Topband: First attempt at beverage antenna, not working as expected
donovanf at starpower.net
donovanf at starpower.net
Sun Jan 16 07:43:54 PST 2011
Obviously something is very wrong with your new Beverage. While your Beverage is too short for really good performance on 160 meters, it should perform very well on 80 and 40 meters. Please run some tests on those bands. If its not performing as you expect on 80 and 40, you have some kind of serious problem in the antenna, transmission line or connectors.
A simplest measurement you can make is DC resistance. Assuming your matching transformer provides a DC short across the far end of your coaxial cable, the shack end of the coax cable should read just one or two ohms.
If thats okay, you need to make some RF measurements. An MFJ-259 is an excellent and inexpensive tool. With the Beverage terminated you should see VSWR less than 1.5:1 across a broad frequency range. When you remove the termination, the VSWR should change dramatically with frequency.
Please share your results with us. Beverages just want to work, its nearly impossible to get really poor performance without a fault in the system unless its installed over salt water.
---- Original message ----
>Date: Sun, 16 Jan 2011 14:15:00 +0000
>From: Rick Stealey <rstealey at hotmail.com>
>Subject: Re: Topband: First attempt at beverage antenna, not working as expected
>To: <topband at contesting.com>
>Sounds like "maybe" something is not working. If you have an antenna analyzer
>can you do a sweep from 160 up to 40 m? There should be a relatively flat
>SWR over the whole range. Without the far end terminated the impedance and
>therefore the SWR will flop all over the place. That would show you that the
>transformer, resistor and connections are ok. Then measure down at the
>shack end of the coax and it should also be flat, maybe even a little
>flatter. If you suspect the coax you can also get a loss reading on
>it with the antenna analyzer by open circuiting it and taking a reading.
>Your length is a bit short, though. As I understand the Bev starts
>playing pretty well at 500 feet and up, so your results might be what's
>expected. Mine is 550 feet and most of the time it beats the inv L
>on EU signals from here in NJ. But not always, and sometimes the
>difference is minimal. But there are times when a signal is at the
>noise level on the L, and switching to the Beverage it becomes readable
>but not a HUGE difference.
>UR RST IS ... ... ..9 QSB QSB - hw? BK
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