mikefox whiskey
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Re: anyone got any ideas on vertical multibands for HF?
Hi Topbuzz, I reckon that it depends on the bands you wish to use, I have used an Imax 2000 vertical with a tuner and it work's superb from 18MHz up. I have seen and heard a few of the inexpensive chinese made multi band verticals made for 3MHz up to 30MHz, the one's with a large matching transformer on the bottom, recently on 45m I heard a station switching from one of these multiband verticals to a Sirio 827, the 827 was a least 3 'S' points stronger than the dedicated multiband. I certainly would not pay hundreds and hundreds of pounds though for one of them multiband cushraft verticals. Dipoles can be mounted vertically too for the bands if you can find a mast or tree tall enough. Good Luck
--- Patrick - MFW / 68 FB750
kenwood TS870s - Astatic 1104c Microphone - 54 meter long doublet - Multiband Delta Loop.
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23/Oct/2009, 8:51 am
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26fb010
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Re: anyone got any ideas on vertical multibands for HF?
i paid £60 for a secondhand diamond CP6 locally, it works well on 6 bands, its small at about 16` tall it looks ok too, got it by asking on the muppet 40 and 2 metres.
ps, i also made a carolina windom with a homebrew 4:1 balun, 41` of wire one side 25` the other, (works very well without a tuner) and cost £10 to build!! pps, you could run a long length of wire up a 9 metre fishing pole, use a 9:1 balun at the bottom with a counterpoise, and you have a very portable/base antenna (multiband)look on ebay, someone is selling these on there.
Last edited by 26fb010, 27/Oct/2009, 9:10 am
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27/Oct/2009, 9:05 am
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John193
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Re: anyone got any ideas on vertical multibands for HF?
What about a 1/4 Lamda multi element vert. four or more if pos ground radials per freq to outer coax braid and any number of 1/4 wave matchin vertical elements from coax core, the top ends can be bent at 90 degrees without any significant loss of performance the elements are a bit interactive so trimming one effects them all a bit. Cheap and effective and with wire is very low impact on the eye. The transmitter only see's the element with the lowest impedance ie the one that is 1/4 wavelength. so no switching is required. The ultimate is a version called a Discone its a 1/4 vert with a conical skirt which means the transmitter see's a harmonic antenna at all frequencies in the range. The ultimate full spectrum vertical. A well constructed wire discone could give you a harmonic antenna from 3.5 megs to 30 megs with a SWR of less than 1.8-2.0 across the full spectrum.
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4/Nov/2009, 5:21 pm
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Hot Fusion
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Re: anyone got any ideas on vertical multibands for HF?
I'd also go with the multiple 1/4 wave verticals if you can - I use this system for 40 & 80 and despite the wires running parallel with the ground and about 2 - 3 metres above it, I seem to get out surprisingly well.
Obviously if the wires were higher the system would perform better, but the point is that it is a workable idea and can be of low visual impact as John said.
You could opt for a trap vertical, but you'd still need the radials and you'd have to part with a fair bit of money.
---
Andy - 26 FB107
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4/Nov/2009, 9:36 pm
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mikefox whiskey
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Re: anyone got any ideas on vertical multibands for HF?
Sorry to jump in on the post, John FB193, do you know where I would find some details of a wire discone like you have mentioned?
--- Patrick - MFW / 68 FB750
kenwood TS870s - Astatic 1104c Microphone - 54 meter long doublet - Multiband Delta Loop.
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4/Nov/2009, 10:40 pm
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Hot Fusion
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Re: anyone got any ideas on vertical multibands for HF?
No input from John yet, so I'll pop in and say that a discone is not a good choice for HF, the reason being the dimensions:
The elements making up the lower cone part should be a quarter wave long at the lowest frequency to be used, and the elements for the disc should be about 3/4 the length of the cone elements.
From this you can see a discone for the 80m band would be pretty big!
Discones won't cover all frequencies and work best within a somewhat restricted range, so you could perhaps get away with building one for all bands from 30m to 10m, and you may even get away with building for as low as 40m and still getting 10m operation, but it'd be a monster.
I don't think they are very efficient on TX either, and really work best as non-resonant antennas for receive work which is how you tend to see them operated.
---
Andy - 26 FB107
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5/Nov/2009, 9:34 pm
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John193
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Re: anyone got any ideas on vertical multibands for HF?
Hi guys, I was trying to find some pics for you. Its basically a wire frame cone with a wire frame disc on top insulated from each other. For 86m up to 30 megs it would be about 43m tall, in my case its a tree delimbed with a couple of old copper pans insulated from each other with the wires soldered to the discs. The disc top is supported by any structural material you can find, if its non conducting then copper wires are strung out to the circumference and all linked together. the cone is made also of wires and the bottom scirt is all linked like the disc. I will scan some dimensions in and post them but the important dimensions are 60 degrees for the skirt which the diameter is 1/4 lamda at lowest freq. At cone angle of 60 degrees the cone height is a bit longer than a 1/4.
I ran two these for over twelve years one for 80m to 20, and the other set higher off the ground on a seventy foot pole that worked 30m to 5m. they dont offer high gain but have a virtual flat lobe and are very efficient at about 96% due to no fancy feed requirements they are about 45 ohms so feed great from coax direct no baluns or anything else. Downside is they are big but most people could only see the pole not the wires anyway so they are not that bad.They work like a horn so dont expect much more than 2.5-3dB but they are omni so its not bad.
If you want the tech stuff and design equations let me know and i'll send you by email Patrick. I've built lots of these (well six)for amateurs with space and they dont need the tuner on these babs. If you want a vert to work all frequencies within a range with no gaps and no tuner then this is and the conical monopole are your only options. They are very popular with broadcast and military listening stations for that reason. The last one i built was for 6.5-23 megs it was 36' high, 26' across at the disc and the cone length wires were 38' long. it was built in a conifer tree in a guys garden was virtually invisible unless you looked for it and was giving a swr of 1.5 from 6.2 megs to 23 megs.
John
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5/Nov/2009, 10:56 pm
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