Re: [Amps] Tetrodes in GG Configuration

["Will Matney" <craxd1@ezwv.com>]

Well, I wasn't for sure as I cant decipher what he wants. He mentioned
wanting to know how to increase the inductance by 300 nH, which
squeezing the coil would raise it. In a Pi-L, the load C is in between
the two coils and tune C at the coupling capacitor off the anode. In
other words, the added coil is between load C and the load. Without
knowing what he wants to do for sure, about the only thing I could
advise is answer his question about how to raise inductance by 300 nH.
With a circuit description in detail, what he's wanting to accomplish,
and at what frequency, I dont know what else to tell him.

Will



On Fri, 21 Jan 2005 13:22:02 EST, <Dennis12Amplify@aol.com> wrote:

Will,
I believe Chris is talking about converting from a PI network to  a Pi-
L
network. The Pi-L having two levels of impedance matching, and a little
  more
harmonic suppression, than the original Pi network.
 Thus the original Tune C becomes the middle capacitor of the Pi-L,
allowing
for a larger value of C, and the plate C is now the new Tune C.
 Also, If his tune cap is already backed all the way out, he needs
LESS
inductance in the tank to tune it, not more... Therefore he would be
SPREADING
the coil turns apart, or removing a turn, or moving the tap towards
less turns,
any of which would result in less inductance in the tank  circuit....
Regards,
Dennis O.
In a message dated 1/21/05 11:49:21 AM Central Standard Time,
craxd1@ezwv.com writes:

A 300 nH  coil (0.3 uH) is not very much. Assuming this would be the
tank
coil, the 10 meter end being the largest in size, one might just
squeeze
the coils together to raise the inductance enough to bring  it in tune.
 If
not, adding 1 to 2 turns of the same size wire, and  same diameter
would
most likely do it. A dip meter would be easier  to use to find the
exact
placing of the tap on the coil if it has  taps. According to the way
the
tube is ran and tube type, some at a  higher frequencies dont need a
tune C
in order to tune correctly  because the tubes output C is high enough
and
takes care of it. In  the amps I've seen this way, a load C was all
that
was  used.

Will


On Fri, 21 Jan 2005 09:00:56 -0800, Chris  <rfcrazy@cox.net> wrote:

Can anyone tell me what size wire  and dimensions to use for a 300 nH
coil? I don't have an inductance  calculator.  I am having a problem
with
a 3cpx5000 that has high  C Out.  The tune vacuum cap is a backed all
the
way out in order  to tune. I read on web site that you can use a 300 nH
coil from anode  to C1 to rectify this.
Thanks for the help,
 Chris




Will

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