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Hello
Group,
Planning a new
single-ended Class E PA for my activities on the Dreamers Band
(8.27 kHz) two
questions came up - perhaps someone can help me:
- Being
interested only in on-off-keying I´m concerned about the capacitor
in parallel
to the power FET which in my case on VLF will be in the uF range.
If the DC
supply is on and without gate drive this capacitor is charged to
the DC supply
voltage. At the first positive gate pulse it discharges via the
drain-source-path,
the current being limited
only by
parasitc impedances - a poorly defined condition which usually has
to be
avoided. Does this mean that I have to apply drive continously and
key the DC
power supply only, perhaps synchronously to the next positive
drive pulse?
- Is
there any rule of thumb for the inductance of the rf choke in the
drain-power
supply path?
Thanks for
any idea!
73,
Tom, DK1IS
www.qrz.com/db/dk1is
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