[Top] [All Lists]

Re: [Amps] Antenna traps

To: Gene Bigham <>,Amps reflector <>
Subject: Re: [Amps] Antenna traps
From: Vic K2VCO <>
Date: Tue, 13 Dec 2005 14:29:02 -0800
List-post: <>
Gene Bigham wrote:
> I know this is not about amplifiers, except for being able to use one on a 
> trapped antenna, but has anyone found a set of traps for 40 and 80 that can 
> handle a legal amplifier output?

You have two problems in making traps: current and voltage.

I made some using 5KV doorknobs (for 160/80) and exploded the doorknobs 
at less than legal power.  This was a result of heating as a result of 
inadequate current capacity.  They also drifted a bit before blowing up. 
  Now I have one made of a 6 KV mica capacitor that is about 3" x 4" x 
3" which worked fine at QRO.

The trick with traps is to make sure they are NOT resonant at a 
frequency that you will operate on!  The voltage across a parallel 
resonant circuit increases enormously as you get close to resonance. 
For example, my 160/80 meter inverted L (used for CW only) trap is 
resonant at about 3480 KHz.  The impedance in the lower part of the band 
is still high enough to isolate the 160 M section, but the voltage isn't 

You can make traps out of coax which will handle the power.  Just google 
'coax traps' and you'll find some information.  They are heavy, though.

Vic, K2VCO
Fresno CA
Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>