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Date: Tue, 05 Dec 2017 13:44:41 +0100
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: LF: RE: Todmorden receiver
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Sounds good! What do you estimate, what is the 'gain' on 2970 Hz 
relative to the old system from the last season?

Soon there will be a signal on 5170 Hz again. Next week at the latest.

73, Stefan

Am 05.12.2017 12:09, schrieb Paul Nicholson:
>
> New H-field rx is coming along well.  Design changes are
> completed - it has a lower system noise, wider bandwidth,
> significantly lower common mode response, and a much better
> line driver.  Like the new E-field rx, it also has a built-in
> calibration port.
>
> Currently testing the design changes on breadboard and it
> performs just as per the Spice model, except for a higher than
> expected system noise.   Should be just below 0.1fT in 1Hz
> but I'm measuring 0.46 fT.   Maybe this specimen of LT1028
> is a bit noisier than others?  It's my last one but I've
> got more arriving hopefully today.   I'll pick the best two.
> Even with this mysterious extra system noise, it's still 20dB
> below the natural noise floor after sferic blanking.
>
> Apart from that it is working perfectly, just as per design
> and looks very good at 137 kHz too.
>
> Hopefully will be able to start the cutting and drilling and
> filing and soldering this week.  That's my least favourite part
> of the job.
>
> What I won't discover until it's finished and installed, is
> whether it actually cures the excess noise at 8kHz and 5kHz
> that we've seen lately.  I haven't been able to identify the
> cause of the relatively (compared to E-field) poor S/N on the
> existing rx.  Hopefully it is a low level of intermod in the
> line driver.  If so the new rx will not suffer that problem
> and we'll see another step improvement in the 8270 spectrogram.
>
> -- 
> Paul Nicholson
> -- 
>