[TowerTalk] Cutting a FT-240 type 33...in half ??
Steve Hunt
steve at karinya.net
Tue Feb 10 08:44:55 EST 2015
In the PPT you linked, there are slightly fewer effective turns on the
binocular than on the tall stack; he's comparing 3 complete turns
through a stack of 8 toroids, with 3 turns through part of the stack and
2 turns through the remainder. You'd expect the relative impedances to
be (8*3^2) and (4*3^2+4*2^2) for the tall stack and the binocular
respectively; that's an impedance ratio of 1.38:1 which is about what
the chart shows consistently at frequencies well below the SRF.
I guess the shift in SRF is then simply down to the difference in
inter-winding capacitance between the two arrangements.
Steve G3TXQ
On 10/02/2015 11:35, Ian White wrote:
> Interesting question about binocular arrangements of cores (two short stacks of cores side by side, vs one tall stack). I found K9YC's comparative measurements [1] but am struggling to explain either (a) the shift in resonant frequency or (b) the difference in |Z| magnitude.
>
>
>
More information about the TowerTalk
mailing list