Jury-Rigging a UHF-BNC Connector for one last return to the air as CX7RT

While packing for a new trip from VE3-land to CX-7-land, I hesitated whether to include the KX3 in the luggage. Finally, I yielded to old memories of record-making contests and found room for it in the carry-on. For simplicity, as an antenna, I opted to bring along only the 15M PAR EndFedZ. If I was to return to participate in the CQMMDX contests, it would have to be in my beloved 15M band.

Once there, with the aid of a thin “Tacuara” cane (see the picture above), I deployed the 15M PAR as a full end-fed dipole: one half horizontal against the roof of the balcony in my 3rd-floor apartment facing NW, and the remaining half slightly sloping down in front of the window of the dormitory.

Then, when went to attach my travel-coax (abt. 10m stretch of RG-58/U cable with a male BNC connector at each end) to the special balun of the PAR EndFed (which sports a UHF female connector), my blood chilled, as I realized that I had not brought along any UHF-BNC female-male converting adaptor, or any other kind of connector converting combination that would permit the coax to connect to the PAR EndFedZ. In CX-Land, coaxial connectors are precious items treasured by local hams and zealously kept in the depth of their shacks. Not being a member of any local radio club and not knowing any local ham in the area I was faced with the possibility of not being able to use the radio during the entire trip.

The pin inside the male BNC at the end of the coax was too thin to make contact inside the female UHF at the balum. I needed to make it thicker. Among the garbage I store in the apartment I found a piece of thin copper wire (probably extracted from a cable found in the street) and a slim screw. I fancied that if I could wind the cable around the screw, once the screw was removed, it would result in a small coil that could fit inside the center hole of female UHF while providing at its center a tight space where to insert the pin of the male BNC. The whole then could be made tight and semi-permanent with a generous stretch of electric tape. It worked on first attempt.

When I first fired up the KX3 thus connected to the antenna, I was exhilarated to notice that the antenna readily tuned to a low SWR not only in 15M but also in 10M and 20M. However, there was an awful background noise in all, likely due to the proximity right next door of the huge antennas of the Uruguayan telephone giant ANTEL. Nothing I could do about it, so I got ready to try my best, but under the circumstances, I knew it would be nearly impossible to make a single QRP contact.

However, on March 9 2024, I was able to make three QRP contacts in the South America 10m Contest (https://sa10m.com.ar/wp/): PY2XL in CW and LU1VDF and PY1AX in SSB.  The next day, also in 10m, I had a very nice SSB QSO chat with Wladimir (Wlad) XQ6CF, near Osorno, in the South of Chile.

On April 20-21 I was ready for the CQMMDX Contest (https://www.cqmmdx.com), one in which I had participated in previous years, and on Sunday April 21, I spent several hours at the KX3 overhearing calls from stations in Brazil, Argentina, Venezuela and Chile (and even got a glance of VE3EJ calling CQ MM from Hamilton, Ontario at 14.025 MHz), but I was only able to complete one single CW QSO, in 15M: with LT6M in Cordoba, Argentina, and it wasn’t even a QRP QSO since I had to jack up the power to 10W to be able to complete it. I did nevertheless submit my log as SO15M LP just to be present in the contest, likely to be my last as CX7RT.