Why so few "random" wire antennas ?

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KL7MJ
Posts: 27
Joined: Mon May 15, 2023 9:06 pm

Re: Why so few "random" wire antennas ?

Post by KL7MJ »

I made a 35/17 EFRW last week, and used it this weekend for Field Day. From my backyard in VA, I made contacts up and down the east coast, and west as far as TX. I even had a QSO with a Venezuelan station - all on FT8 running 5 watts into the EFRW. The only issue I had was RFI getting into my computer on 40m, but I inserted a line isolator and the RFI went away.

I tried it last weekend with my QCX mini, and the mini didn't like it at all - it produced a horrible buzzing tone when I transmitted. I'm sure a CMC would have fixed it (a CMC is on my to do list).

Overall, I'm happy with the EFRW for my FT817. I have no idea how it compares to an EFHW, but it was very serviceable and easy to deploy.
Andrew (grayhat)
Posts: 105
Joined: Sat Jun 11, 2022 2:59 pm

Re: Why so few "random" wire antennas ?

Post by Andrew (grayhat) »

KL7MJ wrote: Mon Jun 26, 2023 7:25 pm I made a 35/17 EFRW last week, and used it this weekend for Field Day. From my backyard in VA, I made contacts up and down the east coast, and west as far as TX. I even had a QSO with a Venezuelan station - all on FT8 running 5 watts into the EFRW. The only issue I had was RFI getting into my computer on 40m, but I inserted a line isolator and the RFI went away.

I tried it last weekend with my QCX mini, and the mini didn't like it at all - it produced a horrible buzzing tone when I transmitted. I'm sure a CMC would have fixed it (a CMC is on my to do list).

Overall, I'm happy with the EFRW for my FT817. I have no idea how it compares to an EFHW, but it was very serviceable and easy to deploy.
start with a good choke

https://www.dj0ip.de/rf-cmc-chokes/diff ... lla-choke/

http://www.ifwtech.co.uk/g3sek/in-prac/index.htm#1005

for QRP the core may be smaller than the ones shown, then for digimodes, add snap on ferrites on the USB and/or other cables between the rig and the computer, as for the coax chokes, place them near the antenna so that the coax won't radiate, for further infos see

http://www.karinya.net/g3txq/chokes/

HTH
KL7MJ
Posts: 27
Joined: Mon May 15, 2023 9:06 pm

Re: Why so few "random" wire antennas ?

Post by KL7MJ »

Thanks for the links! I'm working on an EFHW for the QCX mini - if the rgi doesn't like that one either I'll be making a CMC sooner rather than later.

73,
Mike, KL7MJ
Andrew (grayhat)
Posts: 105
Joined: Sat Jun 11, 2022 2:59 pm

Re: Why so few "random" wire antennas ?

Post by Andrew (grayhat) »

KL7MJ wrote: Tue Jun 27, 2023 3:43 pm Thanks for the links! I'm working on an EFHW for the QCX mini - if the rgi doesn't like that one either I'll be making a CMC sooner rather than later.

73,
Mike, KL7MJ
Before going for an EFHW, try adding a choke to the coax feeding the EFRW (random) placing it right after the 9:1, that and the counterpoise should solve your issue
Andrew (grayhat)
Posts: 105
Joined: Sat Jun 11, 2022 2:59 pm

Re: Why so few "random" wire antennas ?

Post by Andrew (grayhat) »

Andrew (grayhat) wrote: Tue Jun 27, 2023 4:11 pm
KL7MJ wrote: Tue Jun 27, 2023 3:43 pm Thanks for the links! I'm working on an EFHW for the QCX mini - if the rgi doesn't like that one either I'll be making a CMC sooner rather than later.

73,
Mike, KL7MJ
Before going for an EFHW, try adding a choke to the coax feeding the EFRW (random) placing it right after the 9:1, that and the counterpoise should solve your issue
wind 14 or 15 turns of RG174 or RG178 on a #43 toroid (pick an FT140-43 or a smaller one but large enough to fit the turns) that will do, I must thank Rick (DJ0IP) which replied to my email and gave me those infos :D
KL7MJ
Posts: 27
Joined: Mon May 15, 2023 9:06 pm

Re: Why so few "random" wire antennas ?

Post by KL7MJ »

I'll try the choke, but since the QCX mini is a single bander, I just want a simple resonant antenna (so I won't need to carry a tuner with me).
Andrew (grayhat)
Posts: 105
Joined: Sat Jun 11, 2022 2:59 pm

Re: Why so few "random" wire antennas ?

Post by Andrew (grayhat) »

KL7MJ wrote: Wed Jun 28, 2023 12:22 pm I'll try the choke, but since the QCX mini is a single bander, I just want a simple resonant antenna (so I won't need to carry a tuner with me).
Whoops, I overlooked the rig, forgive me ! Well, yes, an EFHW will fit, but contrary to what some people says, give it a bit of counterpoise, 6.5ft or less, depending from the band will fit, won't be an issue to carry and will improve radiation, with that in place CMC should be much less if any
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