KPFK Transmitter Tour
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- เผยแพร่เมื่อ 11 ก.ย. 2024
- A brief look at the KPFK transmitter facility at Mt. Wilson, 5700 feet above Los Angeles. We just finished adding a new antenna system, so the site is a mess at the moment.
The main transmitter is an Armstrong 60000FMT, and the backup transmitter is an older CCA 20000GS. KPFK operates with 110,000 watts ERP (effective radiated power). The new antenna is a Shively 6814-5R.9SS, a high power, reduced wave-spaced design, which allows more power to the audience and less energy on the ground below the tower. The standby antenna is a Jampro 4 bay high power model, and at the very top of the tower is a single bay Shively 6814 backup. The big reddish covers are for ice protection, which is very important up at Mt. Wilson. The winter of 2008 brought lots of ice and snow, and lots of damage to adjacent transmitter sites up there. KPFK did fine, except for one of the STL (Studio-transmitter link) dishes that has a bent feed horn (scheduled for replacement this spring).
The guy you can see evading the camera is Bob Conger, the chief engineer at KPFK. He keeps the whole thing running smoothly.
Hi Don I volunteered with the station during the 90s. Bob Riete and Pablo Garcia were the Chief Engineers then. At the time KPFK (and I think it still is) was the most powerful FM Radio Broadcast Transmitter west of the Mississippi. From its inception through the 90s KPFK' s signal extended from the Mexican Border up through Santa Barbara. Today translators infill areas on the periphery that experience interference. The old CCAs ran 3CX5000 driver stage to a 3CX15000. Two were used. Each produced 28 KW. Both outputs were combined and fed to an antenna with 3 db gain to give an erp of 112kw. In the mid 90s Armstrong equipment came in. (A single 42KW unit). A new antenna with increased gain made up for the reduction in transmitter power). Thanks for the tour Don. It brought back many fond memories.
Actually KIOI in San Francisco at 101.3 FM has 125,000 watts
Doesn’t a station lose its grandfathered status if its reengineered as a Major Change?
And wouldn’t a major change require compliance with current Part 73 class limits?
Thanks for posting, fun to see. I remember visiting Mt. Wilson in the early 1980's with a video camera of the time, and as soon as I got near the site, there was so much RF floating around that my video camera would not work at all, the picture was wiped out.
That is something I seriously doubt.
@@kenjohan were you there?
Nice facility. Thanks for the tour. I've been to many transmitter sites in my life, but only the best ones have a refrigerator! haha. Seriously, even though you say the place is a mess because of some work being done, it's still a good looking site. Thanks again!
Thanks for the video. I used to work at KPFK when Frank Stolz was the News Director. Great guy to work with. Wish I had learned more about the technical side of things....
5:18 I see sparks on that brass box with the big black coax....??
Great stuff, Don! Looks a lot different than the last time I was there (after midnight) with Don Wilson. Nice to know you saved the "KPFK Transmitter" sign that used to be next to the building door. I guess after the incidents at KPFT and 9/11 it was no longer a good idea to ID xmtrs to anyone passing by... Appreciate the post.
There are three parts to the air system. We have a big filtered blower that sends filtered air into the building at 8,000 CFM. The exhaust hood has a blower that pulls air from the building at 6,000 CFM. And an internal air conditioner that cools the building in summer.
Because the site is nearly 6,000 feet above sea level, it mostly stays cool, and only gets warm outside about 40 to 60 days a year. The rest of the time, fresh (filtered) air keeps things nice inside.
When I was training with BBC Transmitters, at the main high power sites such as Sutton Coldfield, Birmingham UK, there were two 20-kw parallel output amplifier units on the ground (one pair for each of BBC Radios 2,3 and 4 as was the case in 1987), feeding into two stacked sets of high gain umbrella dipoles and giving effective radiated power (ERP) of 240 kilowatts. High gain antenna syatem +relatively low final amplifier power = higher efficiency and greater ERP
@donmussell12
Thanks for the info on air handling; I was wondering how that was being done at +5000 feet MSL on Mt Wilson. And thanks for the video tour; no time in this lifetime to make a tour like this in person!
Don, remember the old transmitter? The manufacturer was (GER?) serial number 001, IIRC.
I love all the RF plumbing.. You can put a alcoholic Still in there no one would even notice it. Nice video. Do you sell any old equipment off?
Thank you for the share, great video, love the sounds of the TX Room, reminds me of the Transmitter Hold on the old Radio Caroline. I'm sharing this to my FB. Slainte:-)
Yes, the modern stuff just sits there.
I remember seeing old AM transmitters with mercury rectifiers that would take the 3 phase and modulate to the sound of music.
But this was another era altogether.
No more water cooling ponds, etc.
As usual, put two engineers in a room and get 10 different opinions.
This setup is running good, on the air since July of 2002. I can live with this. I don't want to deal with Bernie ever again.
Because of the location of Mt. Wilson, 5,700 feet above Los Angeles, a high gain antenna is not effective at reaching the service area, which is well below the mountain. A low gain, wide aperture antenna is required to send the signal down enough to reach the audience. Hence, the four bay antenna and high transmitter power.
Hello Don if you still pay attention to this. Just saw your name pop up.
Very nice video! Why in the USA, usually, you use a big power TX and low gain antennas? Here in Italy, for medium range, we use 15/20 KW but high gain antennas: 16 or 24 or 32 yagi array instead of 6 or 8 as I seen on USA repeater. Enrico.
that was a real nice tour of the transmitter site and seeing all those towers, thats kind of like being there for me, i was wondering how you radio and tv people that work on the equipment, how you walk around in the transmitter area without getting radiotion poison or getting burned from rf energy,, i saw the sign that said do not enter high rf energy,,, please notice i am just a viewer, so thats why i was asking, thanks for any response, and thanks for posting your video
The RFR levels at this site do not exceed Federal standards, so it is considered safe as a working environment. Across the street is a private residence where a CalTrans worker and his family lives.
There is no such thing as radiation poisoning when around radio and TV transmitters. It is electromagnetic energy, not gamma radiation that is produced by these stations. Apples and oranges... 40 years of studies have not found any long-term harmful effects from radio-frequency energy.
Appreciate the tour but these new solid-state xmtrs just don't excite me like big glowing bottles in the old tube jobs. During the 1970s I maintained a RCA BTA-50H Ampliphase. 4CX5000s drove two 6696 triodes running 15.3-KV at 4.4-amps. Our back-up use mercury rectifiers which were fun to watch- they had a blue glow that pulsated with the modulation. Visitors always thought that was neat. Today's mosfet xmtrs may be efficient and low-maintenance but not very much to look at.
I forgot to mention that Farnsworth Peak is 10K feet above sea level and 5000 feet above the SLC valley floor.
A Nautel would do you right proud.
"spare Cathermine under bench"- what's that about?
Is the air handler basically an exhaust fan? Do you have (or need) any air conditioning or heat in the trans bldg.?
Is this transmitter still on the air?
are you realetd to Jim Mussell from Santa
Maria? He was a broadcast engineer as well as I was.
Radomes = Awesome
Almost looks like my shack HIHI
Nice transmitter site!
Years ago I maintained an old RCA TTU-110... the good ole days! More water leaks than anything else.
Check out my videos of the Farnsworth Peak Transmitter facility near Salt Lake City. 8 HD transmitters in one room and I stopped counting FM transmitters past 15!! The 3000 HP 16 cylinder Cummins driven Onan gets a test run as well. I will post more as time permits. Transmitter sties are always fascinating. Do a You-Tube search for "Farnsworth Peak Transmitter Site"
You guys have to get a more efficient refrigerator in there. That old thing draws way too much power, and costs too much too run! lol