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/diy/ - Do It Yourself

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347318 No.347318 [Reply] [Original]

I'm having digital TV reception issues, does this antenna look like it needs to be replaced?

Some channels get 80%-90% signal strength but others only get 20% and either don't show up at all or keep cutting out.

It picks up analog TV fine and it is positioned directly towards the closest broadcast tower.

>> No.347319

Is the "closest broadcaster" broadcasting all channels?

Is it possible to improve the received signal strength, in any way, by redirecting the antenna?

>> No.347323

>>347319
Yeah, there is only the one broadcasting tower and it transmits all stations.

>> No.347328

Have any hams put up towers in your neighbourhood recently?

(Kidding!!!)

>> No.347338

Are there any mountains or trees obstructing the signal path?

You could try mounting it on a higher pole.

>> No.347351

Maybe water got in your connectors/cables and you have corrosion.
Seems unlikely that this would affect only some channels, but maybe the channel levels aren't all the same.

How are your neighbours' signals?

>> No.347369

Each channel is broadcast at a different frequency. It could just be that your antenna is not ideal for picking up all the frequencies that are being broadcast. Find out which freq the poorly received channels are on, which freqs the good ones are on and what kind of antenna you have, post the results here. You may need to use a second antenna to get good coverage of all the channels you want. Shouldn't be a big deal, antennas are real easy to DIY.

>> No.349059

>>347318
If you can receive analog TV fine but are having issues with DTV on the same station, odds are you're picking up an echo. I would wager that in analog, you see some minor ghosting on the channels you are having difficulty with. Those stations are probably transmitting on frequencies that bounce well. This is why a lot of TV stations, especially in urban areas, switched to UHF for their DTV transmission - UHF doesn't bounce. The ghosting artifact from an echo on analog was a non-issue, and could even be a bonus if you were in a far-flung area without good LOS to the tower, where the echo could often be a stronger and better signal. However, the same effect corrupts the hell out of a digital data stream.

I would tell you to switch to a directional antenna, but you are already using one. There might be a hack to make it *more* directional so you can better ignore the echo, (some way of shielding to the sides?) but I'm not good enough with antennas to know what would be effective.

>>347369

Doesn't matter, the antenna in his picture is a combo unit that covers all possible TV frequencies (at least in the US). The 4-bay antenna on top does UHF, and the bottom dipole array should cover VHF-hi and -lo, although half of it is cut off by the roof so we will never know.

I'm assuming OP's image is of /his/ antenna, of course, not just some random one he found on the internet.

>> No.349070

>>349059
Yeah, it's my antenna in the photo.

>> No.349073

>>347323
Doesnt mean its Vertical vhf and horizontal uhf, especially if they have added new channels recently. I know my city that im in has lost the need for vhf horizontal which was 2 analog. channels
also if its the higher frequency channels that are missing youve probably got old cables and a non shielded booster which. And lastely digital signal either works or it doesnt unlike analog were you will just get a terrible picture.
Also that antenna on your roof is OLD!

>> No.350005

OP, the antenna type is reasonable, correctly polarized and for the right band used with digital TV. There are, however, all sorts of faults that ruin the signal. First, inspect all contacts that should be made by metal parts on the antenna. The V-shaped poles should be rust-free where they meet the central bus wires. Look at the impedance transformer PCB in the electrical box on the antenna. If it has any active components, like transistors, make sure that your TV sends out the right voltage to feed it. If you are less than 15 miles from the broadcasting tower, consider removing the amplifying PCB and refitting a passive impedance transformer. I know they used to be sold for this exact type of antenna here, not sure what's up now.
Redo the cable connection by any means.
Check the plugs attached to the cable anywhere on its way to the TV. Some plugs are notorious for fouling up the signal ever so slightly so that no fault would be seen with analog TV. Use a plug with robust screws with metal-on-metal threads for the center pin. Those tiny white plugs with set-screws in the plastic are a POS.
If you have splitters in the way of the signal, note that they are often the weak point and your best bet is to find what exact type does one of your neighbors have (assuming they have a good reception) and buy exactly that. The sellers are unfathomably brass so as to sell malfunctioning crap. Here, all-metal splitters are good while those tiny white plastic boxes disable digital signal almost entirely.