TV aerial - external splitter/booster

[dannynolan]

We had an existing continuous cable (brown in photo) from the roof aerial to the aerial socket in our front lounge.

We wanted two new aerial sockets - in our rear lounge and in our kitchen (we had previously been using internal "set top" aerials for these TVs).

The quote for the work stated he would "add external splitter/booster from front lounge TV connection".

There was a grey box housing an old and not used cable TV cable which he has cut/dismantled and used the box to house the new splitter - the box does not now close properly. (see photo)

There is no sign of a "booster".

We are now getting poor or no reception on several channels on our kitchen TV - this is the TV furthest from the splitter.

He has suggested putting a booster internally in the kitchen next to the new aerial socket.

Any thoughts welcome.

Thanks in advance.

 

[Harry Bloomfield]

What has been installed is a splitter, for internal use only, so out side it will soon fill with water. It is just a signal splitter, not a booster/amp.

I would wonder if the guy has ever installed TV antennas before.

 

[dannynolan]

Many thanks for your speedy reply.

I know nothing about this sort of thing, but it didn't look right even to me, lol.

Sadly, he comes up 'recommended' on checkatrade.

Could you give me an idea of what he should have installed, please.

Many thanks.

 

[Harry Bloomfield]

Checkatrade - says it all really

Difficult to be sure, much depends on your received signal strength at the antenna, but either...

1. A water tight mast head amp, powered via the coax, then an indoor splitter mounted indoors
or
2. A combined water tight amp and splitter.

It might well be that your original signal strength from the antenna was adequate to supply one TV set, but he has divided that to a fraction of the signal strength it was, with that splitter. Further more, than bit of signal will soon deteriorate even more, once the rain water gets into those cables.

Very poor job indeed, he was so antenna installer.

 

[dannynolan]

He did say our original cable signal strength was very good so should be ok to split 3 ways, but he would put in a booster to make sure. (The kitchen TV involves a long cable run)

So, as you suggest, I was expecting to see an 'external grade' amp and splitter combi box installed roughly near to what he has done. Would this be ok ? ie. it would be a couple of feet above ground level rather than at roof aerial level.

Also do you have a recommended brand/model for the amp/splitter ?

Your help is very much appreciated.

Thank you again in advance.

 

[Lucid]

He has suggested putting a booster internally in the kitchen next to the new aerial socket.

Any thoughts welcome.

Thoughts?: The guy is a complete cowboy.


If he quoted you for a booster (better term is amplified splitter) then that's what he should have installed. Running a passive splitter is fine if - and only if - there's sufficient signal strength from the aerial to support the losses in signal level across all the muxes due the the splitter, the connections and the cable. All of this is easy to work out if the installer uses a professional meter and measures the signal level for each mux.

Signal losses are predictable and consistent. Good quality all copper cable such as WF100 loses 1.5dB per 10 mtr at Freeview frequencies. Each joint accounts for a 0.25-0.50dB loss. A passive 2-way splitter drops the source signal by 3.5dB. A 4-way splitter drops the source signal by 7dB. Since the ideal target signal level for a TV is 55dB at the set back socket, but most TVs will get by with 35-40dB, but the recommended minimum signal level is 45dB, then we can work back from there to see how much signal the aerial should provide in order to sustain the losses and still hit the targets.

For a basic "fly-lead out of the wall" installation

TV coax..................................... -0.25dB
5m coax to splitter...................... -0.75dB
Connections in/out of splitter.........-0.50dB
4-way splitter..............................-7.00dB

Total loss to the TV point............... 8.5dB

At the cut point then, the ideal signal level in this example should be 55dB + 8.5dB = 63.5dB on the lowest-powered mux.

An acceptable minimum would be 45 + 8.5 = 53.5dB

Whilst measuring, a competent installer would also check the signal quality. There are different error corrections systems for the DVB-T muxes to the DVB-T2 ones. The golden rule here though is not to add splitting to an aerial where there are problems with data errors. It's just asking for trouble.

Passive splitting does have the benefit of maintaining signal-to-noise ratio, which is partly a measure of signal quality. This means that if the signal is strong enough across the board, and will remain so by the time it reaches the set back of the most distant TV, then passive splitting is perfectly valid. However, the fact that you have marginal reception of some muxes suggests that the guy(?) just took a bit of a flyer on doing a cheap-parts-cost job so he could make a bit more profit.

Amplifying at the set backs is a bodger's trick. It's bad form. The fact that he has suggested it means, IMO at least, that the guy isn't taking responsibility for his earlier short cuts biting him in the bum.

 

[Harry Bloomfield]

So, as you suggest, I was expecting to see an 'external grade' amp and splitter combi box installed roughly near to what he has done. Would this be ok ? ie. it would be a couple of feet above ground level rather than at roof aerial level.

If water tight and an amp - yes, but it would need an adaptor behind a TV, to feed power up to the amp. It would though be better if the antenna lead were brought into the loft - splitter and amp in the loft.

Also do you have a recommended brand/model for the amp/splitter ?

No, it is not my area. We have a resident expert who will be able to advise.

 

[Harry Bloomfield]

If water tight and an amp - yes, but it would need an adaptor behind a TV, to feed power up to the amp. It would though be better if the antenna lead were brought into the loft - splitter and amp in the loft.



No, it is not my area. We have a resident expert who will be able to advise.

There you go - ask Lucid

 

[Lucid]

Outdoor passive 4-way splitter with weathershield - Labgear WBOS4F or the PROception equivalent - ball park about £9-£10 from Screwfix or Toolstation if you're buying for DIY.


A 4-way masthead amp with phantom power supply (low voltage DC going up one of the coax cables to power the amp remotely) - prices range from £25-£45 depending on the gain level, noise floor, and whether the amount of gain is adjustable.

 

[dannynolan]

Wow, that was some (first) reply, Lucid. Will have to re-read it with a clear head tomorrow to fully understand it. Thank you very much.
Also many thanks for the more specific parts recommendations.

Thanks again, Harry. Loft is easily accessible and has power so is probably the way to go. Just to check - cable from roof aerial enters loft, connects to amp/splitter with power supply, then new cables exit loft and run externally to new aerial socket positions ?

Thank you so much.

 

[Harry Bloomfield]

hanks again, Harry. Loft is easily accessible and has power so is probably the way to go. Just to check - cable from roof aerial enters loft, connects to amp/splitter with power supply, then new cables exit loft and run externally to new aerial socket positions ?

Yes, that's it. Cables external, if they have to be external, but they are better and tidier run inside if possible. All of mine are inside.

 

[dannynolan]

Cheers Harry - bloke is coming back this afternoon and at least I now have an idea of what I should say to him.
Should've asked on here first - you live and learn ! Will remember next time.

Many thanks for all your help

 

[Lucid]

@dannynolan, did this get sorted out?

 

[dannynolan]

Yes, the guy came back yesterday evening. He replaced the internal splitter with a Technomate TM-4 masthead amplifier placed at the split cable, with power supply from one of our TVs. The set-up may not be not the best, but we are getting good reception on all the channels we need.

Again thanks for the help, much appreciated.

 

[Lucid]

@dannynolan thanks for the update. I'm glad that things got sorted, and pleased we here helped, particularly @Harry Bloomfield for his input.

I know you said you're sorted, but I have a couple of observations just in case you run in to trouble down the line.


Technomate TM-4 masthead amp: If this is the one you've got TM-4 MAST - Technomate then the gain figure is 12-25dB. Two things from that: First, that's a heck of a lot of gain. Second, it's adjustable. [As a sidebar note, there's no proper spec for this splitter on the official Technomate web site. It looks like someone has done a copy and paste job and not bothered to change the specs from the TV recorder that was originally detailed.]

Regarding the size of gain; too much can cause signal loss just the same as too little. Digital TV can be odd like that; there's a minimum but also a maximum level. Going beyond either can create the same picture blocking and freezing issues. Your TV furthest away might be just fine but keep an eye on the TV on the shortest run. It's also getting a minimum of a 12dB boost.

If you start to see issues on that one then first check the masthead amp's gain control hasn't shifted. It should be on the lowest setting. Don't be tempted to add even more amplification. It's likely that the signal is already too strong on the strongest muxes. The level may need to be reduced on that specific feed from the splitter. That's done with an in-line attenuator.


TV as a power supply: Doing this is fine, but bear in mind if you ever change the TV that not all tellies have this feature. If you change the telly and then kfind yourself without Freeview reception then all you need to is add a masthead amp power supply.

Also, if you lose Freeview do go and doublecheck the menu settings. It's not uncommon for firmware updates to reset things. I've had the reverse issue at one house with an LG TV that insists on switching on its masthead amp supply voltage after a firmware update. I've had to put a DC block in place to stop the power getting up to a Log Periodic aerial. TV manufacturers aren't always careful about what happens to their sets during updates.