Topband: remotely-controlled Beverage termination

[Mark Connelly]

I have used the Byan remote Beverage termination scheme on at least two AM
broadcast-band listening DXpeditions to Cappahayden, Newfoundland.  The site
is about 100 km / 60 miles south of the major city of St. John's.  Stations
in the metropolitan St. John's area include VOCM-590, VOWR-800, and
CJYQ-930.  A twisted-pair wire Beverage 1 km in length was aimed towards
Brazil, roughly in the opposite direction of St. John's.  Normally the St.
John's stations strongly dominate their channels, even at night, if the
Beverage is unterminated.  By using the Byan remote termination system,
resistance could be varied for precisely optimum termination at each
frequency.  A meter on the in-shack control unit showed that this value
could be frequency and bearing dependent, thereby justifying the need to use
such a controller.  With optimum terminations selected for a back (north)
null, stations from Brazil, Netherlands Antilles, Argentina, and Uruguay
could be heard through or over the St. John's stations.

The VTL3A27 Vactrol mentioned in Steve's article is no longer being
manufactured, but a suitable substitute is available.  This is the VTL5C4,
obtainable from Newark Electronics as their stock number 43F888 and from
Allied as part number 980-0715.  A circuit using this part may be found in
my Pennant Antenna article at
"http://members.aol.com/DXerCapeCod/pennant.pdf".  Steve Byan's home page,
with the link to the Beverage articles, is
"http://www.ultranet.com/~oakridge/".


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Mark Connelly - WA1ION - Billerica, MA, USA 
e-mail: MarkWA1ION@excite.com 
homepage: http://members.aol.com/MarkWA1ION/weblink.htm 

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