[AMPS] RF filament choke for indirectly heated cathodes?

measures 2@vc.net
Thu, 22 Jun 2000 09:28:31 -0700


>
>If ameritron does right or wrong is another story, but what I can say 
>for sure is that without anode suppressor a 3CX1500 in GG is quite 
>stable and much less prone to VHF parasitic than other common tubes 
>with conventional VHF suppressors.

€  Easy to say.  I have heard of many AL-1500 owners who have had several 
8877s go kaput during the warranty period for no apparent reason.  One 
owner in South Carolina reportedly went through six tubes over a period 
of about 21/2 years.  .  The designer of the 1500 conveniently blames 
Eimac.  

>The anode suppressors in the form of coil and resistors are critical devices 
whose
> effectiveness is very much questionable. 

There is no question that anode suppressors lower the VHF RL presented to 
the anode.  //see Wes Stewart's measurements of suppressor 
characteristics with a HP Impedance Analyzer.  //

>The true reason such suppressors are installed is to satisfy and agree 
>conventional designs and expecially to let people to find out what's 
>typically placed between the plate choke and tubes' anode.
>Most of those suppressors are actually not working at all, and finally 
>they aren't anything better than no suppressors at all.

€  In my experiences, when the ''True Reason'' Card is played, you had 
better fasten yo' seatbelt.  .  

>Last but not least, when suppressors resistors are cracked (typical) 
>oscillation risks are increased.
>
Agreed, Mauri.  An open R-supp is sure to increase VHF gain.  
>> 
>> From    : owner-amps@contesting.com
>> To      : <N6BUU@aol.com>, <2@vc.net>, <n6er@yahoo.com>, 
><amps@contesting.com>
>> Cc      : 
>> Date    : Wed, 21 Jun 2000 17:28:50 -0500
>> Subject : Re: [AMPS] RF filament choke for indirectly heated cathodes?
>> 
>> 
>> >  Ameritron does it right, but alas, no anode parasitic suppressor!
>> >
>> >  (((73)))
>> >  Phil, K5PC >>
>> > IT SEEMS TO ME THAT MAKES EVEN LESS SENCE!           HANK
>> 
>> The designer of the Ameritron AL-1500 has stated here on this reflector
>> that it is possible through proper lay-out and component selection to
>> preclude the need for anode parasitic suppression on 8877 amps.
>> 
>> Please turn off your caps lock, Hank..it is perceived as shouting on the
>> reflector. I don't think you are  mad at me, are you???
>> 
>> (((73)))
>> Phil, K5PC
>> 
>> 
>> 
>> 
>
>
>
>
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>


-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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