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11. 

    grahamlthompson
    

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    chickenlegs - 8 mins ago  » 
    Thank you A1944 for your prompt. I will take note.
    Thank you grahamlthompson for your detailed response. I am confident that the local (relay station) transmitter is Bristol Ilchester Crescent - this hasn't changed in the time we have lived here. The polarity on the aerial is also correct and not changed in 20 years. I haven't "ignored" your suggestion to check the signal strength. There are a few logistical things I need to do before I can due to the set up here; get into the loft, purchase a length of coax and a few connectors etc. As described earlier, I have been part way through the manual tuning process by looking at the digital.co.uk web site, but I will complete this once I have investigated the signal strength suggestion but I can't do this at the moment.
    I'll let you know how I get on.

    From the DTG reception predictor

    Bristol Ilchester Crescent. All mux DVB-T except where noted

    BBC A 41
    D3&4 44
    BBC B 47 DVB-T2
    SDN 42
    ARQA 45
    ARQ B 39.

    To remove the amplifier you just need a coax coupler. Remove the aerial in and the output to the Humax box and use the coupler to connect the two cables.

    https://www.screwfix.com/p/labgear-plastic-coax-couplers-pack-of-10/26904#_=p

    | Thu 26 Sep 2019 8:52:42 #11 |
12. 

    chickenlegs
    

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    Hello again. So I have managed to detach the external aerial cable from all boosting device (including the masthead amplifier (MHA) and divert this directly to the Humax. These are my findings by investigating the MUX channels under the manual tune page, and in the bottom right hand corner of the 'info' area in the Humax for a selection of programmes:

    Test 1
    Ch41+ 73% signal (S), 100% quality (Q), Ch44 73% S, 100% Q, Ch47 (DVBT 2) 79% S, 100% Q, Ch42+ 70% S, 100% Q, Ch45 71% S 100% Q, Ch39 72% S, 100% Q.
    The programmes themselves tell a different story however:
    BBC1, 2, 4 plus all HD programmes - 50% S, 100% Q (by estimating how far the indicator icon is along the bar)
    ITV, ITV2, 3 and 4, plus E4 - "...signal is too weak" message and no picture or sound.
    Channel 4 and 5 - "...signal is too weak" message and no picture or sound.
    Channel 4 HD and ITV HD - 50% S, 100% Q. I haven't checked every channel as life's too short!

    Test 2
    I have made the same direct connection of external aerial to a Sony TV that is equipped with an internal Freeview tuner and ALL programmes are working including the ones that fail to work via the Humax. The TV doesn't have a method of checking signal strength or quality.

    A few questions follow:
    1. Does this indicate in itself that the tuners in the Humax are faulty given that the Sony tv works perfectly well under the same set up?
    2. What does 100% quality actually mean, given that the received, 'unboosted' signal strength falls below the recommended limit in the Humax instructions?
    3. Is it significant that the HD channels seem to work (and appear sharper) so much better than the non-HD channels?

    As a comparison, when the external aerial cable is connected to my MHA and booster/ splitter and then on to the Humax, I get 100% S and 100% Q when looking at the MUX channel manual tuning page, good news you might think, but lower signal and quality figures in each 'info' area for individual programmes. The ITV, Channel 4, 5 and E4 programmes for example show (on average) 75% S and 75% Q.

    Thank you for any suggestions you might have. Chris

    | Fri 27 Sep 2019 12:14:16 #12 |
13. 

    grahamlthompson
    

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    chickenlegs - 8 mins ago  » 
    Hello again. So I have managed to detach the external aerial cable from all boosting device (including the masthead amplifier (MHA) and divert this directly to the Humax. These are my findings by investigating the MUX channels under the manual tune page, and in the bottom right hand corner of the 'info' area in the Humax for a selection of programmes:
    Test 1
    Ch41+ 73% signal (S), 100% quality (Q), Ch44 73% S, 100% Q, Ch47 (DVBT 2) 79% S, 100% Q, Ch42+ 70% S, 100% Q, Ch45 71% S 100% Q, Ch39 72% S, 100% Q.
    The programmes themselves tell a different story however:
    BBC1, 2, 4 plus all HD programmes - 50% S, 100% Q (by estimating how far the indicator icon is along the bar)
    ITV, ITV2, 3 and 4, plus E4 - "...signal is too weak" message and no picture or sound.
    Channel 4 and 5 - "...signal is too weak" message and no picture or sound.
    Channel 4 HD and ITV HD - 50% S, 100% Q. I haven't checked every channel as life's too short!

    Test 2
    I have made the same direct connection of external aerial to a Sony TV that is equipped with an internal Freeview tuner and ALL programmes are working including the ones that fail to work via the Humax. The TV doesn't have a method of checking signal strength or quality.
    A few questions follow:
    1. Does this indicate in itself that the tuners in the Humax are faulty given that the Sony tv works perfectly well under the same set up?
    2. What does 100% quality actually mean, given that the received, 'unboosted' signal strength falls below the recommended limit in the Humax instructions?
    3. Is it significant that the HD channels seem to work (and appear sharper) so much better than the non-HD channels?
    As a comparison, when the external aerial cable is connected to my MHA and booster/ splitter and then on to the Humax, I get 100% S and 100% Q when looking at the MUX channel manual tuning page, good news you might think, but lower signal and quality figures in each 'info' area for individual programmes. The ITV, Channel 4, 5 and E4 programmes for example show (on average) 75% S and 75% Q.
    Thank you for any suggestions you might have. Chris

    You might have mentioned you have two amplifiers in series. If you removed the power to the masthead amp then it effectively stops the signal.

    The corrrect way to do this using a masthead launch amp is to distribute the signal using passive splitters. Doing it your way you are adding a large amount of unwanted noise.

    Without power to the masthead this means nothing. If the power supply for the masthead was in the feed to the TV it's not surprising that the TV then works.

    https://www.aerialsandtv.com/ampsandsplitters.html#AmplifierOrSplitter

    You could try plugging in a variable attenuator on the Humax input.

    https://www.ebay.co.uk/p/Labgear-19114s-In-line-Metal-Variable-TV-Signal-Reducer-Attenuator-0-20db/1005512082?iid=230614951249&chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=230614951249&targetid=594652110360&device=c&mktype=pla&googleloc=1007011&poi=&campaignid=1880674786&mkgroupid=73054546987&rlsatarget=aud-629407027585:pla-594652110360&abcId=1140496&merchantid=7362964&gclid=Cj0KCQjw5rbsBRCFARIsAGEYRwcYfVTPUn7r6b-Takyrvea9pgtHsIbNFTtzPpWpY-sUuvOQIGslrokaAtxFEALw_wcB

    | Fri 27 Sep 2019 12:27:54 #13 |
14. 

    chickenlegs
    

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    Just to update you. I have just spoken to a very helpful person at Humax support who tried to replicate the issue on the same model that he has, he couldn't and the conclusion that he drew was that the SID unit is "probably" faulty as the signal indicated in the manual tuning area should be consistent with the programme channel strength. He also suggested that I try and plug it in in someone else's home to see if the signal strength problem continues there. Not sure I want to bother our neighbours with this!

    | Fri 27 Sep 2019 12:42:20 #14 |
15. 

    chickenlegs
    

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    "You might have mentioned you have two amplifiers in series." I had mentioned this in my original post..."The aerial cable that comes from the external aerial is connected to a Maxview masthead amplifier MHA26U and in turn, connected to a Signal Booster, SLx TV Amplifier Four Output 27820BMR."

    I have not "removed the power to masthead amplifier" - In the test, I did not connect the Humax nor TV to it at all - I described this in my reply. The power supply was not "in the feed to the TV" the set up was exactly the same for both scenarios.

    | Fri 27 Sep 2019 12:51:27 #15 |
16. 

    grahamlthompson
    

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    chickenlegs - 26 mins ago  » 
    "You might have mentioned you have two amplifiers in series." I had mentioned this in my original post..."The aerial cable that comes from the external aerial is connected to a Maxview masthead amplifier MHA26U and in turn, connected to a Signal Booster, SLx TV Amplifier Four Output 27820BMR."
    I have not "removed the power to masthead amplifier" - In the test, I did not connect the Humax nor TV to it at all - I described this in my reply. The power supply was not "in the feed to the TV" the set up was exactly the same for both scenarios.

    So your test had around 10-20dB of amplification in the feed to the Humax which makes it useless. The whole idea is to test the signal from the aerial to the Humax without amplifying it all let alone two in series. If you want to test it this way without removing the masthead you need to be able to reduce the signal level using the variable attenuator.

    | Fri 27 Sep 2019 13:22:12 #16 |
17. 

    Trev
    

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    Does this not clarify exactly what chickenlegs has done (it's at the top of post #12 in which he quotes his results.
    

    chickenlegs - 2 hours ago  » 
    Hello again. So I have managed to detach the external aerial cable from all boosting device (including the masthead amplifier (MHA) and divert this directly to the Humax.

    So not quite sure where GLT gets the 10-20dB of gain from in post #16?

    | Fri 27 Sep 2019 14:24:02 #17 |
18. 

    grahamlthompson
    

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    Trev - 5 hours ago  » 
    Does this not clarify exactly what chickenlegs has done (it's at the top of post #12 in which he quotes his results.

    chickenlegs - 2 hours ago  » 
    Hello again. So I have managed to detach the external aerial cable from all boosting device (including the masthead amplifier (MHA) and divert this directly to the Humax.

    So not quite sure where GLT gets the 10-20dB of gain from in post #16?

    Very selective - the op totally failed to post the detailed reception from this post,

    https://myhumax.org/forum/topic/poor-and-sporadic-reception#post-74105

    Merely detailing the the transmitter without any indication of the likely reception conditions.

    https://myhumax.org/forum/topic/poor-and-sporadic-reception/page/2?quote=74132#postform

    Without a location within a close distance of the OP's location how can anyone have a clue as to the the likely signal strength.

    Basically ignoring the previous requested info. I have to ask is the weak signal due to location or down to the previously not declaring the fact that he used a masthead amp with a gain of generally 10-20dB plus a second amp in series that post DSO would strongly indicate a strong possibility that the issue is as suspected. That's why I posted the link regarding the use of amplifiers re passive splits.

    Had the OP posted more detailed info initially especially regarding multiple amplification that may have been required pre-DSO power increases we might have had a enough info to be able to be able to give a more reasoned opinion as to the likely reasons. Especially as to the detailed DTG reception predictions and the location of the OP.

    I use a loft aerial on Lark Stoke which is approx SE from me. My neighbour is south of me. Moving my loft aerial to the East extremity of my loft so the view misses his roof has resulted in a rock solid signal.

    Short wavelength UHF signals can create a large improvement in signal of only a few feet movement of the aerial.

    | Fri 27 Sep 2019 20:20:38 #18 |
19. 

    chickenlegs
    

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    Thank you all for your replies and for taking the trouble to consider this issue. As I am unable to fully understand some of the technical content of some of the replies, I think I will have to draw this to a close and ask someone to come and review and test the setup that we have here.

    | Fri 27 Sep 2019 21:06:29 #19 |

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