On Sat, 20 Feb 1999 11:04:46 -0600 Jon Ogden <jono@enteract.com> writes:
>
>Was looking at my 89 handbook at some of the amplifier designs to look
>at
>what folks were using for filament chokes. Starting on page 30-50,
>there
>is a design for an 8877 amp. In looking at the schematic, the guy
>uses
>NO filament choke. The two filament lines are both bypasssed to
>ground
>by .01 uF caps. From what I can tell the filaments are on pins 1 & 5
>of
>the tube and the schematic says that pins 2,3,4,6, & 7 are the cathode
>
>input. Yes, it's grounded grid.
>
>Is the 8877 set up this way so that the filament pins are isolated
>from
>the cathode? Is that why he's able to get away with it? I'm ignorant
>of
>how the 8877 is set up.
The 8877 is indirectly heated as is the 8874, 3CX800, YC-156 and others.
A small filament choke is advantageous in order to assure full isolation.
Ameritron uses one as did Dentron which may account in part for their
excellent stability without voodoo .
73 Carl KM1H
>
>Just curious.
>
>73,
>
>Jon
>KE9NA
>
>
>-------------------------------------
>Jon Ogden
>KE9NA
>
>http://www.qsl.net/ke9na <--- CHECK IT OUT! It's been
>updated!!!!!
>
>
>"A life lived in fear is a life half lived."
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampfaq.html
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
>
___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|