Hi Chris,
Thanks for your answer. As you can see in my reply to Allison I will
follow your advices.
With you I hope that more pictures of the filtershape will be
dropped it in this group. The arguments Max gave in his reply makes
more clear to me that a filter design have to be checked by measuring
the result.
On the moment I am still working on the 9MHz filter The first part of
the design (2nd order test filter and calculating new C's and
impedance) worked well. In 4 steps I came to desired bandwith, all
pictures are saved so the process can be followed.
Now I have two things to do:
1. Match te impedance of the filter to the amplifierstages.
2. See how the calculated C's does work out on a 4th order filter.
When there are results I will drop them in this group.
In "RF Amplifier Classics", 1-10 there is a design with two IRF510 in
push-pull on 28 V giving over 40W with 1 W drive. Mail me if you want
a copy of the article.
73
Ruud (PE2BS)
--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:
Hi Ruud,
as I remember, you asked for a solution in the circuit, by using
other
resistors.
I kept the circuit 'original' and added very small transformers,
pictures can be seen in the BITX17 Photos directory.
I did many experiments with several values of components, did many
measurements (by soundcard) so the differences can be seen easily
(as
you know, but other may not).
Best regards,
Chris.
Doing the measurements I noticed that matching the impedance is
very
important for the filtershape. Changing the C's makes great
impedance
changes. (33 pF, R= 328 Ohm, C=76 pF, R= 142 Ohm on the 2nd order
test filter) That's why I asked some information about matching
the
impedance in the amplifierstages in the BITX20 (msg 868). I am
still
waiting for a reply....
