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[KX3] Digital TX issues

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Gary Hawkins

[KX3] Digital TX issues

Just as background, this digital setup has been working successfully for
several weeks and as I mentioned in another post I've recently had over
170 contacts in both JT65/JT9 running 5 or 10W (my KX3 has 3rd third
party heatsink). The ALC was appropriately set based on information Don
provided several weeks ago but it was the first thing I checked. The
mic level was set for 5 bars ALC.

After the last problem, I checked all connections and setting and
everything seemed correct. The PSU was stable at 13.4V and VSWR sweep
on antenna did not show any problems. I connected rig to a power meter
and dummy load and brought up all the s/w. Things started working
again. I then put the radio through a 12 cycle CQ sequence at 10W.
Again all good. I reconnected the antenna and started attempting to
QSOs. PSKreporter showed I was getting out and then I worked two QSOs
without issue. However, on the third QSO, on the second transmission
block the TX power collapsed (KX3 TX light still red) I think midway
into the transmission - I halted TX on WSJT-X. I tried the tune
function on WSJT-X and while the KX3 TX indicator comes on there was no
TX power. ALC shows zero bars.

Thus, I would have to conclude the problem is an intermittent behavior
rather than setup issue. It seems to me the KX3 TX is shutting down in
response to some fault condition. PA temp is well below max, and no
other error messages are observed. Unlike when the unit powers down due
to high temp, the power setting remains at 10W. ALC shows zero bars.

While trying the tune function on WSJT-X after fault condition, I
increase mic gain and ALC bars start to briefly show and TX power
briefly flickers on power meter. However, within a second so the ALC
bars drop back to zero and so does the power. Increasing the mic gain
again results in similar behavior.

I switch all equipment off and call it a night. This morning, I bring
anything up again and the KX3 will not radiate power in digital mode
albeit the TX light is ON. Transmitting in FM the radio seems to be
working!

Again, thoughts would be greatly appreciated.

73's Gary K6YOA

That is a typical behavior when the KX3 (or K2 or K3) is not
provided with sufficient audio drive. It "power hunts".
Increase the soundcard audio output and/or the mic level to produce
4 bars with the 5th bar flickering on the ALC meter. Set the power
level with the power knob. Attempting to control the power level
with the audio drive will result in failure.

73,
Don W3FPR

On 7/12/2015 8:39 PM, Gary Hawkins wrote:

I'm seeing a odd problem working digital today with my KX3.
Sometimes when I go into transmit (power set at 5W) JT65_HF, my
Signalink shows PTT active (red light) , the KX3 shows PTT
active (red light) but no power is being radiated. Antenna
(dipole) has a near perfect match to the KX3. Power still shows
set to 5W on KX3. Problem remains if I switch from the antenna
to a dummy load. Osc and PA temp at 36 and 30C - PSU stable at
13.4V. When I try to transmit is DATA A mode (tune) power seems
to try to ramp up and then immediately falls away. Radio seems
to transmit fine in FM mode. What am I missing please?

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Bob McGraw - K4TAX

Re: [KX3] Digital TX issues

While your test using a dummy load seem reasonable and correct, it would
appear as though you may have an excessive amount of Common Mode current
on the feed line, not being seen by the SWR indication in the radio. I
suggest a Common Mode choke on and at the output of the radio. Perhaps
a fault with a antenna or coax jumper or associated connector.

73 Bob, K4TAX

On 7/13/2015 11:35 AM, Gary Hawkins wrote:

> Just as background, this digital setup has been working successfully
> for several weeks and as I mentioned in another post I've recently had
> over 170 contacts in both JT65/JT9 running 5 or 10W (my KX3 has 3rd
> third party heatsink). The ALC was appropriately set based on
> information Don provided several weeks ago but it was the first thing
> I checked. The mic level was set for 5 bars ALC.
>
> After the last problem, I checked all connections and setting and
> everything seemed correct. The PSU was stable at 13.4V and VSWR sweep
> on antenna did not show any problems. I connected rig to a power
> meter and dummy load and brought up all the s/w. Things started
> working again. I then put the radio through a 12 cycle CQ sequence at
> 10W. Again all good. I reconnected the antenna and started
> attempting to QSOs. PSKreporter showed I was getting out and then I
> worked two QSOs without issue. However, on the third QSO, on the
> second transmission block the TX power collapsed (KX3 TX light still
> red) I think midway into the transmission - I halted TX on WSJT-X. I
> tried the tune function on WSJT-X and while the KX3 TX indicator comes
> on there was no TX power. ALC shows zero bars.
>
> Thus, I would have to conclude the problem is an intermittent behavior
> rather than setup issue. It seems to me the KX3 TX is shutting down
> in response to some fault condition. PA temp is well below max, and
> no other error messages are observed. Unlike when the unit powers
> down due to high temp, the power setting remains at 10W. ALC shows
> zero bars.
>
> While trying the tune function on WSJT-X after fault condition, I
> increase mic gain and ALC bars start to briefly show and TX power
> briefly flickers on power meter. However, within a second so the ALC
> bars drop back to zero and so does the power. Increasing the mic gain
> again results in similar behavior.
>
> I switch all equipment off and call it a night. This morning, I bring
> anything up again and the KX3 will not radiate power in digital mode
> albeit the TX light is ON. Transmitting in FM the radio seems to be
> working!
>
> Again, thoughts would be greatly appreciated.
>
> 73's Gary K6YOA
>
>
> That is a typical behavior when the KX3 (or K2 or K3) is not
> provided with sufficient audio drive. It "power hunts".
> Increase the soundcard audio output and/or the mic level to produce
> 4 bars with the 5th bar flickering on the ALC meter. Set the power
> level with the power knob. Attempting to control the power level
> with the audio drive will result in failure.
>
> 73,
> Don W3FPR
>
> On 7/12/2015 8:39 PM, Gary Hawkins wrote:
>
> I'm seeing a odd problem working digital today with my KX3.
> Sometimes when I go into transmit (power set at 5W) JT65_HF, my
> Signalink shows PTT active (red light) , the KX3 shows PTT
> active (red light) but no power is being radiated. Antenna
> (dipole) has a near perfect match to the KX3. Power still shows
> set to 5W on KX3. Problem remains if I switch from the antenna
> to a dummy load. Osc and PA temp at 36 and 30C - PSU stable at
> 13.4V. When I try to transmit is DATA A mode (tune) power seems
> to try to ramp up and then immediately falls away. Radio seems
> to transmit fine in FM mode. What am I missing please?
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
>
>

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Don Wilhelm-4

Re: [KX3] Digital TX issues

In reply to this post by Gary Hawkins

Gary,

Since you get no ALC bars when the fault occurs, the problem is either
in your Signalink or the audio input section of the KX3.
It could be as simple as an intermittent audio cable connection or a
fault in the audio wire.
If you have an audio amplifier available (like one of those used with an
iPOD or similar), plug the cable that you normally plug into the KX3 and
see if you have the digital tones coming out of the Signalink and that
audio cable - you will hear audio only in the left channel, the
Signalink does not use the right channel.

Since you say FM appears to be working, that sounds like the KX3 mic
audio is not at fault.

If everything works into a dummy load, check your antenna system to
determine if the cause may be RF in the shack that is bothering your
Signalink.

73,
Don W3FPR

On 7/13/2015 12:35 PM, Gary Hawkins wrote:

>
> Thus, I would have to conclude the problem is an intermittent behavior
> rather than setup issue. It seems to me the KX3 TX is shutting down
> in response to some fault condition. PA temp is well below max, and
> no other error messages are observed. Unlike when the unit powers
> down due to high temp, the power setting remains at 10W. ALC shows
> zero bars.
>
> While trying the tune function on WSJT-X after fault condition, I
> increase mic gain and ALC bars start to briefly show and TX power
> briefly flickers on power meter. However, within a second so the ALC
> bars drop back to zero and so does the power. Increasing the mic gain
> again results in similar behavior.
>

Edward R Cole

Re: [KX3] Digital TX issues

In reply to this post by Gary Hawkins

This may not apply to Gary Hawkins' situation with his KX3, but I
have the situation where I get no Tx audio drive to my K3 in digital
modes from the soundcard. Turns out that my XP32 computer is not
doing a handshake at power-up with my emu-0202. Cure is to cycle the
power on the emu0202 to enable connection with the computer and then
restart the digital sw application. This happens with both MAP65v2
and WSJT10. Strange part is Rx audio connection is fine.

I'll attribute it to running an old OS which may not be running well
anymore. May also deal with START functions of the computer.

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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