The problem is that the beam forming plates are connected to the
cathode. That by-passes the shielding between the plate and cathode done
by the grids. You may have instability. In the case of some others such
as some 1625's you can separate the beam forming plates from the cathode
by simply removing the base or drilling a hole in it and unsolder the lead
from the pin and moving it to another pin. You can't with this tube.
73
Bill wa4lav
At 01:44 PM 2/11/2009 -0500, Glen Zook wrote:
>Although not a "high powered" amplifier I am thinking of trying to use a
>5894 (dual tetrode that is the next step up from the 829B) in grounded
>grid rather than the "normal" grid driven configuration on the 222 MHz
>band. The peak output would be around 100 watts.
>
>One of the reasons is because I have between 5 and 10 watts out of my
>transmitting converter and that is way too much for driving the grids of
>the 5894 in a grid driven linear application. Due to the design of the
>transmitting converter (also home brew with a 6360 dual tetrode final
>amplifier) I would have to use an attenuation pad between the converter
>and the linear instead of just dropping the power from the converter by
>detuning, etc.
>
>I started to build the amplifier in the usual push-pull configuration and
>then got to thinking about grounded grid. Anyone have any experience with
>running a dual tetrode with push-pull output in a grounded grid
>configuration? The 5894 has a single cathode connection for both
>tetrodes. Also, since it does have a separate cathode I don't have to
>think about a filament choke.
>
>Glen, K9STH
>
>Website: http://k9sth.com
>
>
>
>
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