Topband: Fwd: Re: Cushcraft MA-160

[Herb Schoenbohm]

Dave,

  If you ground the top of the wire of a quarter-wave sloper to the 
tower and feed the bottom of the slant wire instead (assuming a ground 
rod and some radials laying on the ground at the feed point) you will 
IMHO do much better. Some matching may be required at the feed point but 
it may be no more than a series capacitor to remove the reactance of the 
wire. There my be a very slight bit of directivity in the direction of 
the slant wire, but the overall efficiency of this as a TB radiator may 
be significantly better even with a short tower of 50-60 feet. If the 
tower is more than 60 feet tall and with a beam on top I would suggest 
shunt feeding the tower with a cage feed again assuming you can have at 
least 4 or more radials on the ground even if you need to fold or bend 
the ends a bit to fit in your yard. All half slopers from metal towers 
do IMHO is try to backward excite the tower with RF. Losses can be high 
and performance is generally less than adequate. If you are able to 
shorten the slant wire to get your feed point closer to 50 ohms may also 
be beneficial and should also be considered.

  Good luck, Herb Schoenbohm, KV4FZ

  On 3/16/2012 10:57 PM, David Novoa, W4DN wrote: > Has anyone in this 
reflector installed a Cushcraft MA-160 short vertical > with a couple of 
elevated radials or the K2AV Folded Counterpoise? If > so, results? Any 
recommendations? I need to do something before the TB > season ends. My 
quarter-wave sloper doesn't work properly. > Thanks, > Dave, W4DN > > > 
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