Topband: Noise cancellers, Low Bevgs

[Smith Preston]

Fellow Topbanders

During this period of ~low activity on the reflector I'll add
my 2 cents worth on two topics that have appeared in the past.

1. Noise Cancelling -
   I built the FET null steerer from Vic Misek's "Beverage Antenna
   Handbook".  The circuit is simple and fits nicely on a small
   perfboard.  Here in Chagos where we are plagued with local
   noises it has been dubbed the magic box as S9+ single source
   local noises can be nulled to inaudibility on 160-10m.  Mine
   is bandswitching 160/80/40/20 but with 160m L/C it functions
   on higher bands as well.  An antenna switchbox permits using
   any rx antenna in the arsenal including the tx ant for either
   the "noise" or "primary" antenna inputs to the null steerer.
   Also included is a bypass switch for normal listening and
   3 step attenuators 5-10-20 dB for up to 35 dB attenuation in
   each input used to ~equalize noise level into the "noise" and
   "primary" inputs.
   I'm not familiar with any of the commercial units available
   but it is hard to imagine one outperforming this simple
   device.

2. Beverage Height -
   At home in AZ my most effective Beverages are rolled right
   on the ground supported an inch or more above the surface by
   grass and weeds.  Vs. elevated they seem to exhibit improved
   signal to noise and directivity.  After 11 years on the band
   and using a number of Beverages that's my unscientific
   opinion.  When rain static is an S9 roar on elevated Beverages
   those on the ground are often much quieter.  Between seasons
   they are stored on Cordwynds.
   Disadvantages include being a trip hazard in traffic areas
   and a target for hungry critters.  And signal output as seen
   on the S-meter is lower than with elevated but on 160/80/40
   that's not a problem.

I'd be glad to compare notes, pse reply direct.

Ref Chagos ops on 160, due to spurs from the AFRTS A.M. bcst tx
on 1485 kHz only 300' away we are currently unable to hear weak
sigs and are pretty much confined to QSOs with our neighbors in
south Asia, the Persian Gulf and UA9.  I'm hoping to resolve this
before CQWW in January.

73
Pres N6SS/VQ9SS




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