dermel'ing - Page 3

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Re: dermel'ing

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I did a board like that once. It was about as planar as the average
potato chip. I could put it flat on my desk and give it a twirl and it
would spin for almost a minute.


John Larkin         Highland Technology, Inc

lunatic fringe electronics  

Re: dermel'ing

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There has to be a solution. Rogers sells a lot of pcb material.

Re: dermel'ing
Am 11.07.2017 um 04:15 schrieb Jeff Liebermann:
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I got quite good results even with filters on FR-4.

The filter on the right side was simulated with Empower Electromagnetics
some 10 years ago and home-etched on 0.8mm Bungard FR-4.



It hits quite closely, and is good enough to separate the harmonics
in a frequency multiplier. Adjusting the coupling and making it
compact took quite a time with the simulator.

It is probably not wise to switch manufacturers based on the price of
the day. Ask your manufacturer what their favourite prepreg is and
prescribe it for the future. Always using Isola-xxx in their standard
process should return quite consistent results.

Put test microstrips on unrelated boards and you soon see what to  
expect. Avoid unusual processes. We had delamination with Polyimide
prepregs, it needs hotter baking and has short shelf live. The
manufacturer may be tempted not to throw it away when the time has come.

The inductive part of a resonator is less impressed by varying Er
than the high impedance end. Rhea describes in his filter book how
to make Hi-Q resonators on FR-4. Make them very wide and too short
and replace the hi-impedance end with paralleled capacitors.


I'm not sure if it is exactly that book, mine is light blue and
200 miles away.


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