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The Newsletter of Crawford Broadcasting Company Corporate Engineering MARCH 2014 • VOLUME 24 • ISSUE 3 • W.C. ALEXANDER, CPBE, AMD, DRB EDITOR One Year Later alarm on the monitor module. We have since It’s hard to imagine, but the new KBRT (mostly) corrected that, although we continue to “dial mainland transmitter site passed its first birthday on in” the reference voltage on the comparator. We still February 28! That was quite a day. Mr. Crawford occasionally get false alarms, always when ambient came to the site and “pushed the button” personally. temperature is low. What an honor that was! Then he and I spent a couple We installed a fiber-optic system for of hours on “The Bottom Line” talking about the coupling the alarm outputs of the LED monitors project. across the base insulators. These have worked The first year has gone remarkably well. I perfectly. visited the site often during that year, some visits Other issues have involved fine-tuning our routine and others not so much. Not long after sign- alarm and video surveillance systems. So far, so on the power to the site was interrupted for several good. We have had no theft or vandalism (other than days. We were able to operate for a time from the old a little graffiti that someone drew with a Sharpie). site on an STA, and the remainder of the time we ran The last week of February, the site got a test from the new site at reduced power (40 kW with of its drainage improvements, silt traps and silt dam. MDCL). We got a lot of rain over a few days, and we observed We have had a few power outages since, but the concrete V-ditches properly channeling the water nothing more than a few hours. Our automatic power- right where it was supposed to go. As of this writing back during generator operation has worked perfectly Bill has not been up to the site since the rain let up, – we use the ND50’s Max Power Lockout feature to but we can see on the security cameras no obvious cap the power at 40 kW when the generator is on- erosion on the hillside southeast of the transmitter line. The generator is only rated at 75 kW, and 40 kW building, and there is standing water behind all the with MDCL and HVAC takes it right up to capacity silt traps. My guess is that our downstream (but not over). neighbor’s pond is full of clean water, provided Then at the end of April we had a guy courtesy of our drainage and filtration system. insulator fail, clearly the result of corona. Since the That “rain event” resulted in some rain fades insulators were rated at several times the expected for our 11 GHz microwave link and at least one rain peak RF voltage, we surmised that the failure was fade of our Ku-band satellite link (STL backup). produced by RF plus static electricity on the tower That’s to be expected with the kind of rainfall rates resulting from the dry Santa Ana winds that frequent we were seeing (several inches per hour), and I guess the area. We doubled up the insulators at the top three we can’t complain – we lost probably 15 minutes for levels on the high-power tower and installed corona the whole year from fades, which amounts to rings. Bill Agresta makes frequent inspections of the 99.99997% reliability. That’s a whole lot better than insulators using a spotter scope and has not seen any we got with the T1 to our old island site! further evidence of corona. The only other issues have been ancillary. A Tale of Two Stations The Slatercom LED tower light monitor modules on This tale won’t start with a line about the tower 3 have given us some grief. For some reason best and worst of times, and much of it has been the LED beacon on that tower draws a little less related in these pages in the past so I won’t go back current than the other beacons, producing a false into the whole history. The two stations are KBRT, 1 The Local Oscillator March 2014 which took to the air on 740 kHz in 1953, and KFMB shoe could well be on the other foot – “Do unto (San Diego), which began broadcasting on 760 kHz others…” So I got with the folks at Nautel and they in 1961. An impermissible overlap was produced produced some DSP code for a filter that would go in when KFMB signed on, something that the FCC the exciter, further reducing the upper primaries by waived over KBRT’s objections, and that overlap has another 30 dB or so. existed ever since. For many years, KBRT listeners put up with second-adjacent “monkey chatter” from KFMB, a situation that was cured when the NRSC voluntary bandwidth standard was implemented in the late 1980s (and was later codified). Figure 2 - KBRT Output Spectrum with Filter and EQ I made a trip to KBRT in mid-February and did both a software update and uploaded the filter code to the exciters. The result: not exactly what we Figure 1 - KBRT Exciter Output with Filter had hoped for. Engineers from Nautel looked at the In 2003 or thereabouts, KBRT began digital output of the exciter and confirmed that the upper transmissions, and in 2007, KFMB began primaries were indeed being attenuated as desired complaining about IBOC hiss on their signal in areas (Fig. 1), but the output spectrum of the transmitter well outside their primary coverage area. KBRT still showed them in the mid-50s. That confirmed for cooperated with KFMB and reduced the level of its us that what we were seeing was not the digital upper IBOC carriers, which occupy some of the same carriers themselves but rather third-order IM products spectrum as the lower KFMB audio sidebands, to -51 involving the carrier and lower primaries. That dBc, some 23 dB below the nominal -28 dBc primary explained why HD performance was off – those digital carrier level. We operated at that level for all heavy IM products were confusing receiver decoders. the remainder of our time on the island and continued Nautel engineers jumped all over this, at that level from the new mainland facility. manipulating the equalizer in the NX50, and they Late last year, the KFMB people again were able to get the IM products in the 10.2-15 kHz began complaining of IBOC hiss on their audio up in range down into the low- or mid-60s (Fig. 2). HD Orange County, again well outside their primary performance perked up, and although I haven’t coverage area. I did some investigation and found personally listened, the “noise” situation for KFMB exactly what I expected: KFMB’s signal was very in our primary coverage area should be a lot better. weak in that area and KBRT’s was very strong. Even I could draw a lot of conclusions from this at -51 dBc (the upper primaries were actually at -53 little exercise, and perhaps sometime I will do just dBc by that time, which was as low as we could get that in a detailed discussion. For now, the one them to go), that 250 mW equivalent did produce a conclusion that I will note is that the folks at Nautel “white noise” effect on the KFMB signal up in our are the best of the best. They have been responsive to primary coverage area. our particular needs and put in some significant While we should be protected from such engineering time to come up with a solution that interference complaints by the FCC’s long- works. My hat is off to Brian Walker, Ryan established “newcomer” policy, I nonetheless wanted Swinamer and all the others at Nautel that worked so to minimize any interference to KFMB because the hard to make this work. Great job, guys! 2 The Local Oscillator March 2014 The New York Minutes By Brian Cunningham, CBRE Chief Engineer, CBC – Western New York Hello to all from Western New York! As of temperatures, and causing severe afflictions to 4:00 PM on Thursday, February 27th, Buffalo weather patterns and the earth’s ground temperature? officially reached 104.1 inches of snowfall so far this Unfortunately, not enough solid evidence has been year. Most of the Northeast brought forth to firmly make has seen its worst winter a believer of me that weather since 1950, and greenhouse gasses are weather patterns all across causing these drastic weather the country have skewed pattern changes. from all normal weather With adversity activity to the extreme comes prosperity. One obverse. In the western part hundred miles northwest of of the U.S. they are Dallas, Texas, the town of experiencing drought Wichita Falls has been conditions. Some areas have classified as an exceptional been classified with drought area. The town’s exceptional drought main water source, Lake conditions, which is the Arrowhead, is only at a 27 worst classification of percent capacity and drought. To the extreme, the Northeast has been dropping rapidly. In order to keep the towns residents plummeted with periods of sub-zero temperatures, hydrated, city officials have begun to test turning the scores of heavy winter storms and arctic-fueled city’s waste water (sewage) back into the city’s winds. And the United States is not alone. Malaysia, distribution system, saving nearly 5 million gallons normally known for its steady tropical downpours, of Lake Arrowhead water daily.

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