Dr. Gerald N. Johnson wrote:
> On Wed, 2007-08-01 at 11:14 +0100, Bob Towers wrote:
>> I'm not exactly happy with the Jones filter on my Argonaut II.
>> a) the centre of the bandpass shifts up frequency (on USB) when I
>> tighten the bandpass width
>> b) the narrowest width setting is about 700Hz: I could do with 500Hz or
>> The manual warns against adjusting the two sets of 4-pole filters unless
>> you have a network (spectrum, surely?) analyzer, which I do. Anyway, the
>> adjustment pots are all locked in position with some sort of fixative.
> Network analyzer is a spectrum analyzer with signal source to measure
> the pass band characteristics. It could probably be done with a noise
> source and the spectrum analyzer or manually using a signal generator
> and detector, though that might be slow to get the necessary detail.
>> Has anyone had a go at adjusting the filters?
>> If so, I would appreciate some advice - which might be, of course, don't
>> try and fix it!
> I'd be inclined to go with an external DSP audio filter if the inherent
> selectivity wasn't quite narrow enough. But I tend to prefer wider
> rather than narrower so I can tell what's going on around the QSO I'm
> 73, Jerry, K0CQ
> Thanks, Jerry, for the advice.
I've recently picked up a Timewave DSP-9+ for a silly (=cheap) price and
I'll give it whirl. Been using it on the K2 and I'm quite impressed. I
had a Datong FL3 some years ago and sold it, like a fool....
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