[Elecraft] [K3] Phase Noise / CW Key Clicks

[Matt Zilmer]

Might be both.

matt

On Thu, 13 Sep 2012 08:41:20 -0400, you wrote:

>Very interesting. I was operating at our local submarine for Museum Ships
>Day, using my K2 in the field about 200 yards away from the sub from which
>they were operating SSB on 20 meters. I tried to operate 20m CW but the
>"whooshing" on the band anywhere in the CW segment was just too much. I
>thought it was just blow-by of the K2's xtal filters, but I think now I'm
>learning it was the dirty transmitter they were using - not sure which one.
>
>Chip
>AE5KA
>
>On Thu, Sep 13, 2012 at 12:18 AM, Matt Zilmer <mzilmer at verizon.net> wrote:
>
>> My case study may not be any less interesting than others you've
>> heard.  During Field Day, 2011 K3 #24 (mine) was the centerpiece of
>> our group's CW effort.  The group was a number of aligned clubs, and
>> we operated 12F (emergency operations center, 12 stations).  You can
>> imagine the HF overlap involved, since there were nearly always two
>> stations on one band but on different modes.  Our site was about 350
>> meters in diameter with stations around the outside edges and a couple
>> on VHF/UHF in the middle.
>>
>> Dave, W3DMA, is also a K3 owner.  He and I were partnered on the CW
>> station.  We operated 19 hours out of the 24 allowed, for about 800
>> contacts.  This isn't awful, but it should have been better.  The main
>> cause of our CW count being so low was phase noise from other stations
>> on the same band at our site.  Many were running > 100W too.  That
>> WHOOSH Wayne mentioned wiped out a lot of received transmissions on
>> our end, and we had to constantly ask for AGNs due to a transient high
>> noise floor.  We could see that 15-20 dB rise of the floor on the P3
>> quite easily.  The screen went mostly white during those times.
>>
>> Now - I KNEW better, but I went around to the other stations when they
>> were operating on same bands as the CW station (Dave at the key, were
>> at the computer).  They weren't hearing us AT ALL and didn't even know
>> we were on the same band!  Except for our roving spotter with a
>> broadband panadapter who could see my K3 but not hear it.  No key
>> clicks from us, but of course you could hear them all over the band(s)
>> from remote stations.
>>
>> Phase noise and key clicks are the enemy.  I respectfully suggest that
>> Wayne emphasize (as well) that designing a transceiver to
>> intentionally not produce either of these is a worthy objective more
>> on a moral plane than an operating advantage.  Tactically, having
>> clicks and wideband noise could be put to advantage against other FD
>> groups.  As Wayne pointed out, phase noise may limit receiver
>> sensitivity (if it's not limited first by other factors), but most
>> hams have never thought about it that way.  I suspect, in practice,
>> that in other transceivers phase noise is not the limiting factor in
>> sensitivity - mainly because the front end design is shoddy compared
>> to the K3.  Front end noise figure is perhaps a larger factor in many
>> cases.
>>
>> The main real-world problem is that the K3 is a minority in the
>> general ham rig population.  Maybe someday, the K3 penetration rate
>> will be high enough that we can hear it in how quiet the bands are.
>> Crowded but quiet between signals that is.
>>
>> 73,
>> Matt Zilmer, W6NIA / NNN0UET / NNN0GAF THREE
>> NMCM RMS Winmor: NNU9ET-5: Upland, CA.
>> NAQCC: 6081, 10-10: 10413, KX3 #6/FT
>>
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