parabolic uhf antenna

[jerryd]

Does anyone out there know where one could find what I believe was a Chanelmaster 8" parabolic model. I had one but my ex got it with the house when we split ? Jerryd

 

[Rick0725]

the 8' parabolic was discontined in 2000 cm4251. and they tossed the tooling so it is not coming back.

I stumbled upon this place...claim to have them in stock...they want a fortune $1000.

good catch hey...antenna voodoo

http://www.ultrasatellite.com/SearchResults.asp?Cat=2

 

[Jim5506]

Wade Antennas sells parabolics.

http://www.wade-antenna.com/upa.htm

 

[Jumbo Dumbo]

Wade Antennas sells parabolics.

Looks like the old Delhi parabolics with a frame added - must be a weight issue.

"* A qualified structural engineer should be consulted prior to mounting an antenna on a tower or support structure "

 

[riffjim4069]

I called Andrew (Channel Master) back in 2003 and can confirm that someone tossed out the molds/tooling for their parabolic line. I did some research around that time and found a company in Ontario CA that made a pair of nice parabolic antennas (5-7ft range). I don't recall the price, but I'll post a link if I can find one.

*** Never mind, I'm an idiot...it was Wade Antenna

I'm currently using two CM-4228 bow-tie UHF antennas with matching CM-7775, low-noise (+23 gain - 2.0 noise) UHF pre-amps. This setup works pretty well in my deep-fringe area (51+ miles from Richmond VA, 53+ miles from Charlottesville VA, 55+ miles from Washington DC), but I looked into an untra-low noise (+20db gain.5db) UHF pre-amp in order to receive more reliable reception from Baltimore MD (90+ miles). However, there just wasn't enough benefit to justify the expense of the pre-amp ($$$). Anyway, check out this post if you're interested in a low-noise UHF pre-amp: http://www.satelliteguys.us/showpost.php?p=337640&postcount=3

 

[Rick0725]

what about 2 antennas direct 91xg combined

 

[ralfyguy]

If I had the $$$$ and the time and patience, I would try that. You might not have alot of gain, because of the splitter loss.
What about extending the boom of the XG91 with an addtional element? This antenna has 3 boom pieces and they are clamped together. You could add an addtional piece to the front without any tools. What would happen?

 

[Rick0725]

you can try rg11 quad shield instead of rg6. maybe you can give that a try to cut down on the losses and squeeze some more signal.

You can order the rg11 by the foot with quality compression connectors and install the cable from the preamp to the coax grounding block. also ask them to use weather boots on both ends.

 

[lilyarbie]

Why not try an old C-band dish??? Just remove the feedhorn and replace it with a bow-tie. The UHF parabolic antenna appeared to use long curved rods of metal in a parabola with two bow-ties in the middle. Since antennas are usually recommended to be measured on a half-wavelength basis, the metal rods of the bow-tie would require each metal cross being roughly 13 inches each in order to handle down to channel 14. I've done the calculations and UHF would be the only set of frequencies that would work accurately on such an antenna of 8-10 feet in diameter. VHF would require a much much larger diameter since the Hi-band of VHF would require elements that would block half the diameter of the dish which in turn would block a good portion of the reflector that collects the signal and bounces it back to the elements.

 

[lilyarbie]

Correction: 13 inches in length is what I meant to say in the above post. The bow ties on my 8-bay are roughly around the same length (estimated from ground view to be about 1 foot long each). The question I had in mind was to the approximation of how much diameter each crossing rod of the bow-tie should have total. I'm guessing that the diameter should be much thicker since you would be dealing with a larger reflector behind the elements. Also, I figured the principle that with running signal through wires that you would need more thicker wires to hold more wattage or more signal in turn. I figured the same idea could be used with signals traveling over a terrain. The thicker the metal, the more electrons of the signal will be able to radiate that piece of metal and thus allow for more signal to be collected on the elements. Of course the elements do not need to be too thick as to not block off a good portion of the focal point of the parabola. Another question would be how much distance does the bow-tie elements need to be placed from the focal point to get the most signal quality as well as signal strength when it comes to digital signal reception? The elements would need to be placed at a height where the elements do not block off the focal point where the signal is not able to collect and bounce back to the elements. Also, it would not need to be placed too far away from the focal point as to allow signal to hit the focal point and have the majority of the signal bounce back and miss the elements.