Orrymain,
If you can't change the flatlead from the antenna to inside the house because of not being able to do it physically or money, you can buy an reverse balun. You may already have one.
Any balun will work either way but by reverse I mean it has screw terminals to attach flatlead, then outputs into a coax plug normally.
I am a little confused because in one post you said the flatlead goes to an AB Switch and the other you said it goes straight to the VCR.
You might want to start over and explain your set up. Starting from the flat lead from the antenna, and the cable that brings in the cable signal.
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Then as an aside: The reason I don't suggest twin lead for anything any more is it must be installed perfectly or you have problems. It must be kept several inches away from any metal (remember the old stand offs for twin lead for a mast?). It can't take a corner with a radius any tighter than a 1/4 wavelength at the highest frequency its carrying. Extra can't be piled behind the TV, it has to be draped smoothly and to the right length. You can't just run the stuff through the wall unless it's away from metal studs, metal walls, other wires in the wall that are parallel to it or get hung in the wall where you can't see and get twisted or wadded up.
Ok that said. There is nothing stopping anyone from using flatlead for digital. (again I tell people to avoid it as it's so tricky to install properly)
Good quality flatlead has less loss than coax. Twin and flat lead are used all the time commercially. Most AM radio stations, the tower is feed with some form of flat lead, not coax.
Remember that
ATSC signals come to us
OTA on the same analog medium that
NTSC did called Radio Waves that don't care what is modulated onto them, as far as propagation, loose in transmission mediums.
Know that wire that connects the elements in a standard 2, 4 or 8 bay collinear? That is a form of twin or flat lead in open wires. The wires that connect the many active elements in a combo antenna like a 769xP series are open wire line.
Just about all broadcast arrays that have muliti elements are phased with open wire line.
Heck just about all TV antennas are 300 ohm open wire line till they go in the balun.
Open wire, flat or twin lead are all balanced transmission lines that work on the same principle.
Flat lead is also much more tolerant to SWR or also known as antenna or receiver mismatch.
I found a quote from Antenna Engineering Handbook, for 100':
Channel 4 9 24 44 64
Twin lead 0.9 1.6 3.3 3.8 4.2
RG-59 2.4 4.1 7.2 8.5 8.8
RG-6 1.7 3.0 5.5 6.1 6.8
(my note here. RG6 made today is better see my interpolations from a chart below.)
* RG6 now 1.3 2.5 4.9 5.5 6.0
Balun insertion loss:
*about the same today
Channel 4 9 24 44 64
0.8 0.6 1.1 1.2 1.7
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This is given properly installed flat lead above.
So at channel 24 say a flat lead system to an old TV with flat lead input would have only 3.3
db of loss.
Same setup with a balun at each end and 100 ft of modern RG6 would be
1.1 + 1.1 + 4.9 = 7.1
db loss for RG 6 system.
That is 3.8
db more loss in the coax. In percentage terms that means coax and 2 baluns loose 58% more signal than twinlead at 100 ft.
It amounts to 3db more loss in RG6 over twinlead at only 50 ft. 3b is 50% signal loss.
This doesn't even take into account the fact that most antenna being broadband are not perfect resistive 300 ohms across the TV bands. Stated above twin lead is much more tolerant to small mis matches up to about a SWR of about 2 to 2.5 without loosing little to no signal on a receive antenna system. Coax, with that kind of mis match which is there on some channels is another
db or so.
So considering there is about as much chance the channel you are watching is not perfectly matched at the antenna as it is, you can easily add another
db of loss to the calculations above for coax (RG6). One
db of loss is about 20 percent loose.
I remember trying coax on my dad's TV back in the early 70's and the twin lead gave a better picture. But back then all I had was RG59, which meant on his system, I was loosing about about 6
db on VHF which were our channels. I put the twin lead back.
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But the sheer convenience of coax far outweighs the benefits of twinlead because it can be snaked through about any thing or corner as long as the turn is not so tight the center wire migrates through the insulation.
But this also explains the popularity of mast mounted amps. They overcome the loss in a coax. [Remember most of the improvement in short coax runs, under 20 ft, is not because the signal is amplified, but the amp has a lower noise floor than the receiver, another topic.]
Lets take the above system now with RG6 and an amp.
We have about 1.1
db loss in the balun on the antenna and a short coax to the amp. Maybe lets say, 1.5
db total between the antenna and the amp.
We add just a 12
db mast amp. Now we have negative 10.5 loss (but not more signal, as you can never have more signal than the antenna receives itself).
100 ft of RG6 looses -4.9 more. So at the end of the coax you still have negative 5.6
db loss. Most modern TVs have a 75 ohm input stage so no more loose.
Remember double over, we have not created an extra 5.6
db gain. But the fact the system loss between the amp and the TV is still anything in the negative range, means we have the same signal at the rear of the TV we had at the input of the amp.
So the TV sees about 80% of the signal picked up by the antenna with the only real loss of signal in the balun and coax to the amp from the antenna.
So now we have 100 ft of cable, RG6 on Ch 24 and only have 1.5
db of loss. This beats the twin lead hands down but only because it was amplified at the antenna.
For that matter with that system above you could have used some old RG59 from the amp to the TV and still ended up with negative loss between the amp and the TV.
And this in fact is part of why amps became so popular, as good RG6 until 10 years ago was a lot more expensive than RG59. Now so much RG6 is used in everything, cable, satellite,
OTA, sometimes you find at the store, either no RG59 or it's the same price nearly as RG6. But back in the day RG59 was cheaper and RG6 even at a time was hard to find (remember local sources only or mostly as there was no internet and few 800 number catalogs even).
Most of the older amps only had 12 to 20
db of gain, which even today is enough for most systems.
But important note in the channel 24 example above. If you added a 4 way splitter to 100 ft of RG6 with only a 12
db mast amp, you would end up then with a positive 1 to 2
db of loss after the splitter (4 way adds about 7 to 8
db).
Then they started using more gain as an all encompassing benefit in an amp which it really isn't, as you can have too bid an amp and over load, loosing signal, even worse on digital.
So you don't want to buy too big of an amp for a system due to overload, but in the example above on ch24, 100 ft of RG6 and a 4 way splitter, one needs a 20
db amp at the antenna.
Twin Lead Wire for DTV and HDTV
Linear Mode
