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Hi Arv,

The real issue about those tunable traps is the raduino won't tune them.
Or can it!? Much the same as a tunable preselector. Or plug-in
one-at-a-time low pass filters. Doable yes. Make everybody happy? No.

73,

Bill? KU8H


On 09/04/2018 04:53 PM, Arv Evans wrote:
> Allison
>
> Interesting.? I have been experimenting with resistively loading series
> LC traps and find
> that they can be made broad enough to cover some tunable spurs without
> seriously
> decreasing the attenuation.? They also seem to work better if installed
> some place near the
> middle of multiple pole filters.
>
> In olden days we occasionally used tunable traps, but that doesn't seem
> easily done with
> today's compact rigs.? Today traps are mostly relegated to trap-dipole
> antenna designs.
>
> But, to-each-his-own.? Obviously they might not be for everybody.
>
> Arv
> _._
>
>
> On Tue, Sep 4, 2018 at 8:31 AM ajparent1/KB1GMX <kb1gmx@...
> <mailto:kb1gmx@...>> wrote:
>
>? ? ?Are we ignoring the possibility of using series LC traps to suck out
>? ? ?some of the bugs
>? ? ?(bug traps...?),? ? ? 8-)
>
>? ? ?Arv,
>
>? ? ?No not ignoring them.? They are generally useless as the assumption
>? ? ?is the
>? ? ?spur only happens here which is invalid, they are tunable? you tune
>? ? ?they move.
>? ? ?For examplt the 10M spur for 28mhz its 17 and at 29.9999 its 15.0001
>? ? ?so if you are anywhere in between so is the spur somewhere in between.
>
>
>? ? ?reminder as it seems needed every 24 hours...
>
>? ? ?There are two issues:
>
>? ? ?Spurs that result from lack of filtering for bands over 20mhz.
>
>? ? ?Harmonics due to layout of the low pass filter switching for the
>? ? ?80/40/20 meter bands.? (rewire the relays its fixed).
>
>? ? ?Since the topic is we are hams we do this stuff.? If you whine
>? ? ?about pulling relays and removing tracks to fix the filter issue
>? ? ?I offer no sympathy.? Do that or external filter, or nothing.
>
>? ? ?Allison
>
>
>
>
>
>

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bark less - wag more