1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Loft TV aerial

Discussion in 'Audio Visual' started by DIYspanner, 2 Dec 2019 at 8:51 AM.

  1. DIYspanner

    DIYspanner

    Joined:
    17 Apr 2007
    Messages:
    1,535
    Thanks Received:
    52
    Country:
    United Kingdom
    I get my TV signal from Pontop transmitter and I have this aerial mounted in the loft. Usually good signal strength according the bar on the TV screen but when it rains, the picture tends to fizzle a bit and the splutters.

    Is there any advantage to fitting this type of aerial?
     
  2. Lucid

    Lucid

    Joined:
    10 Sep 2013
    Messages:
    1,324
    Thanks Received:
    629
    Location:
    Cheshire
    Country:
    United Kingdom
    Simple answer is no.

    Tri-booms such as the one in your link are a bit of a blunt instrument crossed with a vanity project for people who feel the need to show off that they bought the biggest-looking aerial in Christendom :D :LOL: :ROFLMAO:

    Your current aerial is not as high-gain as it claims, and it's not 32 element either. They counted each element 4 times. This is common sharp practise for the industry because it's easier to make big-looking numbers than explain how aerials really work. It's just human nature. The 'high-gain' bit only really applies to the upper-end of the frequency range; roughly frequency channels 50 to 68. The thing is that we don't use channels 60-68, and channels in the 50 to 59 range are getting cleared too due to 5G mobile phones.

    What all this means is that aerials such as the Tri-booms and your existing one will no longer be a good match for transmitters that used the upper end of the old ch 21-68 range. The new transmission frequencies will be lower down the range where these aerials don't perform that well.

    The TV is measuring on the optimistic side. Your signal is just over the acceptable level, which for digital is fine, but it leaves very little margin for any level change. In your case the rain on the slates/tiles is knocking off about 5dB and that's enough to cause disruption.

    Short term solutions:

    Fit a loft amp / masthead amp. As long as your quality reading is high (80+%) then you'll squeak by with this.

    Move and align the aerial for better reception in the loft.


    Longer-term solution:
    Change to a Log Periodic aerial fitted with a variable-level masthead amp.

    Ultimately, due to the Freeview retunes as a consequence of selling-off the channel space for 4G and 5G all the frequencies are going to move away from where a high-gain wide band aerial works best. Log Periodics are a good solution where the channels will be spread across what remains of the channel spectrum. That looks to be the case with Pontop Pike.

    If this or any other reply was helpful to you, then please do the decent thing and click the T-H-A-N-K-S button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
     
    Last edited: 2 Dec 2019 at 2:27 PM
    • Thanks Thanks x 2
  3. DIYspanner

    DIYspanner

    Joined:
    17 Apr 2007
    Messages:
    1,535
    Thanks Received:
    52
    Country:
    United Kingdom
    Thanks for the info.

    Based on your knowledge of Pontop Pike transmitter, which Log Periodic aerial would you recommend please?
     
  4. Lucid

    Lucid

    Joined:
    10 Sep 2013
    Messages:
    1,324
    Thanks Received:
    629
    Location:
    Cheshire
    Country:
    United Kingdom
    Go for a Log36pw from these people: https://www.aerialsandtv.com/onlineaerials.html#Log36

    I have no links with the firm, I just find them honest and very knowledgeable. Dealers such as this need to be supported. You save money in the long run because you don't waste time and cash buying the wrong stuff.


    If this or any other reply was helpful to you, then please do the decent thing and click the T-H-A-N-K-S button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
     
    • Thanks Thanks x 1
  5. winston1

    winston1

    Joined:
    11 Jan 2010
    Messages:
    5,065
    Thanks Received:
    355
    Location:
    London
    Country:
    United Kingdom
    Moving your aerial to the roof will probably solve your problem.
     
  6. DIYspanner

    DIYspanner

    Joined:
    17 Apr 2007
    Messages:
    1,535
    Thanks Received:
    52
    Country:
    United Kingdom
    That's the bizarre part. The aerial was on a pole outside, higher than the chimney and still the screen spluttered a bit.

    As per Lucid's recommendation (thanks), I contacted aerialsandtv.com and for my post code, they agreed log36PW was suitable so that's what I'll go for.

    I already have a Labgear meter although the transmitter being 324 degrees clockwise North, aligning by angle is easy enough.
     
  7. Lucid

    Lucid

    Joined:
    10 Sep 2013
    Messages:
    1,324
    Thanks Received:
    629
    Location:
    Cheshire
    Country:
    United Kingdom
    Sorry, but the labgear meter is about as much use as a chocolate fire guard. It's too insensitive and the steps between signal levels are too large.
     
  8. DIYspanner

    DIYspanner

    Joined:
    17 Apr 2007
    Messages:
    1,535
    Thanks Received:
    52
    Country:
    United Kingdom
    I'm inclined to agree with you based on having used the Labgear tuner to tune the aerial I have. Its obvious that the x4 led simply aren't enough to provide incremental change in signal strength.

    I presume the type with the digital display ribbon are more accurate but as I mentioned above, I eventually tuned in using the angle from Goole and referenced the roof apex for the angle in the attic.
     
    • Thanks Thanks x 1
  9. Lucid

    Lucid

    Joined:
    10 Sep 2013
    Messages:
    1,324
    Thanks Received:
    629
    Location:
    Cheshire
    Country:
    United Kingdom
    The Fringe Electronics Combined TV and Satellite Meter at £25 is a bit better, but honestly I wouldn't bother with that either. Out of curiosity, I bought both to test against my professional meter. There's an old post on here somewhere that gives the results of the tests.

    You could do a lot worse than buy a simple 0-20db variable attenuator for £5-£6, and then use that in-line between the aerial and a small portable TV. You'd need one with a single level display in a bar or numbers rather than just 'good, poor, fail'.

    You would start with a rough alignment, then put the TV on one of the stronger muxes - say BBC 1 or ITV 1. Next, display the signal level metering and gradually increase the attenuation until sits just on the cusp of failure. Tweak the aerial position. If the signal improves then repeat the process. If it gets worse, go back to the previous position.

    I would mark the angle of the aerial in some way. Maybe a plumb line off the end since you'll be working indoors?

    Return the attenuator to its lowest setting and repeat the procedure with a station from one of the weaker muxes. Note any difference in aerial angle. The stronger mux should tolerate a bit of loss, so if you have to compromise, then favour the weaker.

    Oh yes, and tilt the Log aerial either up or down. The signal level will improve by as much as 5dB.

    If this reply was helpful to you, then please do the decent thing and click the T-H-A-N-K-S button.
     
    • Thanks Thanks x 1
  10. DIYspanner

    DIYspanner

    Joined:
    17 Apr 2007
    Messages:
    1,535
    Thanks Received:
    52
    Country:
    United Kingdom
    I've got myself a compass and with the angle of the transmitter from my house, I'll use the compass to get it pointing then fine tune, if need be, as you suggest.
     
Loading...

Share This Page