Combining UHF aerials?

Mayo Exile

Theoretical question! Is it possible to combine group B and group C/D aerials? Both would be powered by masthead amplifiers. Just thinking about it, as would such a combination be better than a Group E or a wide band (Group W) single aerial setup?

Rippy

No problem at all. You just need a diplexer. A Triax 5153 would be a good bet(combines channels up to 51 (groupB) with 53 and over (group C/D).
Almost certainly better than single wideband, esp. if transmitters in differrent directions.!
Either or both aerials can be amplified, above or below the diplexer.

Mayo Exile

Thanks for that info Rippy. Any ideas where you would buy one of them via mail order in Ireland?

Mayo Exile

Either or both aerials can be amplified, above or below the diplexer.

Does this mean you have the two aerials feeding into the diplexer and then have a single masthead amp and power unit operating both aerials?

Mayo Exile

Does this mean you have the two aerials feeding into the diplexer and then have a single masthead amp and power unit operating both aerials?

Help! Any ideas?

byte

Yes. Depending on signal levels, introducing a combiner will incur 1-3dB attenuation, though it shouldnt' be enough to concern you.

As for supply, I'd try going to local electrical retailer, or local aerial installer, as these things only cost around 10-20 euro.

I agree with Rippy that a Triax 5153 or a Triax 5052 would do the trick. Some installers may use different brands, like Johansson, Fringe, Antiference, etc but idea is generally the same. Just make sure each leg covers the frequencies you need.

If you want both aerials amped, just feed both aerials into relevant port in combiner, then from combiner to UHF input on amplifier. Ignore the DC bypass screws (if Triax).

For online shops, I guess you could try ringing Donberg.ie or perhaps Maplin or Peats. But your local aerial install place woudl be handier for something so cheap.

Mayo Exile

Byte, thanks for the comprehensive info!

byte

Mayo Exile wrote:

Byte, thanks for the comprehensive info!

No problem!

Keep us up to date on how you get on.

Mayo Exile

Keep us up to date on how you get on.

No problem Byte. Its just an experiment really to see if i can pull in a better signal by combining a group B and group C/D aerial instead of using a wideband group W aerial. Both transmitters are roughly in the same direction and about 5 to 6 miles away.

One is the westport RTE Tx broadcasting RTE1/2/TG4 in group C/D, H, (channels 54, 58, 64)at 40w power. The other is a local deflector broadcasting BBC/ITV etc. in group B, H,(channels 39, 42, 45, 49) and, interestingly, TV3 way down at channel 68, H. Power of this deflector is unknown. In the summer tv3 seems to fade quite badly especially in warm weather. Current setup just uses a wideband aerial ("4 big X's" type) feeding into a wideband masthead amp. Have got hold of a group B 10 element aerial and a group C/D aerial, also 10 elements. It is worth combining the two into a Triax 5153 and see what happens? Both would be powered by the masthead amp. Would it pull in a better TV3 on channel 68 since sometimes it can be difficult to receive a channel at the end of the UHF band?

byte

I hate to say it but you'll probably be disappointed. A 10 element aerial normally isn't as gainful as a grid (commonly known as a Colour King).

Mayo Exile

Not to worry! Might try anyway! But would it pull in a better signal for TV3 on channel 68? Is it true that wideband aerials aren't particularly efficient at receiving signals at the edges of the UHF band?

Mayo Exile

A 10 element aerial normally isn't as gainful as a grid (commonly known as a Colour King).

How many elements would a UHF directional aerial want to have before it is better than a grid for gain?

Frisian

Or you should get yourself a Triax Unix 52 for around 40€. From my experience almost as good as the unix100. http://cgi.ebay.ie/Triax-Unix-52-TV-Aerial_W0QQitemZ5826765328QQcategoryZ73383QQcmdZViewItem
A grid is only a compromise if you don't want to stick up two aerials.

byte

Hmm, as Frisian says, probably a Triax UNIX52, or an ABC Aerials "Quad" aerial

Frisian, I would disagree about the UNIX52 being almost as good as a UNIX100. Only problem with UNIX100, is that it's not very sturdy in Irish weather! Though at least Triax have addressed the bracketry for it!

Better than the UNIX100 is the Hirschmann FESA 815 (I think) equivalent.