The rotator in the center of the VHF PA began to jam. At first, when given the command to turn, it changed the azimuth by a few degrees, and then it stopped rotating the antenna. Checking the cable and loosening the antenna in the rotator revealed nothing that could be causing the problem. Of course, all that tugging on the cables and the inability to aim the antenna didn’t help matters… After about 20 minutes, however, the rotator started turning again.
Fields around Černecký Hill
I had a visitor at Černecký Hill. Oliver OM0RX stopped by just as I was configuring the software for the VKVPA. I use N1MM+, PSTRotator, AirScout, and KST4Contest by DO5AMF.
OM0AAO’s VHF Setup
Setup: Kenwood TS-2000, HA8ET LNA with sequencer, OTRSP antenna switch, rotator controller with ERC interface to the PC, RSP1A SDR, USB hub, sound card
The core of the setup is the Kenwood TS-2000, which includes a G4HUP isolator and an INRAD #92 filter. I managed to get the filter after a long search. Since I’m not satisfied with the TS-2000’s sensitivity, I use a low-noise HA8ET preamplifier with a sequencer. Above it is an OTRSP antenna switch, which allows me to switch between multiple antennas from my PC. Inside the control box of the Yaesu G-650C rotator is a DF9GR ERC interface. At the very top of this tower is an RSP1A SDR clone, a USB hub, and a small sound card. After some issues with power supplies that were incompatible with the generator, I started using a modified HP power supply some time ago, which can be obtained from Poland.
The TS-2000 delivers just under 100W to the antennas. This time, I used the tried-and-true set of four DK7ZB Yagi antennas. The coaxial cable is LCF12-50J – 1/2" CELLFLEX®, 13 meters long. Here’s what it looks like in the car:
The DK7ZB yagi antennas fit perfectly in the car
The VHF PA is starting up
Compared to the situation a month ago, there’s almost no interference from nearby stations. I start by scanning the band and picking up a few locators. For example, JO80 from OL1B. After a while, I start calling at the upper end of the band. Mainly more distant stations like Michael DB7MM/P and Daniel DM1DF are responding. I’m listening on the speaker so that Oliver can hear the VHF traffic as well. It’s more challenging than listening with headphones, but it’s doable. The third German station is DO1CTL
Contest operation
The vacation season is also evident on the band. Relatively few Italian stations are connected to the KST chat, and even some of the usual participants from Croatia don’t seem to be on the band. After a long time, I also spotted Dany YO5LD in the chat. He was probably just testing something, because he didn’t respond. Activity from the southeast and south seemed weaker than usual to me.
In between calls, I try to look for possible multipliers in the chat as well. For example, Joska YO5AVN brought in KN17 and wrapped up the first hour with nearly fifty contacts.
The number of contacts per hour was affected by problems with the rotator
After the contact with Draho OM3CQF, the aforementioned problem with the rotator arises. For the next 13 minutes, no new contacts are made. I look for the problem, but it seems unsolvable. I decide to continue operating in that direction and manually rotate the antenna from time to time. Since I now have a fixed azimuth of approximately 220°, I try stations from the southeast. IK4GNG comes in, and then I try the rotator again. At first it’s reluctant, but then it starts turning!
I turn it further south, and the following stations come in one after another: 9A0V, E77P, 9A8A, 9A7KFF, 9A1O, 9A1CCS, 9A1AAY, I3FGX, S59K, and S56P. A perfect run. In the second hour, however, only 24 contacts were added.
I need to pick up the pace, so I try steering the antenna more toward the west and northwest again. DK4VW from JO40 comes in—a station I don’t usually work. Amid a string of OK stations, Dennis F6DCD/P from JN38 breaks through with a very strong signal—that’s 734 kilometers and an ODX. A moment later, another German station, DF2UQ and DF9ME/P, comes through.
A Yaesu G-650C rotator on a base with a joint. Note the use of plastic-head nuts and a washer made from an old truck tire. At the base is a string used to measure the identical distance between the anchor pegs
I’m trying to make as many contacts as possible, so I’m rotating the antenna. It pays off—I give Ivan OM5UM the number 100, and there’s still time left. At the end of VKVPA, Juro OM4AJK calls OM3KUK, and right at the very end, DH8BQA from JO73.
Map of locator squares in the VHF PA, July 2024
DXCC in the VHF PA, July 2024
In the end, there were 111 contacts across 29 locators, which, at 424 points per locator, totals 12,296 points. The average points per contact is 3.82. It was amazing that there was very little interference on the band. A huge difference compared to last month’s situation.
Thanks to Oliver OM0RX, I have a few photos that I wouldn’t have been able to get otherwise, as well as a pair of helping hands to pack up the setup. TNX!