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Thread: Help with 40m antenna location

  1. #1
    dtrewren's Avatar
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    Default Help with 40m antenna location

    Hello Forum,

    I am after a spot of advice. I have recently decided to get back into Ham radio, more specifically the 40m band. It
    has been decades since I last radiated but the recent purchase of the SDRplay software defined radio has really got
    me interested again.

    I have a FT-450D radio and want to pop up a 40m antenna. My dilemma has been whether to erect the antenna in my
    house loft space or in the garden. The garden is going to be difficult as I have to get is past the wife .......

    So I have used the SDR to perform an experiment directly comparing the performance of a very simple dipole both
    in the loft and in the garden. The difference in performance was really quite evident.

    So I was after some advice from anyone in the know .....

    I have created a couple of videos, one showing the experiment and the second generally on the SDR radio.

    Dipole experiment : https://youtu.be/iED-NMExsAY

    SDRPlay radio : https://youtu.be/5rUacLj6G5Q

    Thanks in advance ....

    Dave

  2. #2
    Super Moderator 2E0FVL's Avatar
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    Outside if possible, mine is in a square along under the guttering on the house and three sides of the garden at only 15ft high and works quite well.
    Pete - 2EFVL
    The QRM Formally Known As M6PAP!!
    www.selseylifeboats.co.uk
    www.amberleymuseum.co.uk

  3. #3
    dtrewren's Avatar
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    Hi Pete, thanks for getting back !

    I have a workshop at the end of the garden which is 9m wide. So I was going to pop a couple of posts up in the two
    back corners. There is a fence running to the right of the workshop back towards the house. The fence would also be
    an anchor point - I was thinking of a 40m delta loop in a horizontal flat triangular arrangement.

    Does that sound ok ?

    How high off the deck should the antenna be ideally ?

    Cheers,

    Dave

  4. #4
    Super Moderator 2E0FVL's Avatar
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    Don't know anything about delta loops, but any antenna as high as you can get it is the way to go.
    My set up was put together using what I had at the time, when I found out it worked and no complaints from neighbours I just left it!!
    Pete - 2EFVL
    The QRM Formally Known As M6PAP!!
    www.selseylifeboats.co.uk
    www.amberleymuseum.co.uk

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    What would your wife think about a nice flagpole vertical?

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    Quote Originally Posted by W5DXP View Post
    What would your wife think about a nice flagpole vertical?
    Well not to put too fine a point on it - I suspect I know where the flagpole will end up

    I have a FT-450D arriving tomorrow and a mate is bringing a bunch of antenna hardware in for me so I am going
    to have a play and see what I can hear. I am so impressed with the SDRplay radio I am going to modify the
    FT-450D to add a 70MHz IF tap. Therefore the SDR will essentially see the same antenna as the 450D with a
    mute on Tx.

    So much tinkering to do and so little time

    Dave

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    So Dave, how did it turn out for you?

    I have a story about the 40m vertical I put up this last fall but I won't hijack your thread with that. Perhaps I will start one for that soon. Still, how'd it go?

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    Hello WZ7U,

    Thanks for asking after progress - I have been getting on well and having a lots of fun.

    The antenna a friend let me have was essentially very broken, lots of water damage and wiring also almost beyond repair. So
    rather than messing around I bought a 80-6m off centre dipole total length 41m before tuning. This fits well within my rear garden
    although ATM is very close to the ground at only about 3m (9 feet) from the deck. I realise this is far from ideal but is still performing
    quite well I think. The current SWR on the 40m is miles out because the antenna needs a tune and has good SWR around 3.5MHz. I
    have about 30m of RG213 feed to the antenna, running back into the house and my office.

    I also got hold of a generic data cable in order to work PSK31. The cable has two 3.5mm mic/audio plugs and a USB connection to
    allow the radio PTT to be controlled from the PC. I fitted a 6pin mini din for connection to the Yaesu FT-450D. Worked really well
    and I had my first PSK31 QSO into Europe only a couple of nights ago. Seem to be able to get well into France and Sprain from the
    UK on only about 20W and that is into a currently badly matched antenna.

    License renewal came through just in time from OFCOM so I am officially back legal as G7IYK.

    On the radio front ... I have sourced a small wide band low noise amp board which will be fitted into the FT-450D to produce an
    RF output suitable as an input to the SDR. This will allow me to use the SDR to effectively see the same antenna as the rig and
    provide ~60dB of isolation during transmit.

    So having lots of fun and planning on making a few little videos to show what's been going on

    Bet you wished you hadn't asked now !

    73's

    Dave (G7IYK)

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    Quote Originally Posted by dtrewren View Post
    How high off the deck should the antenna be ideally ?
    Ideally? 1/2 wavelength. In the real world, as high as you can get it.

  10. #10
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    I am going to try and get it higher if I can get away with it ! I have got hold of an antenna analyser so going to have some fun looking
    at exactly what the antenna looks like across the 40m band and other PSK31 popular bands - hopefully will be able to get out next week
    and do a spot of tuning !

    Cheers,

    Dave

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    Hey Dave,
    That's fantastic! I've had something similar up here for about a year now (30m one side and 15m the other) and it works. An outboard tuner has been essential with this design and it played pretty well without much trouble. My apex is about 7m agl but it needs to be much higher if its to be more than a cloud burner. I mentioned the 40m vertical earlier... I used the same mast the ocf lives on to mount the vertical and as fate has it, my ocf is very upset and won't tune below about 3:1 anywhere. So, it looks like I need to get off my ample arse and get the 80m loop up in the trees about 20m so I can have low bands again. I've also been noodling the idea of an inverted L up in the trees, but I would need to convince my neighbor it would be safe and all that since she has the 40m fir tree I'd likely use as the high point tie-off.

    Someday we will have our skyhooks closer to perfection and on that day I hope to put you in my log. Enjoy the weekend (what's left of it) and best of luck with your antenna.

    73 Eric WZ7U

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    Hi Eric,

    I have just been looking at some photos of your setup on QRZ.COM, looks like you are properly out in the sticks

    I am still amazed that even with my ground hugging currently mismatched OCF dipole I can still get some nice contacts
    all over Europe. This afternoon was really good on 20m with Rxed stations from all over Europe, also from Venezuela and
    Quebec. Best QSO was with a chap in Estonia which is 1100 miles away - he said I was coming through with a good signal
    and 100% decoded.

    Attached is the PSK31 report from just a couple of hours ..... lots of fun

    73 Dave G7IYK

    PSK reporter 261117.jpg

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