Hi Angel,
30 turns #24 on a FT-82-43 core will work just fine at a KW.
With an additional single wire run through the middle, this may also double
as a portion of a cross coupled power sensor ciruit.
73 & Good morning,
Marv WC6W
-- Angel Vilaseca <avilaseca@bluewin.ch> wrote:
I am building a 3.5 to 30 MHz amp and I have been following this
interesting thread.
I have a question about the *other* choke in the output circuit, that is
the one that is wired between the antenna terminal and ground. As I
understand it, its role is to short-circuit HV to ground if case the
tank circuit ever becomes hot with HV (plate cap failure). Its value
should be about 2.5 mH 3 A.
Most chokes of this value that are made available today on dealers
catalogs have a ferrite core.
My question is: can a ferrite choke be used, or should it have a
non-magnetic core?
If a ferrite core is used, could the ferrite saturate and generate
harmonics?
How large sould the ferrite core be and which mu should it have?
Can a toroid core be used?
It is interesting to see that lots of literature have been written about
the plate choke and almost none about the output choke. Both chokes are
in a circuit with high currents and voltages. Both are wired between a
high RF point and RF ground. It seems that the worst problem with the
plate choke - resonance - is simply not an issue with the output choke.
Why?
Also one would expect that the one between the highest impedance point
and RF ground (the plate choke) should also have the largest reactance.
Not so: abt. 200 uH for the plate choke, 2.5 mH for the output choke.
Any ideas?
Angel Vilaseca HB9SLV
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