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#1
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I have a tree here in the Tampa Florida area just begging to have a Hustler 4 or 5 BTV stuck in it. I have had great luck with ground mounted Hustler Verticals when I lived near the sal****er of Tampa Bay. I am now in Brandon Florida, east of Tampa, and far from salt water. I have stuck Hustler Verticals in trees before with radials for most bands, but had access to a bucket truck back then, and did not have stents in my heart. I got to thinking WHY not take a hustler vertical with only ONE Tuned "radial" for each band in the form of the lower part of a 1/2 wave dipole. In other words, make the Hustler Vertical into a multi band center fed 1/2 wave dipole. It will be a lot easier to deal with only one radial for each band if they hang straight down the tree vertically. Has anyone ever done this before ?
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#2
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On Mar 5, 9:25*am, ka7niq wrote:
I got to thinking WHY not take a hustler vertical with only ONE *Tuned "radial" for each band ... You are trusting that each radial will be resonant on only one band akin to a fan vertical antenna. What may happen, for instance, is that the 40m radial may accept an appreciable amount of energy on 15m and direct the 15m signal up at a high take-off-angle - less than optimal for 15m operation. Other interactions are possible, e.g. 28MHz/4MHz=7, 18.14MHz/3.6MHz=5, etc. Any vertical radial resonant at 3/4WL, 5/4WL, 7/4WL, etc. will have a suboptimal effect on the take-off-angle. -- 73, Cecil, w5dxp.com |
#3
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and hang it vertical in the tree ? |
#4
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On Mar 6, 12:24*pm, ka7niq wrote:
Cecil Moore;735465 Wrote: On Mar 5, 9:25*am, ka7niq wrote:- I got to thinking WHY not take a hustler vertical with only ONE *Tuned "radial" for each band ...- You are trusting that each radial will be resonant on only one band akin to a fan vertical antenna. What may happen, for instance, is that the 40m radial may accept an appreciable amount of energy on 15m and direct the 15m signal up at a high take-off-angle - less than optimal for 15m operation. Other interactions are possible, e.g. 28MHz/4MHz=7, 18.14MHz/3.6MHz=5, etc. Any vertical radial resonant at 3/4WL, 5/4WL, 7/4WL, etc. will have a suboptimal effect on the take-off-angle. -- 73, Cecil, w5dxp.com I never considered this Cecil. Would you think it better to use a wire trap dipole instead of the Hustler 4BTV and hang it vertical in the tree ? -- ka7niq My experience with the Hustler 4BTV hasn't been good. Over two hamfest I bought 4 of them, lucky for me I was only buying then for the tubing and mount and paid around $10 each for them. I dont think any of them had a trap that wasnt bad. Jimmie |
#5
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#6
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JIMMIE wrote:
My experience with the Hustler 4BTV hasn't been good. Over two hamfest I bought 4 of them, lucky for me I was only buying then for the tubing and mount and paid around $10 each for them. I dont think any of them had a trap that wasnt bad. Maybe the bad traps were why they were only $10? |
#7
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On 5 mar, 16:25, ka7niq wrote:
I have a tree here in the Tampa Florida area just begging to have a Hustler 4 or 5 BTV stuck in it. I have had great luck with ground mounted Hustler Verticals when I lived near the sal****er of Tampa Bay. I am now in Brandon Florida, east of Tampa, and far from salt water. I have stuck Hustler Verticals in trees before with radials for most bands, but had access to a bucket truck back then, and did not have stents in my heart. I got to thinking WHY not take a hustler vertical with only ONE *Tuned "radial" for each band in the form of the lower part of a 1/2 wave dipole. In other words, make the Hustler Vertical into a multi band center fed 1/2 wave dipole. It will be a lot easier to deal with only one radial for each band if they hang straight down the tree vertically. Has anyone ever done this before ? -- ka7niq Hello Chris, From another thread I concluded you have a flat membrane roof. If you plan to use the 80/75m antenna for NVIS (local traffic) mostly, why not putting a horizontal dipole above your roof. It will be very likely below resonance length, but you can match this to 50 Ohms. This will almost certainly result in better efficiency w.r.t. the commercial vertical. For 40m and below, you can go vertical. If you like to experiment and know the problems w.r.t. RF high voltage, you may try a vertical resonating antenna that is in half wave resonance. You will get end-fed voltages in the kV range, but the common mode current will be significantly less w.r.t. a quarter wave resonating structure. This reduces the requirements for your ground provision and the ground loss. What is the height of the tree that you plan to use as support (in other words what is the maximum vertical height you can use)? With kind regards, Wim PA3DJS www.tetech.nl |
#8
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ka7niq wrote:
JIMMIE;735930 Wrote: On Mar 6, 12:24*pm, ka7niq wrote:- Cecil Moore;735465 Wrote: On Mar 5, 9:25*am, ka7niq wrote:-- I got to thinking WHY not take a hustler vertical with only ONE *Tuned "radial" for each band ...-- - You are trusting that each radial will be resonant on only one band akin to a fan vertical antenna. What may happen, for instance, is that the 40m radial may accept an appreciable amount of energy on 15m and direct the 15m signal up at a high take-off-angle - less than optimal for 15m operation. Other interactions are possible, e.g. 28MHz/4MHz=7, 18.14MHz/3.6MHz=5, etc. Any vertical radial resonant at 3/4WL, 5/4WL, 7/4WL, etc. will have a suboptimal effect on the take-off-angle. -- 73, Cecil, w5dxp.com- I never considered this Cecil. Would you think it better to use a wire trap dipole instead of the Hustler 4BTV and hang it vertical in the tree ? -- ka7niq- My experience with the Hustler 4BTV hasn't been good. Over two hamfest I bought 4 of them, lucky for me I was only buying then for the tubing and mount and paid around $10 each for them. I dont think any of them had a trap that wasnt bad. Jimmie I have decided against the use of the Hustler 4BTV. I am going to buy a CB antenna for use on 17 through 10 meters, keep the feed line short, and use it with a tuner. I have been reading that several Hams are doing exactly this with the Antron 99 and Sirio Gain Master CB antennas, with decent results. I do plan on a self supporting tower one day, but this will get me on the air, until then. If you put an autotuner at the base of a 1/4 wave 10m vertical (i.e. 2.5m long), and some random length radials, for 10,12,15,17, and 20, it will work fairly well. The feedpoint impedance of a half length antenna (i.e. 1/8 wavelength vertical) isn't so horribly different that losses will bite you. (for comparison.. I ran some models a while ago for a 20-odd foot vertical. resonant (Z=39 ohms) at 9.4 MHz, and at 4.7 MHz, the z was 14-271j. I just happened to have that data handy.. you're looking at a shorter antenna and higher frequencies, but the ratios are likely to be similar. W9CF's tuner calculator says a T network for the first case (Z=39 at 9.4MHz) would have 0.1 dB loss (3%), and for the second case, you'd have 1.7dB loss (33%) While it's not great to burn a third of your power in tuner/feedline losses, on the other hand, it's also not horrible. If you can put up something that's around 3-4 meters (10-13 feet) long, that will work even better. A piece of plastic pipe with some 12gauge wire inside it, for instance. or a 10 foot length of thinwall 1/2" conduit (sure, it's steel, but it's also got pretty good surface area.. without actually doing the calculation, it's probably comparable to a 12AWG wire in resistance) |
#9
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#10
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On 9 mar, 01:13, ka7niq wrote:
'Wimpie[_2_ Wrote: ;735960']On 5 mar, 16:25, ka7niq wrote:- I have a tree here in the Tampa Florida area just begging to have a Hustler 4 or 5 BTV stuck in it. I have had great luck with ground mounted Hustler Verticals when I lived near the sal****er of Tampa Bay. I am now in Brandon Florida, east of Tampa, and far from salt water. I have stuck Hustler Verticals in trees before with radials for most bands, but had access to a bucket truck back then, and did not have stents in my heart. I got to thinking WHY not take a hustler vertical with only ONE *Tuned "radial" for each band in the form of the lower part of a 1/2 wave dipole. In other words, make the Hustler Vertical into a multi band center fed 1/2 wave dipole. It will be a lot easier to deal with only one radial for each band if they hang straight down the tree vertically. Has anyone ever done this before ? -- ka7niq- Hello Chris, From another thread I concluded you have a flat membrane roof. If you plan to use the 80/75m antenna for NVIS (local traffic) mostly, why not putting a horizontal dipole above your roof. It will be very likely below resonance length, but you can match this to 50 Ohms. This will almost certainly result in better efficiency w.r.t. the commercial vertical. For 40m and below, you can go vertical. If you like to experiment and know the problems w.r.t. RF high voltage, you may try a vertical resonating antenna that is in half wave resonance. You will get end-fed voltages in the kV range, but the common mode current will be significantly less w.r.t. a quarter wave resonating structure. This reduces the requirements for your ground provision and the ground loss. What is the height of the tree that you plan to use as support (in other words what is the maximum vertical height you can use)? With kind regards, Wim PA3DJS www.tetech.nl The *Tree is about 40 feet tall, and yes I do have a flat roof. I could attach a sloping wire from the tree to the roof, and center feed it with ladder line. This wire would be about 60 to 80 feet long, give and take a little. Unfortunately, it will be very visible! -- ka7niq Hello Chris, My idea is/was to have the (short) 75/80m dipole above your roof (assuming that the roof supporting structure isn't conducting). When you put the matching components and balun function in a box on the roof, you can go down with just a coaxial cable. This will keep the VSWR within acceptable limits to allow further matching in the shack. If space/visibility permits, I would go for the ladder line as you suggested. Main disadvantage of the dipole above the roof: interference from and towards domestic equipment. When the visibility of the dipole above the roof meets aesthetic rules by far, you may put 2 or more wires to the dipole (fan type short dipole). This reduces the reactive component, without reducing the radiation resistance, so matching becomes easier. Visibility, is this really a problem? Given the size of the tree, 40m and below should be possible without huge investment in ground provision. For 10m the wire/tube length isn't good, unless you can add a reactance to get collinear behavior. The above doesn’t mean 80m isn't possible, but due to the low radiation resistance (about 5 Ohms), you need a better counterpoise / ground provision, and the NVIS performance of your vertical isn't good. As with many things, making a choice isn't easy. A tree 60..80 feet from your house looks very attractive from an interference perspective. With kind regards, Wim PA3DJS www.tetech.nl |
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