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Re: [Amps] R. MEASURES PRAYERS ANSWERED

To: "R L Measures" <r@somis.org>,"Steve Thompson" <g8gsq@eltac.co.uk>
Subject: Re: [Amps] R. MEASURES PRAYERS ANSWERED
From: "k7fm" <k7fm@teleport.com>
Reply-to: k7fm <k7fm@teleport.com>
Date: Wed, 31 May 2006 08:50:20 -0700
List-post: <mailto:amps@contesting.com>
"True, however, prayer cloths are not all that reliable. The main
reason for going after a parasite in the anode circuit is that it's
where the damped wave VHF ringing takes place - whenever anode
current changes - that starts the snowball rolling downhill."

It is also possible that a parasitic suppressor is an admission of sloppy 
design work.  There are many amplifiers built using the 8877 tube with no 
parasitic suppressors.  Can you imagine installing a parasitic suppressor 
into uhf cavity?  Perhaps you can make the entire cavity out of nichrome.

When designing an all band hf amplifier, it is probably easier to throw in a 
parasitic suppressor for the assumed
natural frequency of oscillation in the existing structure than to use a 
network analyzer and a lot of effort to reduce the oscillations to a point 
where they no longer will occur.

Rich talks about prayer cloths - but in fact his nichrome suppressor is 
acting as a prayer cloth.  This is a case of putting that in will make sure 
something bad will not happen.  It takes confidence in ones ability to build 
an amplifier without one - because they you are relying on your skill as a 
designer and builder - and expertise in measuring.

I have built amplifiers with and without parasitic suppressors and have had 
parasitics in both - but then again, I am only an amateur.

73,  Colin  K7FM 

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