Hi Dave/G3YXM and group,
the Zobel Network 22 Ohm / 4,7nF in my G3YXM PA gets very hot if driving
the PA in 1kW mode; much hotter than the toroid T2 (output transformer)gets.
I changed the five Watt resistor with a 20 Watt, it gets hot too; with the
cooling fan off the resistor desolders itself.
I think that`s a good sign of the correct dimension: 22 Ohm / 4,7nF means
the open reactive load (T2 and surroundings) oscillates at calculated
1,539MHz; measured 1,776MHz.
But what a heavy loss!
My question:
Is there no other possibility eliminating the instability of that output
system ?
Regards
Uwe / dj8wx
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