Martin Ahnert
P.O.Box 777
Moshi
Tanzania
Radio: 5H2MA
( +255 754 26 99 44
Travel report Iringa Radio Furaha
Giraff passing Mikumi National park
Newsroom Radio Furaha
Live Studio Radio Furaha
Discussion studio
Three band compressor/encoder and STL transmitter
Testing STL trouble
Transmitter up the mountain
Testing Antenna trouble
Testing direct MPX signal
shared transmitter mast with another 3 stations
We took off Moshi on Wednesday 13th of October in the morning. We arrived in Morogoro around 18:30 and got accomodation in the language school in Morogoro. The next morning we tried to see the TTCL service office to request a DSL-Line for our transmitter. But the office was closed because of a publich holliday.
We arrived in Iringa around 17:00 because of many stops of roadwork. We wanted to get accomodation in the Babtist Centre. This was not possible because it was changed in into a secondary school. The Lutheran Guest House was also booked out. We are thankful there was already a room booked within the diocese compound for us!
I attended the morning devotion the next moring and a special guest was greeted: The Ev. Lutheran Bishop from Leipzig- Germany. I got the chance to be showed around everywhere with her. Her Mission department had sent a senjor expert helping Radio Furaha to be set up better. Unfortunately he left suddenly, and we asked the German deligation to contact him and send us the Computer Windows Administration passwords to set up a studio computer network.
On Saturday I go the chance to visit the transmitter site up the mountain. Radio Furaha shares a transmitter mast and shelter with 3 more Radio stations. On the same mountain are another 5 radio stations.
On Sunday moring we had an emergency: The transmitter was no longer on air. We went up again but could not see why the station was not working. It went back on air without problems after resetting everything.
On Sunday afternoon we had off and we visited the "Yellow stone Park" close to Iringa,
On Monday I followed again the posibility networking all computers of Radio Furaha. But ge got stuck on the lackinf Administrator passworts. However the TTCL DSL connection is working excellent enabling Radio Furaha downloading programmes from the Lutheran Radio Centre. I am following up this issue with Leipzig in Germany.
The next problem we faced is that that the STL is not passing a Multi PleX signal:
Listening to the radio to many other radio stations in Iringa give a broad stereo image. Not so Radio Furaha!
Everything seems to be connected correctly. Just the second channel at the STL Receiver does not have any output! Of courde, you can screw up the volume with its output potentiometer, but it is just crosstalk on a very low level.
Then we tried to connect the MPX signal straight to the transmitter, switching the transmitter to MPX-signal input by groundin pin 14 of the 25 pin Remote I/O Connetor as shown in the manual. The transmitter sounds fine, but still no two channel transmission!
So we checked the signal at the STL transmitter. Connecting the two AF channels to the STL transmitter straight shows, that only one input channel is working!!
No Problem- because we connect the MPX signal straight to the correct MPX input! But still no stereo two channelat the transmitter!!
What should we do? I tried to analyse the transmitted signal of the STL transmitter with the comptressor/encoder connected. No pilot carrier or differential stereo signal could be found around +38kHz of the carrier frequency! Just putting the 19kHz pilot to its maximum, I could find a light carrier on +19kHz. Maybe my test method is not working correctly, because even the 19kHz pilot and the AM stereo differential signal on 38k with suppressed carrier is FM modulated on the carrier. But everything seems as if the STL has a Low Pass Filter and is not passing a MPX signal!
Would it be possible this STL is actually a mono unit? Actually we do no need a stereo STL because we have the Processor/encoder infront of it and we can feed the MPX signal to the transmitter straight, which is sounding much better than adding the second signal compression in the transmitter!
I try to follow up this problem with the engineers of HCJB.
Another Problem is that the transmitter runs just on 100 instead of 300 Watts. We checked the Transmitter and Filter. The problem is the Return Power from the other stations on the same antenna mast! I have to follow up this problem with the engineers of HCJB.
I advised Radio Furaha to aquire its own Plot and put its antenna on an own antenna mast to avoid this problem. In Addition they are saving a lot of money renting someons elses shelter and antenna mast.
Afer the morning devotion and a short talk with Bishop Degella we returned to Morogoro on Tuesday. We arrived around 17:00. I could talk to the service office of the TTCL an got an DSL request form.
I left this form with the pastor of the Lutheran Church close to Morogoro Diocese. He promised me to give it to the General secretary as soon as he is back in office.
From Morogoro we went on to Dar Es Salaam. At Thurseday morning I met the cheef engineer of the TBC: Actually he had just one question: Is the Lutheran Radio Centre just asking for a satellite audio channel, or is it requesting to rebroadcast its program in other towns as well?" I told him the Lutheran Radio Centre is just requesting a satellite audio channel right now. There are own booster stations to be connected in the first run. The request rebroadcasting its programmes on other locations may come later.
I asked him about the poor reception of the TBC satellite channel these days. He told me the satellite company Intelsat told them to reduce their power. But they are using 3.5m dishes at their transmitter sites, and they are not getting any problem! So we, in the Lutheran Radio Centre should also use our big 3.5m dish to rebroadcast their news!
On Friday morning we set of ant arrived in Moshi around 20:00 in the evening.
Martin