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Re: [Amps] suppressors

To: <>, <>
Subject: Re: [Amps] suppressors
From: "Tom W8JI" <>
Date: Fri, 13 Jul 2007 12:14:45 -0400
List-post: <>
> Steve said:
>>In every case so far, copper gives

> better 'goodness'.<
> Which, from purely a theoretical viewpoint, is exactly 
> what should be expected.
> 73
> Peter G3RZP

N7WS measured identical magical nichrome and conventional 
Ameritron suppressors, and found at VHF near the frequency 
of suppression there was essentially no difference at all.

As frequency was reduced to HF and lower, the nichrome 
suppressor remained lossy.

A nichrome or other lossy resistive conductor suppressor is 
NOT a "low-Q VHF suppressor". It is actually a low Q low 
frequency suppressor.

This makes perfect sense and follows conventional wisdom, 
since the primary path for lower frequency signals is 
through the inductor. The primary path for VHF and highest 
frequency signals shifts into the resistor. Thus the coil 
loss affects dc the most, and UHF the least. The resistor 
affects UHF and the highest frequencies the most, and dc the 

By adding a resistive conductor we lower HF Q the most, 
while barely changing VHF Q.

If I had an amplifier that was unstable at or near the 
operating frequency and if I couldn't neutralize the 
amplifier, adding resistance that swamps the signal 
frequency might be a solution. If I really had a VHF 
oscillation in an HF amplifier then the solution would be 
increasing inductance and SHUNT resistance.

It's amazing how such a very simple system has become so 
misunderstood, almost to the point of being voodoo.

73 Tom 

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