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Problem with 17m band in K2 + KAT100/KPA100 in EC2

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Marcin SQ2AF

Problem with 17m band in K2 + KAT100/KPA100 in EC2

Hi all,

In last Friday I have been finished KAT100/KPA100 in EC2.
Few days ago one problem occurred - before TX on 17m RX is OK, after TX on
this band RX dropping down. This is only on HI power range, on LOW
power range everything is OK.
When I change band to other then 17m and then come back to 17m RX stay
OK to the TX and then drop down again. When I Off then On K2 or push
TUNE key, RX come back to normal.
Is anyone know what is the problem?

73,
Marcin SQ2AF

K2 #5408
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Don Wilhelm-3

RE: Problem with 17m band in K2 + KAT100/KPA100 in EC2

Marcin,

There is nothing in the KPA100 or the base K2 that would cause that problem
on 17 meters only.
In the base K2, the relay switching is shared for 17 and 15 meters except
for relay K6 in the bandpass filter, and in the KPA100, all circuits are
shared between 17 and 20 meters. You would have a problem on either 20
meters or 15 meters in addition to 17 meters if it was associated with
either the K2 or KPA100 switching relays.

If you have a dedicated 17 meter antenna, you may want to investigate the
switching to that antenna.

TUNE should behave the same as transmit, but you say that receive
sensitivity does not drop after TUNE - that is indeed strange. We need more
data.

73,
Don W3FPR

> -----Original Message-----

> Hi all,
>
> In last Friday I have been finished KAT100/KPA100 in EC2.
> Few days ago one problem occurred - before TX on 17m RX is OK, after TX on
> this band RX dropping down. This is only on HI power range, on LOW
> power range everything is OK.
> When I change band to other then 17m and then come back to 17m RX stay
> OK to the TX and then drop down again. When I Off then On K2 or push
> TUNE key, RX come back to normal.
> Is anyone know what is the problem?
>
> 73,
> Marcin SQ2AF
>
> K2 #5408
>

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Michael E. Dobson

RE: Problem with 17m band in K2 + KAT100/KPA100 in EC2

Don,

I am experiencing the same or a very similar problem as Marcin. It
only happens on 17M and only at high power. That is why we do not
see it after a Tune operation. If I turn the power down to 30W or
less, no problem. It makes no difference whether the KPA100 is the
top cover or remoted in an EC2 with the KAT100. I haven't determined
exactly how much power I have to be running before the problem
occurs. I suspect RF getting somewhere it shouldn't but have not had
the time to track it down. It does seem to be antenna dependent even
though I get a good match to the 102 foot doublet I use. I will get
a chance to test my theory next week when I take the K2/100 portable
for a week using a different antenna than I do at home. If it occurs
only at the home QTH then the problem is in the antenna system and
probably stray RF affecting something in the K2.

73,
Mike K2/100 #2221

At 01:31 PM 9/6/2006, Don Wilhelm wrote:

>Marcin,
>
>There is nothing in the KPA100 or the base K2 that would cause that problem
>on 17 meters only.
>In the base K2, the relay switching is shared for 17 and 15 meters except
>for relay K6 in the bandpass filter, and in the KPA100, all circuits are
>shared between 17 and 20 meters. You would have a problem on either 20
>meters or 15 meters in addition to 17 meters if it was associated with
>either the K2 or KPA100 switching relays.
>
>If you have a dedicated 17 meter antenna, you may want to investigate the
>switching to that antenna.
>
>TUNE should behave the same as transmit, but you say that receive
>sensitivity does not drop after TUNE - that is indeed strange. We need more
>data.
>
>73,
>Don W3FPR
>
>
> > -----Original Message-----
>
> > Hi all,
> >
> > In last Friday I have been finished KAT100/KPA100 in EC2.
> > Few days ago one problem occurred - before TX on 17m RX is OK, after TX on
> > this band RX dropping down. This is only on HI power range, on LOW
> > power range everything is OK.
> > When I change band to other then 17m and then come back to 17m RX stay
> > OK to the TX and then drop down again. When I Off then On K2 or push
> > TUNE key, RX come back to normal.
> > Is anyone know what is the problem?
> >
> > 73,
> > Marcin SQ2AF
> >
> > K2 #5408
> >
>
>_______________________________________________
>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

Don Wilhelm-3

RE: Problem with 17m band in K2 + KAT100/KPA100 in EC2

Mike,

I am certain Marcin will be interested in your results when portable. The
only thing that I can think of is a bad connection in the KPA100 T-R switch,
but then I am just guessing. Marcins's problem continues until the KPA100
switches out at the 10 watt level, so your problem may be different.

73,
Don W3FPR

> -----Original Message-----

> Don,
>
> I am experiencing the same or a very similar problem as Marcin. It
> only happens on 17M and only at high power. That is why we do not
> see it after a Tune operation. If I turn the power down to 30W or
> less, no problem. It makes no difference whether the KPA100 is the
> top cover or remoted in an EC2 with the KAT100. I haven't determined
> exactly how much power I have to be running before the problem
> occurs. I suspect RF getting somewhere it shouldn't but have not had
> the time to track it down. It does seem to be antenna dependent even
> though I get a good match to the 102 foot doublet I use. I will get
> a chance to test my theory next week when I take the K2/100 portable
> for a week using a different antenna than I do at home. If it occurs
> only at the home QTH then the problem is in the antenna system and
> probably stray RF affecting something in the K2.
>
> 73,
> Mike K2/100 #2221
>
> At 01:31 PM 9/6/2006, Don Wilhelm wrote:
> >Marcin,
> >
> >There is nothing in the KPA100 or the base K2 that would cause
> that problem
> >on 17 meters only.
> >In the base K2, the relay switching is shared for 17 and 15 meters except
> >for relay K6 in the bandpass filter, and in the KPA100, all circuits are
> >shared between 17 and 20 meters. You would have a problem on either 20
> >meters or 15 meters in addition to 17 meters if it was associated with
> >either the K2 or KPA100 switching relays.
> >
> >If you have a dedicated 17 meter antenna, you may want to investigate the
> >switching to that antenna.
> >
> >TUNE should behave the same as transmit, but you say that receive
> >sensitivity does not drop after TUNE - that is indeed strange.
> We need more
> >data.
> >
> >73,
> >Don W3FPR
> >
>

Marcin SQ2AF

Re: Problem with 17m band in K2 + KAT100/KPA100 in EC2

In reply to this post by Michael E. Dobson

Don,

Today I have checked all connections in KPA100 T-R switch - they was OK.
After connection checking I assembled KPA100/KAT100 again and started
TX on 17 m again - the problem still occurred.
But .... as you know I'm digi modes fan so, all the TRX keying was
made by computer. Today, when I have been use VOX or foot switch the
problem disappeared!
In this moment I know, the problem occurs only when computer control K2 keying.
So, it clears why TUNE coming back RX to normal sensitivity.
Do you know what can I do now?

73,
Marcin SQ2AF

K2 #5408

2006/9/7, Don Wilhelm <[hidden email]>:

> Mike,
>
> I am certain Marcin will be interested in your results when portable. The
> only thing that I can think of is a bad connection in the KPA100 T-R switch,
> but then I am just guessing. Marcins's problem continues until the KPA100
> switches out at the 10 watt level, so your problem may be different.
>
> 73,
> Don W3FPR
>
>
> > -----Original Message-----
>
> > Don,
> >
> > I am experiencing the same or a very similar problem as Marcin. It
> > only happens on 17M and only at high power. That is why we do not
> > see it after a Tune operation. If I turn the power down to 30W or
> > less, no problem. It makes no difference whether the KPA100 is the
> > top cover or remoted in an EC2 with the KAT100. I haven't determined
> > exactly how much power I have to be running before the problem
> > occurs. I suspect RF getting somewhere it shouldn't but have not had
> > the time to track it down. It does seem to be antenna dependent even
> > though I get a good match to the 102 foot doublet I use. I will get
> > a chance to test my theory next week when I take the K2/100 portable
> > for a week using a different antenna than I do at home. If it occurs
> > only at the home QTH then the problem is in the antenna system and
> > probably stray RF affecting something in the K2.
> >
> > 73,
> > Mike K2/100 #2221
> >
> > At 01:31 PM 9/6/2006, Don Wilhelm wrote:
> > >Marcin,
> > >
> > >There is nothing in the KPA100 or the base K2 that would cause
> > that problem
> > >on 17 meters only.
> > >In the base K2, the relay switching is shared for 17 and 15 meters except
> > >for relay K6 in the bandpass filter, and in the KPA100, all circuits are
> > >shared between 17 and 20 meters. You would have a problem on either 20
> > >meters or 15 meters in addition to 17 meters if it was associated with
> > >either the K2 or KPA100 switching relays.
> > >
> > >If you have a dedicated 17 meter antenna, you may want to investigate the
> > >switching to that antenna.
> > >
> > >TUNE should behave the same as transmit, but you say that receive
> > >sensitivity does not drop after TUNE - that is indeed strange.
> > We need more
> > >data.
> > >
> > >73,
> > >Don W3FPR
> > >
> >
>
> _______________________________________________
> 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
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

Don Wilhelm-3

RE: Problem with 17m band in K2 + KAT100/KPA100 in EC2

In reply to this post by Marcin SQ2AF

Marcin,

As a guess, your computer connections or even the computer itself may be
picking up RF.

Are you listening to the audio on the K2 speaker, or just observing it on
the computer display (or listening to it on the computer speakers? If you
are seeing the drop in audio only on the computer, it may be the computer at
fault and not the K2.

If you do not have ground isolation between your computer and the K2, that
may be necessary. That means transformers in the audio lines to the
soundcard and an optoisolator in the RTS to PTT line. Be careful about how
the optoisolator is powered so you do not negate the careful grounding
isolation that you would do otherwise.

There is a good schematic for proper isolation of the computer and
transceiver grounds in Jan 2006 QST, page 60 (you need only consider the
part in the shaded box). Note carefully the grounding to the enclosure does
not extend to the computer - if you have jacks for the soundcard connections
mounted on a metallic box, that would destroy the ground isolation - you
must either avoid audio jacks at the enclosure or if jacks are used, they
must be mounted on an insulator.

73,
Don W3FPR

> -----Original Message-----
>
> Don,
>
> Today I have checked all connections in KPA100 T-R switch - they was OK.
> After connection checking I assembled KPA100/KAT100 again and started
> TX on 17 m again - the problem still occurred.
> But .... as you know I'm digi modes fan so, all the TRX keying was
> made by computer. Today, when I have been use VOX or foot switch the
> problem disappeared!
> In this moment I know, the problem occurs only when computer
> control K2 keying.
> So, it clears why TUNE coming back RX to normal sensitivity.
> Do you know what can I do now?
>
> 73,
> Marcin SQ2AF
>
> K2 #5408
>
>

Marcin SQ2AF

Re: Problem with 17m band in K2 + KAT100/KPA100 in EC2

In reply to this post by Marcin SQ2AF

Don,

Thank you for patience and fast replays.

As my digital interface I'm using RigExpert and cable connection as on
the www.mixw.net/RigExpert/cable-elecraft-001.gif
After received your last reply I have been examined cable connections
and they are as on the diagram.
I have been checked RigExpert and K2 with my laptop computer also -
the problem also occurred. It means that my home computer is OK.
But there is interesting thing - when I setup 10W (KPA100 is still in
bypass mode) there is no problem, but when I setup 11W or more (KPA100
is on) problem occur.
So maybe the problem is somewhere in KPA100?

73,

Marcin SQ2AF

K2 #5408

2006/9/8, Don Wilhelm <[hidden email]>:

> Marcin,
>
> As a guess, your computer connections or even the computer itself may be
> picking up RF.
>
> Are you listening to the audio on the K2 speaker, or just observing it on
> the computer display (or listening to it on the computer speakers? If you
> are seeing the drop in audio only on the computer, it may be the computer at
> fault and not the K2.
>
> If you do not have ground isolation between your computer and the K2, that
> may be necessary. That means transformers in the audio lines to the
> soundcard and an optoisolator in the RTS to PTT line. Be careful about how
> the optoisolator is powered so you do not negate the careful grounding
> isolation that you would do otherwise.
>
> There is a good schematic for proper isolation of the computer and
> transceiver grounds in Jan 2006 QST, page 60 (you need only consider the
> part in the shaded box). Note carefully the grounding to the enclosure does
> not extend to the computer - if you have jacks for the soundcard connections
> mounted on a metallic box, that would destroy the ground isolation - you
> must either avoid audio jacks at the enclosure or if jacks are used, they
> must be mounted on an insulator.
>
> 73,
> Don W3FPR
>
>
> > -----Original Message-----
> >
> > Don,
> >
> > Today I have checked all connections in KPA100 T-R switch - they was OK.
> > After connection checking I assembled KPA100/KAT100 again and started
> > TX on 17 m again - the problem still occurred.
> > But .... as you know I'm digi modes fan so, all the TRX keying was
> > made by computer. Today, when I have been use VOX or foot switch the
> > problem disappeared!
> > In this moment I know, the problem occurs only when computer
> > control K2 keying.
> > So, it clears why TUNE coming back RX to normal sensitivity.
> > Do you know what can I do now?
> >
> > 73,
> > Marcin SQ2AF
> >
> > K2 #5408
> >
> >
>
> _______________________________________________
> 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
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

Don Wilhelm-3

RE: Problem with 17m band in K2 + KAT100/KPA100 in EC2

Marcin,

I checked the RigExpert specifications, and while they claim isolation on
the soundcard connections, they do not make any such claims for the digital
connections (to the PTT, CW Key, or AUX I/O).

So you still may have a problem with RF getting onto the RigExpert or the
computer chassis ground that is being then transmitted into the K2.

This is not a problem with your connections, but it may be a problem with
the RigExpert on your K2 in combination with your antenna situation. I am
not yet convinced that it is a KPA100 problem.

If you can test it with the KPA100 working into a dummy load, that would be
of interest, but it may be hard to detect if your receive is desensitized
with the dummy load connected.

If you do not have the K2 mic jack shell grounded, you could try doing that
as a first measure of defense.

The other thing you can try is attaching a counterpoise wire cut for a
quarterwave on 17 meters to the KAT100 ground. The far end may carry a high
RF voltage, so keep it clear of human and pet contact (the far end connects
to nothing - just an insulator). If a counterpoise wire corrects the
problem then you can be certain it is caused by stray RF - unfortunately, if
it does not cure it, stray RF could still be the problem, but it is worth a
try - a piece of wire an electrical quarterwavelength on 17 meters is
approximately 3.9 meters long.

73,
Don W3FPR

> -----Original Message-----
>
> Thank you for patience and fast replays.
>
> As my digital interface I'm using RigExpert and cable connection as on
> the www.mixw.net/RigExpert/cable-elecraft-001.gif
> After received your last reply I have been examined cable connections
> and they are as on the diagram.
> I have been checked RigExpert and K2 with my laptop computer also -
> the problem also occurred. It means that my home computer is OK.
> But there is interesting thing - when I setup 10W (KPA100 is still in
> bypass mode) there is no problem, but when I setup 11W or more (KPA100
> is on) problem occur.
> So maybe the problem is somewhere in KPA100?
>
> 73,
>
> Marcin SQ2AF
>
> K2 #5408
>
>
> 2006/9/8, Don Wilhelm <[hidden email]>:
> > Marcin,
> >
> > As a guess, your computer connections or even the computer itself may be
> > picking up RF.
> >
> > Are you listening to the audio on the K2 speaker, or just
> observing it on
> > the computer display (or listening to it on the computer
> speakers? If you
> > are seeing the drop in audio only on the computer, it may be
> the computer at
> > fault and not the K2.
> >
> > If you do not have ground isolation between your computer and
> the K2, that
> > may be necessary. That means transformers in the audio lines to the
> > soundcard and an optoisolator in the RTS to PTT line. Be
> careful about how
> > the optoisolator is powered so you do not negate the careful grounding
> > isolation that you would do otherwise.
> >
> > There is a good schematic for proper isolation of the computer and
> > transceiver grounds in Jan 2006 QST, page 60 (you need only consider the
> > part in the shaded box). Note carefully the grounding to the
> enclosure does
> > not extend to the computer - if you have jacks for the
> soundcard connections
> > mounted on a metallic box, that would destroy the ground isolation - you
> > must either avoid audio jacks at the enclosure or if jacks are
> used, they
> > must be mounted on an insulator.
> >
> > 73,
> > Don W3FPR
> >
> >
> > > -----Original Message-----
> > >
> > > Don,
> > >
> > > Today I have checked all connections in KPA100 T-R switch -
> they was OK.
> > > After connection checking I assembled KPA100/KAT100 again and started
> > > TX on 17 m again - the problem still occurred.
> > > But .... as you know I'm digi modes fan so, all the TRX keying was
> > > made by computer. Today, when I have been use VOX or foot switch the
> > > problem disappeared!
> > > In this moment I know, the problem occurs only when computer
> > > control K2 keying.
> > > So, it clears why TUNE coming back RX to normal sensitivity.
> > > Do you know what can I do now?
> > >
> > > 73,
> > > Marcin SQ2AF
> > >
> > > K2 #5408
> > >
> > >
> >
> > _______________________________________________
> > 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
> >
> > Help: http://mailman.qth.net/subscribers.htm
> > Elecraft web page: http://www.elecraft.com
> >
> _______________________________________________
> 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
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>
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> Checked by AVG Free Edition.
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>
>

Marcin SQ2AF

Re: Problem with 17m band in K2 + KAT100/KPA100 in EC2

In reply to this post by Marcin SQ2AF

Don,

Yes, yes, you are right! - it is caused by stray RF.

I attached counterpoise wire cut for a quarterwave on 17 meters and it
resolve the problem.
Now, with your help, I'm sure that my K2 and KAT100/KPA100 are OK and
my problem is antenna. So, I must go to the roof, recheck antenna
connections and realign it.
Thank you again for your help!

73,

Marcin SQ2AF

K2 #5408

2006/9/8, Don Wilhelm <[hidden email]>:

> Marcin,
>
> I checked the RigExpert specifications, and while they claim isolation on
> the soundcard connections, they do not make any such claims for the digital
> connections (to the PTT, CW Key, or AUX I/O).
>
> So you still may have a problem with RF getting onto the RigExpert or the
> computer chassis ground that is being then transmitted into the K2.
>
> This is not a problem with your connections, but it may be a problem with
> the RigExpert on your K2 in combination with your antenna situation. I am
> not yet convinced that it is a KPA100 problem.
>
> If you can test it with the KPA100 working into a dummy load, that would be
> of interest, but it may be hard to detect if your receive is desensitized
> with the dummy load connected.
>
> If you do not have the K2 mic jack shell grounded, you could try doing that
> as a first measure of defense.
>
> The other thing you can try is attaching a counterpoise wire cut for a
> quarterwave on 17 meters to the KAT100 ground. The far end may carry a high
> RF voltage, so keep it clear of human and pet contact (the far end connects
> to nothing - just an insulator). If a counterpoise wire corrects the
> problem then you can be certain it is caused by stray RF - unfortunately, if
> it does not cure it, stray RF could still be the problem, but it is worth a
> try - a piece of wire an electrical quarterwavelength on 17 meters is
> approximately 3.9 meters long.
>
> 73,
> Don W3FPR
>

Don Wilhelm-3

RE: Problem with 17m band in K2 + KAT100/KPA100 in EC2

Marcin,

Now that you know where to look for the origin of the problem, I am
confident you will correct it.
Stray RF does many strange and unexpected things.

73,
Don W3FPR

> -----Original Message-----
>
> Don,
>
> Yes, yes, you are right! - it is caused by stray RF.
>
> I attached counterpoise wire cut for a quarterwave on 17 meters and it
> resolve the problem.
> Now, with your help, I'm sure that my K2 and KAT100/KPA100 are OK and
> my problem is antenna. So, I must go to the roof, recheck antenna
> connections and realign it.
> Thank you again for your help!
>
> 73,
>
> Marcin SQ2AF
>
> K2 #5408
>
>
>
> 2006/9/8, Don Wilhelm <[hidden email]>:
> > Marcin,
> >
> > I checked the RigExpert specifications, and while they claim
> isolation on
> > the soundcard connections, they do not make any such claims for
> the digital
> > connections (to the PTT, CW Key, or AUX I/O).
> >
> > So you still may have a problem with RF getting onto the
> RigExpert or the
> > computer chassis ground that is being then transmitted into the K2.
> >
> > This is not a problem with your connections, but it may be a
> problem with
> > the RigExpert on your K2 in combination with your antenna
> situation. I am
> > not yet convinced that it is a KPA100 problem.
> >
> > If you can test it with the KPA100 working into a dummy load,
> that would be
> > of interest, but it may be hard to detect if your receive is
> desensitized
> > with the dummy load connected.
> >
> > If you do not have the K2 mic jack shell grounded, you could
> try doing that
> > as a first measure of defense.
> >
> > The other thing you can try is attaching a counterpoise wire cut for a
> > quarterwave on 17 meters to the KAT100 ground. The far end may
> carry a high
> > RF voltage, so keep it clear of human and pet contact (the far
> end connects
> > to nothing - just an insulator). If a counterpoise wire corrects the
> > problem then you can be certain it is caused by stray RF -
> unfortunately, if
> > it does not cure it, stray RF could still be the problem, but
> it is worth a
> > try - a piece of wire an electrical quarterwavelength on 17 meters is
> > approximately 3.9 meters long.
> >
> > 73,
> > Don W3FPR
>