Archive
Transmitter Site Perks
Engineers have some perks in their lives. One of those is transmitter site visits. Not all visits are fun. Most are routine. Some are simple repairs.
Today I arrived at a site, and pulled up to the gate. Opened the truck door when a friend came by.
This made my day. Hope yours is going well!
When Old and New Don’t Mix
A few months back the decision was made to “rush” a MaxxCasting system. The company teamed up with GEO Broadcasting and GatesAir to have this system installed. Currently in analog mode it works fairly well. When the baseball season finally ends, we become the test for doing HD as well. Check it out, it is interesting. The part I have issues is making the old, a 2006 Harris (GatesAir) HTHD+, and the new, a Flexiva FAX50 exciter, play nice.
I knew I would have issues from day one with this installation. Having no involvement other than being told what needs to be done, providing input was limited. At the onset I informed everyone on this project by interjecting a simple question: Will there be any issues utilizing our old HTHD+ transmitter for this? An early 2006 edition of the HTHD+ transmitter as we were “forced” into the early adoption of HD radio, this transmitter installation was a rush job from the get go. As an amplifier I have never had any issues with the transmitter, but I have had issues with exciters. We had 3 different Flexstar exciters in this thing, yet I have only replaced the tube 4 times. Anyways, the answer to the question was basically, yes, don’t worry about it.
Without being involved other than do as you are told routine, the day came to install the FAX50 as an exciter. Without a full rundown of the Geo-synchronization of the whole system, let it be known the Flexstar was not capable, thus the swap. I has the exciter out. I had the filler plate. I had cable adapter kit. Whoa, hold on. The kit labeled for a Z series transmitter? I told everyone this was an HTHD+. Hmmmm? Let’s proceed with getting the new exciter installed in the transmitter. After the first indicator of an issue (the cable), the second indicator of more fun to come was the fact that the exciter did NOT go into the transmitter! I was told otherwise, and I was provided with no instructions. Phone call time. Sure enough, the interface kit was wrong, and no, the FAX does not fit inside the transmitter, but must be externally mounted. New interface cable kit and instructions were on their way.
The new cable kit arrived with the new instructions. Now things began to make sense. I cleared out rack space and place the exciter in a location that was just accessible to comfortably been seen, i.e. not at the top of the rack, but at least a quarter way down. That was the maximum length of the new cables. Installation complete. Testing into the station load I got to learn how to setup the exciter as it did not come setup for our station. It was setup on the wrong frequency and as a transmitter, full 50 watts, not as an exciter of which we run about 4 watts. Details of this for another time. Rest assured it was not too bad and I had the transmitter back on the air soon enough.
Mixing the old and new. As we all know, the HD E2X, or Exporter to Exgine, stream will have packet drops on occasion or some other ISP induced oddity. In the case of anything somewhat prolonged or unusual, the exciters are designed to shut the HD off, suppress the carriers, and the station goes analog only for that brief time. When the E2X stream returns, the exciter detects it and HD carriers return. All good. Well, the FAX series exciters are some fancy boxes and are designed as stand alone transmitter. These range in power from the 50 watts to high power. As such when the E2X is gone, FAX is designed to drop power level and normalize to analog operation. When the E2X stream returns, the FAX adjusts, the power level changes to accommodate the HD carriers. All good when in an all inclusive box, when driving an external transmitter it causes some serous output power swings, and at times even a brief no power out. Our transmitter is licensed for 18kW TPO. I have witnessed this drop to zero and shoot to about 20kW all within a few seconds. I had four occurrences just this morning of lower power alarms followed by high power alarms. The APC and drive level required drops suddenly during this incidences that the transmitter PA cannot handle it. I wonder what stress this will place on my recently replaced tube?
GatesAir is aware of this and is considering options. I have suggested to the company they may wish to just upgrade the transmitter. We will see. I think the lesson that reinforces my philosophy is not to attempt a new project which mixes technology without considering all the pieces, and be prepared to invest in replacing the old even if it is going to cost you. Consistency is key to a smoothly running plant.
Cheers!
All Is Well with Nautel NV20’s
Without getting into the details of version information as that is proprietary with Nautel, I will say we discovered a little issue with the controller on the NV20’s. Needless to say the issue did not cause much of an problem as more of an annoyance. It was a controller reset with no explanation. Random with no warning this reset would occur. I can say now that we worked this out as Nautel works on the next major release of NV software.
It is quite interesting to work through these issues and provide the information necessary to catch it and fix it. I feel good that we got it as quickly as we did. Tech support on Nautel’s side was awesome. If you find your NV series transmitter randomly dropping you off the air for 2 seconds and cannot find the explanation you better give Nautel a call. The fix is there. Get it.
I did drive our friends nuts as I was able to corrupt the AUI software on the transmitter itself. The fix was to ship me a new compact flash card with the “good” files in tact. Did the NV20 operate in this “mode”? You betcha. We had full remote control through the our remote control and we had full control via IP. If you are worried about such things as this with software based systems, you should be relieved to know that the important information is contained on the controller and does not fully rely on the computer running the AUI .
Great job Nautel. I look forward to the next major release so I can break that!
PS- Look forward to a Field Report coming to a trade near you.
Nautel V1-D 12vDC Issue
So the transmitter in question this week was the V1-D by Nautel. The thing has been running great since the installation last month. This week, Monday, we time aligned the digital and analog, then matched the simulcasting station. A day later, the Nautel falls back on power and shows a 12v fault. Hmmmmm?
So we head to the site and check things out. We cannot get it to fail, so we let it be. We get back to the station it starts showing 12v faults again and then a foldback of power. I switch it to the backup and head up the next day.
I talk things over with tech support and we tear into the box. We measure the test points. We check connections. We drop the fans and look under and deeper in. We find nothing out of the ordinary. Next we put it all together and light it up in the dummy load. That surely will heat the room up and cause a fault if it is heat sensitive. One hour and no problem. I have to get back, so we button it up and put the box on the air. IT’S BEEN RUNNING FINE EVER SINCE!
I sent the logs to tech support. This morning I follow up and leave an email stating that things are running just fine now. I get a response that some customers have had the wiring on the fans chafe and begin to exhibit these same symptoms. Short wires from the controller board to the fans. I noticed ours was somewhat tight, so next time up for maintenance I will check on that. For now, it works great and I will not touch a box that is not having any issues.
If anyone has an issue with customer support at Nautel, I sure have not had one. They are really nice and as responsive, or more, than some others I know.
NV20 Preliminary Installation
On 12/30, I finished the preliminary installation of 2 NV20s from Nautel. I plumbed the RF line into the switches and the electrician wired up the panels. One disconnect had to be upgraded to accommodate one of the new transmitters.
I successfully turned both on within 4 hours of each other without modulation. Both came up as expected and it is quite amazing what can be monitored and controlled via the front touch screen. As our IT guy said, we have two 20kW Linux computers!
Next is to finish the air chain and wire the audio into the systems. Nautel has a planned software upgrade for our boxes. This is to be expected as we have the first production runs installed in the real world. I am quite interested to see how they perform.
Tech Notes from the Field 