Shutdown on 50MHz CW

[gm3sek]

Ian J Maude wrote:
>Having used the radio for a while I am now starting to come up with
>some questions.  The first one comes from using RTTY in contests.  I
>generally have the display showing me the PA temp and I stated to
>wonder, what *is* the optimum temperature for the PA?  Also, I can see
>it is rising but I have no idea when it should get critical :)
>Any clues please?

No answers, but maybe a related question...

The rig is a K3 with KPA100 and KAT3.

Having just started to use the K3 intensively on 6m, there is a problem
with the PA shutting down, especially on CW. After 10-20 seconds of
operating, the RF power disappears. Many of the symptoms are
intermittent, showing no clear pattern - except that it only happens on
50MHz.

Moments before the power dies, there are one or two warning clicks of a
relay. There may also be a "HIGH SWR" warning, but not always -
sometimes that warning flashes and it's still possible to carry on for
10-20 seconds. (The SWR is actually OK - tested at 100W using another
rig, and on a dummy load.) The problem is the same on both ANT1 and ANT2
outputs of the KAT3, and either with or without the auto-ATU.

The problem cannot be cleared by cycling TX/RX; but it can always be
cleared (at least temporarily) by cycling ANT1/ANT2. That brings the
power back, making it possible to limp through a short QSO.

However, there *may* be some relationship to the PA temperature. 50MHz
is the only band on which the PA temperature indication is being
affected by RF - on CW, it bounces upward by anything up to 5degC on
every key closure, and I'm wondering if these  transients are triggering
a PA shutdown.

There is no problem on any other band. On 28MHz, I ran off a string of
CW QSOs in the contest, and then tested the KPA100 for about 5 minutes
at 120W continuous carrier. There were no RF-related effects, and the PA
temperature levelled out at about 60degC. It seemed quite happy at this
temperature.

Back on 50MHz, continuous carrier caused the same kind of instant jump
in the indicated PA temperature. The TX did eventually shut down, but
the transient changes seem to have more effect than the actual PA
temperature. There is no problem with SSB, but the PA temperature
genuinely is lower on that mode. CW seems to be the worst mode because
the duty cycle is higher and it also creates lots of transients.


It's all a confusing mess of symptoms... and I may not even be on the
right track with the PA temperature. However, I feel pretty sure that
the problem *is* being caused by internal stray RF.


Since it's Memorial Day, it won't be reasonable to expect a response
from [hidden email] for at least another 30-40 hours. In the
meantime, I'd be grateful for any thoughts and suggestions from the
group.


--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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[Gregg W6IZT]

I am also experiencing the same problem. I was going to do a little
characterization before notifying elecraft. The problem only occurs on 6
with my radio as well. It can be cleared by power cycling the radio, or
changing bands. It seems to be more prevalent at higher power levels, but I
can't say for certain.

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of Ian White GM3SEK
Sent: Monday, May 26, 2008 4:44 AM
To: [hidden email]
Subject: [Elecraft] Shutdown on 50MHz CW

Ian J Maude wrote:
>Having used the radio for a while I am now starting to come up with
>some questions.  The first one comes from using RTTY in contests.  I
>generally have the display showing me the PA temp and I stated to
>wonder, what *is* the optimum temperature for the PA?  Also, I can see
>it is rising but I have no idea when it should get critical :)
>Any clues please?

No answers, but maybe a related question...

The rig is a K3 with KPA100 and KAT3.

Having just started to use the K3 intensively on 6m, there is a problem
with the PA shutting down, especially on CW. After 10-20 seconds of
operating, the RF power disappears. Many of the symptoms are
intermittent, showing no clear pattern - except that it only happens on
50MHz.

Moments before the power dies, there are one or two warning clicks of a
relay. There may also be a "HIGH SWR" warning, but not always -
sometimes that warning flashes and it's still possible to carry on for
10-20 seconds. (The SWR is actually OK - tested at 100W using another
rig, and on a dummy load.) The problem is the same on both ANT1 and ANT2
outputs of the KAT3, and either with or without the auto-ATU.

The problem cannot be cleared by cycling TX/RX; but it can always be
cleared (at least temporarily) by cycling ANT1/ANT2. That brings the
power back, making it possible to limp through a short QSO.

However, there *may* be some relationship to the PA temperature. 50MHz
is the only band on which the PA temperature indication is being
affected by RF - on CW, it bounces upward by anything up to 5degC on
every key closure, and I'm wondering if these  transients are triggering
a PA shutdown.

There is no problem on any other band. On 28MHz, I ran off a string of
CW QSOs in the contest, and then tested the KPA100 for about 5 minutes
at 120W continuous carrier. There were no RF-related effects, and the PA
temperature levelled out at about 60degC. It seemed quite happy at this
temperature.

Back on 50MHz, continuous carrier caused the same kind of instant jump
in the indicated PA temperature. The TX did eventually shut down, but
the transient changes seem to have more effect than the actual PA
temperature. There is no problem with SSB, but the PA temperature
genuinely is lower on that mode. CW seems to be the worst mode because
the duty cycle is higher and it also creates lots of transients.


It's all a confusing mess of symptoms... and I may not even be on the
right track with the PA temperature. However, I feel pretty sure that
the problem *is* being caused by internal stray RF.


Since it's Memorial Day, it won't be reasonable to expect a response
from [hidden email] for at least another 30-40 hours. In the
meantime, I'd be grateful for any thoughts and suggestions from the
group.


--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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[DL5OCD]

Hello Ian,

do you notice high current (abt 20 A) when transmit with 100w on 6 ?
Sometimes more, sometimes less ?

73
Michael

GM3SEK wrote

Ian J Maude wrote:
>Having used the radio for a while I am now starting to come up with
>some questions.  The first one comes from using RTTY in contests.  I
>generally have the display showing me the PA temp and I stated to
>wonder, what *is* the optimum temperature for the PA?  Also, I can see
>it is rising but I have no idea when it should get critical :)
>Any clues please?

No answers, but maybe a related question...

The rig is a K3 with KPA100 and KAT3.

Having just started to use the K3 intensively on 6m, there is a problem
with the PA shutting down, especially on CW. After 10-20 seconds of
operating, the RF power disappears. Many of the symptoms are
intermittent, showing no clear pattern - except that it only happens on
50MHz.

Moments before the power dies, there are one or two warning clicks of a
relay. There may also be a "HIGH SWR" warning, but not always -
sometimes that warning flashes and it's still possible to carry on for
10-20 seconds. (The SWR is actually OK - tested at 100W using another
rig, and on a dummy load.) The problem is the same on both ANT1 and ANT2
outputs of the KAT3, and either with or without the auto-ATU.

The problem cannot be cleared by cycling TX/RX; but it can always be
cleared (at least temporarily) by cycling ANT1/ANT2. That brings the
power back, making it possible to limp through a short QSO.

However, there *may* be some relationship to the PA temperature. 50MHz
is the only band on which the PA temperature indication is being
affected by RF - on CW, it bounces upward by anything up to 5degC on
every key closure, and I'm wondering if these  transients are triggering
a PA shutdown.

There is no problem on any other band. On 28MHz, I ran off a string of
CW QSOs in the contest, and then tested the KPA100 for about 5 minutes
at 120W continuous carrier. There were no RF-related effects, and the PA
temperature levelled out at about 60degC. It seemed quite happy at this
temperature.

Back on 50MHz, continuous carrier caused the same kind of instant jump
in the indicated PA temperature. The TX did eventually shut down, but
the transient changes seem to have more effect than the actual PA
temperature. There is no problem with SSB, but the PA temperature
genuinely is lower on that mode. CW seems to be the worst mode because
the duty cycle is higher and it also creates lots of transients.


It's all a confusing mess of symptoms... and I may not even be on the
right track with the PA temperature. However, I feel pretty sure that
the problem *is* being caused by internal stray RF.


Since it's Memorial Day, it won't be reasonable to expect a response
from [e-mail] for at least another 30-40 hours. In the
meantime, I'd be grateful for any thoughts and suggestions from the
group.


--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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[N5GE]

On Mon, 26 May 2008 09:44:16 +0100, Ian White GM3SEK <[hidden email]>
wrote:

Please see below...

>Ian J Maude wrote:
>>Having used the radio for a while I am now starting to come up with
>>some questions.  The first one comes from using RTTY in contests.  I
>>generally have the display showing me the PA temp and I stated to
>>wonder, what *is* the optimum temperature for the PA?  Also, I can see
>>it is rising but I have no idea when it should get critical :)
>>Any clues please?
>
>No answers, but maybe a related question...
>
>The rig is a K3 with KPA100 and KAT3.
>
>Having just started to use the K3 intensively on 6m, there is a problem
>with the PA shutting down, especially on CW. After 10-20 seconds of
>operating, the RF power disappears. Many of the symptoms are
>intermittent, showing no clear pattern - except that it only happens on
>50MHz.
>
>Moments before the power dies, there are one or two warning clicks of a
>relay. There may also be a "HIGH SWR" warning, but not always -
>sometimes that warning flashes and it's still possible to carry on for
>10-20 seconds. (The SWR is actually OK - tested at 100W using another
>rig, and on a dummy load.) The problem is the same on both ANT1 and ANT2
>outputs of the KAT3, and either with or without the auto-ATU.
>
>The problem cannot be cleared by cycling TX/RX; but it can always be
>cleared (at least temporarily) by cycling ANT1/ANT2. That brings the
>power back, making it possible to limp through a short QSO.
>
>However, there *may* be some relationship to the PA temperature. 50MHz
>is the only band on which the PA temperature indication is being
>affected by RF - on CW, it bounces upward by anything up to 5degC on
>every key closure, and I'm wondering if these  transients are triggering
>a PA shutdown.
>
>There is no problem on any other band. On 28MHz, I ran off a string of
>CW QSOs in the contest, and then tested the KPA100 for about 5 minutes
>at 120W continuous carrier. There were no RF-related effects, and the PA
>temperature levelled out at about 60degC. It seemed quite happy at this
>temperature.
>
>Back on 50MHz, continuous carrier caused the same kind of instant jump
>in the indicated PA temperature. The TX did eventually shut down, but
>the transient changes seem to have more effect than the actual PA
>temperature. There is no problem with SSB, but the PA temperature
>genuinely is lower on that mode. CW seems to be the worst mode because
>the duty cycle is higher and it also creates lots of transients.
>
>
>It's all a confusing mess of symptoms... and I may not even be on the
>right track with the PA temperature. However, I feel pretty sure that
>the problem *is* being caused by internal stray RF.
>
>
>Since it's Memorial Day, it won't be reasonable to expect a response
>from [hidden email] for at least another 30-40 hours. In the
>meantime, I'd be grateful for any thoughts and suggestions from the
>group.

I have experienced the same behavior on 6m, although I didn't do any extensive
testing.  Thanks the effort you put into your tests.

Tom, N5GE - SWOT 3537 - Grid EM12jq

"Those who would give up
Essential Liberty to
purchase a little Temporary
Safety deserve neither
Liberty nor Safety"

An excerpt from a letter
written in 1755 from the
Assembly to the Governor
of Pennsylvania.

Support the entire Constitution, not
just the parts you like.

http://www.n5ge.com
http://www.eQSL.cc/Member.cfm?N5GE

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[G4LNA]

CONTENTS DELETED

The author has deleted this message.

[Dick Hanson]

Gentlemen....
Since I will be leaving in a few weeks for CY0 with my K3, I am more than a
little interested in this discussion.

Here is what I know thus far.
I have running my K3, in beacon mode; typical CQs followed by call,
repeating every six seconds.
100 watts out into dummy load.

Been running beacon for an hour thus far with no problems.
Other than my 100 watt dummy getting pretty warm:).
73
Dick, K5AND

>No answers, but maybe a related question...
>
>The rig is a K3 with KPA100 and KAT3.
>
>Having just started to use the K3 intensively on 6m, there is a problem
>with the PA shutting down, especially on CW. After 10-20 seconds of
>operating, the RF power disappears. Many of the symptoms are
>intermittent, showing no clear pattern - except that it only happens on
>50MHz.
>
>Moments before the power dies, there are one or two warning clicks of a
>relay. There may also be a "HIGH SWR" warning, but not always -
>sometimes that warning flashes and it's still possible to carry on for
>10-20 seconds. (The SWR is actually OK - tested at 100W using another
>rig, and on a dummy load.) The problem is the same on both ANT1 and ANT2
>outputs of the KAT3, and either with or without the auto-ATU.
>
>The problem cannot be cleared by cycling TX/RX; but it can always be
>cleared (at least temporarily) by cycling ANT1/ANT2. That brings the
>power back, making it possible to limp through a short QSO.
>
>However, there *may* be some relationship to the PA temperature. 50MHz
>is the only band on which the PA temperature indication is being
>affected by RF - on CW, it bounces upward by anything up to 5degC on
>every key closure, and I'm wondering if these  transients are triggering
>a PA shutdown.
>
>There is no problem on any other band.
>Back on 50MHz, continuous carrier caused the same kind of instant jump
>in the indicated PA temperature. The TX did eventually shut down, but
>the transient changes seem to have more effect than the actual PA
>temperature.

>It's all a confusing mess of symptoms... and I may not even be on the
>right track with the PA temperature. However, I feel pretty sure that
>the problem *is* being caused by internal stray RF.
>

I have experienced the same behavior on 6m, although I didn't do any
extensive
testing.  Thanks the effort you put into your tests.

Tom, N5GE - SWOT 3537 - Grid EM12jq


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[gm3sek]

Paul G4LNA wrote:
>
>My first reaction is it sounds like RF getting in somewhere, as a
>matter of interest does it happen when you run it into a dummy load?
>
Yes, with antenna or dummy load, on either port of the KAT3, and with or
without the auto-ATU in line.


--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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[N9BX]

Good Evening:

The exact same thing happens to me also.  All of a sudden I get a High
SWR reading but their is none and it happens on 6 meters only.  BTW I am
in Bypass Mode as SWR is 1:1

Bruce N9BX 73
K3 775

PS Which menu command lets you key the rig when in USB for CW without
switching to that Mode?


Ian White GM3SEK wrote:
> Paul G4LNA wrote:
>>
>> My first reaction is it sounds like RF getting in somewhere, as a
>> matter of interest does it happen when you run it into a dummy load?
>>
> Yes, with antenna or dummy load, on either port of the KAT3, and with or
> without the auto-ATU in line.
>
>
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[Julian, G4ILO]

GM3SEK wrote

Paul G4LNA wrote:
>
>My first reaction is it sounds like RF getting in somewhere, as a
>matter of interest does it happen when you run it into a dummy load?
>
Yes, with antenna or dummy load, on either port of the KAT3, and with or
without the auto-ATU in line.

I can confirm this, too. On 6m only, power set to 100W, dummy load attached to ANT1, the PA temperature indicator jumps from 28C to 37C when I key down.

[N5GE]

On Mon, 26 May 2008 16:40:28 -0400, "John King" <[hidden email]> wrote:

>Hello Tom,
>
>I had the same problem on 6m CW with K3 S/N 795.
>
>The problem started after I installed the KAT3
>ATU. I reported the problem to Elecraft last week.
>
>I removed the KAT3 and re-installed the KANT3
>board and the problem went away. They are sending
>me a new KAT3 to try.
>
>Do you have the KAT3 ATU installed?
>
>73,
>
>  john WA1ABI
>

Yes I do have the KAT3 installed.  Mine is a factory built rig, so I guess I
don't have the option of replacing it with the KANT3 board, but will call them
tomorrow about it.

I also discovered that when using CW while in SSB mode on all bands and then
going back to SSB without changing anything was causing severe overdrive
patterns on my monitor scope, but only if I used more than 100 watts of power on
HF through 6m.  It's not a problem with any of the XV series XVTRS I have.  When
I notified Elecraft they said they knew about it and were working on a firmware
solution.  You might want to check on that also.  I wouldn't have noticed it if
I didn't do a lot of weak signal work on 6m and up, where using CW and SSB at
the same time is advantageous.

Thanks for the info.

73,

Tom, N5GE - SWOT 3537 - Grid EM12jq

"Those who would give up
Essential Liberty to
purchase a little Temporary
Safety deserve neither
Liberty nor Safety"

An excerpt from a letter
written in 1755 from the
Assembly to the Governor
of Pennsylvania.

Support the entire Constitution, not
just the parts you like.

http://www.n5ge.com
http://www.eQSL.cc/Member.cfm?N5GE

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[Dave Zeph]

I've observed the same behavior on 6M - into a Dummy Load.  Holding TUNE and
near Full Power Output, with the SWR Display reading 1.0:1, I suddenly hear
a relay click, the display changes to read HIGH SWR, and the Output Power
drops to 0.   Taking the K3 out of TUNE and then immediately returning to
TUNE briefly resets the K3 to normal Power Output before the behavior
repeats.  

 

This also happens with a low SWR antenna as well.  In either case, it makes
no difference whether the ATU is in-line or Bypassed.

 

 

73 ---> Dave, W9ZRX

 

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[Bill N2BC]

Similar symptoms here, K3/100 #929 /w 1.96MCU, KAT3.

It never shuts down though and no high SWR warning.  Indicated PA temp jumps
about 6C at
key down,  I noticed two unexpected relay transfers during one test.

Testing into a Bird 500W dummy load at 100W, a mix of CW and solid key down
until reaching appx 60C PA temp.
FWIW my power source is a 50A Astron.

I disabled the KAT for the next two tests and did not notice any relay
transfers.  Tried it a 4th time with the KAT enabled & again no relay
transfers.

Only symptom here is the apparent RF getting into the PA temp sensing.

73, Bill  N2BC

----- Original Message -----
From: "Bruce Osterberg" <[hidden email]>
To: "Ian White GM3SEK" <[hidden email]>
Cc: <[hidden email]>
Sent: Monday, May 26, 2008 5:37 PM
Subject: Re: [Elecraft] Shutdown on 50MHz CW

> Good Evening:
>
> The exact same thing happens to me also.  All of a sudden I get a High SWR
> reading but their is none and it happens on 6 meters only.  BTW I am in
> Bypass Mode as SWR is 1:1
>
> Bruce N9BX 73
> K3 775
>
> PS Which menu command lets you key the rig when in USB for CW without
> switching to that Mode?
>
>
> Ian White GM3SEK wrote:
>> Paul G4LNA wrote:
>>>
>>> My first reaction is it sounds like RF getting in somewhere, as a matter
>>> of interest does it happen when you run it into a dummy load?
>>>
>> Yes, with antenna or dummy load, on either port of the KAT3, and with or
>> without the auto-ATU in line.
>>
>>

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[Ken Kopp-3]

No hint of the problem after several days of SSB
(only) on 6M.

73! Ken Kopp - K0PP
       [hidden email]
       K2 #5665
       K3 # 56
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[N5GE]

On Tue, 27 May 2008 09:19:41 +0100, Ian White GM3SEK <[hidden email]>
wrote:

>Hello Gary
>
>>    Based on the datasheets for the drivers and the finals, I suspect that
>>the problem is with the LPA (10W) drivers rather than the 100W PA. 
>>Y?all can help to prove or disprove my suspicion by testing to see if the
>>same thing happens below the crossover point where it 100 W PA kicks
>>in.  (I don?t recall exactly where that is & somewhere between 8 and 12
>>watts.)  Or better yet, you could temporarily disable the PA in firmware. 
>>In this way you might be able to push the drivers harder still.
>
>With the PA bypassed, the problem disappears. The PA temperature
>indication still works, but it remains steady because the PA is
>inactive.
>
>This is exactly what we should expect  - that is, <IF> the problem we're
>all experiencing is due to RF affecting the PA temperature indication,
>and then triggering some protective shutdown mechanism. (The LPA does
>not send a temperature output to the CPU.)
>
>Other things that haven't helped:
>
>* Bypassing the PA temperature sensor (Q1). I wondered if this
>diode-connected transistor might have been rectifying RF, but evidently
>it isn't - the PA temp indication bounces around same as before.
>
>* Making a shorter ground connection between the top rear corner of the
>KAT3 board and the nearby bolt for the ANT1 socket. Directly soldering
>two solder tags together made no improvement.
>

*** IMPORTANT ***

>Probably the most relevant thing at this time is the message from Tom,
>N5GE, that Elecraft are aware of it and are working on a firmware
>solution. With the Es season already in full swing, it can't come soon
>enough!

Although I am experiencing the power shutdown on 6m, the issue I reported to
Elecraft was not related to power shutdown.  It was related to using CW in the
SSB modes on all bands.  I just happened to find the trouble while on 6m during
last week's opening.

The anomaly I reported was that after using CW on SSB on any band and then
speaking into the microphone showed extreme flat topping on my monitor scope
(SM-230).  It was as if I hade turned the compression and mic gain up to
maximum.  Keeping the output power at 100w or below avoids this issue on my K3
(SN 806).  This is what Gary at Elecraft told me they knew about.

Tapping the ATU TUNE button puts things back in order.  Probably because the
tuner reduces the power to do the tuning and doing so may set everything back to
normal.

*** END ***

As for the 6m power shutdown issues, I'm sure that Elecraft is very aware of the
6m power problem after the 6m band openings we experienced here in North America
during the past week.

73,

Tom, N5GE - SWOT 3537 - Grid EM12jq

"Those who would give up
Essential Liberty to
purchase a little Temporary
Safety deserve neither
Liberty nor Safety"

An excerpt from a letter
written in 1755 from the
Assembly to the Governor
of Pennsylvania.

Support the entire Constitution, not
just the parts you like.

http://www.n5ge.com
http://www.eQSL.cc/Member.cfm?N5GE

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