HS antenna amplifier?

[Exnihiloest]

Bunch of broquignoles.... Who are worried about finding a solution to receive TV... Econology has really fallen into the bottom of the bottom...

It may be precisely because Econology has fallen into the background, and social networks in general (but less all the same ), let's fall back on the TV!

[phil59]

Bunch of broquignoles.... Who are worried about finding a solution to receive TV... Econology has really fallen into the bottom of the bottom...

Why are you so bitter, Macro?

[izentrop]

That's what I would do, put a simple T

Never been unhappy
We lose the impedance matching, it's the door open to parasites of all kinds,
...

If you believe that the impedance of the antenna and that of the TV is 50 ohms from one end to the other of the band, it is that you have traded the technical realities for a commercial spec.
At 25 ohms instead of 50 ohms, we stay in the margin for good reception, and with the wild assumption that everything else is correct, you would only see the difference with careful measurements. In addition too marked reflections, and there it would not be the case, it was a pb at the time of the analog; digitally, you can't see it.

loss of the shielding function of the coaxial cable...

There is theory and practice. Can you tell us what the standing wave rate will be when we go from 50 to 25 ohm? And the gain of the antenna that would now constitute the cable which would "lose" its shielding?

Anyone with a bit of knowledge would tell you:

Do you observe the presence of a molded "T"? if so, it is essential to remove it, put a 2-way splitter

https://forums.commentcamarche.net/foru ... ptions-tnt (old tips, problems with 4G not mentioned)

You spoke of 17 VATC cable rightly, it is the coaxial cable to be recommended for TV, because it has a strip which increases its protection against parasites and offers less loss as it ages than the old cables.
It is indeed in our interest to replace a long 50-year-old cable with this type of coaxial https://www.elbac.fr/datasheet?fichier=100160-00-E.pdf

On the other hand, its characteristic impedance is not 25 or 50 ohm, but 75 ± 3 Ω.
Breaking this impedance in a mismatch creates spurious signal reflections. In the analog era, it caused an echo in the image... In digital, it causes a loss of quality on certain multiplexes, with freezes, freezes, untimely images or downright loss of multiplexes.

[Exnihiloest]

...
Anyone with a bit of knowledge would tell you:

Do you observe the presence of a molded "T"? if so, it is essential to remove it, put a 2-way splitter

https://forums.commentcamarche.net/foru ... ptions-tnt (old tips, problems with 4G not mentioned)

You fell badly, my poor. HF is one of my areas of expertise, reception and transmission. Yes, we have an approximate impedance match. No, it has no practical consequence except in really limited signal level cases, and then even without T you would have pbs on one channel or another. I've been using one for years to serve 2 TVs, no problems and the signal isn't particularly strong. Given the price of a T, it's obviously what you have to try first and which has every chance of working.

You spoke of 17 VATC cable rightly, it is the coaxial cable to be recommended for TV, because it has a strip which increases its protection against parasites and offers less loss as it ages than the old cables.
It is indeed in our interest to replace a long 50-year-old cable with this type of coaxial https://www.elbac.fr/datasheet?fichier=100160-00-E.pdf

On the other hand, its characteristic impedance is not 25 or 50 ohm, but 75 ± 3 Ω.
...

Yes. I'm so used to 50 ohm pro that I forgot it's 75 ohm for TV. But what I said remains valid, you can always calculate the SWR for 37.5 ohm instead of 75 ("± 3 Ω" , in addition it will never be purely resistive, measure a TV antenna with a VNA and you will understand, there are some less than 80 € today, and very reliable).

[izentrop]

...
Anyone with a bit of knowledge would tell you:

Do you observe the presence of a molded "T"? if so, it is essential to remove it, put a 2-way splitter

https://forums.commentcamarche.net/foru ... ptions-tnt (old tips, problems with 4G not mentioned)

You fell badly, my poor. HF is one of my areas of expertise, reception and transmission.

Falls ? it's not a game, just a discussion between adults. Are you a radio amateur? I also have the license, but no longer active for a long time.

We do not have the same requirements in HF as in UHF. You have a good reception with 2 tee, without pixelation, so much the better for you, it is far from being the general case.
A splitter divides the input signal to distribute it equally on each output, without creating a standing wave, in a bandwidth of 5 to 2400 Mhz in general... A tee causes reflections.
The digital may not be disturbed by certain echoes, but it's haphazard luck, they vary according to the frequency...

[Exnihiloest]

...
Anyone with a bit of knowledge would tell you: https://forums.commentcamarche.net/foru ... ptions-tnt (old tips, problems with 4G not mentioned)

You fell badly, my poor. HF is one of my areas of expertise, reception and transmission.

Falls ? it's not a game, just a discussion between adults.

Exactly, don't switch roles, please. Rehashing the cliches found on the net, without evaluation in relation to the specific case we are talking about, I do not call that a discussion.

A tee provokes reflections...

That's what I said.
But if you don't quantify them or assess their impact, saying that or nothing is the same thing. That's like saying arsenic is deadly. No it is not fatal, we have atoms of it in the body, it is a question of dose.
I explained to you that going from 75 to 37 ohm causes reflections, but weak ones, which can even be lower than those related to the variations of the impedances of the TV or the antenna according to the frequency. So it matters little.

If you got the license, you should know that a 37 ohm load for a 75 ohm antenna and cable, gives you a standing wave ratio of 2, which corresponds to a reflected power of 11,1%. The input impedance will only receive 88,9% of the power instead of 100%, which corresponds to a loss of 0,5 dB (in addition to the 3dB related to the power distribution between the two receivers) .

0,5 dB is negligible, you wouldn't even see them on the S-meter, and 0,5 dB is even lower than the insertion loss of a passive splitter which is supposed to respect the impedance! So obviously the T is the solution to try first. And if that doesn't work, a splitter won't do any better unless it's amplified.

[izentrop]

Indeed my references on the radio go back a long way and have become a little dulled over time.

Apart from the operator's psychological fixation aspect which can lead to severe neurosis, ROS is not the enemy that one would think.
It causes some additional losses, it still has to be high, it does not cause interference on TVs contrary to what is said here or there (on the contrary it reduces them by reducing the transmitted power).

http://meteosat.pessac.free.fr/Cd_elect ... lt/swr.htm