Topband: Surge suppression for Beverage?

[Tom Rauch]

> I would appreciate any suggestions on adding surge suppression to the
> terminating end of a single wire Beverage.
> 
> I have a small 12vdc relay powered down the wire that I use to switch
> between uni/bi-directional, and routinely blow its coil.

You might bypass the relay coil with a .1 uF 50 volt capacitor in 
parallel with a low voltage MOV. Choke each of the leads leaving 
the coil with a single layer choke of about 100 uH. Be sure you tie 
one terminal of the coil directly to the relays metal frame or pole-
piece if you can.  

Buy some cheap spare chokes. 

> I've also seen my multi-watt carbon terminating resistors vaporize.

Are the resistors "real" carbon composition resistors or are they 
carbon film? Virtually all carbon resistors are now carbon film, 
which have very poor immunity to surges.

Metal or carbon film resistors will fail constantly no matter what 
wattage you use. Also, be sure to use close spaced spark-gaps at 
the antenna ends!

73, Tom W8JI
w8ji@contesting.com


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