Questions on building a monoband vertical for 17 meters

[danesgs]

OK, perhaps this should be on QRZ or EHAM.net but I figure its worth an ask. I have built a really good 20 meter vertical that also does double duty on 40. But now I want to build a single band vertical for 17 meters. I measured out the wire for 25 feet for the radiator and am feeding it at the base. The mast is bamboo at 27 feet. I made a 7 turn RF choke to keep the power where it should be going and a few radials off the ground side at the bottom of the mast but I cannot get the SWR down to a level it will load properly. Has anyone built a 17 meter vertical here who can off some ideas?

Thanks
KJ4DGE

 

[KX0Z]

1/2 wave vertical?

 

[KB4MSZ]

This sounds like a halfwave vertical. The impedance would be in the thousands if end fed. Some sort of transformer would be required, likely in the 40:1 to 60:1 range. Is this what you built for 20 meters? I assume the RF choke you refer to is a coaxial wrap for common mode suppression of RF. I run a 1/4 wave on my pickup truck when parked that uses a MFJ stainless telescopic whip. Works well on any band from 14 MHz and up.

 

[prcguy]

Cut that vertical down to about 13ft and it will match to 50 ohm coax on 17m. Or make or buy a matching transformer for an end fed half wave and you can use as is and get rid of the ground radials. You can make a transformer that will handle up to about 400w SSB for about $10, let me know if you need the plans.

OK, perhaps this should be on QRZ or EHAM.net but I figure its worth an ask. I have built a really good 20 meter vertical that also does double duty on 40. But now I want to build a single band vertical for 17 meters. I measured out the wire for 25 feet for the radiator and am feeding it at the base. The mast is bamboo at 27 feet. I made a 7 turn RF choke to keep the power where it should be going and a few radials off the ground side at the bottom of the mast but I cannot get the SWR down to a level it will load properly. Has anyone built a 17 meter vertical here who can off some ideas?

Thanks
KJ4DGE

 

[W5lz]

Do you want a 1/4 wave or 1/2 wave vertical? (Go with the 1/4 wave, it's a lot easier. And as a reminder, 234/f (Mhz) = length of a 1/4 wave vertical.) Start a bit long and whittle it down to resonance.

 

[danesgs]

Cut that vertical down to about 13ft and it will match to 50 ohm coax on 17m. Or make or buy a matching transformer for an end fed half wave and you can use as is and get rid of the ground radials. You can make a transformer that will handle up to about 400w SSB for about $10, let me know if you need the plans.

Yes please send me the plans if you could..Greg/KJ4DGE

 

[TheSpaceMann]

Check Zed Zed's page and YouTube channel! He has loads of antenna plans, including verticals which could be made for different bands! www.AmateurRadio.bz

 

[danesgs]

Thanks! gave me some ideas.

 

[NC1]

Check Zed Zed's page and YouTube channel! He has loads of antenna plans, including verticals which could be made for different bands! www.AmateurRadio.bz

That could keep me busy for a while. Building your own is always so much more satisfying.

 

[danesgs]

Well I built a 12.890 ft. vert with 13 foot radials coming off the ground braid side and its only 1.5 to one at 28.4 MHz. Damn built a 10 meter antenna when I wanted a 17 meter one LOL.

 

[danesgs]

This sounds like a halfwave vertical. The impedance would be in the thousands if end fed. Some sort of transformer would be required, likely in the 40:1 to 60:1 range. Is this what you built for 20 meters? I assume the RF choke you refer to is a coaxial wrap for common mode suppression of RF. I run a 1/4 wave on my pickup truck when parked that uses a MFJ stainless telescopic whip. Works well on any band from 14 MHz and up.

Actually the 20 was a fluke I think. basically I built a 40/20 vertical I am saying that cause it loads well on either band but to be honest you have to tune it pretty much up and down 20, its not real resonant on 20 but when I tune it for the portion of the band it kicks ass. 40 pretty much is 1 to one ....

 

[danesgs]

now I have a similar antenna that was built for 17 meters but is crap there. But works wonders on 10. Damn thing is 1.2 SWR . It hears well also on ten but I think I will not change it for another band, really it hears well on ten.