Search found 118 matches

by Andrew (grayhat)
Wed Jun 28, 2023 9:29 am
Forum: Questions & Advice
Topic: JNC cs-818 tuner
Replies: 16
Views: 4984

Re: JNC cs-818 tuner

Ok, ran a quick test, built a NEC model with a 1/2 half wave (on 40m) radiator and a 17ft counterpoise, placed the radiator at 20ft meters from ground and ran a sweep from 1 to 30 MHz, then changed the impedance from 2450 (49:1) to 450 (9:1), the results are in the attached image below, the antenna ...
by Andrew (grayhat)
Wed Jun 28, 2023 6:55 am
Forum: Questions & Advice
Topic: JNC cs-818 tuner
Replies: 16
Views: 4984

Re: JNC cs-818 tuner

Brian, probably I oversimplified, what I mean is that one may like being able to jump on a non harmonically related band, so just by changing the EFHW length to a "good" one for a random and changing the tap to 9:1 we would then be able to jump on (say) the 30 meters band or whatever else...
by Andrew (grayhat)
Wed Jun 28, 2023 5:34 am
Forum: Questions & Advice
Topic: Operating from a beach
Replies: 5
Views: 2047

Re: Operating from a beach

My first reaction to your question would be to use a 20m or 17m vertical with a radial into the salt-water. I'm sure there are other things... All great advice! My partner and I will probably be seeking out the least crowded area we can - We'll be nearby to a few nature preserves that might let me ...
by Andrew (grayhat)
Tue Jun 27, 2023 8:56 pm
Forum: Questions & Advice
Topic: Operating from a beach
Replies: 5
Views: 2047

Re: Operating from a beach

just to give you an idea, have a look here

https://www.proantennas.co.uk/i-pro-traveller

:D
by Andrew (grayhat)
Tue Jun 27, 2023 7:47 pm
Forum: General Discussion
Topic: Why so few "random" wire antennas ?
Replies: 26
Views: 12238

Re: Why so few "random" wire antennas ?

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 coun...
by Andrew (grayhat)
Tue Jun 27, 2023 4:11 pm
Forum: General Discussion
Topic: Why so few "random" wire antennas ?
Replies: 26
Views: 12238

Re: Why so few "random" wire antennas ?

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 coun...
by Andrew (grayhat)
Tue Jun 27, 2023 3:55 pm
Forum: Questions & Advice
Topic: JNC cs-818 tuner
Replies: 16
Views: 4984

Re: JNC cs-818 tuner

Brian, probably I oversimplified, what I mean is that one may like being able to jump on a non harmonically related band, so just by changing the EFHW length to a "good" one for a random and changing the tap to 9:1 we would then be able to jump on (say) the 30 meters band or whatever else,...
by Andrew (grayhat)
Tue Jun 27, 2023 1:38 pm
Forum: Questions & Advice
Topic: JNC cs-818 tuner
Replies: 16
Views: 4984

Re: JNC cs-818 tuner

Hi Mark- A lot of auto tuners, and internal tuners in modern radios are not able to tune much more than a 3:1 SWR. Maybe try a 9:1 transformer between the antenna and tuner: http://www.earchi.org/proj_homebrew.html This is not the same as a 49:1 transformer for end fed half wave antennas. Dont get ...
by Andrew (grayhat)
Tue Jun 27, 2023 1:05 pm
Forum: Questions & Advice
Topic: JNC cs-818 tuner
Replies: 16
Views: 4984

Re: JNC cs-818 tuner

regarding chokes, as I wrote, my reference design is the one from Rick (DJ0IP) https://www.dj0ip.de/rf-cmc-chokes/different-kinds-of-chokes/d2-guanella-choke/ but that's for QRO and uses a quite heavy toroid (FT240...) which adds some weight to a portable kit, for QRP a 140 should suffice, going for...
by Andrew (grayhat)
Tue Jun 27, 2023 6:09 am
Forum: General Discussion
Topic: Why so few "random" wire antennas ?
Replies: 26
Views: 12238

Re: Why so few "random" wire antennas ?

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 compu...