Am 30.01.2015 um 02:41 schrieb Alexander Pummer:
And the narrow notch for the harmonic is not required anyway, since
the fundamental is fare enough, therefore a high Q LC trap will work
better, also with the setting of the biasing af the active devices the
spures could be reduced to [ just observe the output with a spectrum
analyzer and set the bias of one site to minimum harmonics, there will
be no common optimum for all harmonics, but a good compromise could be
achieved ]
As usual, it depends. If you want absolutely deep notches, it is easy
with the usual molded chokes
to produce craters at 5 and 15 MHz that meet at 10 MHz, even producing
some loss there.
The harmonics are gone, then.
At the -3dB point of a resonator we have 45° phase shift, now calculate
how many ps delay that
is at 10 MHz and then speculate on temperature stability.
On MY doubler board, Amidon toroids are in the layout, too, and I have
written that they are good enough.
They are hard to get. I have heard that Amidon is really Micrometals,
but have no cross
reference. A good alternative would be Siemens K1 pot cores, but they
are much too big and probably only NOS.
But everybody can get 5 and 15 MHz crystals for 35 cents.
BTW, this is the spectrum of a Morion MV89A that happenes to be on my table:
<
https://picasaweb.google.com/lh/photo/4UEjkc8uy_vkE5nTUR0BEdMTjNZETYmyPJy0liipFm0?feat=directlink
>
10 dB external attenuator. Could use some filtering, too.
regards, Gerhard
ps
My two BF862 are quite different. delta Vsource = 100mV.
Changing that would be the cheapest improvement.
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