28 MHz Antenna – 4-element Yagi
Exactly one year ago, the OM0A contest team came together for the first time to participate in the CQ WXP Contest. Now we had the chance to see how much progress the team members had made in just one year.
Back in January, however, it didn’t look at all like we’d be contesting as a team. As the contest date approached, though, the number of participants grew: OM0AAO Viliam, OM7KW Števo, Igor OM6CI, Peťo OM6PR, Mišo OM0AAB, Gabo OM0AAG, Dano OM4AQP, Oliver MW0JRX, and Rado.
Looking at last year’s band results, we decided that we definitely needed to improve our 7 MHz antennas. So a mast began to rise behind the building. A directional Moxon antenna was supposed to be mounted on it, but after one arm broke, it was replaced by a tried-and-true 2-element DK7ZB Yagi for 14 MHz. During the winter, the antenna was at a low height. On Friday, despite the unpleasant wind, we raised the antenna to its operating height (approx. 15 m).
A dipole was put up in place of the intended 7 MHz antenna. It is raised to its operating height using a simple cable system. The hardest part was climbing the tree and looping the auxiliary cable over a branch. The antenna was tested in the ARRL DX Contest.
In addition, we decided to transmit using both antennas simultaneously. Therefore, Viliam OM0AAO built a power divider (stackmatch) and an interface to the transceiver. The usual quarter-wave vertical antenna for 7 MHz was modified from ground radials to a single raised radial.
Workstation No. 2 after modification
Since we wanted to avoid complicated antenna switching between stations, we attempted to network three transceivers in the M2 category, with the operators in the room coordinating band changes. The N1MM networking was partially successful, so we were able to start the contest in the planned configuration.
After a few hours, however, the 7 MHz station reported only a few dozen contacts. This was followed by disconnecting the stackmatch and engaging the switch. By comparing the antennas, we found that the quarter-wave vertical with a raised radial was much weaker than the dipole. However, the dipole is located close to the 14 MHz antenna, and when transmitting through it, it causes interference on that band. We also adjusted the N1MM configuration and the operating stations.
During the night, however, the operators did very well on 80m. The combination of the inverted V, the beverage antenna, and the new PA is working great.
In the morning, the first signals begin to appear on 15m. There isn’t much traffic—just some DX hunting. The rotator is a nuisance; after a few hours of operation, it becomes desynchronized with the control unit. The indicator points west, but in reality, the antenna is pointed toward Japan.
The highest band, 10m, just won’t open up properly. It stayed that way until the end of the contest…
We adjust the poorly performing vertical antenna for 7 MHz. It finally works as it should, but over time we notice occasional loss of sensitivity in the receiver. We switch transceivers, try a different PA and tuner—it’s a little better. On Sunday, I turn on the PA and run tests—no faults found. But then a lifesaving idea strikes—suppress the return currents from the antenna. I clip a few ferrites onto the coaxial cable. It works!
Števo OM7KW with Dan OM4AQP at 14 MHz
14 MHz is working perfectly. Some signals from W/VE stations are almost unbelievable. You can really see how important the antenna’s height above ground is.
Peťo OK1FCJ, who was vacationing in the Tatras, and Juro OM8ACE also stopped by to visit us briefly. Peťo even made a few contacts on 80m, for which he deserves our heartfelt thanks. He did very well.
On Sunday evening, we connected a small PA to the 160-meter band. Once again, we had to remove the cover, tinker a bit inside, and the power was flowing again. After a while, however, it stops working, so we move the coaxial cable from the 160-meter antenna to the second operating station.
During the contest, a trio of non-ham radio operators led by Cyro Zvolen took care of keeping our stomachs full and our spirits high. No wonder we achieved such an excellent result! MNI TNX, guys!
A final look at the monitor:
| Band | Connections | Points | WPX |
| 1.8 MHz | 114 | 225 | 28 |
| 3.5 MHz | 770 | 1,761 | 323 |
| 7.0 MHz | 641 | 1,623 | 200 |
| 14 MHz | 616 | 1,068 | 212 |
| 21 MHz | 220 | 602 | 93 |
| 28 MHz | 25 | 73 | 3 |
| TOTAL | 2,386 | 5,352 | 859 |
| RESULT | 4,597,368 |
The OMA Team—back row, from left: Igor OM6CI, Števo OM7KW, Vilo OM0AAO. Seated, from left: Oliver MW0JRX, Peťo OM6PR, Dano OM4AQP, and Rado
In numbers: 61% more contacts than last year and 125% more points! After the contest ended, we raised a toast to that—why not, HI.
On Monday, after breakfast, we took down our stations and antennas. The team has now gone their separate ways to various parts of Slovakia, only to reunite for the next event. We thank all stations for the contacts and the encouraging words!
