A Knife, an Oscar Wilde Quote and the “GU7TR” Antenna…


This is the story on how the left panel on the above picture led to the one on the right…

After many years of working the World with an end-fed quasi-vertical long wire hanging in the backyard from a tall maple-tree branch while held in place with the aid of a thin brown cord leading down to the inside of the fence, the unthinkable happenned: the cord was cut… First, I thought it had happened out of wear during one of the winter storms, but on close inspection it was evident that the line was not worn out or torn apart, it was simply and neatly cut just above fence-level, likely with a sharp blade (see the panel to the left of the picture). Thus, courtesy from this anonymous knife-wielding neighbour, for the last few months the QTH has been without its tree-antenna. Yes, I could have replaced it but nothing indicated that the same “accident” would not happen again. What was needed was a stealthier antenna and if possible, one of a sturdier material. I was in the yard thinking about which could be the longest and most vertical metal structure nearby the house when I suddenly remembered a quote from Oscar Wilde, and I looked up and there it was. And this is how I happened to re-discover this very old, ever-compromised but faithful multiband HF antenna that has been the last resort of many antenna-deprived amateurs, the one with an almost Guernsey callsign (GU7TR…?): the rain gutter antenna.

As it happens, at the QTH, the point of exit of the very short coax (1-2 Ft.) that leads through the wall from the remote tuner (an LDG RT-100 placed in between walls) to the banana-sockets on the outer wall (one for the antenna wire and another for the elevated counterpoise wires) does so less than a foot away from the rain gutter downspout. Then all that was required was to replace one of the screws joining two sections of the metal pipe with a new metal screw while making sure that, in so doing, it would also hold, between itself and the metal, a ring terminal casually soldered to a short piece of wire, which at its other end just happened to have a banana plug fitting the antenna socket in the wall. Assuming that it does not electrically connect with any other conducting structure, this GU7TR would have a “T” shape with a vertical section going up the rear wall of the house (abt. 15m) and a horizontal portion along the edge of the roof, a shape not too dissimilar from that of a Marconi “T” antenna (as the one in the Titanic), with the top horizontal portion providing for added capacitance.

Yes, the metal structure is old; yes, a portion of the pipe rests on the ground; yes, all of it is against the house; yes, it gets wet and even full of water when it rains; yes, it must have rusted connections between its parts; yes, the cables for the Wi-Fi as well as the pipe for the water intake are near its base; yes, etc. but —and this was a big BUT— it still had to be better than nothing…

And that, it was. On first try, the RT-100 (with a 4:1 unun) was able to tune the GU7TR across all HF bands (10M-80M) to SWR values of 2.0:1 or less. The best match was in the 40M band where the SWR could be brought down to 1.2:1. Also, on first try, in 40M, the IC-703, was able to load a 5W standing wave to the GU7TR (as per the Elecraft WII meter) and get a 559 RST from Mike NO8C operating from Miller City, OH. Then, during the weekend SKCC WES, several CW QRP QSOs were logged in OH, PA MD and MO (this last one in 20M). Then, using the 706MKIIG, with a load of ~50W, a 20M CW QSO was completed with Bob F6EJN in Puylaurens, East of Toulouse in France. And on Sunday, participation was also possible in two 80M local nets (the SSB Pot Hole Net and the CW Pot Lid Net) without any major difference in the signals heard or the reports received in comparison to previous participations using the random end-fed wire. Also, so far, there has been no indication of any RF or any ill-effect on any of the electronics around.

Of course, this GU7TR antenna is intended only as an emergency antenna, and in the future, I may choose to operate from the QTH only portable with any of the portable antennas in my collection (W3EDP clones, PAR EndFedZ’s, Buddipole or Alexloop, or even random long wires raised for the occasion within the yard with the help of the DK9SQ or the S9 v.43 telescopic poles). However, rain, snow and strong winds are strong hindrances for these portable set-ups and it is nice to be able to count on the always ready and ultimate stealth “GU7TR” antenna.

After all, as Lord Darlington says in Oscar Wilde’s Lady Windermere’s Fan: “We are all in the gutter but some of us are looking at the stars.”