ne1s wrote:
Geoff/W5OMR writes:
I'm soliciting ideas on grid inputs on a 4-125.
Thoughts?
What worked out well for me on the FR deck in the big PDM rig (pair of
7527A's in parallel) was to load the grid with ~2500 ohms non-reactive
(a bunch of non-X 7W resistors in series) and match it from a 50 ohm
source with a T network - two series variable caps with a
tapped/switched inductor from their junction to ground. This allows me
to tune the grid circuit from 160M - 10M, and the resistive loading is
good for stability. Since to drive a class-C amplifier we LIKE
harmonics there is no liability employing the T network. It takes
about 25 - 30W on the low bands, more as the network becomes lossy at
higher frequencies to get 30 mA grid current. (I use my TS-440S as the
RF exciter, so no problem there). For a single 4-125 you will need
less, of course.
GL,
Thanks, Larry...
This has been added to my folder of notes on construction.
--
73
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