This morning there were no cutbacks on the overnight transmitter log, so it looks like our adjustments to arc gaps are proceeding in the right direction. Will increase the audio input by 0.1dBu to 8.0dBu for tonight’s transmissions and see what happens.

Today I provided information to Joe Barker for ordering red sidelight glasses to replenish stock after Lionel used the last one to replace the one on top of Tower 3 that was destroyed by lightning. I also provided a list of other spare parts (and prices) that might be needed.

Wrote an email to TWR Swaziland about the possibility of using thermal imaging, infrared scanners or infrared thermometers in transmitters to detect ‘hot spots’ that might indicate an imminent failure. This might also be a way to avoid unnecessary disassembling for routine inspection, especially when disassembling has risks of causing other unrelated problems!

After a lunch of tuna sandwich and papaya fruit, Virginia accompanied me to the transmitter site for the afternoon. My primary task for the afternoon was to move the repaired PA Module into its ‘proper’ slot and return the original spare to stock. What should have been an easy task uncovered several unanticipated tasks.

Actually my first priority was to reset all the control/monitoring equipment. Last night we lost remote access to the transmitter. Fortunately there were no transmitter problems. Resetting or repowering of four units restored remote control. [I do this at home when my wireless modem gives me problems! The principle must be the same 🙂 ]

The first unanticipated task was repairing the cover over the wiring that carries control signals to the eight left-side PA modules. There are two guide pins on the bottom edge of this cover that slip into holes to keep the bottom in position, while the top is attached with lever type fasteners. One of the guide pins fell off into one of the bottom holes. The bottom channel, with the holes, had to be removed to find the guide pin. After retrieving the guide pin, I tightened the hardware that holds both guide pins. The identical cover over the eight right-side PA modules’ control wiring also had both guide pins near to falling off, so tightened those, too.

While swapping around PA Modules, I found that the face plate on one of the PA Modules was very loose. Of course to fix it, this module had to be removed from the transmitter and the side panels of the module had to be removed to get to the loose hardware to tighten it.

After the face plate was tightened and upon putting the module back into the transmitter, I noticed that the bottom retaining screw did not want to thread in. (I had noticed something was not exactly right when removing this module earlier.) Upon closer inspection, I noticed that the front flange under the module was bent, and not at the correct angle to line up the screw and threaded insert. Using a Crescent wrench, and several layers of paper to protect the finish, I was able to remove the bend. I again installed this module into its slot only to find the retaining screw still did not line up properly. Further inspection showed the side rails were also bent causing the PA module to be shifted slightly to one side. The Crescent wrench ‘fix’ was applied again and everything lined up nicely.

Now that all the PA modules were situated in their correct places, the transmitter was powered up to 100kw and all modules performed properly. I prefer to do a test like this rather than finding out at the last minute that something is wrong and losing valuable air time!

With this out of the way, Joe Barker, who was in town, wanted to test another method of carrier control for the transmitter. This method is called Amplitude Modulation Companding (AMC), which actually reduces the carrier level with modulation. It saves a lot of power and research has revealed that listeners could not detect the difference when compared to normal broadcasting. At O% modulation, the carrier level is 100% and, at 100% modulation, the carrier power level is 50%. At 50% modulation, the carrier power level is 75% and, at 125% modulation, the carrier power level is ~41%. There are other advantages to AMC besides power savings. The peak voltages on the RF system from the transmitter to the antenna are reduced. Also, if engines are used for power, whether continuously or for standby, the power requirement does not vary dramatically with modulation. This is a tremendous advantage over Dynamic Carrier Control which most engines can not tolerate. There is also less variation in power input required from 0% to 100% modulation with AMC when compared to standard modulation.

Joe controlled setting up the test from town and I was able to watch what he was doing on the computer monitor at the site. It’s kind of eerie watching the cursor moving around on the computer monitor and making selections without my touching anything! The test seemed to work well. When Joe switched off AMC, he inhibited the RF to make the switch. For some reason, this switch needs to be done only when the transmitter in ‘off’ mode. Not doing so, caused a lot of unexplainable faults of the transmitter that could not be cleared from the control panel or computer using normal procedures. The only remedy was to turn off all power to the transmitter to reset everything back to normal. [I have often done this to my computer as a last resort to get it working!] Joe showed me how this could be done remotely by a feature that has been added to the remote controls. A relay purposely causes the 3 phase detector protection device to temporarily send a ‘missing phase’ fault to the transmitter thus ‘shutting down’ power. This same relay can also be used to ‘restore’ the power.

Everything was set back to normal AM modulation for tonight’s broadcasts. Tomorrow Joe plans to walk me through the setup procedure to implement AMC for regular broadcasting. From what I have learned, the audio input level has to be set up for proper AMC, then fixed to remain at that level, otherwise gross over-modulation might occur. This will be a new learning experience for me.

We got ready for our swim this evening only to find that there was a big party going on at Flamingo beach, so we missed our swim for tonight. We could have gone to another beach, but by the time we would gotten there, it would have been too dark.

For supper, Virginia surprised me with one of the Indian Mystery Steaks that was mentioned in her 22 Oct 2010 Friday blog entry. We had green beans and rice with it. It was all very good and the ‘mystery’ is solved!

There was a couple of transmitter cutbacks early this morning. I reduced the audio input by 0.1dBu to 7.9dBU. Will be doing some arc gap adjustments this afternoon at the transmitter site.

Upon arrival at the site, I found Benny cleaning about 6 layers of paint off of the ball gap for Ant 4. I had him set the gap to about 0.560″ (about 1/8″ wider than it was). This is the only ball gap that has shown recent signs of arcing and is suspect in causing the VSWR trips when on the south pattern.

I resumed the search for the PA Module test cables. I had called Rich West earlier this morning and he was not aware that there were any, nor where they might be found. When Benny returned to the building, he thought of a couple more places to look without success.

With confidence that everything had checked out properly, I decided to check the repaired module (Ser# H154) using full voltage in the transmitter. The module in position 6 (Ser# H145) was removed to make room for testing the repaired one.

The transmitter was ran at 25kw and the repaired module looked OK. Verification of the repaired module’s performance as done by inhibiting it to see how much the output power dropped. This was then compared to the drop from a couple of ‘good’ modules. The drop was the same, indicating the repaired module was operating properly.

This test was repeated at full power (100kw) with the same results. I then momentarily increased the power to 120 kw without modulation and it continued to preform well. Power was reduced back to the 100 kw in preparation for the evening broadcast.

Tomorrow I plan to return all PA Modules to their original positions.

After taking safety precautions, I went out to Tower 3 to check the gaps and reduced the ball gap to 30mm (1.18″) compared to the 1.75″ that it was before. It is still a little wider than it should be, but did not want to go too far at one time.

I then checked the arc gap inside (antenna tuning unit) ATU 3 more closely than on Friday. There has been a lot of arcing here with melted brass on the grounded ‘point’ (possibly partly caused by the lightning strike that broke the red sidelight glass on top of the tower). I filed off some sharp edges and ‘cleaned’ the arc gap, then increased it to 1.375″ (an increase of 1/8″). I am fairly convinced that this is cause of VSWR trips on the non-directional antenna pattern (NDA).

After completing these adjustments, I tested the transmitter at full power to verify everything was in order for the evening’s transmissions.

I have noticed that often we hear squealing brakes in front of or near our house. The other day I discovered that people drive really fast up the road and then when they get to the drempel, they slam on their brakes! The drempels are well marked, but for some reason, if you drive fast enough, I guess the sign disappears.

Today we had three rain storms come through. The first one was this morning shortly around 8:30, while I my clothes were in the washing machine. It was a short lived storm, and I hung my clothes outside. Around 10:30, I decided to bring in the dry clothes. I had not had them in long before the second rain came through. It was a little longer than the first one. The third rain came through just before our evening swim. The sea was a little rougher than usual (the waves where we swam this evening were huge — 18 inches at most!) probably because of the storms in the area.

I took some unique pictures today. I took a picture of the sign of probably the only Donkey Safari Park in the world! Evidently, the wild donkeys were becoming a nuisance, causing accidents and getting into people’s yards, etc.. The ancestors to these donkeys were used in the salt fields long ago, and when equipment took their place, they were left to fend for themselves and, of course, multiplied. Someone decided that the donkeys should be protected, so started the Donkey Refuge. Unfortunately, the donkeys on the outside of the refuge are fairing much better. The refuge is struggling to feed the donkeys and the ones that are still free are fat and healthy.

NOTE — To see a bigger (and in some cases, expanded) version of any of the images in this blog, just click on the one you want to see.

Finally another night with no transmitter cutback in power!

See Virginia’s blog entry for today about out adventures. One thing she did not mention was the row of wind turbines just north of the Indian inscriptions. I have heard various stories. One by a tour guide that they are supplying 70% of Bonaire’s power needs. The other was by an engineer who says they are still awaiting the equipment to tie them into the power grid. Since no power lines were seen near the area, I tend to believe the engineer.

At 5pm this evening the transmitter ‘called’ and indicated there was a problem. By accessing the transmitter site using the internet, it was discovered that the transmitter site had no power. The monitoring/control equipment is on an uninterruptible power supply, so we can still have remote access. This is fortunate, because we havd to turn the transmitter on remotely when the power came back on. Of course, we could have traveled to the site to turn it on, but that was not necessary!

NOTE — To see a bigger (and in some cases, expanded) version of any of the images in this blog, just click on the one you want to see.

Sunday we again worshiped with the small group of believers at the International Bible Church. It is truly an international church. They come from Holland, U.S.A., various countries in South America and Bonaire. We were a little late this Sunday, because we had locked our keys in the car the night before and had to wait for the spare set to be delivered. As a result, there were very few seats left. Hopefully, I will be able to get a picture of the congregation one of these days. The Pastor continued the study in Revelation 2 on the Pergamus church. In Sunday School, (yes, they do still call it that in some places) we are beginning a survey of Paul’s writings. We watched a video on the end of Acts and then had a discussion.

After lunch and naps, we decided to try going to the other side of the island again. Larry found a somewhat better route to the area, but

we did not make it to the lighthouse this time. We saw some desolate looking spots, the desolation reinforced by the donkey skull, dried and bleached by the sun and the towering cacti.

We also saw some of the paintings. These depict the stars and were their compass. We also saw a hole in a roof of a cave that is traditionally connected with the Star of Bethlehem. It is usually covered to keep the goats from falling through, but opened at Christmas to let the star shine through the opening. Hopefully you will be able to read the story on the picture of the sign (if you click on it to enlarge it).

I thought the cacti growing on this big rock were so pretty. It must really be nice when they bloom.

I also took a picture of a fence that has the flags of many countries painted on it. I don’t know what the place is, but thought the fence was interesting.

Of course, there are the cacti fences. They are very effective!

This tree is one that we learned about on the tour we went on

when we first arrived. It is known as the ‘Tourist Tree’. If you look closely, you will probably be able to observe that it is red and peeling.

We also took a picture of some of the blue rocks like the ones we followed

Saturday. We have now found out that the blue rocks mark the route of the first ever Bonaire Xtreme Duo mountain bike race — a 75 km (47 mile) bicycle race — held this morning! Wonder how many tires needed repair? The route on Saturday was not nearly this nice!

NOTE — To see a bigger (and in some cases, expanded) version of any of the images in this blog, just click on the one you want to see.