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A bonus picture here. The one on the left is a 3 foot in diameter loop.

Note: The little box at the bottom of the small one contains an air variable capacitor for tuning.

Compare it to the 5 foot in diameter loop on the right. ‘

5 Foot Mag Loop

I made a QRP CW contact with this mag loop from right where it stands in my drive way.

Small Loop Feeds the Big One

Home Made Capacitor Clamps.

Home made cap clamps. The clamps are soldered to keep the contact resistance low.

This is very important with High Q antennas.

5 to 150 Pfd capacitor

Russian capacitor. It is available at E-Bay for about $150

Easy to Make PVC Pipe Stand

Where would hams be without PVC pipe!

This stand is made from 2 1/2 inch sewer pipe.

This is  a fun antenna to build and use. I made my first contact with W9GY this afternoon on 20 meters. I used 5 watts, he used 10. RST out was 459, RST in was 579. The antenna was in my drive way in front of the garage that you see here. And Jeff was in Indiana. What a hoot! Making contacts on a home made antenna is great fun. The parts are readily available and with a little planning and shop time you can have a Magnetic Loop antenna to play with.

This is my second Mag Loop. The first one is 3 feet in diameter and covers from 20 through 15 meters. I’m planning another for 17 meters through 10 meters. Mag Loop calculator is available at http://aa5tb.com/index.html

Yahoo has Mag Loop groups that are very helpful to get you started. http://groups.yahoo.com/group/MagLoop/

and http://groups.yahoo.com/group/MagneticLoopAntenna/

Copper foil or strapping is available at http://stormgrounding.electrical-insulators-and-copper-ground-bars.com/copper-foil-2.html

If you’d like more information about Mag Loops, please feel free to contact me. [email protected]

73 De AA1IK

Ernest Gregoire

I always like reading about what can be achieved using a stealth antenna system, so I always enjoy reading the blog of John, N8ZYA.

From a town house in Charleston, West Virginia using 3 watts of CW to an indoor random wire, John has made 1,830 contacts including 361 DX stations in 73 different countries. Simply amazing!

I hope you don’t mind me pinching your picture, John!

Transceivers with a power supply of 1 and 2 Volts, how much can one achieve with that? Well, actually quite a lot according to DL2AVH, Helmut, who together with DL4ALJ, Gero, wrote two articles about that in the German QRP-Report in 2011. I am impressed by the output power, up to 200 mW with one battery cell (1.5 Volts) and 0.5 Watts with two cells.

I wrote about this in April last year where I also mentioned that the 1 Volt design from 2000 later had been corrected. Those corrections can be found in the article in QRP-Report 3/2011: “Niederspannungs-Schaltungtechnik – der 1-V- und der 2-V-transceiver” (Low voltage circuit technology – the 1 Volt and the 2 Volt transceivers). The improvements are concerned with better input filtering at 14 MHz with a quartz crystal in the front-end filter and better efficiency in the mixer and removal of an audio stage in the direct conversion receiver. This design only uses bipolar transistors and no ICs.

This is different in the newer 2 or 3 Volt transceiver for 7 MHz. Here an impressive figure of only 5 mA power consumption for the receiver is achieved. The transmitter consumes about 250 mA. Several MC1496P balanced modulator/demodulator ICs are used for the mixers in the transmitter and the superhet receiver, and for the product detector of the receiver. They seem to run quite comfortably on only 1.8 Volts as supplied by a low-droput regulator from the battery supply. The TDA7050 is used for the audio output stage. This is a low voltage audio amplifier for headphones which can operate with  a supply voltage down to 1.6 V.

The design is said to benefit from low voltage technology of mobile phones. This is the case for circuitry like that of the output stage of the transmitter which consists of a pair of BFG21W transistors. However, both of the ICs have been around for many years.

I think this was a very inspiring read, and the final comment about power consumption from the second article is interesting. They say that with two AA-batteries, the receiver will last for 285 hours, which is the same as 70 days of listening of 4 hours per day. With transmission for 10% of the time, the set of batteries will last for 4 weeks!

• Related post: Whatever happened to the 1 Volt QRP Transceivers?