8 replies to this topic

[dandufunk]

Hey guys,


I've just recently did a whole revamp of the coax in my house, everything is now RG6 quad shielded coax, matchmaster splitter and masthead amp, and the antenna got installed by a local tradie and is now a Matchmaster 01MM-DC21A.

Signal is great to TV 2 and 3, but TV 1 is horrid..... TV 1 gets turned on and you have to wait around 3-5 mins before the signal kicks in and you have a picture.

TV 1 is the shortest run out of the lot being around 3.5m from the splitter, the other two TV's are 12m+.

When TV 1 is turned on I can check the SNR and i get almost 99% noise and 0 for signal, when the picture finally kicks in its the other way around, almost 0% noise and 99 for signal.
I'm guessing that because it's such a short run the signal strength is too high to that TV and it's crapping itself....???

Even before I had the masthead amp installed it still had the same issue but would kick in slightly quicker..... now it's taking a lot longer to get a picture.

Here's a crude drawing of my setup, any input would be awesome. Thank you for reading.

Daniel

[Adelaideltpc]

Double check all F connectors, ensure they're not shorted (look carefully for those little strands)
Get a signal meter (from Jaycar) and check the signal strength before the masthead amp, and every other points ..

[nbound]

Whats your location and masthead gain rating?

But honestly sounds like theres a problem with the TV itself, if its too high its going to adjust straight away or it wont. Try swapping 2 TVs around.

[andrewlace]

If it was doing this before the amplifier was installed it is less likely to be too much signal (unless you previously had a strong signal). I'd try restoring the settop box to default and doing an auto scan first.

[jsmith]

dandufunk, on 20 June 2012 - 10:19 PM, said:

Here's a crude drawing of my setup, any input would be awesome. Thank you for reading.

Daniel

Have you tried taking the amp out of this picture... or did you have a low signal prior to installing?

Of course most DVB tuners have a dB limit, too little and the signal drops out but of course too much and that same thing happens... signal loss happens in the splitter, around 10dB per connection and it doesn't matter whether the TV is on or not. The best signal range is between 30 and 65dB.

Good luck.

JSmith

Edit:  P.S. Bear in mind the amp also amplifies any noise so can sometimes make an ok signal worse...

Edited by jsmith, 21 June 2012 - 04:23 PM.

[nbound]

jsmith, on 21 June 2012 - 04:14 PM, said:

Of course most DVB tuners have a dB limit, too little and the signal drops out but of course too much and that same thing happens... signal loss happens in the splitter, around 10dB per connection and it doesn't matter whether the TV is on or not. The best signal range is between 30 and 65dB.

On a 3 way splitter 10dB would be a little on the high side. Also Im yet to see a TV tune/lock onto any transmission at 30dBuV. You will want probably about 50dBuV before a channel reliably locks. Of course without a meter its pretty hard to tell what signal levels you have. MER/BER are better indicators of reception quality/reliability.

Edited by nbound, 21 June 2012 - 06:48 PM.

[dandufunk]

Wow, awesome replies thanks all.
First thing to do is swap the TV around to another point, see how that goes.
Second thing I'll do is check the f connectors, I am a bit ocd with my neatness of cabling and crimps but its worth a look.
After that I'll go get a Jaycar tool or see if one of elecs at work has a signal tester.

Can you check signal with a multi meter?

Thanks again guys,
Dan

[mtv]

dandufunk, on 21 June 2012 - 09:54 PM, said:

Can you check signal with a multi meter?

No... and Jaycar don't sell professional digital signal meters either.

To measure digital TV signals accurately, you need a meter/spectrum analyser which measures the digital channel power (DCP) in dBuV, modulation error ratio (MER) and true pre-viterbi bit error ratio (BER).

You still haven't mentioned your location and which transmission site your antenna is pointed at and the make/model of amp you are using.

This will help provide an indication of likely signals in your area.

Signal quality is more important than signal strength, however, if signal strength is too high, it can create errors in the digital data stream and reduce signal quality.

Depending on where you are, it is possible you don't need an amp at all for a 3-way split.

[dandufunk]

Before I went into the roof cavity thought I'd check the tv by taking it to another point in the house.... Same problem..... 100% tv is the problem.

Thanks for the input everybody.

Dan