I do not have the schematics of the Ameritron amps but take a look on the
schematic of the popular SB 220: If I remember right, you had at the cold
end of the first plate choke a red 1000pF/5kV?? doorknob beetween the
junction of the two plate chokes and ground. The reactance of the
combination of the first plate choke and decoupling condenser in series is
in paralell with the C1 and carries rf current on the lower bands . The
doorknob can take more rf current then a disc capacitor and is a decoupling
condenser at higher bands. What about the Ameritrons? Do they also have two
plate chokes in series and a 1000pF decoupling beetween them? Then 1000 pF
would be OK Mr Rich Measures? Even on 160?
Forgive my poor English but I am getting ready for our Midsummer celebration
to-night. Young girls put 7 seven flowers under their pillows in order to
dream about the man they will marry one day. Me, a 73 year old bachelor will
put 7 cactuses under my pillow and dream about the girls I have behind me,
hi.
Prosit de Hans SM5KI
----------
>Från: measures <2@vc.net>
>Till: <N6BUU@aol.com>, <n6er@yahoo.com>, "AMPS" <amps@contesting.com>
>Ämne: Re: [AMPS] RF filament choke for indirectly heated cathodes?
>Datum: ons 21 jun 2000 20.29
>
>
>>
>>In a message dated 06/21/2000 09:36:32 AM Pacific Daylight Time, 2@vc.net
>>writes:
>>
>><< In other
>> words, put a jumper between the cathode and the heater, and use a heater
>> choke - the same as one would do for >>30MHz operation >>
>>MAKES U WONDER JUST HOW MUCH MORE IT WOULD COST THE MFG. TO DO IT RIGHT!
>>
>Good point, Hank. My guess is that most of the manufacturers have
>engineers with limited educations. . For instance, all of the
>Ameritron/MFJ amps use a HV ''bypass'' cap that has 88-ohms of Xc at
>1.8MHz (1000pF). What kind of a bypass is 88-ohms of Xc? During a
>debate with Ameritron/MFJ's head engineer, it became apparent that he did
>not understand algebraic or scientific notation.
>
>cheers
>
>- Rich..., 805.386.3734, www.vcnet.com/measures.
>end
>
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
>
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|