{"id":8033,"date":"2014-08-11T08:00:02","date_gmt":"2014-08-11T12:00:02","guid":{"rendered":"http:\/\/www.engineeringradio.us\/blog\/?p=8033"},"modified":"2023-03-26T09:42:09","modified_gmt":"2023-03-26T13:42:09","slug":"transmitter-repair","status":"publish","type":"post","link":"https:\/\/www.engineeringradio.us\/blog\/2014\/08\/transmitter-repair\/","title":{"rendered":"Transmitter repair"},"content":{"rendered":"\n

Sometimes it is obvious and relatively easy, other times not so much.\u00a0 This summer we have had wave after wave of afternoon thunderstorms.\u00a0 It is almost like living in Florida; almost, but not quite.\u00a0 Anyway, with the storms occasionally comes some lightning damage.\u00a0 At most of the transmitter sites we service, every step has been taken to ensure good grounding and adequate surge suppression.\u00a0 This is especially true of sites that have been under our care for a few years.\u00a0 Even so, occasionally, something gets through.\u00a0 After all, those five-hundred-foot steel towers do attract lightning.<\/p>\n\n\n\n

\"Broadcast<\/a>
Broadcast Electronics AM5E output tuning section<\/figcaption><\/figure>\n\n\n\n

This is the output section of the BE AM5E transmitter at WROW.  The transmitter got pretty trashed; a bad PA module and power supply and this capacitor in the output section.  This particular transmitter is 14 years old and this is the first major repair work we’ve had to do it.<\/p>\n\n\n\n

\"Broadcast<\/a>
Broadcast Electronics AM5E output tuning capacitor<\/figcaption><\/figure>\n\n\n\n

The capacitor was fairly easy to change out.  As a general precaution, both capacitors were changed.  There was a spare PA module and power supply on the shelf, thus the transmitter was returned to full power relatively quickly.<\/p>\n\n\n\n

\"Broadcast<\/a>
Broadcast Electronics AM5E output forward and reflected power meters<\/figcaption><\/figure>\n\n\n\n

The rest of the antenna system and phasor were inspected for damage, a set of common point impedance measurements taken, which showed that no other damage was sustained.<\/p>\n\n\n\n

Next, the 30 year old Harris SX2.5 A transmitter at WSBS.\u00a0 This failure was slightly more exotic; the transmitter started randomly turning itself off.\u00a0 The culprit, in that case, was this:<\/p>\n\n\n\n

\"Harris<\/a>
Harris SX2.5 remote control interface bypass capacitor<\/figcaption><\/figure>\n\n\n\n

Literally, a two cent part.\u00a0 The transmitter remote control uses optoisolators.\u00a0 The inputs to these opto-isolators are RF bypassed to ground on the back of the “customer interface board.”\u00a0 After determining that the remote control was not malfunctioning, it was down to either a bad opto-isolator or something really silly like a bypass capacitor.\u00a0 This capacitor was on the ground side of the remote off terminal.\u00a0 It shows short on the capacitance meter and 4.1 K on the ohm meter, just enough to randomly turn the opto-isolator on and shut down the transmitter.\u00a0 Being a Harris transmitter, removing and replacing the “customer interface board” was no easy matter.\u00a0 Overall, it took about three hours to find and repair this problem.<\/p>\n","protected":false},"excerpt":{"rendered":"

Sometimes it is obvious and relatively easy, other times not so much.\u00a0 This summer we have had wave after wave of afternoon thunderstorms.\u00a0 It is almost like living in Florida; almost, but not quite.\u00a0 Anyway, with the storms occasionally comes some lightning damage.\u00a0 At most of the transmitter sites we service, every step has been … Continue reading Transmitter repair<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[21,4],"tags":[87,245],"class_list":["post-8033","post","type-post","status-publish","format-standard","hentry","category-tales-of-disaster","category-tech-stuff","tag-am","tag-am-transmitter"],"_links":{"self":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/8033","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=8033"}],"version-history":[{"count":6,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/8033\/revisions"}],"predecessor-version":[{"id":11250,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/8033\/revisions\/11250"}],"wp:attachment":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media?parent=8033"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/categories?post=8033"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/tags?post=8033"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}