AmateurRadio.com

Mads LA1TPA recently visited Julian G4ILO’s shack and was so impressed by his approach to cutting through the QRM using an MFJ-1026 Noise canceler and a pa0rdt-Mini-Whip active broadband RX antenna, he’s replicating the solution at his own QTH.

His post links to info on both the MFJ-1026 and the pa0rdt Mini-Whip.

MFJ-1026 noise canceler

Julian G4ILO’s site has an extensive description of the MFJ-1026 explaining that it’s a noise canceler, not a noise blanker or a noise reducer – as well as a ‘look under the bonnet’. It’s most effective when the noise is coming from a single point source, not multiple sources. So the canceler can reduce noise from a neighbour’s switch mode power supply, TV or computer it may be less successful dealing with general powerline noise.

For Julian’s station it did the trick and as he concludes,

“The MFJ-1026 is expensive for what it contains and quite poorly made, so I don’t feel any pride of ownership of it. It’s also a hassle having to tweak its controls whenever I change bands. But pressing the button to take it out of circuit quickly reminds me just why I have it.

I’d probably had sold my equipment and quit the hobby if it wasn’t for the MFJ-1026.”

You can also preview the MFJ-1026 manual here.

pa0rdt mini whip

The English-Dutch-Italian pdf about the pa0rdt Mini Whip explains,

“After several fruitless attempts to make an active loop work in a city environment, it was found that the electric field from local noise sources was contained within the house. The magnetic field of local noise sources was not contained inside the house, making weak signal reception at LF impossible.

Hence an electric field antenna was called for. Tests were performed using an active whip antenna, designed by G4COL. Results were encouraging and the whip length could be reduced from 100 cm to 30 cm without loss of performance. It became clear that at LF an active whip is a capacitance coupled to the electric field.

If it is accepted that a whip is a capacitance coupled to the electric field, shape becomes irrelevant, as long as the required capacitance is available. In practice the “whip” can be e.g. a small piece of copper clad printed circuit board.”

Looking back over some older email list posts today I came across an interesting exchange of posts on the QRPp list.

In early August Arnie Coro CO2KK announced latest progress on the ‘Super Islander Version 5 QRP transceiver project’. Key design criteria include using “as much as possible parts that could be recycled from easy to find sources of electronic components” such as toroids from PC boards salvaged from failed compact flourescent globes, and other treasures from broken VCRs, TVs and fax machines.

Via the short Wikipedia bio of Arnie Coro I discovered a link to more than seven years of transcripts of his weekly radio program ‘DXers UNnlimited’ broadcast by Radio Habana Cuba. Earlier transcripts are here. He also has a blog last updated in June. They’re practical and full of useful ideas.

One transcript is reproduced on dxzone.com and is an undated description of the project detailing what appears to be the first valve version of the project – I think designed by his friend Pedro, CO7PR. It brings home in a softly stated way the challenges and barriers facing radio enthusiasts in countries which for one reason or another don’t enjoy relatively high wages to afford factory made gear, and who have to be much more resourceful in making do with what they have available to get on the air.

A rude dismissive comment on the QRPp list prompted a firm but calm response from Arnie.

“Yes amigos, it is very easy for people having access to the money and the possibility of buying factory built radios or even well designed kits with full instructions and each and every part required… even washers , to just sign a check or complete and electronic transaction that will bring to  their homes a nice piece of equipment…

But that is not the case for many of us, that do enjoy very much the amateur radio hobby, and think not only about ourselves, but also about those that may benefit from also well designed, easy to assembly and to adjust radios that can be built using locally available parts.

Try to find even the lowest cost ceramic filter for building a single sideband rig in no less than 130 countries around the world and you will meet with the fact that they are impossible to locate, and the same goes for ferrite and powdered iron toroids, IF transformers, RF power transistors, small relays , RF connectors, resistors and capacitors, not to mention quartz crystals and integrated circuits !”

SolderSmoke named Arnie ‘Homebrew Hero’ earlier this year.

Arnie Coro CO2KK

Arnie ended one of his missives to the QRPp list with this plea:

“Maybe one day the International Amateur Radio Union could sponsor a similar project to help promote amateur radio among young persons that live in poor nations where buying a factory made transceiver may be equal to the full salary of a worker during five years or more !!!”

I remember that one of the first QRP designs I ever built (back in the late 1970s) was a simple VXO controlled 6 W 20 m transceiver that appeared in QST (Dec 1978). It was later suggested as a prototype IARU transceiver as ham aid for developing nations.

Arnie’s idea appears much more economical and self reliant, drawing on the potential of recyclable components. It’s also a design thought through from a Cuban perspective rather than a first world one.

You can even hear an interview with Arnie Coro recalling the Bay of Pigs invasion in 1961. [audio]

The October edition of WorldRadio Online magazine is available now.

Highlights include:

* An End-Fed Dipole That’s Easy to Build and Great for the Field – a trail-friendly design inspired by Kurt N. Sterba’s Aerials column in the August edition of WorldRadio Online, where four stacked F114-61A toroids are the secret weapon along with one-quarter wave of RG-174U coax…

* Seeing What Others Are Hearing: A DX Cluster Primer – How to tap into the information flowing through the DX Cluster network

* Radio & Relaxation = The Great Family Vacation – One ham’s adventures combining radio fun with family holidays.

Charles Preston, a member of the Buddipole User Group email reflector has just posted links to two clear and useful guides to using the A123 Battery Packs available from Buddipole. While the Buddipole site links to documents about the batteries there’s very little practical information available about how to nurture these batteries. Similarly the Cellpro Multi4 charger documentation is more geared to the primary market – radio controlled airplane enthusiasts – so it’s great to see advice directly relevant to our intended use.

The first document is a Guide for Buddipole A123 Battery Packs and it explains how to maintain them and likely operating times for popular transceivers. The core of the document is how to charge the A123 Packs using the Multi4 charger (also available from the Buddipole site). There’s also mention of how to approach charging the Battery Packs with a solar panel and mention of the Genasun GV-4 Li 14.2 V MPPT controller. BatterySpace.com also sell a version of this charger designed for LiFePO4 batteries. Prices between US$110-119.

It’s great to have all of this information available.

The second document is Charging a Buddipole 4S2P or 4S4P A123 battery pack with a Cellpro 10s charger and focusses on the larger charger.

Three cheers for Charles Preston!