This is a multi-part message in MIME format.
--------------C654013017CEA0CD31057F23
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
--------------C654013017CEA0CD31057F23
Content-Type: message/rfc822
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
X-POP3-Rcpt: ka4u@popserv
Return-Path: <ka4u@vnet.net>
Received: from popserv.vnet.net (popserv.vnet.net [166.82.1.29])
by lmd.vnet.net (8.10.1/8.10.1) with ESMTP id e68CuBb13769
for <ka4u@vnet.net>; Sat, 8 Jul 2000 08:56:11 -0400 (EDT)
Received: from vnet.net (ka4u.vnet.net [166.82.121.171])
by popserv.vnet.net (8.9.1a/8.9.1) with ESMTP id IAA22503
for <ka4u@vnet.net>; Sat, 8 Jul 2000 08:55:54 -0400 (EDT)
Sender: ka4u@vnet.net
Message-ID: <3966495A.762FD031@vnet.net>
To: <amps@contesting.com>
Date: Fri, 07 Jul 2000 17:19:22 -0400
From: John Simmons <ka4u@vnet.net>
X-Mailer: Mozilla 4.7 [en] (X11; I; Linux 2.2.14-15mdk i586)
X-Accept-Language: en
MIME-Version: 1.0
To: John Simmons <ka4u@vnet.net>
Subject: Re: Tuned Input
References: <396643F4.3C9C4390@vnet.net>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Mozilla-Status2: 00000000
John Simmons wrote:
> I am new to this so hopefuly I can pose a intelegent question that
> some kind of answer. Sence the thread seems to be running long the
> line of input matching I thought now would be a good time to pose this
> question. I have recentley become intrested in trying to building a
> HF amp using the russian gs-35b. I have been told that the tube
> charistics are similar to the 3cx1500 (8877). Based on the Arrl
> hand book (76) construction artical the 8877 is quoted as having a
> chatode impedence fo 54 ohns. I have not seen any Information on the
> GS-35b that flatley states the chathode impedence for this tube is
> X. I have looked through the handbook to see if I could find a
> formula to calculate the input impedence based on bias operating
> point or something similar to the formulas used to estimate the plate
> load resistance. It would seem to me that there should be some kind
> of relationship between bias , gain , drive level , input capitance or
> something which would give a clue as to where to estimat the input
> restistamce. I know that one of Wing field programs gives a set of
> numbers for use of a pi input network on based on the expexted cathode
> resistance of a triode.
I mashed send to soon !!!!!!!!
T he question I am posing is there a way to estimate the cathode input
resistance .
I also noted that the 8877 has a indirectly heated cathode where it appears
from the schematic that the GS-35b has the cathode tied to the heater
element. I am making am making the asumption that instead of using a
transformer heat connection as used in the 8877 I will need to use a
choked input to isolate the heater transformer from rf input on the
cathode.
The tube charistics can be viewed at
http://www.tubes.ru/techinfo/TransmittingTubes/gc-35b.html
Any help would be greately appricaeate as this looks like it might be a
great alternative to the $800 + bucks for a 8877.
de John Simmons KA4U
mailto:ka4u@vnet.net
--------------C654013017CEA0CD31057F23--
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|