Re: Topband: Toploaded vertical - SWR
Me too. But I wasn't ready to present them yet. I'm away from home at the moment. Wes Sent from my iPhone > On Sep 19, 2018, at 6:04 PM, Roger D Johnson wrote: > > I did a quick model in EZNEC and came up with very different values. > > 73, Roger > > >> On 9/19/2018 6:53 PM, Wes Stewart wrote: >> I suspect your data. For a 0.1 lambda vertical, the radiation resistance >> will be quite low particularly with sloping loading wires and with your >> radial system the ground loss will be high. Additionally, I think the top >> loading is insufficient to achieve resonance. Yet you seem to have it. >> Your feedpoint Z is 15 ohm which seems too low, yet your SWR curve is too >> broad. Something just looks funny to me, but I've been wrong before. >> Wes N7WS >>> On 9/18/2018 1:44 PM, Ashraf Chaabane wrote: >>> Hi all, >>> >>> I just finished setting up my vertical antenna for 160 in 3V8SF location. >>> It is 17m (55 ft) long with 2 top loading wires 12m each (40ft), angle to >>> vertical about 40 deg. I added 8 radials, 20m each (65ft). >>> With no shunt matching, the SWR at antenna base is 3.2 and at radio side is >>> 2.8. Is there any way I can improve the SWR further? >>> >>> Photos of the antenna along with SWR curve can be found here: >>> https://drive.google.com/drive/folders/1_3FsWZI3zdi56zz0LOiKNOmfgiWeN6yG?usp=sharing >>> >>> >>> 73 Ash 3V8SS/KF5EYY >>> www.kf5eyy.info >>> _ >>> Topband Reflector Archives - http://www.contesting.com/_topband >> _ >> Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Toploaded vertical - SWR
I suspect your data. For a 0.1 lambda vertical, the radiation resistance will be quite low particularly with sloping loading wires and with your radial system the ground loss will be high. Additionally, I think the top loading is insufficient to achieve resonance. Yet you seem to have it. Your feedpoint Z is 15 ohm which seems too low, yet your SWR curve is too broad. Something just looks funny to me, but I've been wrong before. Wes N7WS On 9/18/2018 1:44 PM, Ashraf Chaabane wrote: Hi all, I just finished setting up my vertical antenna for 160 in 3V8SF location. It is 17m (55 ft) long with 2 top loading wires 12m each (40ft), angle to vertical about 40 deg. I added 8 radials, 20m each (65ft). With no shunt matching, the SWR at antenna base is 3.2 and at radio side is 2.8. Is there any way I can improve the SWR further? Photos of the antenna along with SWR curve can be found here: https://drive.google.com/drive/folders/1_3FsWZI3zdi56zz0LOiKNOmfgiWeN6yG?usp=sharing 73 Ash 3V8SS/KF5EYY www.kf5eyy.info _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Toploaded vertical - SWR
Several suggestions, some already mentioned - Although your swr plot shows you are in the ballpark for resonance, the feedpoint resistance is very low, as mentioned likely 12 to 20 ohms. A transmission line transformer stepdown will help a lot. 4:1 likely the best choice. If parts are hard to obtain, parallel two 50 ohm coax cables 1/4wl long (measured electrically, considering velocity of propagation) That will make a 25 ohm matching section between 50 ohms and 12.5 ohms which is a better match than 50 ohms. The swr curve is broadband which says you need a lot more radials to reduce ground loss. They appear to be buried or on the ground so 20 or 30 more will make a difference, longer than 65' if you can but more 65' is better than a few longer ones. Increasing the angle of the top hat appears to be possible, so that will decrease the shielding of the antenna by them and improve its performance. Grant KZ1W On 9/19/2018 9:36 AM, Herbert Schoenbohm wrote: An L network with a coil in series and a 500pf variable to ground might do the trick. You impedance of the antenna is to low and you need to bring it up. You can also try extending the top hat wires by 20' each and see what difference that makes. Herb, KV4FZ On Tue, Sep 18, 2018 at 5:44 PM Ashraf Chaabane wrote: Hi all, I just finished setting up my vertical antenna for 160 in 3V8SF location. It is 17m (55 ft) long with 2 top loading wires 12m each (40ft), angle to vertical about 40 deg. I added 8 radials, 20m each (65ft). With no shunt matching, the SWR at antenna base is 3.2 and at radio side is 2.8. Is there any way I can improve the SWR further? Photos of the antenna along with SWR curve can be found here: https://drive.google.com/drive/folders/1_3FsWZI3zdi56zz0LOiKNOmfgiWeN6yG?usp=sharing 73 Ash 3V8SS/KF5EYY www.kf5eyy.info _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Multiple verticals one feed-point.
Gary, I am not sure about all bands, but I have done it with 3 bands. I run my 160 inverted L, a vertical for 80 and a vertical for 40 all off of the same feedline and ground radial system. At least for these three bands, they don't have a lot of interaction. My 4NEC2 model showed this, and my experience as I added each additional antenna wire required minimal or no adjustment of the previous elements. My wires are spaced about 12" apart. 73, Joel N9LQ On Wed, Sep 19, 2018 at 3:35 PM Gary Smith wrote: > My HF antennas are all wire verticals; 20M > vertical, 30M vertical, 40M vertical, 80 > INV-V & 160 sloper. Using the Ameritron > remote coax switch it allows me to select > one of these antennas and this allows a > match to everything from 160-6 except for > 60 meters which I don't use anyway. All > are connected to the radial plate which > has maybe 40 or so 130' long radials. I > use the 160 sloper for 160, 12, 10 & 6M (I > now have a 7 el yagi for 6M) > > This latest thread has me wondering about > what would be likely to happen if I didn't > use the coax switch and instead ran all > the wires off a common feed-point? The > only think I can think of that jumps out > at me is the possibility of harmonics. > > Perhaps harmonics are not an issue? I've > long used a 40M antenna for 15M as well > with no complaints. I used to use a > Mor-Gain antenna as a Novice & General and > it was a multi band dipole which seemed to > work fairly well, but in the sunspot cycle > peak back in the late 70's a coat hanger > would let you work DX. > > 73, > > Gary > KA1J > > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Multiple verticals one feed-point.
Gary as long as the verticals are isolated above ground when not switched in. You should be ok. 73 Clive GM3POI -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Gary Smith Sent: 19 September 2018 20:35 To: topband@contesting.com Subject: Topband: Multiple verticals one feed-point. My HF antennas are all wire verticals; 20M vertical, 30M vertical, 40M vertical, 80 INV-V & 160 sloper. Using the Ameritron remote coax switch it allows me to select one of these antennas and this allows a match to everything from 160-6 except for 60 meters which I don't use anyway. All are connected to the radial plate which has maybe 40 or so 130' long radials. I use the 160 sloper for 160, 12, 10 & 6M (I now have a 7 el yagi for 6M) This latest thread has me wondering about what would be likely to happen if I didn't use the coax switch and instead ran all the wires off a common feed-point? The only think I can think of that jumps out at me is the possibility of harmonics. Perhaps harmonics are not an issue? I've long used a 40M antenna for 15M as well with no complaints. I used to use a Mor-Gain antenna as a Novice & General and it was a multi band dipole which seemed to work fairly well, but in the sunspot cycle peak back in the late 70's a coat hanger would let you work DX. 73, Gary KA1J _ Topband Reflector Archives - http://www.contesting.com/_topband --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Multiple verticals one feed-point.
My HF antennas are all wire verticals; 20M vertical, 30M vertical, 40M vertical, 80 INV-V & 160 sloper. Using the Ameritron remote coax switch it allows me to select one of these antennas and this allows a match to everything from 160-6 except for 60 meters which I don't use anyway. All are connected to the radial plate which has maybe 40 or so 130' long radials. I use the 160 sloper for 160, 12, 10 & 6M (I now have a 7 el yagi for 6M) This latest thread has me wondering about what would be likely to happen if I didn't use the coax switch and instead ran all the wires off a common feed-point? The only think I can think of that jumps out at me is the possibility of harmonics. Perhaps harmonics are not an issue? I've long used a 40M antenna for 15M as well with no complaints. I used to use a Mor-Gain antenna as a Novice & General and it was a multi band dipole which seemed to work fairly well, but in the sunspot cycle peak back in the late 70's a coat hanger would let you work DX. 73, Gary KA1J _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Toploaded vertical - SWR
f6aoj.ao-journal.com and then « tuning short vertical » , menu left side. It could help you to match your antenna. 73 to all. F6FYA / Jean-Paul Envoyé de mon iPad > Le 19 sept. 2018 à 20:41, Tim Shoppa a écrit : > > Your suggestion of a hairpin is a high-pass. Herb's suggestion for a > series-L shunt-C L-network is a low-pass. Sometimes you might prefer one > over the other. > > Or choice might be entirely driven by parts on hand. > > I happen to have some big old variable capacitors so all my tuners use them. > > But a younger ham probably wouldn't and might rediscover the variometer or > other solution. > > Tim N3QE > >> On Wed, Sep 19, 2018 at 1:46 PM Clive GM3POI wrote: >> >> What I don't understand is why would you use more components than needed. >> Why a capacitor (possibly vacuum). What is wrong in using a hairpin which >> also DC shorts the vertical to ground. A combination of hairpin size and >> top loading will give you 1:1 at your favourite 1.825 or anywhere else. >> Perhaps WX0B's article needs a reprint in the NCJ. It really is simple just >> a few microhenries of inductance and you are done. >> 73 Clive GM3POI >> >> -Original Message- >> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Don >> Kirk >> Sent: 19 September 2018 17:29 >> To: Herbert Schoenbohm >> Cc: topband; ash.kf5...@gmail.com >> Subject: Re: Topband: Toploaded vertical - SWR >> >>> >>> Herb (KV4FZ) mentioned an L network, and that is what I always use. Very >>> simple, and you just plug you're measured complex impedance values (at >> the >>> frequency you want to be resonant) into one of the many online L network >>> calculators to determine the amount of inductance and capacitance >> required >>> for the L network. I normally just wind my own coil for the inductance, >>> and use high voltage silver mica caps for the capacitor. >>> >> _ >> Topband Reflector Archives - http://www.contesting.com/_topband >> >> >> --- >> This email has been checked for viruses by Avast antivirus software. >> https://www.avast.com/antivirus >> >> _ >> Topband Reflector Archives - http://www.contesting.com/_topband >> > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Toploaded vertical - SWR
On 9/18/2018 4:19 PM, Joe Subich, W4TV wrote: 2) use a 4:1 auto-transformer at the feed point - your antenna analyzer says the real impedance is about 15 Ohms. A 4:1 auto-transformer will get the SWR down to about 1.2:1. Generally speaking, you will get a wider bandwidth with a autotransformer than you will with an LC network. To match 15 ohms to 50 ohms, you can wind 7 turns on a high-mu toroid and drive the whole 7 turns from the radio. The antenna is tapped down to 4 turns. 7/4 squared is close to 50/15. Less than 1.1:1 SWR. BTW, an autotransformer automatically DC grounds the antenna. Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Toploaded vertical - SWR
Your suggestion of a hairpin is a high-pass. Herb's suggestion for a series-L shunt-C L-network is a low-pass. Sometimes you might prefer one over the other. Or choice might be entirely driven by parts on hand. I happen to have some big old variable capacitors so all my tuners use them. But a younger ham probably wouldn't and might rediscover the variometer or other solution. Tim N3QE On Wed, Sep 19, 2018 at 1:46 PM Clive GM3POI wrote: > What I don't understand is why would you use more components than needed. > Why a capacitor (possibly vacuum). What is wrong in using a hairpin which > also DC shorts the vertical to ground. A combination of hairpin size and > top loading will give you 1:1 at your favourite 1.825 or anywhere else. > Perhaps WX0B's article needs a reprint in the NCJ. It really is simple just > a few microhenries of inductance and you are done. > 73 Clive GM3POI > > -Original Message- > From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Don > Kirk > Sent: 19 September 2018 17:29 > To: Herbert Schoenbohm > Cc: topband; ash.kf5...@gmail.com > Subject: Re: Topband: Toploaded vertical - SWR > > > > > Herb (KV4FZ) mentioned an L network, and that is what I always use. Very > > simple, and you just plug you're measured complex impedance values (at > the > > frequency you want to be resonant) into one of the many online L network > > calculators to determine the amount of inductance and capacitance > required > > for the L network. I normally just wind my own coil for the inductance, > > and use high voltage silver mica caps for the capacitor. > > > _ > Topband Reflector Archives - http://www.contesting.com/_topband > > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Toploaded vertical - SWR
What I don't understand is why would you use more components than needed. Why a capacitor (possibly vacuum). What is wrong in using a hairpin which also DC shorts the vertical to ground. A combination of hairpin size and top loading will give you 1:1 at your favourite 1.825 or anywhere else. Perhaps WX0B's article needs a reprint in the NCJ. It really is simple just a few microhenries of inductance and you are done. 73 Clive GM3POI -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Don Kirk Sent: 19 September 2018 17:29 To: Herbert Schoenbohm Cc: topband; ash.kf5...@gmail.com Subject: Re: Topband: Toploaded vertical - SWR > > Herb (KV4FZ) mentioned an L network, and that is what I always use. Very > simple, and you just plug you're measured complex impedance values (at the > frequency you want to be resonant) into one of the many online L network > calculators to determine the amount of inductance and capacitance required > for the L network. I normally just wind my own coil for the inductance, > and use high voltage silver mica caps for the capacitor. > _ Topband Reflector Archives - http://www.contesting.com/_topband --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Toploaded vertical - SWR
> > Herb (KV4FZ) mentioned an L network, and that is what I always use. Very > simple, and you just plug you're measured complex impedance values (at the > frequency you want to be resonant) into one of the many online L network > calculators to determine the amount of inductance and capacitance required > for the L network. I normally just wind my own coil for the inductance, > and use high voltage silver mica caps for the capacitor. > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Toploaded vertical - SWR
An L network with a coil in series and a 500pf variable to ground might do the trick. You impedance of the antenna is to low and you need to bring it up. You can also try extending the top hat wires by 20' each and see what difference that makes. Herb, KV4FZ On Tue, Sep 18, 2018 at 5:44 PM Ashraf Chaabane wrote: > Hi all, > > I just finished setting up my vertical antenna for 160 in 3V8SF > location. It is 17m (55 ft) long with 2 top loading wires 12m each > (40ft), angle to vertical about 40 deg. I added 8 radials, 20m each > (65ft). > With no shunt matching, the SWR at antenna base is 3.2 and at radio side > is 2.8. Is there any way I can improve the SWR further? > > Photos of the antenna along with SWR curve can be found here: > > https://drive.google.com/drive/folders/1_3FsWZI3zdi56zz0LOiKNOmfgiWeN6yG?usp=sharing > > 73 Ash 3V8SS/KF5EYY > www.kf5eyy.info > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
