On Nov 3, 2004, at 11:11 PM, K7RDX wrote:
OK...Strange a fellow would order your kit if he couldn`t solder the
"Thing"
in place.Jim.
He thought it was a bolt-on kit.
----- Original Message -----
From: "R.Measures" <r@somis.org>
To: "K7RDX" <k7rdx@earthlink.net>
Cc: "Amps reflector" <amps@contesting.com>; "Vic Rosenthal"
<vic@rakefet.com>
Sent: Wednesday, November 03, 2004 10:21 PM
Subject: Re: [Amps] SB-220 parasitic suppressors
On Nov 3, 2004, at 4:02 PM, K7RDX wrote:
Vic is absolutely correct about resistors changing value due to
heat/age/mistuning,etc. Another way to tame especially squirrly amps
is to
add a supressor to the cathode side in addition to the usual anode
ones. I
read somthing about that idea several years ago and found it
effective
in
taming my pair of 4-1000`s when running 6700vdc. My hf GS-35b AMP
has a
supressor only in the cathode and has been super stable for the last
four
years.....AL-1500 Owners might give that one a try.
A GS-35b has 0.12pF of anode-cathode feedback C. An 8877 has 0.10pF
of
it, so they have a fairly similar amount of internal feedback. Our
8877 low VHF-Q parasitic suppressor retrofit kit has both an anode
suppressor and a cathode suppressor. It comes with a money back
guarantee. So far, the only refund has been to a guy who said he did
not know how to solder.
-- Today's trivia question: At its max freq of 1000MHz, what is the
reactance in ohms of the output/input feedback path in a (g-g) GS-35b?
Parasitic discussion
sure brings out the pros&cons as well as the snake oil
guy(s.)......Jim
K7RDX
----- Original Message -----
From: "Vic Rosenthal" <vic@rakefet.com>
To: "Amps reflector" <amps@contesting.com>
Sent: Wednesday, November 03, 2004 2:04 PM
Subject: [Amps] SB-220 parasitic suppressors
One reason that an SB-220 can develop VHF parasitics is the
following:
the
original suppressors use 2-watt carbon composition resistors. These
resistors
tend to increase in value when they age, and especially when they
are
heated.
If an SB-220 has been used heavily, especially on 10 meters or --
worst
case --
on 10 (or 11!) meter AM, the resistors will have gotten quite hot
and
may
have
changed significantly in value, or even opened up.
If the resistors are discolored, they should definitely be replaced.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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