Another liquid-cooled GatesAir transmitter installation was completed for WYPR, Baltimore, MD. This unit replaced a Continental 816 which had a long life.
The area around the transmitter site is not the best neighborhood. The building was formerly the WBAL-TV transmitter site and was built circa 1947.
WYPR transmitter siteOriginal four-legged Blaw Knox self-supporting tower from the WBAL-TV daysPump station and HTF tubingWall-mounted heat exchangerFLX-20 transmitter
The transmitter room is a little tight, so it was difficult to get a good shot of the front of the unit.
The station is running HD Radio with -10 dBc.
This site has a strange 3-phase delta AC power configuration. The middle leg is at ground potential, and the other legs all measure 240 VAC to ground. I’ve never encountered that before. This is known as a corner grounded Delta, which gets rid of the high leg associated with most closed 3-phase delta systems.
Ultimately, all the leg-to-leg measurements are 240 volts, so the power supplies are satisfied. With these transmitters, the phase rotation does not matter because there are no actual 3-phase loads in the transmitter.
Inventory control, Home Depot Reisterstown Road, Baltimore, MD
Recently, I installed this very nice GatesAir FAX60HD.
This project was for WPGC, Washington, DC. WPGC (Prince George’s County) is an Audacy station with a Hip-Hop and R&B format. I was listening to The Good Morning Show on my drive from the hotel to the transmitter site, and those guys were hilarious! It’s nice to hear a well-programmed radio station.
It is always fun to accept new and interesting challenges. This is, to date, the largest transmitter either AM or FM that I have ever installed. Previously, I installed several FLX-40 units, which is quite a bit of power for the FM side of things.
MSC unit with touch screen pad controls both transmitters and exciters
This transmitter combines two FAX30 transmitters and is controlled by an MSC unit. The content stream for HD comes from an FMXi4g, which has several great features.
BDI inline watt meter
This station’s TPO is 45.7 KW with the HD carriers at -14dBc. While this is a class B station with an ERP of 50 KW, the four-bay half wave-spaced antenna requires a lot of wattage to make that TPO. This is a largely residential neighborhood, which is, I surmise, the reason for the half wave-spaced antenna.
WPGC main and backup antennas, Capitol Heights, Maryland
I was told that this is not the greatest part of town. The station has had some theft of outdoor air conditioner equipment in the recent past. That being said, it is much nicer than many areas we normally work in the NYC metro area. The transmitter site has been here since the station signed on in 1948.
WPGC transmitter siteFAX60HD power supplies and power amps installed
It took a bit of time to install the 42 power supplies and 48 power amps. The power amps were installed in the same slots as during the factory test cycle. Thus the data on the test sheet matches the data seen on the transmitter GUI when we turn it on.
FAX60HD cabinet interconnects completed
All of the cabinet interconnects; RF plumbing, grounding, AC supply, sample lines, and various control lines were completed.
Transmitter hybrid combiner for the two FAX30 transmittersFAX60HD, WPGC-FM Washington4 Inch Dielectric coax switch with 60 KW loadWPGC 4th harmonic
Most of the harmonics (2-10) looked like this. However…
WPGC 5th harmonic
This is something interesting that came up during the proof. When measuring the harmonics, most of them were in the -130 dB range. This one is slightly higher than that, which is due to the proximity of WFDC-DT on channel 15 (476-482 MHz), 1000 KW ERP about 10.6 miles away. Their signal was coming back down the transmission line from the FM antenna. This is a good demonstration of how other unwanted signals can get into the final sections of transmitters which can cause intermodulation mixing products. In this case, the FAX60 has several low-pass filters that remove this and other signals before that happens.
This is replacing a pair of combined BE FM25-T transmitters that were getting a little bit long in the tooth. The air staff has commented on the noticeable improvement of the station’s sound. The downside of tube transmitters is the delicate tuning procedure to reduce the AM noise. High-powered transmitter tubes are also getting more expensive and, for some types, harder to source.
I finished up another GatesAir FLX-10 install recently. This one was way out in Provincetown, MA at the end of Cape Cod for WOMR (Outer Most Reaches). That is a community radio station that has an eclectic mix of programs. The studios are on the second floor of an old church.
Main studio, Wheatstone ConsoleTalk Studio, up/down studio furniture
The transmitter site is located about a mile away from the studios.
WOMR antenna
A few details on the installation; the antenna is mounted on the water tank, which is the tallest thing around for many miles.
WOMR antenna, Shively 2 bay 6810 mounted on a water tank
The building is less than 120 square feet, which made working a little tight.
WOMR transmitter building, Provincetown, MAGatesAir FLX-10 transmitter placedPump Station
There was very little room outside for the heat exchanger because of the need to get vehicles around the water tank for maintenance. The area around the building was taken up with a generator and HVAC gear. We ended up mounting it to the side of the building horizontally. The main reason was that the wind at this location could come from any direction. If mounted vertically, there was a chance that the wind could blow into the heat exchanger against the fans, possibly causing some overheating problems. Also, the horizontally mounted unit will have a smaller surface area during Hurricanes and Nor’easters.
Heat Exchanger, mounted horizontally on the northeast-facing wall
To do this, I made a unistrut frame and attached it to the outside wall.
The liquid-cooled transmitter takes up much less floor space than the prior transmitter, a Nautel V-10. This installation also included activating an HD Radio signal for this station.
The GatesAir FMXi4G importer/exporter resides at the transmitter site. Currently, the station has HD-1 on the air, no word on any future sub-channels.
Looking North towards the Atlantic Ocean
We had nice weather on one of the days. On the last day (Friday) it was raining with 35 MPH wind guests.
Speaking of Marconi, the US’s first trans-Atlantic wireless transmission station is a few miles down the road in South Wellfleet. Nothing is left of the site; time and erosion have taken all traces away.
Postcard, South Wellfleet Marconi StationBronze plaque placed in 1953 by the Wellfleet Historical Society
Here we are standing on the location of the transmitting building. The last two tower bases tumbled over the cliff edge in 2011.
It’s always an enjoyable time installing a liquid-cooled transmitter!
I have been looking over this data for a few weeks and there are some interesting data points. First, I would like to thank everyone who participated. This is not a scientific poll, but rather an informal survey of those who chose to participate.
The survey consisted of ten questions and was posted on Facebook, Reddit as well as Radio World. There were 114 responses, which is a relatively small sample size and is less than anticipated. There were 5 people who opened the survey and then did not take it. This may indicate a level of apathy towards the subject. Most responses were from the United States, but there were a few from China, Europe, and Brazil. The average time to complete the survey was 1 minute 40 seconds.
The first question was a warm-up question and it shows a lukewarm response at best with the top two responses being “It’s Okay,” or “I am indifferent.”
A vast majority of respondents feel that testing other Digital Audio Broadcasting systems such as DRM30, DRM+, or DAB+ would be a good idea. In MB docket 19-311, the FCC left the door open for such testing in the future, stating in paragraph 26 “Finally, we (the FCC) emphasize that by approving use of HD Radio technology, we do not foreclose the possibility of authorizing alternative technologies in the future, if they are properly before us.”
Question #2 was an attempt to find out where most people are listing to HD Radio and radio in general. Not a great surprise that it is mostly in-car listening. The in-home listening is a little bit surprising. What is even more surprising is that 30% of the respondents do not have an HD Radio. HD Radio has been the digital audio broadcasting standard in the US since October 2002, when the FCC first authorized its use. Receivers are still an issue some 20 years into the project. I know that when I purchased a new vehicle (Ford) in April of this year, HD Radio was not an option in any but the highest trim packages. My first HD Radio receiver was a tabletop Sony XDR-S3HD purchased in 2006 or so for $200.00 which was a lot of money. A quick look on Amazon shows that the least expensive HD Radio is the Sangean HDR-14 for $70.00.
Questions #3 and #4 deal with the “analog sunset,” as originally proposed by iBiquity, the developer of HD Radio technology. After a period of time, according to the original plan, stations would turn off their analog signals in favor of all digital transmissions. In October of 2020, MB Docket 19-311 the FCC has allowed AM stations the option to do just that. Thus far, four AM stations have transitioned to all-digital broadcasting, one of which is off the air since the owner passed away.
According to the survey respondents, by a slim margin of 53-47%, all-digital AM is supported. The FCC has yet to consider all digital FM and by an equally slim margin of 46-54%, all digital FM is not supported.
Question #7 asks about perceived audio quality. I received a few email comments about this question. Three respondents noted worse audio quality on HD-2, HD-3, or HD-4 channels due to reduced bit rate CODECS. Five people skipped this question.
This gets to the crux of the problem; for radio station owners, it is expensive to purchase and install HD Radio equipment. If there are no great perceived improvements, what is the point? I find AAC audio codecs to be okay, however, there is a noticeable difference between CD player PCM and streamed audio no matter what the source. Low-bit rate codecs sound like they are coming from underwater. Why do we listen to the radio? Information and entertainment. I posted something many years ago: Listening to the Radio is like doing Cocaine. For the maximum dopamine effect, I like my music to sound like music, not some watery approximation.
Question #8 asks about additional features, most people find Program Associated Data (PAD) useful. Even in non-digital FM stations, RDS is an important feature and stations will get phone calls if the RDS is missing or stuck on one song for a prolonged time. Listeners have become used to glancing at the radio to answer that age-old question; what’s the title of this song?
In response to question #9 (How many hours per week do you listen to the radio (including streaming terrestrial broadcast radio stations via a website or smart device)? The average was 19.6 hours with a minimum of half an hour and a maximum of 90 hours. Interestingly, there were four people who put in 0 weekly listening hours.
Question #10 is very interesting. In spite of the lukewarm feelings it seems that most respondents would favor the FCC mandating a transition to all digital audio broadcasting by a margin of 62% with most opting for “at some point in the future.”
HD Radio has been stalled for some time. The technology has not lived up to the hype and for most stations, it is a way to feed an analog translator with additional programming. There is an overall lack of interest, the majority of those who did take the survey stated HD Radio was “okay.” Receivers are expensive and still difficult to obtain. All digital AM (HDMA3) has not progressed very far since the FCC allowed its use. Yet, the people who did respond felt that additional testing of various Digital Audio Broadcasting systems should be allowed. I don’t know, that ship may have already sailed.