I knew that this might not to be the restful Saturday we had planned when my cell phone woke us just before 7:30 this morning.  Klaus was already at the transmitter site trying to sort out multiple problems that were keeping TX2 from  going on the air.  He wanted me to come out to help.  About 10 minutes later and just before I left, he called to say the transmitter was on the air and that we should plan on going out at 2pm this afternoon for further investigation as to what was happening.

We harvested a few more nartjies (mandarins) this morning, but the rest still have some green on them.  These will wait until next week.  Virginia picked a few lemons that are turning yellow.  I watered three small trees, which have been planted fairly recently.  They are less than three feet tall and at least two are citrus trees.  The bunch of bananas that we cut down on Wednesday has ripened only a little bit.  As we have finished up the previous bunch, we hope these are ready in a couple more days.

Klaus and I left for the transmitter site about 2:30.  TX2 came up with no problem for testing, but the metering for RF Exciter Q3&Q4 currents was still showing the drifting up and down like last night.  We investigated further and once again found these currents were actually steady.  All the other metering points on the same card were steady and we could find no other similar anomalies.  I examined the log of faults that occurred this morning and noted that door interlock faults seemed to be the fault most frequently shutting the transmitter down.  Klaus had temporarily bypassed the door interlock this morning to get the transmitter back on the air.

TX2 came up fine at 4pm for its first short Urdu transmission of the evening and was performing well, yet the ‘drifting’ remained.  We continued to ‘scratch our heads’ as to what was happening.  The transmitter was then off for about 30 minutes before the next longer transmission.  So we looked at the computer screen with all the metering information to see if other readings showed a similar drifting.  Only one was found, but it was drifting over a much smaller range and in the opposite direction of the drifting of Q3&Q4 currents.  This one was the RF Exciter +24 volt supply voltage.

Fortunately we decided to stay for TX2 to start the second transmission.  Every time the high voltage vacuum contactor switched on, the door interlock light flashed and one or more of the optical arc detector lights came on.  These were the same symptoms that the transmitter had this morning.  We noted that +24 volts supplies the interlock string.  Klaus quickly bypassed the door interlock like he did this morning, but the problem persisted.  The arc detector supplies are +15 volt.

Klaus decided to measure the voltage on the RF exciter supply when the contactor switched on and noticed a significant momentary drop in voltage.  I suggested paralleling an additional capacitor across the one in the supply, so Klaus quickly found a 230 uf capacitor that he pressed against the terminals of the one that was already there.  The transmitter switched on!  Now we had another problem — could Klaus hold the capacitor like that for at least another 20 minutes!  I managed to find some clip leads and we were able to replace Klaus by some strategic connecting of the clip leads.

We discovered that the capacitor that was bad was 10,000 uf and the one paralleling it was only 230 uf, so we searched for a bigger one in the stockroom.  The largest one that could be found was 5,000 uf, but we figured if 230 uf could help get the transmitter on the air that the larger one would work until a replacement could be ordered.  Using clip leads, we connected the 5,ooo uf capacitor which promptly tripped the transmitter off, but we turned it back on immediately.  We should have put a resistor in series with the capacitor to charge it up before connecting it.  Not doing so, the voltage dropped momentarily when the capacitor initially charged.  Maybe next time we’ll remember!

We finally left the site at about 5:30pm with confidence that the problems had been solved, but I am still ‘scratching my head’ trying to figure out why the Q3&Q4 metering currents were drifting, while their actual currents were steady.  Also, why were the optical arc detectors also triggering on, as they were on a 15 volt supply?  These mysteries will have to wait until Monday, when the schematics can be reviewed some more.

This evening we were able to watch Samuel and Henri playing on the beach via Skype and Angelique’s smart phone.  They were at South Haven, Michigan for the day.  Oh, the wonders of today’s technology!  Later we got to talk to, and see, Allan and their children.  We learned that Audrey’s Upward Soccer team was undefeated this year.  Allan, Joyce and Mark were her team’s coaches.