[Elecraft] K3 at KH6LC in Stew Warmup

[Bill W4ZV]

Curt Knight wrote:
> 
> 
>>Considering recent posts, maybe you would be interested to hear about
> the setup we used at KH6LC during the Stew Warmup.  I brought my K3 SN
> 469, which has 2.7, 1.8, and 0.4 filters in the main and matched 2.7
> and 0.4 in the sub. Now I know that I should have sprung for the other
> 1.8 filter and saved myself the labor of installing it later. 
> 
> <Snip>
> 
>>The roofing filter mismatch between 400 Hz and 1800 Hz bandwidth was
> sometimes noticeable, but it wasn't a big thing.  One mod I would like
> to see would be an option to have the subreceiver bandwidth and shift
> track the main as it's an aggravation to have to double click the A>B
> when you want that.  Of course, you would like the option of having
> them separate, too.
> 
> ???  What firmware were you using.  Everything in the Sub's DSP should
> track the Main when in Diversity mode.  Your comment about filters is also
> confusing.  If you had DSP set to 400 or below, both roofing filters
> should have been 400 Hz.  If just above 400 Hz DSP, you would have had
> 1.8k in the Main and 2.7k in the Sub.  If you didn't like the offset
> effect, you could have disabled the 1.8k in the main so that both 2.7k
> filters would have been enabled above 400 Hz DSP BW.
> 
>>This K3 was the subject of a post last week ("Bad CW Note") and I can
> report that this problem seemed to us to not be present last weekend,
> but those of you who heard us may tell a different story and if so I
> would be happy to hear from you directly.  In between the post and the
> weekend, I had partly disassembled the case to look into putting a
> strap directly from the antenna tuner RF ground to the rear panel
> connectors, but I decided I didn't have the time to finish so I just
> replaced the panels, and maybe that improved the ground.  On the other
> hand, we did get bad reports on the CW keying.  One report said that
> it sounded like the keying was "soft".  Another report said
> "distinctive, but not fatally obnoxious".  It appears now that this is
> a problem mainly with the computer keying from the rear panel jack,
> and not the CW generated from the internal keyer, and that it may be
> connected to the TX DLY setting that I had at its maximum value to
> accommodate my old TL922 linear.  I have backed the setting off to 15
> and the CW weight looks more consistent on my scope now.  At KH6LC
> there is a modern linear and the nominal value should be enough.  We
> are still looking into this and also the buzz on the note and the
> story may change.
> 

You may want to check that the RX ANT port in the KXV3 has had the RX
Isolation Mod installed.  If not, you may have been getting RF feedback into
the K3 via the RX ANT input.

http://www.elecraft.com/K3/k3_app_notes.htm

73,  Bill  W4ZV

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