In a message dated 4/30/00 8:22:06 PM Eastern Daylight Time, w2ge@home.com
writes:
>
> Wt8r@aol.com wrote:
> >
> > In a message dated 4/30/00 7:18:43 PM Eastern Daylight Time,
n2bc@stny.rr.
> com
> > writes:
> >
> > >
> > > I do have an Autek RF-1 analyzer. Would a useful approach be to
> provide
> > the
> > > desired plate load via a resistor, approximate the values of C1 and
C2,
> > then
> > > adjust L1 and L2 for 50 ohms at the output measured by the RF-1?
> > >
> > > Any other real world approaches (sans fancy instruments) ?
> > >
> > > THX, Bill N2BC
> > >
> > >
> >
---------------------------------------------------------------------------
> ---
> > --------------------------------------
> >
> > Bill,
> >
> > I am currently doing the same thing with a Pi-L tank. I use a carbon
> > resistor of the proper value to simulate the anode impedance. I use a
> > capacitance meter to set the proper values of capacitance for Ct & Cload
> and
> > drive the tank output with my MFJ SWR Antenna Analyzer, using the
> frequency
> > meter and SWR bridge to determine the resonant frequency of the tank.
>
> As I have been told, that is not enough power to place through the pi
> circuit to get any sort of realistic reading. (That is from the MFJ
> analyzer)
>
> Phil W2GE
>
> Since
> > capacitance vaues can be determined very accurately, it is best to set
> them
> > and then adjust the inductors to bring them into comformance.
> >
> > Good luck.
> >
> > Dave, WT8R
> >
------------------------------------------------------------------------------
----------------------------
Phil,
I hope seeing is believing............When I feed the output of my MFJ
Antenna Analyzer into the output of the Pi-L tank, I tune the exciting
frequency to obtain the lowest SWR. Both the tune capacitor and the load
capacitor cause the expected peaking and dipping of the SWR meter. When too
much capacitance is required at a given frequency to maintain the Q,
increasing the inductance causes a corresponding decrease in the required
capacitance and the SWR moves closer to 1:1 at the desired frequency.
The reality of this is verified by using a Grid Dip meter to verify the
frequency. I have never heard that the power output of the MFJ meter was too
low to excite the tank. I would be interested in hearing your rational
concerning this.
Seems to me a little like the SWR being independent of the power level being
measured.
Dave, WT8R
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