"Frank Mikkelsen" wrote in message ...
I whant to double a frq. between 200 and 265 MHz. I had tryed to used the
Mini-circuits RK2 doubler and som BP filters, but because of the band pass
200-265MHz it is diffeculd for me to suppress the input frq. and the 3*inp.
to min 50-60dB.
Is there any other ideas to realise this.

I think the doubler may be the easiest way to do it. Because your
output frequency range is so limited, it should not be difficult to
build a bandpass filter for that range, perhaps even with "zeros" on
the input and on 3*input. Even without the zeros, a simple
5-resonator 0.1dB ripple Chebychev design from RFSim99 shows 30dB
atten at 300MHz, and that's the worst-case 1*input, 3*input atten.
Admittedly, you won't achieve quite that much in a practical
implementation, but should be close. (Quick playing with a zero at
300MHz makes me think a 3-resonator filter with that added zero might
be enough.) Add that to the rejection of 3rd you should already be
seeing (30dB min according to MiniCkts) and that should do the trick
for you. Also, you can "trim" a doubler to have high rejection of the
third, and low feedthrough of the fundamental, if you want.

You may also find some interesting ideas on the Wenzel web sites:
specifically at http://www.wenzel.com/pdffiles/diodedbl.pdf, but you
may find other things under the RF Circuits section of
http://www.techlib.com/electronics/index.html.

Cheers,
Tom