[Elecraft] KX3 Filter Blow-By

Oliver Dröse droese at necg.de
Mon Oct 8 14:59:44 EDT 2012


Hi Jim,

did you have VFO NR enabled by chance? I suppose yes, as the KX3 is quite 
unusable on the high bands without. :-( There is a known issue = bad effect 
of the DSP leading to "artifacts", i.e. hearing signals +/- 5-6 kHz again 
from strong stations. If you turn off VFO NR it goes away, but then the VFO 
noise is much too strong. :-( Another bad effect is even with VFO NR enabled 
if you tune "over" strong stations you suddenly have strong VFO noise until 
you stop turning the wheel. Afterwards it's gone again. And if you turn the 
VFO fast enough you will not even recognize even 59+ signals. :-( All 
problems from the VFO NR DSP implementation as confirmed by Elecraft. And no 
matter if with or without roofing filter and with/without 8 kHz shift 
enabled. Still wonder why nobody else is complaining about those effects? 
Cannot be that everybody has an s4 noise level on 12, 10 & 6 m that would 
mask the VFO noise and thus no need to enable VFO NR.

I documented all those effects on video and sent it over to Wayne. He said 
he and Lyle are working on it, hopefully with some results soon, otherwise 
the KX3 is of no use for a high band op like me. :-( Never seen such 
problems with *any* other rig owned so far ...

73, Olli - DH8BQA



----- Original Message ----- 
From: <Jimk8mr at aol.com>
To: <elecraft at mailman.qth.net>
Sent: Monday, October 08, 2012 7:46 PM
Subject: [Elecraft] KX3 Filter Blow-By


>A recent KX3 owner (# 1677), I've noticed hearing out of passband  signals
> from loud CW stations. I can hear such stations up to several KHz  away. I
> suspect the range is limited by the audio response of the system, 
> including
> my ears. Both sides of zero beat, though less so on the opposite side  of
> the zero beat.
>
> In the CA QSO Party this weekend, maybe the loudest 10% of the stations on
> 10 CW Saturday afternoon were leaking through. (I've heard the leakage on
> other  bands as well.)
>
> I don't have any roofing filters. (I figured any stations weak enough  for
> me to need the filter to hear, would never be able to hear me anyway).
>
> Is this normal, or is there some shielding or other issue affecting my
> unit? (It is a kit version).
>
>
> 73  -  Jim  K8MR
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