[TowerTalk] Antenna Distance From Shack
n4zr at contesting.com
Fri Aug 18 15:06:49 EDT 2006
You're right, Bob, it was a typo.
The idea was that I wanted to have a half-wavelength (or close to it) at the lowest frequency of operation, meaning 160 meters. But I also wanted to measure as accurately as possible, which meant measuring at 28 MHz. I used an RG-11 pigtail so that I could get the length within an inch or so of being x half-waves at 28 MHz.
As for the loss measurements, W8JI told me that with a composite feedline like this, I could not get a usable loss number. The 259B manual says "be sure the distant end... is not terminated in any resistance" and also says that non-50-ohm systems cannot be measured.
73, Pete N4ZR
At 01:23 PM 8/18/2006, Robert Chudek - KØRC wrote:
>Can you elaborate on the "1750 Hz (measured at 28 MHz) of 3/4" CATV" you mentioned? First, I assume you meant 1750 KHz, but aside from that, I'm not following what you mean.
>Also, measuring loss at the shack with the MFJ-259B... Unless you install a non-resonant 50 ohm terminator at the opposite end, your readings in the shack will continue to 'vary widely' (although maybe not as "widely"). If you installed a 50 ohm load on one port of a remote antenna switch that would accomplish the task, but I'm thinking this is not what you had in mind regarding measuring loss.
>73 de Bob - KØRC in MN
>Date: Fri, 18 Aug 2006 08:13:14 -0400
>From: Pete Smith <n4zr at contesting.com>
>Subject: Re: [TowerTalk] Antenna Distance From Shack
>To: TOWERTALK at contesting.com
>Message-ID: <126.96.36.199.2.20060818080204.05175928 at mail.adelphia.net>
>Content-Type: text/plain; charset="us-ascii"
>Frank and Bill make good points. For the last 10 years, I have been using 3/4" CATV for most of the 190-foot run from my house to my antennas. To be specific, I use RG-213 up the tower and across the roof of my house to my 2nd-floor shack, but use multiples of a half-wave at 1750 Hz (measured at 28 MHz) of 3/4" CATV in between.
>-- some stuff snipped here --
>I want to be able to monitor loss from the shack, something that my composite feedline doesn't seem to let me do (the indicated loss on my MFJ-259B varies widely with frequency).
>-- trailing text snipped here --
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