Fun in the sun with QRP

After being inspired by Dick’s (ZS6RSH) blog on his Kruger Park “dxpedition” shortly before he left to return to the USA (see the full write-up in the April edition of CQ Centurion), I thought I would try something different during the winter SARL QRP contest on Saturday 18 July 2015.

Instead of being shack-bound, I operated “portable” from a temporary set up on the lawn at the front of our house.  My station (see Picture 1) was all homebrew of course.  Looking at the picture, the equipment, from left to right was a newly constructed, balanced, transmatch, the resistive type SWR bridge, the old faithful DCS401 transceiver (described in the September 2014 CQ Centurion - VXO on RX, xtal controlled on TX with three crystals – 7020, 7022 and 7030kHz and 3W output, operating from a 7AH SLA battery) and of course my straight key.  Incidentally, I also have a 7025kHz xtal, but after a single contact with it, the frequency was permanently occupied by a fellow contestant for the duration!

As previously mentioned the set-up was all homebrew – even the operating table consisted of a piece of chipboard screwed to the folding legs salvaged from a trashed ironing board!  

The antenna used was a W3EDP, an end-fed 84ft length of wire operated in conjunction with a 17ft insulated counterpoise lying on the ground.  The nearside of the antenna was supported at a height of about 3.9m on the pole attached to my  swimming pool net (see Picture 2) and the other end chucked over a tree in the corner of the garden.

I admit being totally blown away at the results I got with this primitive set-up - in the hour I operated I made contact with 2 x ZS5s, a ZS4 and 5 x ZS6s.  It was great to hear so much activity on CW for a change.   I really don’t know why things seemed to work so well, but I think one can put it down to good propagation as well as the newly constructed transmatch for the W3EDP which tuned beautifully.

Picture 1 : The operations centre

Picture 2 : The near-end antenna support

The balanced transmatch used was a link-coupled design using a T130-2 toroid.  The simple circuit diagram is shown in Figure 1 for those who may be interested in trying out the W3EDP antenna system in the future, particularly for field-day type operation – well worth doing I might add.  Pictures 3 and 4 show details of the physical construction of the transmatch as well as a close –up of the toroidal transformer

Figure 1 : Balanced 40m Transmatch

Picture 3 : Physical construction – bread-board style

Picture 4 : Details of toroidal transformer

Try something different for a change – I did, and have never had so much fun in a long time.   Really put the spice back into amateur radio for me!

73 de ZS6AZP

References:

“The PW Severn, QRP 7MHz Transceiver”, G3RJV, Practical Wireless, August 1983. (description of the W3EDP)

“Carrying on the Practical Way”, G3RJV, Practical Wireless, February 2009. (details of the link coupled toroidal transformer for the W3EDP “tuner”)