[Amps] SB-220 parasitic suppressors

[R.Measures]

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 at somis.org>
> To: "K7RDX" <k7rdx at earthlink.net>
> Cc: "Amps reflector" <amps at contesting.com>; "Vic Rosenthal"
> <vic at 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 at rakefet.com>
>>> To: "Amps reflector" <amps at 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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>>>
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>>>
>>>
>>
>> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>>
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org