>[cut and paste]
>>> --------- Forwarded message ----------
>>> From: W0YR@aol.com
>>> Think about it.
>>> The Swan amps don't furnish ANYWHERE NEAR
>>> 3,400 Volts B+. Why even bother to point out the
>>> bias requirements of a 4-400 operating in GG
>>> with 3,400 volts on the plate?
>-
>Because other options are open season... One
>might judge the value of a Dahl retrofit xfmr. Some
>vintage Henry amps (with excessive filament and
>Anode values) arrived with 3-400z's on board, an
>SB-220 might be considered a candidate should
>the owner have a supply of cheaper 4-400's when
>the original tubes go away. The original post
>asked for information to compare the two tube
>types... the posted reply was very useful, on topic
>information.
>-
>I've found the 4-400 a bit "stiff to drive" compared
>to the 3-500z, but it's a nice tube to play with. One
>could easily apply a bit of screen voltage for lower
>drive (and higher gain) applications.
* More gain is obtained with DC screen V applied only if the RF driving
signal is applied between the control grid and the screen grid. With
both grids at RF-ground and the cathode driven, this does not happen.
However, with the grid being driven, more gain is available provided that
the DC screen potential is high enough.
>grid could be grounded (bias applied in the fil xfmr
>ct) or dc floated (I don't prefer floating control grids
>if a choice is available). But then you get away from
>the simplicity of zero bias operation.
* good point
>
>Adding tetrode operation to a swan amplifier is
>also not out of the question. There's lots of space
>inside....
* Which would also solve the problem of no tuned input.
>One or two classic ARRL type 4-400 Handbook
>projects come to mind with lower anode G-G
>AB2 operation.
>-
>>> Unless, of course one wants to point out his
>>> library skills.
>-
>Pretty rude of you to attack Rich's about his
>post offering valid information. The posted
>information was on topic.. provide your on topic
>information and get off your bitter horse ride.
>-
>>> In case you DO want to up the Swan Amp's
>>> plate voltage to 3,400 volts in order to
>>> obtain the requisite idling current, there are
>>> any number of authorities on the subject,
>>> RIGHT HERE? Just ask!
>-
>If the answer is on topic, why not post it
>instead of playing personal attack 101 and
>stingy with your info.... buck'o.
>-
>One is not limited to the mentioned 3400 volt
>potentials as a min value to "obtain the requisite
>idling current," there are any number of amps
>members willing to offer up various options
>and opinions without the additional cannon
>fodder (personal attacks) attached.
>-
>The 4-400 is a tetrode and some very
>innovative things can be done with that
>old swan amp. Just ask.... right here!
>-
>cheers
>skipp
>
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- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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