KCBS 740 AM San Francisco Transmitter Tour Part 1

so i wanted to do a short introduction to this video to explain why it looks like a work in progress i originally conceived these videos in september of 2017 and i shot them in september october november of that year the whole idea was i wanted to do a series of videos that showed all of the cbs radio transmitter sites in the san francisco bay area by september of 2017 i decided i wanted to retire in june of 2019 and i wanted a video record of all of my transmitter sites i also wanted to be able to show the people downtown the announcers the office staff and the sales people exactly what the transmitters looked like because believe it or not many of them never get to see a transmitter site no matter how long they're in radio so one day i just grabbed my video camera went up to the transmitter set it up and started walking around waving my hands in the air ad-libbing the narration and just recording some concept video the idea being that i would shoot everything i thought was important then go back home review it and try to assemble it into some kind of coherent order and then go back and shoot the real video now in some of the video you'll notice that the audio changes and in fact in some parts of the video you'll notice that i had to put in captions because those segments were shot using the on-camera microphone later on i used two different types of wireless microphones and ended up with a little bit better audio unfortunately the other transmitter side videos never got off the ground because in november of 2017 the cbs radio network was sold to intercom after the purchase went through the engineering department was so busy trying to combine the two clusters we were building new studios taking care of new transmitter sites that i just let this project languish and i never really got back to it a little while ago i was looking at the video i did shoot and i thought to myself yeah i could probably make a pretty good video out of what i had so what you see here for better or for worse is the result of that decision now i'm going to present this tour in two parts the first part covers driving into the transmitter site and then a walk through the building where i will show you the transmitters equipment racks and some other items the second video takes place outside the building and i'll show you the towers tuning networks generator and whatever else there might be some things i never got video for and i'll probably just show them to you is stills with narration so i hope you enjoy this it'll give you a pretty good idea about what it takes to keep a major market network-owned all-news radio station on the air so let's set the wayback machine controls to september 2017 and the kcbs transmitter site in beautiful novato california hi and welcome to a series of videos we call let's go to the transmitter this is your chance to take a look at all six cbs radio station transmitter sites here in the san francisco bay area and see just where all that news information and music comes from my name is dave wigfield i'm the technical supervisor for three of those stations kllc also known as alice at 97.3 kfrc at 106.9 fm and the station we're going to be visiting today kcbs kcbs is an all news radio station on 740 kilohertz and operates at a power of 50 000 watts we use two directional antenna patterns one for day and one for night but we'll tell you more about that later but for right now let's go to the transmitter so here we are on beautiful binford road in nevada california that's the novato boat and rv storage on the right and on the left is novato storage and here's the road to the transmitter so the road out to the transmitter is about two miles long and it would take about eight to ten minutes for you to see the whole thing so we're just going to pick it up near the end of the road okay now you can see all four towers left to right they are tower number one tower number four tower number two tower number three the towers are 505 feet high around 3 8 of a wavelength is 740 kilohertz and they form a parallelogram roughly 660 feet on the long side and 330 feet on the short side that small building on the left houses the water pump that keeps the fields dry the fields being six feet below sea level would eventually fill back up if the pump was not there [Music] this is our building and the smaller green building to the left is our generator shed there are also two 5 000 gallon diesel tanks but only one of them is in service straight in front of us is our dumpster and the green building on the right is a storage shed and here we are so okay so i guess we should start the tour with the most important part of the transmitter site the kitchen this is our king kitchenette it was put in when the building was built in 1950 and is still working today we don't use the oven or stove anymore but the refrigerator section still works just fine as you can see the fridge is filled with all the essentials water tea diet pepsi and mountain dew also keep other essentials like cookies and pretzels in the cabinets and rounding out our 50s motif is this lovely dining room table and chairs over here to the right of the transmitter room door is our transmitter status panel we built this box to give us an indication of the plant's status as we enter or leave the building it tells us things like the status of the pg e power which transmitter is on the air what pattern we are in what audio source is on the air and most importantly for when we are leaving whether we have left one of the remote controls and local that light is the most important one because if we leave without putting the remote control back in remote it's a long drive back to push one button okay so you've seen the important place where we keep our food and our water and especially the soda the mountain dew and now i think it's time to go into the transmitter this is what you see when you first walk in the box on the left is the phaser that's what generates our directional antenna patterns farther down with the black handles sticking out that's our main transmitter dx50 it's a harris 50 000 watt am transmitter and the kind of gray box sticking out down there at the end that is one of our backup transmitters it's a twelve and a half thousand watt uh not tell xr12 also on this side we have uh storeroom our transmitter studio and our transmitter office the door at the far end leads into another storeroom and the dummy logo okay you're looking at the front of the phaser this is the system that takes the power [Music] this is he went in around 1990 probably one of the best translators i've ever worked with down here [Music] is [Music] this rack is [Music] [Music] [Music] to the transmitters another power supply for the relays and other storage that we have this rack has one of our two remote control systems [Music] it still works main backup switchers each rack has a ups for backup the foreign is keeping all of the critical equipment so that when we come back on the air you know it's about six seconds six to 10 seconds okay moving farther down has our antenna monitoring we have to monitor the phase and current uh this box um [Music] [Music] um [Music] um [Music] all this is probably the most important box in any radio station the um goes out everybody runs around yelling and screaming yeah [Music] [Music] odd monitor transmitters receivers another arbitrage monitor this one is our modulation monitor lets us know how loud the signal is four meters and 10 occurs for each tower through cd plan we [Music] fm modulation monitor up here because this is all the cvs stations for audio distribution this guy right here monitors the incoming three-phase 480 volts allows us to [Music] the lights will last on also if there's a power failure like the latch on there's no one phase and it's also sent to our remote control system so you know immediately downtown we've lost one phase two phases on all three things indoor outdoors [Music] [Music] [Music] [Music] monitor speakers [Music] [Music] this is [Music] [Music] [Music] [Music] um so what generates that uh rf signal that you hear on the air well it's our transmitter this is our harris dx50 it's a 50 000 watt solid state transmitter went in around 1990 been on the air pretty much continuously since then with very very few problems probably one of the best am transmitters i have ever worked with the other one would be my bauer 707 that i had ktim many many years ago but as far as transmitter goes i just absolutely love this guy consists of pretty much four cabinets this is the output tuning network this is what takes the rf power feeds it out to our phaser this cabinet contains rf modules and control circuitry again this cabinet contains rf modules and control circuitry this cabinet contains drivers and some more control high voltage power supply is in there as well when i say high voltage in this transmitter i'm not talking thousands of volts like the old tube transmitters this one is running at about 225 volts at about 230 amps it's basically a big arc welder power supply but it does generate 50 000 watts being a solid state transmitter there's not like one big transistor in it it's actually 128 power modules each power module is generating about 1500 watts and then there are several power modules in there that do binary steps low power binary steps they turn on in gradual steps and then when they reach the maximum of those steps then it turns on what's called a big step amplifier then they those binaries turn off again and do the count again so it builds up the waveform gradually this is the inside of one of the cabinets control circuitry on this side power supplies power supplies up here that's 64 amplifiers right there solid state amplifiers right there same thing in here i'll show you in a second this panel here allows us see how much voltage we have going into it how much current it's consuming to make the power and how much power is coming out also i can use this switch here to look at various power supplies and other things on the transmitter that i need to know there's three power settings on this guy high is 50 000 watts we have the medium set to 25 000 watts and low power is set to 12 500 which is our non-directional power power trim controls here we can raise and lower the power separately for each power level that's the off button i don't want to touch that and this is looking at our forward or reflected power this panel over here basically gives you an overview of the condition of the transmitter green lights are good red lights are bad but it's telling me that the oscillator the buffer amps pre-driver all the rf amps they're happy analog the digital converters output monitors power supplies and there are no overloads currently on the transmitter okay so here's a view inside that second cabinet behind that panel with all the slots in it are 64 rf power modules and if i zoom in here you can see that they're being turned on and off this is how we generate the rf waveform and also apply the modulation so that you can hear the voice commercials whatever on the air it's kind of like a big led vu meter this is looking in the other rf cabinet again there are 64 rf modules in there and you can see a lot of the control circuitry now we're looking in the last cabinet where the pre-driver and rf drivers are also some more control and behind that panel down at the bottom that's where the high voltage power supply is located okay so we're up to like take 493 on this as i wing this okay so what happens to all that rf power that's generated by the transmitter well it goes out of the transmitter through a feed line and comes into the phaser up here you can see four feed lines three of those are for the three transmitters that we have and the fourth one feeds into our dummy load in the dummy load room we'll show you that later on so just what does a phaser do well the phaser takes that power from the transmitter and it divides it up between the four towers it uh varies the amount of power going to each tower and it also varies the timing relationship of the signal to the four towers you combine those things and that allows us to direct our power where we want it to go during the day we let the power out a little more to the north and to the east at night we pull that power in and we send it more to the south that's what the phaser does and let's get one thing straight right from the beginning this is a phase or not a phaser that's two entirely different things so let's take a look at the phaser in a little more detail so the kcvs phaser consists of four cabinets the first cabinet here brings in the power from the three transmitters has switches in it so that we can select which transmitter is on the air it also has the common point meter allows us to see how much power is going into the phaser has another meter that allows us to see how much power is going into the dummy load when we're doing testing and it also has a common point bridge which allows us to measure the impedance and reactance of the input of the phaser for both day and night very important when we're figuring out you know amount of power going into the array second cabinet down here [Music] these are the matching networks they match the 50 ohm impedance of the transmitter uh to the impedance of the actual phaser where it's being divided up allows us to set the reactance and the resistance for both day and night this is the night resistance in reactants and this is the day resistance in reactants down here third cabinet this is where the power gets divided up and the phase gets changed the top part here is for night tower one power and phase adjustments tower two power and phase adjustments down here this is for daytime again tower one power tower one phase tower two power tower three phase it allows us to adjust um the uh the array when we need to pretty stable and hardly ever need to touch this thing fourth cabinet down here is the same thing only it's for towers three and four tower three night time power and phase tower four nighttime phase and power they're reversed don't ask me why down here daytime phase and power of adjustments for both tower 3 and tower 4. then after everything gets divided up and everything gets phase shifted and the power gets adjusted it all goes out on these four feed lines up here they go out outside the building and then head out to the towers okay so you've heard me mention the switching the switching is how we switch between transmitters we switch between our two patterns day and night or we switch into one of our non-directional patterns how do we do that well we use these small rf switches here this one is made by kintronics it's an 80 amp 30 000 volt switch rather large switch there are 17 of these in the day and night patterns not all of them are switching when we switch between day and night but there are 17 of these switches that are used to help get the rf power out to the towers they have two large solenoids on them and we command them from our antenna controller when we go to day or night we apply voltage to the solenoids and it flips the arm over i'll show you how that works here so here's the rf contactor the connections are made here that's where we make all of our radio frequency power connections there are two solenoids down here solenoids flip this bar right here back and forth you can see this switch is already marked up for day and night patterns so what would happen right now the bar is between these two sets of contacts these two sets of contacts so this is a switch is now in day pattern when we go to night pattern we'll kill the power to the out of the transmitter momentarily pulse will be sent out to the solenoids solenoid will do that flip it so now we're in night pattern you can see the bar has moved between this set and this set when that happens rf power will come back how do we know that the switch has actually made it there are micro switches down here on the side and they come back to tally lights and tally relays on our transmitter controller it lets us know the pattern has successfully made it to whatever pattern has been requested and allows the transmitter to come back on the air so as you can see there's a little more involved getting that power from the transmitter through the phaser and out to the towers than you would normally think this panel here with all the lights this is the phaser controller this side allows us to select the transmitters this side allows us to select what pattern we want day night a non-directional operation on tower number one or non-directional on tower number two these three buttons select which transmitter goes on the air these three buttons select which transmitter is feeding our dummy load these four select the patterns the lights are tallies and they come off of that rf switch that i showed you earlier those little micro switches they come back to the controller to relays the relays all have to close for the appropriate pattern and all these lights here have to light up and if they don't it won't allow the transmitter to come back on the air so what we're looking at here is these lights here are indicating which transmitter is feeding the dummy load right now it shows that the harris 3dx 50 is going into the dummy load and these lights each represent a rf switch down here this is our backup xr12 transmitter and it's not going anywhere these lights are out and this light is out saying that it's not feeding anything this is our main transmitter the harris dx-50 and as you can see its lights are lit so this is the path right here and then out to the tower these five lights here represent the phaser the rf contactors inside the phaser these lights out here represent the switches inside each tower each tower is a tuning unit tower one has three relays tower two has three relays tower three has two tower four has two this is a final tally that says yes everybody has made it i'm going to turn the transmitter back on the air so what happens when we switch patterns i will show you so what we're going to do here is we're going to switch between day and night and what you'll see is all these lights will shift down here one of those lights doesn't come on we don't come back on the air so uh we'll do that right now we'll do it during the upcoming hourly cbs news covers the world next what's happening at why so here we go tonight that was it that's how fast we switch patterns sequence of events was i told it to go to night pattern i pushed the button relay closed inside of here it muted the rf out of the transmitter momentarily all the switches switched all the lights came on as soon as it's as soon as the controller saw that all the lights were back and everybody was in the proper position it unmuted the transmitter and we're back on the air takes less than a quarter of a second it's really fast all you hear on the air is a slight pop so let's go back today pat here comes dave patterson so now we're back in day pattern as you can see everything shifted back up all the lights came on transmitter came back on the air everybody is happy if i wanted to change transmitters into the dummy load i could select the not tell here now you can see that these lights are on going up to this light which represents a relay switches between these two transmitters down to the dummy load put the 3dx back in to dummy loads it's easy

Channel: Steam Powered Radio

Views: 28,056

Keywords: KCBS, KCBS AM, KCBS San Francisco, CBS Radio Network, CBS Radio, AM Transmitter, Broadcast Transmitter, Radio Transmitter Tour, Transmitter Tour, KCBS Transmitter Tour

Id: R4YcA62SAPE

Length: 36min 12sec (2172 seconds)

Published: Sun Nov 22 2020