Portable power for active antennas

CPI1000 mit Powerbank

CPI1000 mit Powerbank

Many thanks to Dennis at Bonito for sharing a link to an article he recently published on the Bonito blog:

Autonomous power supply of our active antennas via USB and power bank

It is getting to be more and more difficult to procure reasonably priced analogue external plug-in power supplies because just like old light bulbs they are no longer allowed to be produced due to power consumption restrictions. We are spending a lot of time to find and buy remaining stock so that we can offer our customers noise-free external power supplies. But for years, there has been an alternative.

Our MegaLoop ML200, ML052, the MegActiv MA305 as well as the GigActiv GA3005 can be operated internally with as little as 5V and so can be powered by the supplied CPI1000DP / CPI3000DP bias tee via a USB cable.  In light of the annoying switching power supplies, PowerLAN and heightened mobility of listeners, this is a very practical alternative and offers much more flexibility for the customer.  Unfortunately, this fact is not well known and that is why I would like to shed some light on this subject.[…]

Continue reading at the Bonito website.

Thanks, Dennis!

RaspberryPirate-EtonBlockI should note that there are a multitude of 5 VDC powerblocks on the market. I have two made by Eton Corp (see above) that even have hand-crank power generation. I recently used one to power my Raspberry Pi (Raspberry Pirate!) for several hours.

As Dennis states, using a DC source certainly cuts down on interference from noisy power supplies.

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11 thoughts on “Portable power for active antennas

  1. DL4NO

    A switching power supply need not be *that* bad. First you must find out what belongs to your antenna. Quite often this is much more than you think – remember the outdoor experiences of London Calling with his DX Patrol or what it was that he described here some time ago. He was very surprized after he switched to a symmetric antenna…

    Power banks like the one shown in the picture above also contain a switching power regulator: The battery in there is a single LiPo cell that delivers 3.7 to 4.2 V depending on its depletion state. This must be converted to 5 V. Even its load regulator might be of the switching type as the unit could not dissipate the heat of a series regulator.

    1. Dennis Walter

      Hi Alex,

      this one did not show any noise in the HF Bands. It was plug and play and works without any problems. If you visit the Funktag in Kassel or the Hamradio in Friedrichshafen, I can show it to you live on air.

      1. DL4NO

        Hi Dennis,

        as I wrote above: You must determine what belongs to your antenna. If you include a switching regulator in your antenna system you need not wonder if you hear it.

        Antenna is where unsymmetric currents flow, that can reach the receiver input. If you directly connect a piece of wire to the antenna jack or or use a typical telescopic antenna on a portable rig, all of your rig gets part of your antenna system. Even an old “power brick” with a transformer and a analog serial regulator can introduce RFI – from the mains grid.

        We might meet in Friedrichshafen. I will do a short presentation at noon on Saturday: Chances and limits for HAMNET on 70 cm. HAMNET is our Middle-European hamradio intranet that relies on better WLAN components.

  2. rcxb

    Power banks have noisy, switching components in them, too. Stepping up a 3.7V li-ion battery to 5V takes some conversion, and cheaper units absolutely do introduce unwanted RF noise.

    1. Dennis Walter

      this maybe. I have tested around 35 different types and non of it did noise in the HF Band.

  3. Dennis Walter

    Hello Thomas,
    Thank you very much for sharing my article.
    I am very happy about this because I think that this will help many listeners to get better signals and having more fun with their hobby. Most of the listers live meanwhile in an area with noisy PowerLAN, Switching power and other noisy devices. In this areas it is mostly hard to receive anything. With our magnetic loop Antenna MegaLoop ML52 for example and a simple powerbank you can lower your noisefloor in your Flat / Apartment. Or you can extend your range and get away from noisy environments while listening somewhere outdoors. Even when you are on a holiday or business trip you don’t need to renounce your hobby.

    Thomas, I know that you are traveling a lot at the moment. I will send you a MegaLoop ML52 and a matching Powerbank, you can test this combination while you are traveling and share your results with us. What do you think?

    I will be at the Dayton Hamvention (I think Booth 46 in the Hara Arena) and show everybody live how it works and I would be happy if I could welcome some Hams and SWLs there and talking about our Hobby.

  4. Tha Dood

    Actually, it’s not too hard to build your own linear +5VDC power supply for USB power, with no RF hash. A step down power transformer of 120VAC to 10VAC that handles 1A, a full bridge rectifier, a 3,300uF – 16VDC electrolytic CAP, and an LM7805 +5VDC regulator. Then the 1A fuse and a switch. Can be done for $25.00, or less if you have much of the part junked on-hand. Yep, I’m cheap.

    1. Michael Black


      In reading the piece, it struck me that they were thinking in terms of “new”.

      Lots of garage sales I go to have a box in the corner of ac adapters, usually all twisted together, sometimes cables are intertwined. They are treated as a step up from garbage, so they are cheap.

      Those should be harvested. The connector may be wrong, or at least the polarity, bit a bit of cutting and soldering makes use of them.


  5. Eric Cottrell

    I noticed these USB Power Banks are getting bigger and bigger in capacity. I bought a 8,000 mAH one a couple of years ago. It works great. I recently saw a slightly larger 20,000mAH one on offer at a local big box store. Reviews mainly deal with their primary purpose, to charge cellphones and tablets.

      1. DL4NO

        Powerbanks have long gone beyond USB.

        You find models that can power a notebook by providing switchable output voltages and a set of adapters for different brands of notebooks.

        These days you can even find units that claim to provide up to 200 A to start a car with a dead battery. But how often?

        Internally these power banks usually contain several standard lithium cells in series. The capacity claimed is the sum of the nominal capacities of these cells. The mAh rating therefore refers to the 3.6 … 4.2 V of the cells. A Wh rating is far more meaningful. But remember the voltage converter efficiency!


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