• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

Inside a TV transmitting station

Status
Not open for further replies.
That was really awesome. Watched the whole thing. The workmanship and engineering that went into those cabinets... geargasm.
 
Always wondered what was inside those towers. All we have at work are a few microwave dishes.

I knew they were still using vacuum tubes because they're better suited to those kind of power loads than transistors. An inhuman amount of BNC snaking through those machines too.
 
mmntech said:
Always wondered what was inside those towers. All we have at work are a few microwave dishes.

I knew they were still using vacuum tubes because they're better suited to those kind of power loads than transistors. An inhuman amount of BNC snaking through those machines too.
Click to expand...

I was most impressed by the giant coaxial cables made out of pipes.
 
Yeah the solid coax is quite something. I think this is very similar to wave guide. Cell towers and microwave towers use that. At least for CDMA. For HSPA they can't use waveguide due to the higher frequencies I believe so the radio is actually up in the tower. A maintenance nightmare actually. The nice thing with waveguide/coax is all the equipment is on the ground and within easy access, and in a warm building that is much better to work in than on top of a tower when it's 30 below.

What's interesting is that all this was essentially a free service, too.
 
Holy crap, on this subject, I was curious about the digital OTA TV, as I never figured we got it here when they turned down analog since the channels were always all snowy on my new TV. Well it turns out you NEED an antenna for that. I shoved a piece of wire inside the coax plug on the back of my TV and I can get Global in HD and it's crystal clear, that's quite incredible. The other two channels are unwachable but I get enough signal for the TV to register there's a channel there. I would probably get them with a proper antenna.
 
Red Squirrel said:
Holy crap, on this subject, I was curious about the digital OTA TV, as I never figured we got it here when they turned down analog since the channels were always all snowy on my new TV. Well it turns out you NEED an antenna for that. I shoved a piece of wire inside the coax plug on the back of my TV and I can get Global in HD and it's crystal clear, that's quite incredible. The other two channels are unwachable but I get enough signal for the TV to register there's a channel there. I would probably get them with a proper antenna.
Click to expand...

I've been happy with this $10 antenna. I am it towards the TV towers and get great signal.

http://www.amazon.com/HomeWorx-HDTV-...s=hdtv+antenna
 
TV and Radio stations will always use tubes for the transmitters. Solid State devices can not put out the required power and heat removal would be a big problem. A company called Eimac makes the power tubes and I know for a fact they are not cheap. Some of the bigger ones are so large and heavy, they actually have handles on them for installation and removal.

img01.jpg
 
bruceb said:
TV and Radio stations will always use tubes for the transmitters. Solid State devices can not put out the required power and heat removal would be a big problem. A company called Eimac makes the power tubes and I know for a fact they are not cheap. Some of the bigger ones are so large and heavy, they actually have handles on them for installation and removal.

img01.jpg
Click to expand...

Magnetron!
 
I wonder how fast you could cook a TV dinner over that. :biggrin:

Actually I wonder if a microwave oven magnetron could be converted into a transmitter. I think it's the control circuitry that generates the frequency/wave form and not the magnetron itself so you could probably hook it up to a device that is modulating a different kind of signal. Damnit, I should have kept my parents' old microwave when it died! I think it was the magnetron that died though.

Hook it up to a wifi router. Wifi for 100 miles. (and cancer for 10 miles)
 
Last edited:
As much as I adore valves, solid state transmitters are taking prevalence. The valve is super robust and can be twisted further and is rock solid in comparison with rare events (EMP) but lightning is much more common and they are likely to survive hits, etc.

SS amps also don't need as much attention as their valve counterparts and high power units are liquid cooled and have higher AC to RF conversion efficiency. The cabinets around those large Eimacs have high airflow to cool those valves and must be kept clear of FOD at all times. Those (valves) are expensive too!

IIRC the microwave magnetron has a very high fundamental superimposed on its output. This is why plasma balls in the cavity hum at either 50 or 60 Hz depending on your mains AC. I have not had the pleasure to try those experiments on a modern inverter design, however.

What happens after the box can be downright fascinating as well!

Arc modulated very clearly here (high power!):

http://www.youtube.com/watch?v=6pjrWjlBf4Q

Arcing on tower guys:

http://www.youtube.com/watch?v=NvHd_IZIYew

This is most likely an isolated radiator accumulating a high DC (static) potential that flashes over the guy coupling insulators.

A similar (sound) is realized in rural areas where lightning rods are used and the bonding isn't the best on the conductors at the grounding stakes. When a close lightning strike occurs a loud pop or crack will be heard which is a spark jumping across the bad connection.
 
Status
Not open for further replies.

TRENDING THREADS

Back
Top