[Elecraft] K3 deaf when narrow filter engaged

[Matt Zilmer]

The chances of that are negligible.  You should send your original
email and all follow-ups to k3support at elecraft.com.

I have heard of a lot of strange K3 symptoms, but this one is beyond
the pale.  It sounds like one of the pre- or post-roofing filter
components is somehow shifting the resonance, and looking at the
schematic I just don't see how that's possible unless there is a
bypass-value in place of a regular cap.  Conventional SMT assembly -
that would not happen.

I'm no expert, but this probably is not some trouble that can be shot
over email.  One of the Elecraft gang can help you narrow it down, but
it should probably be done interactively over the phone or Skype or
whatever.

You *may* be able to avoid the additional hassle by running the EE
INIT procedure on your K3 and starting over.  This will only work if
there isn't some defect in the hardware, but that is so unlikely that
running EE INIT is your best bet.  See p66 of the Owner's Manual (rev
D7), or use Adobe to search for "Parameter Initialization".  If you
dorked a setting, then EE INIT will solve that problem and put your K3
into its factory default settings.

Good Luck.  No matter what you can or can't get done in short order,
Elecraft will assist you with any problem.

73,

matt W6NIA
K3 #24

==


On Fri, 08 Jul 2011 23:40:40 -0400, you wrote:

>Filter placements are correct, and no empty slots are enabled -- I've done
>the setup both ways: manually via CONFIG on the K3 itself, and via the K3
>utility.  Done it many times now.
>
>Here's the odd part:
>
>If I change the frequency offsets in the K3 (via CONFIG menu), I can dial
>across the range of value offsets and peak a signal almost to the point at
>which things sound like they're operating properly.  Same thing happens for
>3 of my filters -- the 2.7k, 400 Hz and 200 Hz.  In all cases the specified
>offset is not the one value that gives the strongest signal.  Using the
>specified offsets, it seems like the signal is not properly centered in the
>passband.
>
>What are the chances all three of my filters have the wrong offsets?
> Possible but doubtful.
>
>Is there some other setting on the K3 that I may have inadvertently tweaked
>during calibration that would have thrown off all filters?
>
>I'm stumped.
>
>--Andrew, NV1B
>..
>
>
>
>
>
>On Fri, Jul 8, 2011 at 9:35 PM, Guy Olinger K2AV <olinger at bellsouth.net>wrote:
>
>> The most likely cause of your problem is that the filter placements as
>> viewed in the K3 utility and as actually installed on the main board
>> do not actually match.  Next is that you have left an empty slot
>> ENABLED in the K3 utility.  After that, a filter not plugged all the
>> way in or defective.
>>
>> 73, Guy.
>>
>> On Fri, Jul 8, 2011 at 8:06 PM, Andrew Moore <andrew.nv1b at gmail.com>
>> wrote:
>> > New K3 with 3 filters:
>> >
>> > FL1 - empty
>> > FL2 - 2700 Hz
>> > FL3 - empty
>> > FL4 - 400 Hz
>> > FL5 - 200 Hz
>> >
>> > FL2,4,5 enabled, offsets and bandwidths entered, and filters plugged into
>> > right slots (FL1 can remain empty right?)
>> >
>> > When I turn the bandwidth encoder CCW, everything's fine until I hit 400
>> Hz.
>> >  At 450, I hear signal. At 400, when FL4 kicks in, receiver goes quiet
>> from
>> > then on.
>> >
>> > Ideas?
>> >
>> > Also - RF calibration - I'm using an XG2 to feed the K3 a 50 uV signal.
>>  The
>> > K3 hears it at about S5 max, not even close to S9.  Followed the
>> calibration
>> > instructions.
>> >
>> > --Andrew, NV1B
>> > ..
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