Topband: Beverage Frustrations

[Donald Chester]

I have been noticing lately a dropoff in performance of my beverage.

Lightning got my little toroidal transformer a few weeks ago, so I rewound 
it and this time wired it inside the base of an old tube, and mounted a tube 
socket in a cheap rural-type mailbox.  When the beverage is not in use, I 
simply open the mailbox, unplug the transformer from the socket and store it 
far enough away from the antenna wire that it won't get zapped.

The degradation in performance suggested that the lightning had also zapped 
the terminating resistor.  It consists of several 1 to 5 watt carbon 
composition resistors in series-parallel configuration to give approximately 
500 ohms.  Sure enough, checking with an ohmmeter, I got an oper circuit 
reading.  The resistors were mounted in a little plastic Radio Shack box.  I 
opened the box, and the resistors checked ok, but moisture had got into the 
box and corroded all the connections until there was no longer continuity.  
I had used top quality nickel plated brass hardware but nothing would take 
solder, not even the tinned copper hookup wire.  When I constructed the 
unit, I sealed up everything - box lid and wire feed-through terminals - 
using silicon glue and roofing tar.  The only way the water could have got 
inside is by condensation after the unit would cool off at night and create 
a partial vacuum and suck in moist air.  With such a small box, I hadn't 
anticipated that happening.

Rather than repairing the thing - I know this would turn into one of those 
20-minute jobs that consume the better part of a day (without solving the 
basic problem), I have decided to take some other approach.  I have some 
ideas,  but before re-inventing the wheel I would like to hear from others, 
how you solved the problem of protecting the terminating resistor from the 
weather and moisture condensation.

Also, for now would it be better to mount the resistor on the ground and run 
a wire up to the antenna, or mount the resistor at the top of the downlead 
right at the end of the antenna?  Next winter after the crops are harvested 
I plan to add some additional length to the antenna and let it gradually 
slope to the ground.

Don K4KYV


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