Cell carriers generally do not like working on AM towers. It is out of their comfort zone and adds a layer of complexity to the project. However, sometimes they don’t have a choice, mainly when there is an existing site and they need to make changes. We have also had mixed results with tower contractors employed by various cell carriers. In one incident, a contractor showed up and re-tensioned the guy wires breaking all of the porcelain insulators. Another time, a contractor showed up to install footings 10 feet away from the tower and ripped up all the ground wires. One tower climber found one of the skirt wires was in his way, so he cut it off with a hack saw.
Those experiences demonstrate that it is far less expensive to have somebody on site while tower contractors are doing installation work on any skirted AM tower. And so it was today.
AT&T 5G sector assembled waiting for lift
This tower has two AM stations diplexed as well as two FM translators combined into one Nicomm antenna. We did before measurements on the AM stations using an OIB-3. Once the installation is done, we will do the after-measurements and then assist the licensee with any FCC 302 filings if the base impedance has changed significantly.
WENU, WMML W250CC and W245DA towerLifting the North Sector
With each lift, I went out to the base of the tower and made sure that the skirt wires were clear of the mounting brackets and not touching anything else. The tower crew was Russian speakers. When they asked if the transmitter was still on, which was kind of comical (he motioned to the skirt wire, made like he was grabbing it, then jerked around like he was being electrocuted). I had to wrack my brain to try and remember: Передатчик выключен. The literal translation is “Not working.” The difference between “working” and “not working” is one consonant at the beginning of the second word which is pronounced soft for off and hard for on.
I am watching, with great interest, the hand-wringing over the removal of AM radio from various vehicles. Not that I desire that to happen, but on the current trajectory, it is almost certain that AM and then FM radio will become optional if not removed completely from dashboard entertainment systems.
The ubiquitous AM radio
What can be done… what can be done…
Interestingly, several have pointed to a few successful AM stations that are still making a go of it. WABC in New York is one such station. What is the difference between WABC and other stations? Local content, perhaps? Yes, WABC is a 50 KW clear channel (Class A) station. While that does help somewhat mitigate the electrical noise problem, in and of itself, being a 50 KW station does not automatically mean success. There are other 50 KW stations in the New York Market, they are not doing that well.
I would posit; what troubles AM radio and all of radio in general, is low-effort, low-quality programming, and a general lack of community engagement. The vast majority of AM stations are running some type of syndicated programming. That is not a huge issue provided there is local content mixed in, a local morning show for example. If everything is syndicated then what is compelling listeners to tune in? If I can get better information or more entertainment by listening to a podcast on Spotify or Substack, why would I listen to the radio at all? This is a growing problem for FM as well. All of the generic “Greatest mix of the 70s, 80s, and 90s” formats are dull and boring.
One reason for all the dullness is that shy corporate lawyers to are risk-averse and do not want to be sued for profanity. Remember the Janet Jackson Superbowl incident where CBS was fined $550,000 for briefly, very very briefly showing a nipple on TV? If you were blinking at the time, you would have missed it. I missed it. I am a first amendment guy, I have two words regarding the FCC obscenity rules; fuck that. The FCC should get rid of all the outdated and patronizing profanity regulations. They stifle free thought and they are not protecting anyone from anything. I have two children and they would come home from kindergarten swearing like drunken sailors. This is why podcasts are popular; hosts are allowed to roam freely express themselves, and explore controversial topics. You may not like what you hear, in fact, you may even be offended. However, there are no constitutional protections against being offended. All radios are equipped with tuning buttons and off buttons.
AM also suffers from a perception problem. When a station does show moderate success, it is still very difficult to sell advertising because the potential advertisers believe that no one listens to AM radio anymore. This is more a self-inflicted wound than anything else. For years, AM spots were bonused with an FM buy. If radio owner’s themselves don’t value their product, how can you expect advertisers to value it? Besides, I know lots of people listen to AM radio for one reason or another.
There are some technical aspects to this conversation as well. First and foremost, the AM noise problem is the biggest technical challenge for AM listeners. The use of FM translators to retransmit AM signals is more of a gimmick than some type of solution. Especially when the maximum power for a translator is 250 watts (many are licensed at much lower power levels). While the AM signals they are associated with are 1,000 watts, 5,000 watts, 10,000 watts, or even 50,000 watts. A translator can be significant in the case of an AM daytimer (class D station) after-sign-off. Otherwise, they do not offer too much else for the typical AM stations. Most other “technical improvement” initiatives from the AM revitalization era were more aligned with cost savings for owners rather than actual technical improvement.
One of the great advantages of AM radio is it can cover large distances with moderate amounts of power. Transmitters and receivers are relatively simple devices that can function without an internet connection. As I learned from my contacts in Ukraine, broadcast radio is often the communication line of last resort when the grid is down. FEMA has spent a good deal of money hardening AM radio facilities across the US to ensure that they will remain operational during a crisis.
FEMA PEP station map, 2015
Regarding the alleged sound quality issues; I notice the AM radio in my Subaru sounds pretty good even when listening to music. What is interesting to me, when I first land on an AM station, it sounds pretty narrow-banded audio-wise. After a few seconds, it opens up and I get much better-sounding audio. I am not sure if this is just some random radio software function or if the IF adjusts itself for wider audio when the signal strength is good. In either case, the AM radio in my car sounds much better than the previous cars I have owned.
It would be very interesting, at least for me, to see a head-to-head test of HD Radio MA-3 vs DRM30 vs Analog AM vs a 250-watt FM translator. More research and testing of all digital audio transmission on Medium Wave frequencies should be done.
In short, saving AM is going to be an uphill battle in both directions. It comes down to three basic things:
This lovely transmitter is 33 years old! I thought we’d celebrate by changing the electrolytic capacitors! It appears that some of the capacitors were changed in 2009, but many are original to the transmitter. Gates Air recommends replacing the electrolytic capacitors during the course of regular maintenance cycles. Dried-out capacitors can lead to a variety of mysterious fault conditions including low drive levels, poor audio quality, difficulty starting the transmitter, and so on. See Harris service bulletin AM-579-JK.
DX-50 transmitter
Some of the Low Voltage Power Supply capacitors were at least partly dried out. They felt a little bit light and one of them rattled when I shook it.
Replacing large PA capacitors
Gates Air has a full replacement kit, part number 973-2100-391. When I looked into it, the price of this kit is very reasonable and is closely aligned with the prices from Mouser Electronics.
Old capacitors for disposal
Here is a full list of capacitors needed, I put the Mouser part numbers in just in case:
Nomenclature
Amount
Gates Air PN
Mouser PN
Cap, 5,100 uf 350 V
17
524-0341-000
598-DCM512T350DG2A
Cap, 5,500 uf 200 V
4
524-0219-000
75-36D552F200DF2A
Cap, 15,000 uf 100 v
2
524-0322-000
594-MAL210119153E3
Cap, 76,000 uf 40 v
4
524-0342-000
75-36DX763G040DF2A
Cap, 120,000 uf 40 V*
2
524-0380-000
75-36DX124G040DJ2A
Large Capacitors for DX-50 transmitter
*See Harris service bulletin AM-474-TLH for information on the -8 volt power supply.
Board is green, Returned to service
Most of the capacitors in the PA section were original to the transmitter, as well as those in the 30-volt and 60-volt driver supply.
One important detail; pay attention when installing these things. You do not want to reverse the polarity on an electrolytic capacitor, it will likely explode. These units are pretty big and the explosion would be loud and messy.
With that done, I also went through the transmitter and reset all of the voltage levels according to the factory test data sheet. When it was returned to the air, it sounded great!
Call it climate change or an unfortunate coincidence; we seem to be getting more icy weather in this area. It used to be this region would see one mild event every one or two years. Recently, however, we are getting two to three moderate to severe events per year.
This can create problems for the utility company. Even if the power stays on, the transmitter may not. Excessive ice on the antenna may cause the transmitter to fold back or shut down completely.
We have several clients that have various FM antennas with electric resistance type de-icers. One client has three such stations however I found there were no automatic controllers at any of them. Back in the day, when there were people working at the station, they probably turned the de-icers on and off manually via the remote control. These days, not so much. When we began servicing these facilities, the previous engineer stated that he turned the de-icer breaker on around Thanksgiving and turned it off around Easter. Not terribly efficient.
As a part of moving into a new transmitter building, I began looking for something that would automatically turn the de-icer on when it is precipitating at or close to freezing temperatures and then turn it off after a couple of hours. That would certainly reduce the electric usage for that transmitter site and keep the transmitter happy.
I found this simple snow melt controller:
ETI LCD-8 snow melt controller
This is sold on Amazon for about $570.00. This has an internal relay that can switch 240 volts at 16 amps. However, that 240-volt heating circuit goes up to the top of the tower where the FM antenna is mounted making it vulnerable to lightning damage. I figured an outboard relay switched on and off by this controller was a better way to go. That way, there is an operating indicating lamp and a bypass switch.
De-icer controller relay
Outdoor icing sensor mounted on the ice bridge.
Now, the de-icer stays off most of the time. When it is needed, it comes on automatically and turns off three hours after the precipitation has stopped. Since installing last fall, it has worked well and the station stayed at full power through at least two ice events.
I measured the current on each leg, which was 2.6 amps or 624 watts. That is the same as it was before. A quick calculation, I estimate the number of hours this system was previously energized when the breaker was left on all winter to be roughly 3,400. Thus 3,400 hours x 624 watts = 2112 kWh. These days, our electric rates are running $0.16 to $0.18 per kWh so the total cost would be $380.00 to run continuously. The control system will pay for itself in less than two years.
