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Re: 6 m repeater antenna

 

Number one that's a poor picture because it's doesn't show everything and I can't zoom in, number two that looks like a homebrew antenna because the wood support boom and it looks like PVC holding up the far end of the folded dipole (is it folded?)? That's not a DB212 ... I'm not even sure that's a 50 ohm antenna. DB products in their DB212 uses a special harness designed for both impedance and bandwidth. To connect two 50ohm antennas together,? you need a phasing harness of 75 ohm coax odd multiple of 1/4 wave length ..this raises the antenna Z to 100ohm at the end and a T with both antennas tied to it becomes a 50ohm feed.

Chris WB5ITT?

On Thu, Mar 27, 2025, 11:58 PM Hudson, John@CalOES via <john.hudson=[email protected]> wrote:

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John N. Hudson III, Regional Emergency Communications Coordinator?California, Governor¡¯s Office of Emergency Services

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On Mar 27, 2025, at 13:29, Roger willey via <kc4jnn=[email protected]> wrote:

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I think they should be on the same side of the tower 12 feet apart. My frequency is ?53.050 input is 52.050?

On Mar 27, 2025, at 2:56?PM, John via <jhaserick84=[email protected]> wrote:

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If the coax to the T is 50ohms, then yes , an electrical 1/4 wavelength of 35 ohm coax from the T to the feedline. You could? less ideally alternatively do two? 1/4 wavelength 75 ohm coaxial cables in parallel . Try to use polyethylene jacketed coax for longer life.. Both 50 coaxial cable antenna pigtails need to be the same length, but can be any length.? ?
I recommend mounting both antennas on the same tower leg.Those UHF T connectors are difficult to waterproof. without using butyl rubber under Scotch 88. First tape one layer of 88 , then squeeze and mold the butyl rubber, then 2 layers of 88 on the outside, to make it easier to remove the butyl rubbber when it eventually gets disassembled. Messi and Paolini in Italy make great 75 ohm direct bury type coax, if you are forced to go that route.
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John
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On 03/27/2025 12:32 PM EDT Roger willey via <kc4jnn=[email protected]> wrote:
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Begin forwarded message:

From: Roger willey <kc4jnn@...>
Date: March 26, 2025 at 2:45:40?PM EDT
To: [email protected]
Subject: 6 m repeater antenna

I have a 6 m folded dipole antenna, two of them with coaxial lines going to a T what length of cable should I use out of the T to get The impedance and the length? I was thinking maybe 35 Ohm
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