Is a K2 Realignment Advisable

[Jim Harris-4]

Hi Folks,

Several days ago I raised the question here as to
whether it is advisable to realign my K2 after having
it in use for several months.  Several people replied
to which I am thankful for their advice.  Everyone
seemed to think, in my case, it would probably be
helpful to redo the alignment and include Spectrogram.

While chasing 3Y0X on the upper bands I realized those
bands may no be doing as well as the middle and lower
bands and especially on RTTY receive.  As the K2 is
only capable of doing RTTY with AFSK I'm presuming LSB
mode would be used like other rigs.  The received RTTY
in MMTTY on the K2 looks much more ragged and seems
less copyable than with my IC-746Pro.  Is there a
special filter setting for RTTY?

Now to find some time to work on it and make a great
rig even better.  There is just too many things do and
not enough time to do them when you are retired.  -;)

Thanks and have a great day!!

Jim, AB0UK

 

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[Don Wilhelm-3]

Jim,

Yes, there is a special set of 4 filters labeled RTTY filters in the K2 -
they can be turned on and off via the menu.  These 4 filters are independent
of the settings used for the other modes (CW and SSB).  The RTTY filter set
also allows independent adjustment of the menu SSBC parameter - it would
normally be set to 1-1 for the best IMD performance on transmit.

Your BFO range may limit the filter bandwidth that you can achieve should
you attempt to use a narrow filter aligned at a high tone because the BFO
range is not adequate to handle it.  You will be able to adjust one sideband
or the other as a narrow filter, but normally not both, so you may have to
manipulate the sideband reversal capability of your RTTY hardware or
software to adjust for this situation.

Adjusting the filters to demodulate tones below 1kHz is usually not a
problem (as is th ecase for most soundcard data modes), but if you attempt
to demodulate the RTTY high tones 2175 and 2225 Hz in a narrow filter, you
can expect to run out of range.

73,
Don W3FPR

> -----Original Message-----
>
> While chasing 3Y0X on the upper bands I realized those
> bands may no be doing as well as the middle and lower
> bands and especially on RTTY receive.  As the K2 is
> only capable of doing RTTY with AFSK I'm presuming LSB
> mode would be used like other rigs.  The received RTTY
> in MMTTY on the K2 looks much more ragged and seems
> less copyable than with my IC-746Pro.  Is there a
> special filter setting for RTTY?
>
> Now to find some time to work on it and make a great
> rig even better.  There is just too many things do and
> not enough time to do them when you are retired.  -;)
>
> Thanks and have a great day!!
>
> Jim, AB0UK
>

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[Tom Skinner-2]

Hello Group,

Well, you can add me to the list of folks who think their noise blanker is
not working.

Now I don't have a lot of noise problems, but do hear the occasional light
dimmer or neighborhood power tool.

I have tried the scratch test, but results were inconclusive.

Today I brought home a 75,000 volt Tesla coil and lit it off across the
room.  As expected, the noise level jumped from S1 to a bit over S9.

The noise blanker has absolutely no noticeable effect in any position.

I have re-inspected the placement of every component and confirmed every
solder joint.  The preps on the RF board were done correctly.

I checked the two diodes and they appear to be neither open nor shorted.

The Tesla coil is probably overkill, but if the noise blanker is working
shouldn't it have SOME effect?

I really don't know what to check next - any suggestions?

TIA es 72/73,

Tom, KJ3D
K2 # 4991

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[Ron D'Eau Claire-2]

No. The Tesla Coil produces exactly the sort of QRN that the noise blanker
is NOT designed to suppress. It is as close to the random racket we call
"band QRN" as you can get: the effect of millions of discharges of varying
intensity and duration all overlapping in time.

The noise blanker is designed to suppress repetitive high-amplitude pulses
such as you get from a *controlled* spark gap, like an automobile ignition,
or a controlled impulse generator like a cheap lamp dimmer. These impulses
are especially annoying because they have very, very high amplitude coupled
with very short duration, so the average level is quite low, comparatively.
Your "S" meter may say the noise is S7 or S9, but the actual peaks are far,
far stronger than your S-meter is reporting. The KNB2 is excellent for
suppressing them by anticipating the pulse and actually shutting off the
signal path for an instant while it passes. If it tried to do that with the
sort of QRN you get from the Tesla Coil it'd simply turn the receiver off
completely <G>.

As an aside, it is fortunate for me that the sort of noise produced by a
Tesla Coil is indistinguishable from common QRN. Many years ago I fired up
my prototype 8-foot tall Tesla Coil, excited by a spark gap wired to the A-C
mains, and wiped out "I Love Lucy" on TV's for blocks around. My neighbors
knew all about the "Ham Kid" in area but they didn't equate a TV screen
filled with "snow" with the sort of thing they were used to seeing from my
QTH, nor did I feel compelled to enlighten them.

Ron AC7AC

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Tom Skinner
Sent: Friday, February 17, 2006 1:48 PM
To: 'Elecraft'
Subject: [Elecraft] Inoperable KNB2


Hello Group,

Well, you can add me to the list of folks who think their noise blanker is
not working.

Now I don't have a lot of noise problems, but do hear the occasional light
dimmer or neighborhood power tool.

I have tried the scratch test, but results were inconclusive.

Today I brought home a 75,000 volt Tesla coil and lit it off across the
room.  As expected, the noise level jumped from S1 to a bit over S9.

The noise blanker has absolutely no noticeable effect in any position.

I have re-inspected the placement of every component and confirmed every
solder joint.  The preps on the RF board were done correctly.

I checked the two diodes and they appear to be neither open nor shorted.

The Tesla coil is probably overkill, but if the noise blanker is working
shouldn't it have SOME effect?

I really don't know what to check next - any suggestions?

TIA es 72/73,

Tom, KJ3D
K2 # 4991

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[John E. Reiser]

Hi Tom,

My KNB2 doesen't work either on a lot of things that I consider noise.  But,
for that particularly nasty type of QRN, the loud crackling that sounds like
frying a big pan of bacon, it works superbly.  My KNB2 takes that stuff out
completely.

If I ever build another K2 (and I'm thinking about doing that) it will
include the KNB2 for sure.

73,

John, W2GW

K2/100 #4970, KAT100-1, K1-6 #1205, KX1 #1258, etc.


----- Original Message -----
From: "Tom Skinner" <[hidden email]>
To: "'Elecraft'" <[hidden email]>
Sent: Friday, February 17, 2006 4:47 PM
Subject: [Elecraft] Inoperable KNB2

> Hello Group,
>
> Well, you can add me to the list of folks who think their noise blanker is
> not working.
>
> Now I don't have a lot of noise problems, but do hear the occasional light
> dimmer or neighborhood power tool.
>
> I have tried the scratch test, but results were inconclusive.
>
> Today I brought home a 75,000 volt Tesla coil and lit it off across the
> room.  As expected, the noise level jumped from S1 to a bit over S9.
>
> The noise blanker has absolutely no noticeable effect in any position.
>
> I have re-inspected the placement of every component and confirmed every
> solder joint.  The preps on the RF board were done correctly.
>
> I checked the two diodes and they appear to be neither open nor shorted.
>
> The Tesla coil is probably overkill, but if the noise blanker is working
> shouldn't it have SOME effect?
>
> I really don't know what to check next - any suggestions?
>
> TIA es 72/73,
>
> Tom, KJ3D
> K2 # 4991
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
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> Elecraft web page: http://www.elecraft.com
>

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[Tom Skinner-2]

Thanks to all who responded.

Something tells me that I should have known the Tesla would not produce the
kind of noise the KNB2 is designed to handle - someone earlier had suggested
a buzzer, and my Tesla _buzzes_ like mad - thought it would be perfect.  

Maybe I should just be thankful that I live in a relatively quiet location.

Unfortunately I can't get my car close enough to the K2 or its antenna to
use it as a source.  Maybe I'll move the K2 outside when its a bit warmer -
snowing right now (perfect for Frostfest tomorrow).

Anyway, the DSP sure clobbered the Tesla, so that works great.

Thanks again, es 72/73

Tom, KJ3D

PS - Ron, I fondly remember the days when high school and college science
fairs were full of 8 foot tall Teslas and Van de Graaff generators with 2
foot domes - and a lot of homebrew rock-bound cw rigs - bet you do to.

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Ron D'Eau Claire

As an aside, it is fortunate for me that the sort of noise produced by a
Tesla Coil is indistinguishable from common QRN. Many years ago I fired up
my prototype 8-foot tall Tesla Coil, excited by a spark gap wired to the A-C
mains, and wiped out "I Love Lucy" on TV's for blocks around. My neighbors
knew all about the "Ham Kid" in area but they didn't equate a TV screen
filled with "snow" with the sort of thing they were used to seeing from my
QTH, nor did I feel compelled to enlighten them.

Ron AC7AC

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