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    by MouldBuilder πŸ‡¬πŸ‡§ ( Midshipman)
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    101 Posts 100 Replies 57 Photos 236 Likes
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    jbkiwi
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    Country: πŸ‡³πŸ‡Ώ New Zealand
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    Was that a flight of F16s that just went over?!!! (kiddin)πŸ˜€ Interesting stuff.
    Nerys
    Chief Petty Officer 1st Class
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    Hi Doug,
    In reply, Alice tells me she agrees with everything you say about the loop aerial. It has a motorised airspaced variable capacitor that can resonate it from about 3.4 to 10.2 Mhz. Yes it is very directional and should be on a rotator. It is a bit low to the ground but it does have a two sharpish nulls. It is designed for transmitting, but at very low efficiency! The capacitor won't arc over at even 100 watts of SSB! (Alice doesn't have a linear) but Alice uses it as a receiving aerial or extremely low power transmit because of the danger of high RF flux in the vicinity of it. The phone lines around here are overhead drop wires some are still unscreened pairs. She could be wrong as there are other noise sources, such as ethernet over mains wiring adaptors, SMPSU's and all sorts of poorly suppressed cheap crap but Alice thought that ADSL frequencies were something like 262Khz to 13.7Mhz well within the HF spectrum.

    Cheers,
    Nerys
    When the winds before the rain, soon you may make sail again, but when the rain's before the wind, tops'l sheets and halyards mind
    RNinMunich
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    Absolutely NerysπŸ‘
    many of my (former) customers wanted to use these things on HF, mostly from aesthetics or stealth (πŸ™„) aspects. Er! Efficiency? Wossat? πŸ˜‰
    They're not actually designed for transmission! Unless the circumference is a significant proportion (>30%) of the wavelength to be transmitted.
    Even then, put significant power into it and you risk burning anyone near it!
    Put just a few watts RF power into a small loop antenna and you get kilovolts on the antenna terminals, that's cos the TX current in the antenna is so high. So it needs a large expensive resonating capacitor with a very high breakdown voltage and low dielectric loss.
    What you have there looks more like a DF receiving antenna to me.
    I trust it is rotatable cos it's propagation/reception characteristic will be two main lobes 180Β° apart on the axis through the centre of of the circle.

    You mention "frequencies it's designed for", what frequencies are you using it for?
    I assume shortwave.
    Surprised that you have interference from ASDL! Although I realise that ASDL uses frequencies from 26.075 Megs upwards to 137Megs for the Upstream communication ASDL connections are usually screened underground cables which shouldn't bother you!?
    Unless there's a fault in the cable or your local distribution box😠

    I only came across such loops (or more usually rectangular frame antennas) on board ships as an attempt to reduce the radar signature. Unfortunately at the expense of COMMS efficiency.
    ☹️
    Cheers,Doug 😎
    Young at heart - slightly older in other places πŸ˜‰ Cheers Doug
    Nerys
    Chief Petty Officer 1st Class
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    Marky and Martin, that's a magnetic loop aerial, it's a very compact aerial for the frequencies it's designed for, but is better for receiving than transmitting. It's just one of the aerials in the garden.

    cheers,
    Nerys
    2
    When the winds before the rain, soon you may make sail again, but when the rain's before the wind, tops'l sheets and halyards mind
    Nerys
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    Thanks for the compliments jbkiwi, Alice has a FRG7, sitting in the kitchen, it works but she has a lot of problems here with noise from overhead power distribution, ADSL broadband etc, but we can go up the mountain, a couple of miles away to practically complete silence.

    Cheers,
    Nerys.
    When the winds before the rain, soon you may make sail again, but when the rain's before the wind, tops'l sheets and halyards mind
    Nerys
    Chief Petty Officer 1st Class
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    Thank you for all those kind words Doug. Alice's call sign is G(W)7SEH which she has had since she was 18, but she isn't on the air at the moment as her 'shack' had to go when the room was converted to a Dialysis chamber (of horrors). To prove that I could learn something new at over eighty, four years ago, I did the Foundation course and have the call sign M(W)6TLN. Once the shed is completed, Alice will set the shack up again complete with work benches for her main interest of restoring vintage radios.
    Future exploit, Alice wants to buy a milk float when one comes up at a sensible price and not too far from home and convert it into a campervan.

    Cheers,
    Nerys
    1
    When the winds before the rain, soon you may make sail again, but when the rain's before the wind, tops'l sheets and halyards mind
    Martin555
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    Marky that is just a DF loop for one of her models LOL!

    Martin555.
    2
    If it looks right it probably is.
    marky
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    Nery's ,that's some serious radio antenna in the garden,or just bad telly receptionπŸ˜€,Great bit of workshop building πŸ‘
    Cheers Marky
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    jbkiwi
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    Don't you mean "that's another Yagi" These ladies sure have a big 'Array' of talents don't they! Still have my old 1978 Yaesu FRG7 comms rec in its original box, can't seem to get a lot from this place, (facing Nth but have 10000v, 400v power lines down the road outside and just get tons of noise. Going to have a crack one day at putting a big whip up my 16m Macrocarpa tree, (had one while working on Norfolk Island (between NZ and OZ) and I got from Scott base to the Coast Guard in Kodiak island Alaska.) Used to enjoy listening to the US Coast Guard chasing smugglers etc.
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    jbkiwi
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    You're onto it Martin, you'll be fine cuddling up to your specially heated giant model Sea Bass comforter!! (with LED night lights and Marylin Munro sound unit πŸ˜‰
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