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[Amps] suppressors

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Subject: [Amps] suppressors
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Date: Mon, 5 Aug 2002 08:18:36 -0700
**  A parasitic suppressor's design is a compromise that hinges on the 
dissipative capability of R-sup.
To wit:  If R-sup burns out at 29MHz, VHF oscillation becomes 
substantially more possible.  However, if R-sup has very low-R to reduce 
its dissipation, VHF-Q increases, VHF ringing-V increases, and 
oscillation becomes more probable. ["Calculating Power Dissipation in 
Parasitic-Suppressor Resistors", March, 1989 *QST*]

> Here is a point I've never seen discussed , anywhere, and I've often
>wondered about it !!

**  such has been discussed on AMPS.  The key hurdle is understanding 
parallel/series-equivalent circuits.  (p.7 in the aforementioned *QST* 

>   what reason is there for a specific value of resistor in a
>parasitic suppressor. ?? I have seen 50 ohms, 100 ohms, and two 50 ohms in

**  lLowest VHF-Q is generally achived when XL = R - Provided R-sup can 
withstand the dissipative burden @29MHz.  

>! Is there a valid reason for using any particular value ?? over
>the years it seems that 50 ohms was the usual value, but today I found in
>the amp I'm working on , a 100 ohm, two watt unit.

**  As a rule of thumb, if R-sup burns up (@29MHz), VHF-Q was too low.  
If R-sup runs warm, VHF-Q is too high and an oscillation may be nigh.  If 
R-sup runs hot as hell, but does not burn out, VHF-Q was just about right 
to dampen the invisible bell.  

cheerz, Carl

-  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,  

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