Hustler DCX.

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Hustler DCX.

Postby m0lsx » Fri Dec 14, 2018 9:29 pm

I have been chatting to a friend this afternoon & a he has recently given the Hustler DCX a go & says it's a proper discone.
Image

These antenna cost around £45 & the suggestion is that they work QRP ( 5 watts,) on 2, 70 & 446. Or his does. Despite this being an RX only antenna.
My friend said he plugged it into his SWR analyser & saw really low SWR across a big chunk of spectrum, so gave TX a go using his cheap ebay handheld & got some surprising results.
This antenna is vertically polarised & may make a good option for someone who wants a proper discone. As most of the alledged discones, are anything but.
This discone is not much different to the Larkspur Discone. The Larkspur has 4 elements, this has 3.
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Re: Hustler DCX.

Postby mickydt » Sat Dec 15, 2018 2:37 pm

i got one similar to the one shown except is also has a small top antenna rod

it receives from 25mhz up to around 1300 but also at the same it can transmit on certain frequencies, i have never tested it on transmit though although it is a shame as it would tell if it claims what it is stated on the website i got it from, does need replacing at some point as around here it is getting a battering and has now been up around 3 years.
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Re: Hustler DCX.

Postby m0lsx » Sat Dec 15, 2018 2:46 pm

mickydt wrote:i got one similar to the one shown except is also has a small top antenna rod.



If it has top vertical, then it is NOT a discone. The bottom cone is the active part of the antenna. This is why they are vertically polarised. And if something is called a discone, but needs something like a mobile whip on the top, then it is NOT a Disk Cone. But a short vertical base fed dipole with radials, which is a totally different antenna.

mickydt wrote:, i have never tested it on transmit though although it is a shame as it would tell if it claims what it is stated on the website i got it from,


Not really. As a light bulb would show a good match & would be safe to transmit into. As would any other form of dummy load. My mate checked his antenna on a analyser. You probably have a two or three band mobile whip on your antenna.

mickydt wrote:i got one similar to the one shown except is also has a small top antenna rod

it receives from 25mhz up to around 1300.


A straightened out paper clip could also be said to receive between 25 & 1300 MHz. Or even on Medium Wave or Short Wave. Virtually any piece of metal connected to a RX, can be said to work between specified frequencies. The issue is, does it so so as well as it should?

There is a yearly amateur radio event where people use non antenna like metal objects, as antennas. Things like Wheelbarrows & even metal sculptures are used.
A discone was designed as a aircraft antenna, because it has a wide bandwidth & has a low profile. It has no need for a vertical, which would narrow it's bandwidth & unlike a vertical dipole it does not warm the sky, as it fires it's RF at the horizon, as the radials of the Disc are above the Cone & it's the cone, that is connected to the Coaxes centre core.
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Re: Hustler DCX.

Postby mickydt » Sat Dec 15, 2018 3:36 pm

it is not a true discone but is described as discone style also now gone to nearly £70 i got mine for around £40 talk about inflation within a few years
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Re: Hustler DCX.

Postby Chris P » Sun Dec 16, 2018 11:16 pm

Alan On a true Discone Its the disc that is connected to the centre core the cone is connected to the outer shield of the cable
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Re: Hustler DCX.

Postby m0lsx » Mon Dec 17, 2018 9:21 am

Chris P wrote:Alan On a true Discone Its the disc that is connected to the centre core the cone is connected to the outer shield of the cable


But that would make it horizontally polarised, which yes, is how the original aircraft fitted discones were designed & even how I believe the Military HF discones are configured. But the old Larkspur (military) & properly built amateur radio / scanning discones are Vertical, with even the Larkspur Mil Airband discones being, I believe, vertically polarised.
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Re: Hustler DCX.

Postby Chris P » Mon Dec 17, 2018 10:47 am

all true discones have the disc connected to the centre core the polarisation and impedance is determined by the angle between the disc and the cone , the dimensions of the insulation between the two not the alignment of the elements

please find below the definition from WIKIPEDIA


The discone antenna has a useful frequency range of at least 10 to 1.[2][3] When employed as a transmitting antenna, it is often less efficient than an antenna designed for a more limited frequency range. SWR (standing wave ratio) is typically 1.5:1 or less over several octaves of frequency.[4] A discone antenna consists of three main parts: the disc, the cone, and the insulator.
The disc: The disc should have an overall diameter of 0.7 times a quarter wavelength of the antenna's lowest frequency. The antenna's feed point is at the center of the disc. It is usually fed with 50-ohm coaxial cable, with the center conductor connected to the disc, and the outer conductor to the cone.
The cone: The length of the cone should be a quarter wavelength of the antenna's lowest operating frequency.[2] The cone angle is generally from 25 to 40 degrees.
The insulator: The disc and cone must be separated by an insulator, the dimensions of which determine some of the antenna's properties, especially on near its high frequency limit.
another source gives this description


The Discone Antenna

This antenna is often implemented in a skeleton form. Small, UHF forms may be constructed of sheet metal and thus exhibit the distinctive Disk and Cone.
This is the basic form for a 16 spoke, Discone Antenna. The cone section below the disk will have the cone apex angle changed in a suite of tests. What appear below are Smith Chart snapshots of the characteristic Impedance of this antenna through the iterations of changing the cone angle from 20 degrees to 90 degrees. The cone angle for the antenna illustrated here is 60 degrees. This angle is very typical.
The length of the cone side is 0.25 of the wavelength of the lowest frequency of interest. The Disk, or Top Hat, diameter is roughly 0.175 of the wavelength of this same, low frequency. These two dimensions are approximate and should be approached with standard caution (although they are easily within the suggested dimensions of many authors). More care should be considered in the gap of the disk and the cone. The cone can never come to an absolute point (the coax center conductor has to emerge, unshorted, somewhere), and there are compounding issues of construction. This will take more than standard caution, but reasonable solutions have been shown in the literature. Expect to have to adjust the separation of these two regions by up to 1 foot for HF applications (40 to 10 M). I will repeat at this point that it is conventional to bring the transmission line up beneath the cone to the open apex. The shield should be connected to the cone section and the center conductor is passed through the open apex to the disk section.
The Smith Charts below will display a very different characteristic compared to other antennas. The resonances of this antenna are distinct, but very broad. For certain configurations, these nulls begin to blend. The Data speaks for itself.



I am sure if you apply a meter to any of the commercially available true discones as well as those used by the military you will find the core is connected to the disc , all of the discones I have used have had this configuration .



The so called double discones are in fact bicones with open ends and are effectively a three dimensional Bowtie which in theory is a very wideband antenna with its impedance and bandwidth determined by the angle between the two sections .


adding a loaded vertical whip to the top of the disc is supposed to improve the lower frequency response but it also has a negative effect on the higher frequencies
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Re: Hustler DCX.

Postby m0lsx » Tue Dec 18, 2018 8:08 pm

Chris P wrote: adding a loaded vertical whip to the top of the disc is supposed to improve the lower frequency response but it also has a negative effect on the higher frequencies


I have a discone that has a mobile whip on the top of the disc & the disc & the cone are both connected to the coax outer core. The antenna it's self covers, 6 meters, 2 meters & 70 Cm on TX & I seem to remember something about 23 CM coverage too, but SWR is off the scale on 23Cm. Not that I would expect a mobile whip to perform there.
The three TX band it does cover, it covers each equally badly.
On all three TX bands I am able to get low SWR on one or two using the adjustment on the whip. But never a radio friendly level of SWR on all three. & judging by the reception reports I got with the antenna. I suspect checking more than the SWR would be a depressing experience.
As an RX antenna, I found it to be very good on VHF & OK on UHF.
I only stopped using the discone as I wanted better 6 meter TX performance.
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