[Amps] Design VS parasitic

[Alex Eban]

At Tadiran we tried once to add a diplexer with a 50 MHz crossover frequency
and with a load connected to the high pass section. We got all kinds of
interesting results, except the wanted one!
Drop it! DO WHAT A FEW FELLOWS SAID HERE! Add a circuit that drops gain
around 100MHz (TRAP!!!!) and let it do its work. It's a true and tried
solution. The real reason for oscillation is known for 50 years and the
solution has emerged from looong experience! It's based on sound theory
(Bode) and proven use it!.
Alex	4Z5KS

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Carl
Sent: Monday, August 24, 2009 5:22 PM
To: Roger; dezrat1242 at yahoo.com
Cc: Amp Reflector
Subject: Re: [Amps] Design VS parasitic


----- Original Message ----- 
From: "Roger" <sub1 at rogerhalstead.com>
To: <dezrat1242 at yahoo.com>
Cc: "Amp Reflector" <amps at contesting.com>
Sent: Monday, August 24, 2009 1:49 AM
Subject: Re: [Amps] Design VS parasitic


>
>
> Bill, W6WRT wrote:
>> ORIGINAL MESSAGE:
>>
>> On Sun, 23 Aug 2009 08:28:50 -0500, "kingwood" <k5jv at kingwoodcable.com> 
>> wrote:
>>
>>
>>>        Now, if we know the frequency of this unloaded parasitic, why 
>>> can't
>>> we build a trap, or load, inside the final compartment to absorb it 
>>> before
>>> it does any damage?
>>>
>>
>> REPLY:
>>
>> You are missing the fundamental purpose of a parasitic suppressor. It 
>> does not
>> "trap", "load" or "absorb" the parasitic. Instead, its job is to  reduce 
>> the
>> gain at the parasitic frequency enough so the tube will not oscillate.
>>
>>
>
> Wouldn't it be correct to say (paraphrasing): Designing a circuit to
> prevent parasitic oscillations rather than designing one to deal with
> the results of one?
>
> 73
>
> Roger (K8RI)

How do you propose to do that when the tube itself is the source?

Carl
KM1H


_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps