>On Mon, 30 Mar 1998 17:10:39 -0700 John Lyles <firstname.lastname@example.org> writes:
>>I apologize to you ham amplifier designers as your frequency range is
>>soooo broad. Bound to hit a sneak resonance if you're not careful, not to
>>mention a lot of losses across your plate circuit. There have been a number
>>segmented schemes which seem to work in a fashion. Seems to me that
>>using a GDO is like setting your timing in your automobile engine by
>>your eyes fast.
>C'mon now John....what do you think the commercial companies used back in
>days of old?
Amen, Carl. Dipmeters are still good for finding resonances, and they
always will be. A dipmeter showed me the falacy of using gapped choke
sections on the same form.
>A 1/2" diameter is ideal for 80-10M and maybe even 160M. The SB200-220
>choke is only 50uh but the first series resonance is around 45MHz. I have
>not tried extending that form factor to 100 + uh but it might bear some
As expected, the resonance moves down into the HF region, so you gotta be
careful on which frequency you park it.
>Also back in the 80's there was a HRM article mentioning the use of a
>ferrite rod inside a choke form...the reference was a 5KW commercial
>application with no series resonances 2-30MHz. Later on B&W used that
>concept on their BBC-5K choke.
Two potential problems is that ferrite can saturate and ferrite is a
R. L. Measures, 805-386-3734, AG6K
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