CH7 Sydney 300W NEC TV Transmitter Teardown
Вставка
- Опубліковано 23 лют 2024
- This is the actual NEC V360CH 360W TV transmitter that was used for the CH7 analog TV transmission in Sydney for many decades until analog TV was switched off.
Video extracted from my 1000th video.
If you find my videos useful you may consider supporting the EEVblog on Patreon: / eevblog
Web Site: www.eevblog.com
Main Channel: / eevblog
EEVdiscover: / eevdiscover
AliExpress Affiliate: s.click.aliexpress.com/e/c2LRpe8g
Buy anything through that link and Dave gets a commission at no cost to you.
T-Shirts: teespring.com/stores/eevblog
#ElectronicsCreators #Teardown #Sydney - Наука та технологія
Circulator, circa 1982. Splitter/ combiners used in all kinds of RF applications. More please. It is rare that Dave does something with RF involved and would love to see more.
RF design is a form of art.
ha ha, people at work said its black magic. the same people who are doing more complex things 🤣
Circulators are a bit more advanced than that. Basically it's a multi-port device, and if we label the ports (for a 3 port device, port 1, 2 and 3), RF that comes in on port 1 goes out port 2., RF that comes in on port 2 goes out on port 3, and RF that comes in on port 3 goes out port 1. They are very useful in amplifiers because you can put the amplified output in port 1 and have port 2 be the antenna, and if you receive anything on port 2 (either due to antenna mismatch or a received signal), it goes out on port 3, so you can transmit and receive on one output. Useful for things like modems and such where you want full duplex operation so your cable modem transmits out to the cable, and receives on the cable and the tx and rx circuits are relatively isolated so you're not blasting your rx circuit with transmit power.
I have been waiting for the teardown of this unit for years 🥺
Me too
Brain melts at the idea of a 300 watt pre amp!
"Little stargates inside". Well, that was certainly unexpected lol
Always appreciating a teardown, especially if it comes in a 19" form factor. Thing of beauty, joy for ever.
IMSAI Guy made a few videos on circulators, BTW.
when i eat i use to watch your tear down videos...don't know its kind of wired for the person sitting next to me or others in the room...but i enjoy watching your tear down videos long ones specially.....this gonna be a wonderful one ...cause i kind of develop interest in RF recent days...lots of things to learn...
Soooo and Sydney is off the air for Channel Seven's Twentieth Century Time Travelers - Dave took apart the amp 🤣
Ingenious construction, thanks for the example .
Durability and protection circuits. Things have to be important to design all that in.
The 'preamp' is actually an IPA, an intermediate power amplifier.
The 'rigid' coax looks more like semirigid coax; it can typically be formed by hand, whereas rigid coax is exactly that, manufactured in the particular shape rather than being made from coax cable from a roll as semirigid cables are.
You're right, I became a tripod when that cover came off
Can't help but say that the circuitry looks beautiful!
Looking at the right side it seems the board was hand drawn. Non of this CAD laziness. 😁 Just beautiful.
I have a device that looks like this but it has way more stages but also in 19" rack format. The combiners and spliters in the one I have are made from discreet torroids. The final stage has an off the shelf combiner that takes the signals from all the amplifier stages, combines them and spits the signal out the output jack. The one I have appears to take 3-phase AC as input which is rectified to DC for all the power stages.
Wow - VHF TV, That's not been used for many decades here, I think the last UK stations was retired in 1985 owing to the 1.21 GW of power needed. Good to see something RF. The main PA would probably have been a valve back then.
Please do a full video of this!!❤❤❤
Circulators can also be used to connect Tx PA and Rx LNA to a single antenna
Circulators are also used to separate out RX and TX to/from a shared antenna system are they not?
Beautiful
The signal path trembles. More
Love to have a unit like this to fire up pirate TV. I live in the mountains and there is only one radio station before the internet. I have run a pirate radio for years as i can only broadcast to the valley. So nobody ever bothers me. Have an audience of about 200 at any time.
bad news, regular tv receivers are not built nearly as sensitive as radios. u will be lucky to get a few km clear range with this thing.
i got 500m with a 7 watt test. that means 700 watts only gets u 5km. inverse square law. this is why this 300 watt thing is a only a preamp.
also dont forget this is a class B linear design, so the power consumption can reach 1000 watts, its thousands of dollars per year in power bills.
the bang per buck just isnt there.
@@echelonrank3927 That's not great. I only have a 5km by 15km area to cover.
@@Mr.Unacceptable its no loss, stick to radio, it keeps people free to do other things as they listen instead of getting them stuck to a screen like zombies.
@@Mr.Unacceptable Antenna whit field distribution as needed, yagi perhaps. Why waste power all ower...
so this box contains black magic.
Can't believe that transmitter tour video is 10 years old
Yikes!
@@davidkilpatrick1640 You were in it weren’t you? Thank you, it was very interesting. I have periodically googled waveguide ever since :). I hope all is well with you. Greetings from Pennsylvania.
We make some ridged coaxs where I work like this. There are some odd shaped one's!
I would steer clear of those RF transistors especially if any of the cases look cracked. Possible that they contain Beryllium oxide which is very nasty.
meh. i cracked some of those open. despite myths, beryllium oxide doesnt disintegrate easily into nasty dust, it just cracks in half.
We're in like flynn.
1:37 the coax connection to the BNC input inside look rather weird I think! What frequency? 300MHz?
I don't believe the circulator protects the output. What it does is re-direct reflections into a dummy load.
the circulators are used as power splitters and combiners
It does both, reflected power is sent to a load instead of causing damage to the output stage.
@@echelonrank3927 No, that isn't what circulators do.
@@cambridgemart2075 right, it even says combiner on the schematic because its not what they do.
dont forget u just watched an RF video by a guy who keeps calling RF black magic and not a qualified RF engineer.
@@echelonrank3927 I know, but I am an RF guy! It isn't possible to use a circulator as a combiner, but it can be part of a combiner, in fact they often are used on the inputs to combiners to prevent cross leakage.
Any idea if it could be modified/retuned for amateur radio use?
I think the Transistors could be used for 145MHz.
A little 'Circilator'? You mean a little circus near a stargate? Nice.
Capacitor de poliéster no desacoplamento em circuito de VHF???? Como pode isso se eles não trabalham bem a partir dos 5MHz?
Schematics ?
defo a pice to hold on to. you could get a dummy load for it
i will never understand people transmitting into a dummy load
Moar pls
...nice bit of gear....
but...how is a Pre-Amp a "transmitter"... cmon Dave, youre better than that...
If you put an antenna on the output, rather than connect it to the upstream RF amplifiers, it becomes a transmitter.
First !
Imagine the amount of fake news that went through that thing
and also a few real nudes