How to use Spacelab DF200 Aerial Signal Strength Meter

Discussion in 'Freeview & YouView' started by gilbey666, Aug 2, 2012.

  1. gilbey666

    gilbey666
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    I need to align a Televes DAT45HD Boss aerial and have been loaned a Nikkai Aerial Strength Meter which I believe came from Maplins but seems to be a generic type meter like the Spacelab one. I believe I place it in line between my Distribution box and aerial. I am using CT100 type cable and there is an in line masthead amp. Grateful for advice.
     
  2. Rodders53

    Rodders53
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    Use a compass and point the aerial the right way and correct polarisation. Using data from the 'detailed vieew' of Digital UK - Postcode checker

    I believe the Boss has a margin raising device (MRD) aka an amplifier built into the X-shaped dipole... that needs dc power from a TV or mains power unit to work (but it's not 100% essential). You shouldn't really have - or need - a separate masthead amplifier in line with the Boss but that will need DC power in the same way as the MRD.

    Tune a TV in using the manual frequency channel numbers for the transmitter. Most TVs incorporate signal strength and quality meters to confirm things are OK.

    There will be little to gain from using a simple meter over pointing the aerial via a compass... Ricability | Aerial signal meters | digital TV recorders | set top boxes | Digital Switchover | Digital TV dtates the Nikkai is 'very difficult to use' or 'poor' depending on precise model.

    http://www.maplin.co.uk/aerial-signal-strength-meter-221768?c=AffilWin86732&t=20680322 Q&As may help?
     
    Last edited: Aug 2, 2012
  3. gilbey666

    gilbey666
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    That doesn't sound too encouraging!

    I wanted to use this to get the best alignment as we are in a fringe area with the best reception not always at the normal bearing. Access to the aerial is also difficult as on pole in roof valley as we are in a conservation area, so wanted to use this before leaving the roof.

    Do you know where I can get instructions? I believe you roughly align aerial as you suggest, use the gain knob to centre the needle, then tweak the aerials heading until the sound rises or needle goes off the scale. Then centree the needle again and do the same. Does this sound correct? The dial shows, OFF to the left, then 10% to ON, then 1 - 8 in increments to the right.. The gain control is 0 at centre, minus to left, plus to right. Power comes from the Mast Head Amp
     
  4. Rodders53

    Rodders53
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    Welcome To SPACELAB doesn't have it so unlikely you'll find them (and would they be much use anyway?).

    You have the right concept to adjust to obtain the maximum signal. (which will be highest needle reading with minimum rotation of the gain knob. Max 'smoke' indicated by such a simple meter may, however, not be the best for signal quality... and may well only be for one of the many frequencies it responds to... By all means use it as you describe - but you will need to be prepared to go up and down to readjust.

    If the 'best' signal isn't direct from the transmitter but a reflection off a hillside/tree/building it may well vary with the seasons and or other factors. Unless the first attempt gives good results via the TV's meter for all 6 multiplex frequencies (100% quality and good signal level), the aerial may need adjusting up/down (in height), and crabbed left/ right and fore/aft to find the 'best spot'... A process that needs checking for all 6 multiplex frequencies via the TV meter after each adjustment. [Moving the aerial in a cube of space with sides 1 metre long is all that's needed, typically, but moving only a few centimetres at a time! An aerial installer would use a meter with a spectrum analyser display to aid this process.]

    IF the meter passes DC then the Boss HD's margin raising device amplifier (up to 12dB gain) will be operational, if it doesn't then the aerial will be 'passive'. DO try the aerial and MRD without an additional masthead amplifier in circuit as that should give the lowest noise signal. If you then need it, check if the masthead amp blocks DC to the aerial connection or not (it's best to not cascade amplifiers).

    An indication of location and the outlook from your roof valley toward the transmitter (trees, buildings, etc.,.) would help. Is the roof metallic at all (e.g. thatch with chicken wire) as that could cause 'oddities' at UHF if the aerial is near (within a metre at any point). Feel free to PM me with your postcode - unless there's a very nearby school, village hall, shop or pub you can publish in this thread.
     

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