1/4 Wavelength of D10?

Discussion in 'Royal Signals' started by bibo_boy, Aug 6, 2007.

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  1. Anyone know the number to work out 1/4 wave length using D10 cable?

    Also, anyone had experiences using it?

  2. I used it to garot a previous partner who threatened to expose me
  3. Take a wavelength and divide it by 4.
  4. 71.4, or 68.something? Just use your TURF lad!

    (edited for biff fingers)
  5. elovabloke

    elovabloke LE Moderator

    Common – you know long range comms is the RAC’s domain. :party: Ring Bovvy, they will be happy to help.

  6. As a rule of thumb, 68, 67, or 69.

    I am assumiong you are talking HF freqs??

    If so..


    FREQ. LENGTH FREQ. LENGTH. FREQ. LENGTH. 2 31.2 11 5.4 21 2.6
    3 21 12 5 22 2.4
    4 15.7 13 4.5 23 2.3
    5 12.4 14 4.2 24 2.2
    6 10.3 15 3.8 25 2.1
    7 8.7 16 3.5 26 2
    8 7.6 17 3.3 27 1.9
    9 6.7 18 3.1 28 1.8
    10 6 19 2.9 29 1.7
    20 2.7 30 1.6

    Now why the fek does that look one way when I write it and a ball of bollarks when I post it???
  7. velocity = frequency x wavelength

    so 1/4 wavelength = speed of light / frequency / 4

    = 300000000 / (something between 20000000 and 100000000) / 4

    So start at 3.25m and cut off 100mm at a time until you get a good reception. If your antenna is less than 750mm long, you've gone too far and will have to start again.
  8. Surely that is the wrong way of looking at it?

    D10 cable is just that - a cable! It can be turned into an aerial and tuned to a frequency with the simplest of tools - a wirecutter!

    What frequency do you want to send/receive? Then use the calculation:

    Wavelength (m) = speed of light(m/s)/frequency (Hz)

    As a part-time geek, I always check that I have the correct formula by using Radio 4 which transmits on 1500m Long Wave at 200KHz:

    Lambda = 300,000,000/200,000

    which in this case = 1500m.

    Insert your own frequency and divide the result by 4.

  9. 68/f
  10. Where f is in MHz of course... otherwise your antenna ends up a bit short.

  11. Fcuk me! You must have a bloody big mast.
  12. Do you connect both elements (halves/side) of the D10 or only one? Also do you connect the steel and the copper or just the copper? So many questions... :twisted: Oh and can you use quad, if so whats the calculation?
  13. Is that a wah, coz I'm tempted to answer. DI0 - 4 copper wires for conductivity and 3 steel for strength.
  14. Curious. What you describe sounds like D7 - a seven strand cable used in WW2. D10 was a post war development having ten strands for reduced resistance and better resilience, though extensive war stocks of D7 continued to be used at least into the 1980's and were (erroneously) referred to as D10.

    Are we still using 60 year old cable or has the specification changed?
    Or was I wahed all those years ago?

  15. Surely the 3 steel strands are for forming a cross-shaped framework on top of the old MKI kero heater in order to produce the finest 'Toast a la Line Bedford'?