runs our civilization.

I like it. I do it.