RV News RVBusiness 2021 Top 10 RVs of the Year, plus 56 additional debuts and must-see units → ×
Open Roads Radio forum for Ham, Amateur Radio and RV camping


Reply
 
Thread Tools Display Modes
 
Old 09-16-2014, 04:08 PM   #1
Radio
Administrator
 
Radio's Avatar
 
Join Date: Nov 2007
Location: Fayetteville, GA, USA
Posts: 3,017
Default 12 volt TV

As part of our home disaster preparedness I have a marine deep cycle battery (planning to get another) that I keep charged. One will run the entire ham radio station and the other will run other volt 12 stuff elsewhere in the house. I can recharge them with jumper cables off the truck in a power outage.

One of those other things will be a small, quality, 12 vdc powered TV. I don't want one with batteries inside it, unless it can be run without them. I can make my own cable to run from the battery, so ideally a 13 inch or so that takes a 12 volt wall wart would be great. It could double as a bedroom TV in the trailer.

It's interesting to me that last time we had a major ice event, and many were without power including me, that all the really useful information was being delivered via TV... and here we are with no power to run the thing!

Any suggestions as to model and brand?
__________________

KU4OJ "Wade" Ships Captain, CFO, Chief Engineer
KG4DQQ "Kathy" 1st Officer, Navigator, Best Friend
2007 F-150 SuperCab - 2009 Rockwood 8280SS
Lot's of mostly Kenwood stuff

Radio is offline   Reply With Quote
Old 09-16-2014, 09:21 PM   #2
NN5I
Carl, nn5i
 
NN5I's Avatar
 
Join Date: Sep 2011
Location: Tallahassee, FL
Posts: 1,441
Default

Wade, you might do better with true deep-cycle batteries, which "marine" batteries are not. If you get batteries designed for use in golf carts or similar equipment, they will be true deep-cycle batteries. Marine batteries are a kind of in-between -- they can stand a few deep discharges (which automotive batteries cannot), but they withstand them nowhere near as well as true deep-cycle batteries do.
__________________
-- Carl
NN5I is offline   Reply With Quote
Old 09-17-2014, 02:34 PM   #3
wa8yxm
Senior Member
 
Join Date: Nov 2007
Location: Mobile, on the road
Posts: 1,139
Send a message via AIM to wa8yxm Send a message via Yahoo to wa8yxm Send a message via Skype™ to wa8yxm
Default

First: most of the self contained battery ones DO have an external power (and in some cases charger) port.. I once ran a 12 volt car radio on D-Cells for a long, long time.

Second... I have a Samsung 21" Wide Screen that takes not 12, but 14 volts from its brick.. Not sure this woudl be good for you but here in the wheeld house (motor home) it is more likely to see 14 volts from ye old battery system.. That said I run it on 120vac)


Finally, If the battery storage location is both easily accessable and can be easily vented to the outdoors (And I can come up with several ways to do that). DEEP CYCLE (Such as GC-2 Golf car batteries in series or G-12s (12 volt golf car) are way better than Marine/Deep cycle.

But they are harder to find in non (or limited) Venting Maintenance Free designs.

The Reason: Marine/Deep cycle are first MARIN (Starting) Batteries, with lip service paid to deep cycle 50 percent is harmful on these batteries

DEEP CYCLE are designed to go to 50 percent,, And if you go lower than that, stand a decent chance of recovery if promptly recharged, Marine types... Not so good at recovery.
wa8yxm is offline   Reply With Quote
Old 09-17-2014, 05:29 PM   #4
Radio
Administrator
 
Radio's Avatar
 
Join Date: Nov 2007
Location: Fayetteville, GA, USA
Posts: 3,017
Default

The idea is for the batteries to be portable. So a deep cycle but portable battery would be what? Not a golf cart battery. And for clarification, these are for emergency use primarily in the stick house.

For what it's worth I have run a weeks worth of IOTA operations on a ordinary car battery just fine. So one battery for the radio station and another for TV, lights, inverter, laptop and all that.

A TV made to be used in a vehicle might be fine, but as long as it has a 12 - 14 volt wall wart I can make my own power connections to the battery.
__________________

KU4OJ "Wade" Ships Captain, CFO, Chief Engineer
KG4DQQ "Kathy" 1st Officer, Navigator, Best Friend
2007 F-150 SuperCab - 2009 Rockwood 8280SS
Lot's of mostly Kenwood stuff

Radio is offline   Reply With Quote
Old 09-18-2014, 09:01 AM   #5
wa8yxm
Senior Member
 
Join Date: Nov 2007
Location: Mobile, on the road
Posts: 1,139
Send a message via AIM to wa8yxm Send a message via Yahoo to wa8yxm Send a message via Skype™ to wa8yxm
Default

Wll, for portability,, You coudl us a GC-12 (12 volt golf car) a pair of GC-2's is a bit heavy.

But this is one area in which AGM batteries are preferred, You can get smaller DEEP CYCLE AGM's (liek Group 27-31 sizes) and not only are they low gassing (Sealed Valve Regulated Lead Acid batteries, very nearly non venting in fact) Which makes them better for indoor use.. They do not come with a "This side up" sticker, so if you lay it on it's side or even upside down (Both common with portable devices) no damage.

They are, however, more expensive.
wa8yxm is offline   Reply With Quote
Old 09-18-2014, 09:57 AM   #6
N3LYT
Senior Member
 
Join Date: Jun 2012
Location: Maine
Posts: 709
Default

I had often though about a set up like that and thought a RV switching battery charger/inverter would be the perfect set up with a pair of batteries either gel cell or glass mat. My only concern would be with the radios I'm not sure the supply would be clean enough but a simple switch would cure that when using the radios.
N3LYT is offline   Reply With Quote
Old 09-20-2014, 09:51 AM   #7
Mr. Ham
Member
 
Join Date: Aug 2014
Posts: 95
Default

I apologize for being rude - but it seems that with most internet posts, if the post goes for more then 3 replies, that it quickly drifts off topic, and the question is not answered, and all you get is opinions.

Terrestrial Television today is all digital.
The OP did not specify which television he planned to use.

Reception would require a decent outdoors UHF antenna - such as the Antenna's Direct XG 91and a rotor - since most network television stations migrated up into the UHF portion of the band, while most of the Fox stations stayed or migrated back down into the VHF - where power consumption costs are much lower.

Unless you can see the light blinking on top of the tower, I would not recommend trying to use rabbit ears antenna's for terrestrial reception.

I did work out a formula for antenna lengths for reception, that required you to change the length of the antenna, and aim the antenna directly at the station each time you changed the channel.

There seems to be a multitude of 12 VDC flat screen televisions available for sale today - most are aimed for use by campers and truck drivers.

http://www.truckers-store.com/12-vol...n-tv-with-dvd/

http://www.overstock.com/Electronics...8/product.html

I cannot comment on the quality of reception of these units or the power consumption requirements -

http://www.12volt-travel.com/12-volt...ons-c-684.html

A simple 1500 watt inverter box would convert your 12 volt battery to 120 volt, but is very inefficient and would consume part of your batteries power in the inversion process.
In the long run, you would probably also need to purchase a battery booster
http://stores.tgelectronics.org/the-...ost-regulator/
that would take voltages of less then 12 volts and boosts it back up to 13.8 VDC - like you would use for your amateur radio...

You would need to purchase deep cycle batteries, not automotive starting batteries.
Deep cycle batteries are not designed to be used to start a engine.

My friend Steve ran his whole house off 12 volts for a year.
He had several large diesel batteries - designed to start the drilling rig he works on and several deep cycle batteries - used to run the 12 volts interior lights and charge the cell phones and lap top computer.
Steve said that with 6 large batteries and the two starting batteries in his one ton Ford diesel pickup that he could run the wide screen television, the 12v inverter box, one light and the modem for the internet for about 6 hours with one charge.

The inverter box did not have enough juice to run the fridge - even though it was a 3000 watt commercial inverter..

I think it had something to do with the distance between the inverter and the fridge and the wiring in the house acting like a toaster.

In the summer, when no one was home, the solar panel made just enough power to maintain the juice in the batteries and keep them at a full charge.

The inverter was only turned on when he wanted to watch television or use the internet.

Solar panels are only efficient if they are in direct sunlight.

Solar panels do not produce electric at night.

The controller for the solar panel consumes power, so you don't get 5 amps out of a 5 amp panel when you connect it to a controller and battery bank.
Mr. Ham is offline   Reply With Quote
Old 09-20-2014, 11:21 AM   #8
NN5I
Carl, nn5i
 
NN5I's Avatar
 
Join Date: Sep 2011
Location: Tallahassee, FL
Posts: 1,441
Default

Quote:
Originally Posted by Mr. Ham View Post
... with most internet posts, if the post goes for more [than] 3 replies ... it quickly drifts off topic, and the question is not answered, and all you get is opinions.
I think that's one of the things that make the conversation interesting and fun. Sort of like a wandering bull session in a college dorm. But it sometimes drives the OP crazy with frustration. Whether I judge this as good or bad depends upon who the OP is.

Quote:
Originally Posted by Mr. Ham View Post
Terrestrial Television today is all digital.
Is that true? All the countries I've heard of are terrestrial, and I had read somewhere that in some countries NTSC and PAL were still to be found. But I can't claim really to know.

Quote:
Originally Posted by Mr. Ham View Post
VHF - where power consumption costs are much lower.
Could be, for all I know. But it would surprise me to learn that UHF transmitters are so much less efficient than VHF transmitters.

Quote:
Originally Posted by Mr. Ham View Post
The inverter box did not have enough juice to run the fridge - even though it was a 3000 watt commercial inverter ... I think it had something to do with the distance between the inverter and the fridge and the wiring in the house acting like a toaster.
Three KW is enough to run many compressor-type fridges, but not enough to start almost any of them. Most types of electric motors (including the ones sealed into refrigeration compressors) require as much as ten times the power to start that they require to continue running after starting.

Some 3KW generators, especially the simpler ones, can supply the temporary starting surge, but inverters are (typically) a bit less able to do so.


Quote:
Originally Posted by Mr. Ham View Post
Solar panels are only efficient if they are in direct sunlight.
Actually their efficiency (power out divided by power in) is nearly constant, although it depends somewhat on the color of the light. But at night they don't get significant (sunlight) power in, so can't produce significant (electric) power out.


Quote:
Originally Posted by Mr. Ham View Post
Solar panels do not produce [electricity] at night.
Sure they do. But they produce a heckuva lot less and it's not enough to be useful.
__________________
-- Carl
NN5I is offline   Reply With Quote
Old 09-20-2014, 08:19 PM   #9
Mr. Ham
Member
 
Join Date: Aug 2014
Posts: 95
Default

Quote:
Originally Posted by NN5I View Post
I think that's one of the things that make the conversation interesting and fun. Sort of like a wandering bull session in a college dorm. But it sometimes drives the OP crazy with frustration. Whether I judge this as good or bad depends upon who the OP is.
It fustrates me that no one gave the OP a answer, or at least a good answer.



Is that true? All the countries I've heard of are terrestrial, and I had read somewhere that in some countries NTSC and PAL were still to be found.
But I can't claim really to know.

My question to you is - how many foreign - European countries are you going to drive your motorhome to? Yes there are different types of digital television, but for the most part what we have in Canada and the US is the same mode of broadcast.



Could be, for all I know. But it would surprise me to learn that UHF transmitters are so much less efficient than VHF transmitters.
Since you ask, I will explain it to you in my post. OK?
About 8 years ago - I found myself needing a new hobby.
I got into DX television.
Yes I know to a truest ham Dx means out of country, but for practical purposes - lets call DX anything that is not normal reception.

In the analog days - the first broadcast networks ABC - formed from the NBC Blue Network, NBC, CBS - since they were the first on the block they had the pick of the best channels ( frequencies ) for broadcasting television.
Usually each network would have one VHF channel in each market - and the band plan specified that there was a one channel - ( guard channel) between channels.

Lets use Pittsburgh PA as an example - Pittsburgh started with WDTV - Dumont network.. Dumont had a 100% market share - this means that when you turned on your television - the only channel you could get before 1949 was channel 3 - WDTV. When you were done watching TV you shut it off! This was because Dumont was responsible for the coaxial cable that was strung through the coal fields of Pennsylvania and Pittsburgh was the golden spike that allowed broadcast television to go west beyond Pennsylvania.

Before that time, there was to separate places where most programming originated - New York City and Los Angeles California.
If a program was made in New York, they had to transfer it to a disc called a Kinescope and then transfer it back into a television camera and rebroadcast it. After that - Dumont gave each network a period of time when they could use his cable to transmit their programming and his stations could pick and choose which programs they desired to broadcast. So basically you could watch programs from each network on the Dumont network - it was the 7th largest market in the country.

As more and more television stations were put on the air, the bandwidth was taken up with the now 4 broadcast networks.
You see Westinghouse had their world headquarters in Turtle Creek PA and they didn't like it that they couldn't get a permit to build a television station in Pittsburgh, so they pressured the Dumont network to sell them their station in Pittsburgh.. To get the FCC to go along with it, they promised the FCC that they would share the channel with the college - what we now call Public Broadcasting - PBS.... KDKA later migrated to channel 2 and WQED PBS moved to channel 13 when the ban was lifted and people were allowed to build new television stations..
Coincidentally WPSU - Penn State University got channel 3 in State College, the transmitter was located in my backyard atop Rockton Mtn. near Clearfield PA.

The reason why no one wanted to be on UHF was because the Superheterodyne technology of the day did not work well on UHF and the televisions made before 1958 didn't even come with a UHF tuner - you had to use a converter box - much like what happened when we switched from analog to digital and we had all those analog televisions still in use.

A 15KW analog VHF signal atop a 1000' stick, atop a mountain, on channel 3 had a service contour area of about 120 miles - 65 miles in each direction - with no problems.
This allowed someone with a roof top antenna in Punxsutawney PA to watch television that originated in Pittsburgh, Johnstown and Altoona virtually at will, with nothing more then a good antenna rotor and a long range antenna.
3 markets with one antenna - in one location...

When the television stations went to migrate to digital, it was found that digital stations worked better on UHF then VHF.

UHF is like a flashlight, when you shine the beam north, it does not go south.
When you shine the light up, it does not come back down and shine on the ground, unless there is something in the clouds that is reflective.
When the signal travels through the atmosphere - unless there is something for it to reflect off of, it eventually just travels straight out into space.

VHF is like sound, if you stand on one side of a house and you yell real loud, the people on the other side of the house can hear you.
VHF goes up one hill and down the next.
But because it is a longer wavelength, it is more susceptible to noise.

" Remember now - we are HAMS! We are supposed to know this!"

Motor brush noise, ignition noise, fence charger noise, static discharges from lightning all disturbs reception.
Mr. Ham is offline   Reply With Quote
Old 09-20-2014, 08:33 PM   #10
Mr. Ham
Member
 
Join Date: Aug 2014
Posts: 95
Default

Fox - was one of the last players to get into the game when television was analog, so many of the Fox stations were already in the UHF range of channels.
When the broadcasters wanted the UHF, they had to buy those channels and trade channels with Fox - in order to get permission to move their signal into the UHF.

As an example - WPSU migrated to channel 15 and started out broadcasting with 1 million watts of transmit power. They were later told that they were only allowed to use 865,000 watts and when the transmitter was broken in - they reduced their signal even further - down to 835,000 watts!

The difference in range between 1 million watts and 835,000 watts was about 3 miles loss of coverage!
This is what makes me giggle when I hear those CB'rs on the HF that thinks that they are going to set the world on fire with a 1500 watt amplifier!

Noise is Inverse the Square of the Frequency.
The lower in frequency you go, the more noise you experience.

Channel 8 - WWCP - did not change channels when they converted to digital.

Channel 11 in Pittsburgh traded frequencies with another signal - The CW and they migrated to channel 21 after the conversion, while the CW moved to channel 27 and 11.. KDKA to channel 25, WJAC to channel 34, WTAJ to channel 32...

WWCP transmits on channel 8 with a ERP of about 9.300 KW ...
You can pick it up easily anywhere within its 65 mile contour range as long as you have a decent location and a decent VHF antenna and coax.

WTAE in Pittsburgh is on the frequency for channel 51 - and has a ERP of 1000.00 KW

How much of a difference do you think there is in the electric bill between the transmitter for WWCP VS WTAE?
Mr. Ham is offline   Reply With Quote
Old 09-20-2014, 09:36 PM   #11
NN5I
Carl, nn5i
 
NN5I's Avatar
 
Join Date: Sep 2011
Location: Tallahassee, FL
Posts: 1,441
Default

Thank you; now I understand a bit better. When you meant North American TV you wrote terrestrial TV instead. Nave of me to suppose you would use the word that meant what you were trying to say. Forgive me; I'm a follower of Mark Twain, who once wrote "The difference between the right word and the almost-right word is the difference between the lightning and the lightning-bug." But actually I was uncertain whether NTSC and PAL were still in use anywhere. I still don't know. The only non-terrestrial TV I ever knew about was sent from the Moon by Apollo crews. I watched in awe when it was retransmitted via terrestrial (North American, NTSC) TV.

As for power cost comparisons between UHF and VHF TV, I understand you to say that, to achieve an equal footprint, one must run higher power than on VHF. I didn't know that, but have no reason to doubt it, and your explanation in terms of noise makes sense and is probably correct. Thanks for teaching. But first I had translate your use of noise to the standard engineering term spectral noise density, sometimes written noise spectral density with the same meaning. The second usage seems more precise to me but is a bit less common.

When, in your discussion of Channel 11, you refer to "the CW" I have no clue what you are talking about. That's not clearly enough expressed for old EEs like me.

Incidentally, you wrote "since you ask" but if you read it again you may see that I didn't ask. Careful reading is as important as careful writing, if communication is to be clear.

Cheers! Maybe we can talk about this stuff over a pizza some time. I'll buy. It'll be fun, because each of us knows stuff the other doesn't know.
__________________
-- Carl
NN5I is offline   Reply With Quote
Old 09-21-2014, 09:11 AM   #12
Radio
Administrator
 
Radio's Avatar
 
Join Date: Nov 2007
Location: Fayetteville, GA, USA
Posts: 3,017
Default

I've decided to ask Sweet Wife for a small 12 volt TV for Christmas.

She can figure it out.
__________________

KU4OJ "Wade" Ships Captain, CFO, Chief Engineer
KG4DQQ "Kathy" 1st Officer, Navigator, Best Friend
2007 F-150 SuperCab - 2009 Rockwood 8280SS
Lot's of mostly Kenwood stuff

Radio is offline   Reply With Quote
Old 09-21-2014, 05:38 PM   #13
N3LYT
Senior Member
 
Join Date: Jun 2012
Location: Maine
Posts: 709
Default

A 32" TV only draws about 240 watts most any little inverter will power it and the inverters are better than 90% efficient just turn them off when you are done to conserve power they do have a small idling current.
N3LYT is offline   Reply With Quote
Old 09-21-2014, 10:34 PM   #14
NN5I
Carl, nn5i
 
NN5I's Avatar
 
Join Date: Sep 2011
Location: Tallahassee, FL
Posts: 1,441
Default

Back when I was a TV repairman in 1958 or so, a 32" TV, if there even was such a thing, would likely have needed a kilowatt or more. How times change. I hear tell they don't even use 6SN7 dual-triode tubes any more. Madman Muntz would be perplexed.
__________________
-- Carl
NN5I is offline   Reply With Quote
Old 09-22-2014, 08:36 AM   #15
N3LYT
Senior Member
 
Join Date: Jun 2012
Location: Maine
Posts: 709
Default

Quote:
Originally Posted by NN5I View Post
Back when I was a TV repairman in 1958 or so, a 32" TV, if there even was such a thing, would likely have needed a kilowatt or more. How times change. I hear tell they don't even use 6SN7 dual-triode tubes any more. Madman Muntz would be perplexed.
We had a 9" round TV when I was growing up it seems like it had 50 knobs and you had to twist all of them to get a decent (black and white) picture It ran hot enough to make toast. Of course not know a thing about how they worked when some thing went wrong you took all of the tubes to the drug store to test them. I think it was a Philco and of course back then no one cared about watts I wonder just how much power it did take to light that thing up?
N3LYT is offline   Reply With Quote
Old 09-22-2014, 10:30 AM   #16
NN5I
Carl, nn5i
 
NN5I's Avatar
 
Join Date: Sep 2011
Location: Tallahassee, FL
Posts: 1,441
Default

Quote:
Originally Posted by N3LYT View Post
It ran hot enough to make toast. I think it was a Philco
I remember those Philcos. They were called "Philco dual chassis" because they had, well, two chassis, each with about fifteen tubes or more, and a great mass of wires going between the chassis. If tube-swapping didn't fix the problem in the customer's home, the outside tech wuld pull both chassis and bring them to me (I was the bench man who fixed them in the shop). Philcos were actually pretty easy to work on, unlike some others like Muntz, Hallicrafters, Hotpoint and GE. Hotpoint was GE's brand name for their cheaper stuff.

Muntz was hardest to fix because of the circuit design. They used a single amplifier string for both IF and AF. Each stage had input and output coupling for both frequency ranges. The signal went through the tuner, into the mixer, through about three or four stages of IF amplification, then the detectors; then the audio went back through the same tubes the IF had gone through. Muntz saved many vacuum-tube stages that way, but it made them a bear to diagnose sometimes. Muntz was the first brand of TV to sell under $100.

Hallicrafters and Hotpoint used metal cabinets with a picture tube that was mostly metal. Only the screen and the neck were glass. A metal CRT in a metal chassis, with about 15KV between them, meant the tech got bit pretty often. We hated them.

The shop was in Miami, back when Miami was an American city. One day a Cuban walked into the shop, declaring that he was the best TV repairman around. We had an old Hotpoint, or maybe it was a Hallicrafters, in the shop that no one could fix, and let him try to diagnose it. It had a metal CRT and a metal case. He took off the back, fired it up with a cheater cord, and stuck his head inside. His hands were on the metal case. He got a hot spark to the tip of his nose and jerked back, cutting the back of his head on the inside edge of the case. This caused him to jerk his head forward in reaction, and he got another spark to the tip of his nose. After about five cycles of this oscillation I managed to cut the bench power with the emergency switch. He pulled his head out of the case, looked around dazedly, and walked out. We never saw him again.
__________________
-- Carl
NN5I is offline   Reply With Quote
Old 09-22-2014, 06:04 PM   #17
Mr. Ham
Member
 
Join Date: Aug 2014
Posts: 95
Default

Quote:
Originally Posted by NN5I View Post
Thank you; now I understand a bit better. When you meant North American TV you wrote terrestrial TV instead. Nave of me to suppose you would use the word that meant what you were trying to say. Forgive me; I'm a follower of Mark Twain, who once wrote "The difference between the right word and the almost-right word is the difference between the lightning and the lightning-bug." But actually I was uncertain whether NTSC and PAL were still in use anywhere. I still don't know. The only non-terrestrial TV I ever knew about was sent from the Moon by Apollo crews. I watched in awe when it was retransmitted via terrestrial (North American, NTSC) TV.

As for power cost comparisons between UHF and VHF TV, I understand you to say that, to achieve an equal footprint, one must run higher power than on VHF. I didn't know that, but have no reason to doubt it, and your explanation in terms of noise makes sense and is probably correct. Thanks for teaching. But first I had translate your use of noise to the standard engineering term spectral noise density, sometimes written noise spectral density with the same meaning. The second usage seems more precise to me but is a bit less common.

When, in your discussion of Channel 11, you refer to "the CW" I have no clue what you are talking about. That's not clearly enough expressed for old EEs like me.

Incidentally, you wrote "since you ask" but if you read it again you may see that I didn't ask. Careful reading is as important as careful writing, if communication is to be clear.

Cheers! Maybe we can talk about this stuff over a pizza some time. I'll buy. It'll be fun, because each of us knows stuff the other doesn't know.
Terrestrial - means that it is broadcast through the air.
In today's world less then 30% of all television reception is done via terrestrial reception - due to the cable television and satellite television reception being the norm.

The type of digital broadcast is irrelevant - since we are not going to go to Europe or Japan to watch television in our motor homes.
Truthfully - the European standard was a much better type then the type we use in the USA - these decisions are made by the telecommunications Union - which the USA and Canada are a part of.

NTSC - never the same color twice - was an ancient way of broadcasting television. It was very inefficient - only allowed you to have one signal per a band - 6 Mhz of bandwidth..
The analog television transmitter was effectively two transmitters.
The video used a form of Vestigial Sideband ( 8VSB ) ( AM ) where most of the power was forced up into the one side band.
The audio was FM at a much lower power level, since FM did not have to over come the noise like the video did.

It's now possible to fit 5 channels into the same bandwidth as the one analog signal.

The CW is a television Broadcast Network, like Fox, NBC, ABC , CBS , ION etc. http://www.cwtv.com/

http://en.wikipedia.org/wiki/Television_station

VHF stations often have very tall antennas due to their long wavelength, but require much less effective radiated power (ERP), and therefore use much less transmitter power output, also saving on the electricity bill .
In North America, full-power stations on band I (channels 2 to 6) are generally limited to 45 kW digital ERP.

Stations on band III (channels 7 to 13) can go up by 5dB to 160 kW digital.

UHF, by comparison, has a much shorter wavelength, and thus requires a shorter antenna, but also higher power.
North American stations can go up to 1000 kW digital.

Low channels travel further than high ones at the same power, but UHF does not suffer from as much electromagnetic interference and background "noise" as VHF, making it much more desirable for TV.

Digital television transmission more efficiently uses the available bandwidth and can easily integrate other digital services.

Digital television has the potential for resolutions and sound fidelity far higher than those of analogue broadcasts.
t is also possible to offer far more channels by way of digital multiplexing, and subchannels, distinct simulcast programming, from the same broadcaster.

The amount of sub channels a station provides and the quality of the primary channel, has an impact on the quality of the remaining sub channels.

Decreasing the bandwidth available to the existing channel(s) meaning overall lower picture quality due to compression artifacts and non-proportional anamorphic widescreen digital scaling.
Mr. Ham is offline   Reply With Quote
Old 09-22-2014, 07:15 PM   #18
N3LYT
Senior Member
 
Join Date: Jun 2012
Location: Maine
Posts: 709
Default

The old thing we had was wooden with gold numbers and letters. My father worked for Westinghouse as an engineer so one day he brought home a Westinghouse TV it was huge! Well for a kid it was might have been 21" two days later it caught fire! That TV after it was repaired sat in the living room for more than 20 years I don't remember them ever buying another TV. Man today a 4 year old TV is really old the last one I got was at the dump cost me $3.17 for two caps in the power supply nice plasma 32” gets used maybe 5 hours a week.
N3LYT is offline   Reply With Quote
Old 09-22-2014, 07:23 PM   #19
N3LYT
Senior Member
 
Join Date: Jun 2012
Location: Maine
Posts: 709
Default

Here you go great reading for those nights you just can't sleep all you really wanted to know about TV transmitters. http://www.americanradiohistory.com/...th-Edition.pdf
N3LYT is offline   Reply With Quote
Old 09-23-2014, 02:47 PM   #20
NN5I
Carl, nn5i
 
NN5I's Avatar
 
Join Date: Sep 2011
Location: Tallahassee, FL
Posts: 1,441
Default

Quote:
Originally Posted by Mr. Ham View Post
Terrestrial - means that it is broadcast through the air.
No, it doesn't, even in technical jargon. In general usage it means of, or related to, Earth, and in the technical jargon of broadcasting it means broadcast from the surface of the Earth as opposed to being broadcast from a satellite, a spacecraft, an airplane, or even a ship at sea.

In the jargon of astronomy it means Earthlike. Mars and Venus are sometimes called terrestrial planets.

But even if it did mean what you say it means, it still wouldn't substitute for North American, which clearly is what you originally meant. Why so defensive? Everyone uses the wrong word now and then, and most don't get their hackles up when clarification is asked.

Let's start over. Speak kindly of your fellow hams instead of badmouthing every ham you've ever met; say something pleasant now and then; be less defensive when someone suggests you may be mistaken about something; and -- by the way -- could you tell us your name and callsign? Among hams that particular courtesy is as nearly universal as a smile; more universal, really, for in some cultures it is not customary to smile when meeting strangers. In Japan one maintains grave and respectful dignity, and a neutral expression. But one gives one's name everywhere, and among hams your callsign is part of your name. Refusing it, like refusing your name, suggests aloofness and hostility.
__________________
-- Carl
NN5I is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 02:44 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
×