[UK-CONTEST] Setting up a vertical

[Clive Whelan]

What's your call Brian?

Assume you refer to the MA5V, the MA5B being a mini beam?

It's described as a half wave vertical, and therefore the radials are not
really radials in the normal sense of the word. It's important to understand
that concept first, as a half wave end fed, doesn't strictly require a
ground plane per se ( lots of caveats to that however). Therefore the size
of the "radials" is largely immaterial, just forget about them. Keep well
away from the water tank which will otherwise detune the antenna. The
scattered feeders might also do that, but you have no choice I guess?

If you tune the thing right ( an analyser such as the MFJ is absolutely
invaluable), then the length of coax is largely immaterial. Shorter the
better to avoid losses. Don't even think about using RG58, RG8/RG213 is
mandatory really. If you haven't got an analyser, you'll just have to leg it
back to the shack every time you make an adjustment ( per band of course).
In that case an exact number of halfwaves of coax will replicate the antenna
feed R/jX at the tx, but that's probably not possible across all bands?


How far are the climes, KH6 or EA6!!

73


Clive
GW3NJW

-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com]On Behalf Of brian coyne
Sent: 22 June 2005 18:40
To: uk-contest at contesting.com
Subject: [UK-CONTEST] Setting up a vertical


Forgive lack of punctuation I am using a strange keyboard

I am in foreign climes and have obtained a Cushcraft MA5 = In all my years
of homebrew antennas I have never used a vertical I have no textbooks with
me or available

I have a penthouse apt 100 mtrs from the sea and the ant will be 40 mtrs asl
= the rooftop is spacious enough but littered with cable for terrestial and
satelite tv = there is a large water tank available / would bonding onto
this be likely to cause any tvi problems I want to consider elecrical storms
as well here / there would only be 100w o/p at this stage

As coax replacement may not be easy I dont want to suck it and see so is the
shortest run to the shack ok or should there be an odd number of quarter
waves used for the feeder and if so which qrg should that be based upon

Any hints and tips from vertical and MA5 users would be very much
appreciated

Also the radials on this ant do look a bit lacking in dimension = maybe it
will work but any ideas on rooftop radials would be appreciated in case it
doesnt do what it says on the tin

Regards to all and TIA

73

Brian


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