{"id":12510,"date":"2023-11-13T21:47:15","date_gmt":"2023-11-14T01:47:15","guid":{"rendered":"https:\/\/www.engineeringradio.us\/blog\/?p=12510"},"modified":"2023-12-09T07:34:36","modified_gmt":"2023-12-09T11:34:36","slug":"the-rhode-and-schwarz-thr9-transmitter","status":"publish","type":"post","link":"https:\/\/www.engineeringradio.us\/blog\/2023\/11\/the-rhode-and-schwarz-thr9-transmitter\/","title":{"rendered":"The Rhode and Schwarz THR9 transmitter"},"content":{"rendered":"\n

Part II of II<\/p>\n\n\n\n

This thing is on the air! There are still some tidying-up things to finish, but it is up and running and sounds great! Here are some pictures of various stages of the installation work:<\/p>\n\n\n\n

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Making harmonic measurements<\/figcaption><\/figure>\n\n\n\n

The filing cabinets hold manuals and spare parts. There is not a lot of room left in this building, so workspace is at a premium. The filing cabinet on the left needs some Windex and elbow grease.<\/p>\n\n\n\n

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Main disconnect and conduit to 400-volt transformer<\/figcaption><\/figure>\n\n\n\n
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Outdoor coolant run<\/figcaption><\/figure>\n\n\n\n
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3\/0 cables, 240-volt input to Hammond HPS Sentinal K transformer<\/figcaption><\/figure>\n\n\n\n

The transformer does not have a neutral reference to the power company. The neutral for the transmitter is derived from the Y output connection. The transformer is also designed to suppress harmonics from non-linear loads like switching power supplies. <\/p>\n\n\n\n

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Wiring in Square D I line panel<\/figcaption><\/figure>\n\n\n\n
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Square D I-line panel rated for 600 volts<\/figcaption><\/figure>\n\n\n\n
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#2 SOOW cable feeding upper and lower sections of transmitter<\/figcaption><\/figure>\n\n\n\n
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Wiring to disconnect switch on transmitter<\/figcaption><\/figure>\n\n\n\n
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Pump station during system fill<\/figcaption><\/figure>\n\n\n\n
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Heat exchanger<\/figcaption><\/figure>\n\n\n\n

The wiring on the pump station and heat exchanger needs a little more work. The client wanted to get this on the air as soon as possible because they are in a book and were running at 50% power. Once things calm down a bit, I will put the backup transmitter on for an afternoon and properly dress the wires.<\/p>\n\n\n\n

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FM modulation analysis<\/figcaption><\/figure>\n\n\n\n

I found this FM modulation analysis function on my spectrum analyzer very useful. The station deviates slightly more than the allocated 75 KHz because of a subcarrier. Overall, it looks good. I measured the harmonics out to the 10th harmonic, most of them were in the noise floor. A few made a slight appearance, but well within FCC tolerances. It is important to document this, as this site has colocated cellular carriers and several E911 services.<\/p>\n\n\n\n

FCC part 73.317 states:<\/p>\n\n\n\n

\n

(d) Any emission appearing on a frequency removed from the carrier by more than 600 kHz must be attenuated at least 43 + 10 Log10 (Power, in watts) dB below the level of the unmodulated carrier, or 80 dB, whichever is the lesser attenuation.<\/p>\n47CFR 73.317<\/cite><\/blockquote>\n\n\n\n

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WHUD fundamental<\/figcaption><\/figure>\n\n\n\n
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WHUD fundamental with two Mini-Circuits NHP-200 high pass filters installed<\/figcaption><\/figure>\n\n\n\n

The rest of the harmonics were measured down to -130 dB with the two NHP-200 high-pass filters in the circuit. The 3rd, 4th, 5th, 6th, and 8th harmonics were unmeasurable. The 8th, 9th, and 10th made slight appearances.<\/p>\n\n\n\n

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WHUD 6th Harmonic, noise floor<\/figcaption><\/figure>\n\n\n\n
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WHUD 8th harmonic makes a little appearance<\/figcaption><\/figure>\n\n\n\n
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Main antenna VSWR<\/figcaption><\/figure>\n\n\n\n
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Antenna VSWR according to the transmitter directional coupler<\/figcaption><\/figure>\n\n\n\n

Pretty close, the VNA was inserted at a patch panel, which is the last thing before the transmission line leaves the building. The transmitter goes through an ERI switchless combiner, which probably gives it a slightly better load.<\/p>\n\n\n\n

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Backup antenna SWR<\/figcaption><\/figure>\n\n\n\n

Aside from the finishing details, I need to keep an eye on this for a week or so and top off the Heat Transfer Fluid as needed. It takes a bit of time to get all of the air out of the coolant loop. Another thing; the operating pressure on this is 4 Bar, which is almost 60 PSI. That is higher than other liquid-cooled transmitter systems I have installed before.<\/p>\n","protected":false},"excerpt":{"rendered":"

Part II of II This thing is on the air! There are still some tidying-up things to finish, but it is up and running and sounds great! Here are some pictures of various stages of the installation work: The filing cabinets hold manuals and spare parts. There is not a lot of room left in … Continue reading The Rhode and Schwarz THR9 transmitter<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":12544,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[337],"tags":[82,15,338],"class_list":["post-12510","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-installations","tag-fm","tag-fm-transmitters","tag-rhode-schwarz"],"_links":{"self":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/12510","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=12510"}],"version-history":[{"count":7,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/12510\/revisions"}],"predecessor-version":[{"id":12593,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/12510\/revisions\/12593"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media\/12544"}],"wp:attachment":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media?parent=12510"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/categories?post=12510"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/tags?post=12510"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}