[Amps] Parasitic Suppressor 4-1000A

[R at contesting.com]

On Mar 9, 2006, at 8:15 AM, aborg wrote:

> Hello Amp Users,
>
>    I have a homebrew 4-1000A amplifier that works
> perfect on every band but 20 meters. When I attempt to
> load it arcs lightly on the 20 meter band switch. The
> current parasitic suppressor is a 1 inch wide copper
> silver laced strap, 3 turn coil 1 inch diameter with
> two value resitors or inductors. I haven't taken then
> apart to measure or determine what they really. When I
> measure the , I vitually get nothing. I made another
> suppressor using a copper tubing .25 inch that I
> flattened with a hammer and silver tinned the ends.
> Next I put 3 100 ohm 3 watt resistors in parallel and
> did the normal resistor in the coil configuration.
> When I key amp with this configuration, I get an awful
> screeching sound and my computer monitor puts on a
> small light show. The new sound and light show is only
> with my newly created suppressor. Sorry this was so
> long. Any suggestions ?

Mike -- The VHF parasite suppressor you described probably has a Q of 
c. 5 at the anode's self resonance.  In  my experiences, a suppressor 
with a Q of c. 1.5 will provide fewer fireworks than conventional, 
higher Q suppressors.  The tradeoff is a 2% or so reduction in P-out at 
28MHz.  We make a low VHF-Q suppressor retrofit kit for the 4-1000A / 
8166.  If you would like to try one, send me your usps adr.  If you 
report the results on AMPS, the retrofit kit is free.
>
> 73's
>
> Mike-KK4MS
> a_borg at yahoo.com
>
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Rich Measures, 805.386.3734, AG6K, www.somis.org  r at somis.org is my 
real e-mail adr.