{"id":13187,"date":"2024-12-12T08:05:25","date_gmt":"2024-12-12T12:05:25","guid":{"rendered":"https:\/\/www.engineeringradio.us\/blog\/?p=13187"},"modified":"2024-12-12T08:05:27","modified_gmt":"2024-12-12T12:05:27","slug":"installing-a-60-kw-fm-transmitter","status":"publish","type":"post","link":"https:\/\/www.engineeringradio.us\/blog\/2024\/12\/installing-a-60-kw-fm-transmitter\/","title":{"rendered":"Installing a 60 KW FM transmitter"},"content":{"rendered":"\n

Recently, I installed this very nice GatesAir FAX60HD.<\/p>\n\n\n\n

This project was for WPGC<\/a>, Washington, DC. WPGC (P<\/strong>rince G<\/strong>eorge’s C<\/strong>ounty<\/a>) is an Audacy <\/a>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.<\/p>\n\n\n\n

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.<\/p>\n\n\n\n

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MSC unit with touch screen pad controls both transmitters and exciters<\/figcaption><\/figure>\n\n\n\n

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.<\/p>\n\n\n\n

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BDI inline watt meter<\/figcaption><\/figure>\n\n\n\n

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.<\/p>\n\n\n\n

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WPGC main and backup antennas, Capitol Heights, Maryland<\/figcaption><\/figure>\n\n\n\n

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.<\/p>\n\n\n\n

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WPGC transmitter site<\/figcaption><\/figure>\n\n\n\n
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FAX60HD power supplies and power amps installed<\/figcaption><\/figure>\n\n\n\n

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.<\/p>\n\n\n\n

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FAX60HD cabinet interconnects completed<\/figcaption><\/figure>\n\n\n\n

All of the cabinet interconnects; RF plumbing, grounding, AC supply, sample lines, and various control lines were completed.<\/p>\n\n\n\n

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Transmitter hybrid combiner for the two FAX30 transmitters<\/figcaption><\/figure>\n\n\n\n
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FAX60HD, WPGC-FM Washington<\/figcaption><\/figure>\n\n\n\n
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4 Inch Dielectric coax switch with 60 KW load<\/figcaption><\/figure>\n\n\n\n
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WPGC 4th harmonic<\/figcaption><\/figure>\n\n\n\n

Most of the harmonics (2-10) looked like this. However…<\/p>\n\n\n\n

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WPGC 5th harmonic<\/figcaption><\/figure>\n\n\n\n

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<\/a> 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.<\/p>\n\n\n\n

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. <\/p>\n","protected":false},"excerpt":{"rendered":"

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 … Continue reading Installing a 60 KW FM transmitter<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":13215,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[337],"tags":[82,15,303],"class_list":["post-13187","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-installations","tag-fm","tag-fm-transmitters","tag-hd-radio"],"_links":{"self":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/13187","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/comments?post=13187"}],"version-history":[{"count":11,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/13187\/revisions"}],"predecessor-version":[{"id":13216,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/13187\/revisions\/13216"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media\/13215"}],"wp:attachment":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media?parent=13187"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/categories?post=13187"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/tags?post=13187"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}