Monday 29 August 2022
Today’s forecast was to almost reach 90F, so no jacket required when I left this morning.
I finally had time to identify the unknown inductors for Selema to put into stock and also reiterated the convenience of having a HC100 part number (or family tree identification) linked to each part description. The location of a part number or family tree ID can make it so much easier to locate where a part is used in the transmitter (sometimes multiple places) or to find a part in stock when it is needed in the transmitter. There is a detailed bill of materials list that links all items and where they are in the family tree. In addition all the individual drawings have links to the assembly drawing where that part is used. When there are thousands of parts in a transmitter there needs to be a way to trace this information.
Tobi wanted to verify the nulls in the medium-wave AM antenna pattern. These nulls in the pattern toward the Indian Ocean help strengthen the signal in the opposite direction towards where listeners actually live. The previous measurements were done along the Panata Ranch road, but that road now has at least four remotely controlled gates that need to be opened (via cell phone) each time we pass through. I suggested using the new airport road a little further away to do the measurements.
We got out the new field strength meter on loan from the TWR West Africa station to learn how to operate it. It is a Potomac 4100 with built in GPS location capability and memory to store information for each reading taken including location coordinates, date and time, field strength in mV/m or Dbu, elevation, distance from antenna center, azimuth from antenna center and even the temperature. This meter is digitally tuned to the frequency and self calibrates.
We also we got out the 40 year old Potomac FIM-41 which only has an analogue meter for a read out and must be tuned and calibrated for each use. Each reading must be written down and each location accurately documented so it can be found for future measurements. At the end of our work day, we loaded both meters into the site vehicle for use in the morning.
Tuesday 30 August 2022
Today’s forecast is for about 30F cooler than yesterday. Definitely took and wore my jacket today.
When we turned onto the frontage road for accessing the freeway, there was a whole lot of traffic on the frontage road. First thing that popped into my mind was that there had been a big pileup going into town. When we got to the overpass to cross over the freeway, there were solders stationed on each end. When we got to the freeway ramp we were directed by police and soldiers to continue on the frontage road. The same thing happened at each access ramp that we approached. We saw a few lone vehicles travelling on the freeway. At one point, Tobi stopped the SUV and got out to see what was happening. I got out and climbed the ridge separating the frontage road we were on from the freeway. Cresting the ridge, I saw a convoy of about 40 vehicles bunched together traveling at a high rate of speed. There was also a helicopter flying of to the side. That confirmed my suspicion that there was some dignitary(ies) arriving from the airport. [Later we were told that King Mswati II had arrived back from a trip to Malaysia]. At the next ramp, we were allowed onto the freeway and quickly got to our destination, which was almost six kilometers north of the traffic circle for the airport.
We began taking field strength reading at that point and every ~500 meters for just over 20 kilometers. Tobi used the new meter and I used the old meter for comparison. After that we took readings at greater intervals, because we were outside the region of the two nulls.
Back on the Mafutseni road, we noticed lots of huge tents set up at Mpisi Farm (government run). Tobi mentioned it was for sheltering all the girls getting reeds from the White Ubulizi river for the Reed Dance Celebration coming up this weekend. I tried to get a photo as we went past.
We spent most of the afternoon analyzing all the data that was taken and in the evening I used my laptop at home to make a polar plot of our readings.