Can't Tune 1/4 wavelength vertical for 17 m and higher

[popnokick]

If you need a tuner for 6m, you're doing something wrong.

Indeed. My 31 foot Eagle One vertical works quite well "barefoot" on 6M with less than a 2:1 SWR. However, unlike many tuners my IT-100 doesn't have a tuner bypass switch so it is inline all the time. A tuner without a bypass switch that was not designed for 6M might impede the transmitted signal. And if it was as easy as simply bypassing the tuner by connecting the antenna directly then I'd do that. But in my camper that is a hassle and does not permit rapid band switching.

 

[kn6msc]

Thank you all for all the recommendations...I am going to try them, starting with testing the SWR of the line alone with a dummy load at the end of the coax, followed by the addition of a 4:1 transformer, etc.
I like the 1/4 WL vertical because it takes little space in the 17 m and up bands, although it radiates in many directions and does to get the dB of a beam, for instance...

 

[prcguy]

A 1/4 wave vertical with ground plane would match close to 50 ohms at resonance. Putting a 4:1 balun in line would change the feedpoint impedance to around 200 ohms and nowhere near a good match. You might use a 4:1 for a random length wire on multiple bands or your design is known to land in a medium impedance range like 100-400 ohms on multiple bands.

Thank you all for all the recommendations...I am going to try them, starting with testing the SWR of the line alone with a dummy load at the end of the coax, followed by the addition of a 4:1 transformer, etc.
I like the 1/4 WL vertical because it takes little space in the 17 m and up bands, although it radiates in many directions and does to get the dB of a beam, for instance...

 

[kn6msc]

Hi there, on the face of it there should be no reason why. A 1/4 is a 1/4 is a 1/4 wave assuming radiating and radial elements
are trimmed up to frequency. However, I wonder if there might be the possibility of a little CMC on the coax for 17m/15m ? I have read a source that 1/4 waves ideally need de-coupling using a choke of some kind.. (ugly balun or a ferrite ring with coax turns) It may be this lack of de coupling could be having some unforeseen effects which you are getting away with on 20m.

Here is the material I read:

Ground Plane Verticals

I hope one day we can make a QSO. I love speaking into California and the Western states, they are tricky to work as I am mainly out in the day times. I was out the other day at 5AM but chose the wrong band sadly, I was on 15m and I made the wrong call, in the early morning 15m needs longer to charge up I think at least at recent SFI's (indicator MUF remained low) so it was dead as far as DX goes just one YB station heard at 1/0 with QSB just before I QRT'd at 8:15AM. I was too tired to change band (I use 1 antenna per band)

If you want a cracking DX vertical.. I mean one to outperform them all (if you can get it up very high - close to 1 wavelength).... I suggest a mono band EFHW elevated as high as possible off the ground. In models I am seeing very significant gains at very low DX angles on 15m and 10m and my DX results on a 100W are bearing that out.

1.5:1 is fine actually but I do like to see lower SWR myself as well. Even though for balanced/ladder line users SWR is less of a concern and as I gather field strength is a better indicator of RF radiating out of the antenna than SWR.

What happens across 15m it is a pretty wide band ? Are you getting lower/higher readings at band edges than 1.5:1 ?

Thank you for your excellent observations. I will read the material in the link you provided.
Yes, same here, hope we can make a QSO one of these days. I am ussually out in the mornings (Pacific time) and evenings ( During the day my shack is too hot since I have not installed an AC yet. I don't know what your experience was, but the last few days ( July 10 through 13) propagation conditions for me were really bad. Today ( July 14) the bands started to pen up for me and even I was able to do several DX's in 20 m. By the way, for me the 20 m band works very well across the US.

Going back to your last question. I get the best (lowest) SWR at the center of the band because I trimmed the lengths of radiating element and radials to get lowest SWR at the middle of the band. At the edges of the band I get from 1.7 :1 to 2:1.
73's and best regards,
Jesus L.

 

[RadioDXfun]

No worries I do hope it resolves the issues. Understood, with SWR lowest in the middle. So it does seem the antenna is in the best state
of tune it can be for the current situation. No doubt with those numbers it will still work. It is just nice to get things as low as possible, even if for a feeling alone.

I am going to be out on 15m later today SFI 169. I am UK portable and will be calling 15m band from around 17:30 local time with a 20m fibre glass vertical pole with EFHW attached. (14:30UTC) W. Coast time.. 09:00 approx. I try and hang around the 21.250 mark up and down as need be.

We can only try and put our best signals out there and see what happens !

 

[kn6msc]

Sorry; I didn't see you your message until now ( 7/15/2022, 9:45 Pacific Time, 16:44 UTC) and missed you in the 15 m band. Right night I am listening (through the SDR monitor in Utah) to a couple of stations in Central America and Europe and seem conditions are good. I am away from my shack though. I will try later today; around 11 pm Pacific time ( 6:00 UTC).
73's
Jesus L.

 

[RadioDXfun]

No worries sched contacts are always a long shot at the best of times. Conditions were poor for the first 1.5 hours then picked up (made a few contacts as per the "Making contacts/On the air part of the forum). I was out Saturday also and conditions even more poor, just 5 DX contacts in 4 hours. 2 into Brazil (S0/S1's) and 3 East Coast USA (Rhode Island, Massachusetts and Florida) Rhode Island was a 2 by 0... a real struggle for the ears but we both persisted and made the contact.

High SFI and yet no real Geomagnetic storms present, just a few low level flares. I find the HF conditions statistics about as much use as a
wax spark plug.