Elecraft

K3 output power failure.

Classic

List

Threaded

5 messages Options

Eric Rosenberg

K3 output power failure.

In the middle of the ARRL 160 contest, my K3 stopped putting out any RF.
No explanation that I can think of... all of a sudden, ZERO watts out
when the radio was keyed, either by software (N1MM+ or WSJT-X) or
pressing the TUNE button. The TX LED was lit, the meter showed audio,
which I could hear via the radio MON.

I could not get it to come back. I shut it off for a couple of minutes
and then it came back.

Everything seemed fine until this weekend's ARRL RTTY Roundup. After
being on the air for about 4 hours, once again there no was RF output
(the meter said "0 watts with two dashed lines above it), The radio
keyed (the TX LED went on and the meter showed audio which could be
heard via the radio MON), and the meter said "0 watts with two dashed
lines above it. I disconnected everything but the antenna, and still...
no change. I did a system reset. Again, no change.

I quit for he evening and came back in the morning, On a lark, I hooked
it all back up, and lo and behold, everything worked as if nothing had
gone wrong.

I'm stumped. I've never opened up the radio -- the only time it was
opened was at Elecraft last year.

Any advice is appreciated!

73,
Eric W3DQ

______________________________________________________________
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]

na5n

Re: K3 output power failure.

Eric Rosenberg writes:

> Everything seemed fine until this weekend's ARRL RTTY Roundup. After
> being on the air for about 4 hours, once again there no was RF output

Eric,
Sounds like an over temperature problem. Especially if running RTTY at
near full power. The high duty cycle of RTTY can cause the PA to get very
hot. When it gets too hot, the radio shuts the transmitter down for
protection until it cools off in 15-30 minutes. Too much audio gain/ALC
can cause the same. Review the tech manual on transmitter setup about over
driving the K3 or external amplifier. Just sounds like you're driving the
K3 a bit too hard for prolonged periods.

GL es 73, Paul NA5N
______________________________________________________________
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]

Clay Autery-2

Re: K3 output power failure.

Alternatively, you might (if you feel comfortable doing so) open the
unit up and inspect it for any foreign debris that may have made its way
into the case, thus challenging the airflow design/volume/velocity.
The PA is in its own shielded enclosure, and thus relies heavily upon
the fans to suck air through and out of the PA enclosure and overall
enclosure).

Additionally, I would encourage you to hook the K3 up to a dummy load
and check to see if the fans are running properly. Do they spin at all
when the unit is sitting at idle (PA somewhere around 36C or so in my
stack). Then, set power at 100 W and Press and Hold the XMIT/UNE button
to engage tuning ops in CW mode. As the PA warms up, the fans should
start to spin up as indicated by warm airflow increasing in temperature
and velocity out of the fans on the rear panel.

_*WARNING:*_ Make sure VFO Display is showing the PA temp in the
display and WATCH IT CLOSELY.... If the fans don't start spinning up
from slow speed by 40 or 41, tap XMIT and stop the TUNE procedure. IF
you forget to tap XMIT, you will put the PA into protection mode at some
point, and MAY WELL DAMAGE THE PA, et al.

If the fans are not spinning at all, you MAY have dead fans or other
pwr/signal issues to the fans.
IF the fans don't spin up as PA temp increases, you have issues that I
am not qualified to help you troubleshoot properly or fix.

73,

______________________
Clay Autery, KY5G
(318) 518-1389

On 01/05/20 22:40, [hidden email] wrote:

> Eric Rosenberg writes:
>
>> Everything seemed fine until this weekend's ARRL RTTY Roundup. After
>> being on the air for about 4 hours, once again there no was RF output
>
> Eric,
> Sounds like an over temperature problem. Especially if running RTTY
> at near full power. The high duty cycle of RTTY can cause the PA to
> get very hot. When it gets too hot, the radio shuts the transmitter
> down for protection until it cools off in 15-30 minutes. Too much
> audio gain/ALC can cause the same. Review the tech manual on
> transmitter setup about over driving the K3 or external amplifier.
> Just sounds like you're driving the K3 a bit too hard for prolonged
> periods.
>
> GL es 73, Paul NA5N

______________________________________________________________
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]

Bob McGraw - K4TAX

Re: K3 output power failure.

In reply to this post by Eric Rosenberg

What was the PA temperature? And how are the fans set in the CONFIG menu.

Bob, K4TAX

Sent from my iPhone

> On Jan 6, 2020, at 12:15 AM, Eric Rosenberg <[hidden email]> wrote:
>
> In the middle of the ARRL 160 contest, my K3 stopped putting out any RF. No explanation that I can think of... all of a sudden, ZERO watts out when the radio was keyed, either by software (N1MM+ or WSJT-X) or pressing the TUNE button. The TX LED was lit, the meter showed audio, which I could hear via the radio MON.
>
> I could not get it to come back. I shut it off for a couple of minutes and then it came back.
>
> Everything seemed fine until this weekend's ARRL RTTY Roundup. After being on the air for about 4 hours, once again there no was RF output (the meter said "0 watts with two dashed lines above it), The radio keyed (the TX LED went on and the meter showed audio which could be heard via the radio MON), and the meter said "0 watts with two dashed lines above it. I disconnected everything but the antenna, and still... no change. I did a system reset. Again, no change.
>
> I quit for he evening and came back in the morning, On a lark, I hooked it all back up, and lo and behold, everything worked as if nothing had gone wrong.
>
> I'm stumped. I've never opened up the radio -- the only time it was opened was at Elecraft last year.
>
> Any advice is appreciated!
>
> 73,
> Eric W3DQ
>
> ______________________________________________________________
> 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]

Eric Rosenberg

Re: K3 output power failure.

W3LPL and other mentioned the PA temp and sagging power supply.

I didn't think to check the PA temp until later (how much later, I don't
know), If I remember correctly, it was 35C. In both cases, I was operating
in a contest (ARRL 160 and ARRL RTTY RU) with the RF power set to 100w

Sitting in front of the rig now (been powered for 15 or so minutes), the PA
is 26C.What did catch my eye was the voltage and current at the rig: 13.3v
& 1.2a in RX

I then keyed the radio, brought the power to 100w, it's a the voltage went
to 11.8v/17.9a and then shut down. The voltage went up to 13.3v/1.2a but
still no output. PA temp is 31C

I swapped power the Astron power supply for an Alinco DM-330MV switching
supply (1 ft power cable to the radio). I set the power supply so the radio
reads 14.5v. I also turned up the fan up to level 4 (it hadn't gone on
previously).. The radio read 14.5v/1.3A on RX. PA temp 22C, FP temp 30C in
RX

Still no TX output, although the radio went to 14.2v and 2.3a when I first
keyed the radio. It quickly ramps up to ~4.a and stays there until I unkey
it.

Any ideas as to what's going on?

73, Eric W3DQ

On Mon, Jan 6, 2020 at 9:29 AM Bob McGraw K4TAX <[hidden email]> wrote:

> What was the PA temperature? And how are the fans set in the CONFIG
> menu.
>
> Bob, K4TAX
>
>
> Sent from my iPhone
>
> > On Jan 6, 2020, at 12:15 AM, Eric Rosenberg <[hidden email]>
> wrote:
> >
> > In the middle of the ARRL 160 contest, my K3 stopped putting out any
> RF. No explanation that I can think of... all of a sudden, ZERO watts out
> when the radio was keyed, either by software (N1MM+ or WSJT-X) or pressing
> the TUNE button. The TX LED was lit, the meter showed audio, which I could
> hear via the radio MON.
> >
> > I could not get it to come back. I shut it off for a couple of minutes
> and then it came back.
> >
> > Everything seemed fine until this weekend's ARRL RTTY Roundup. After
> being on the air for about 4 hours, once again there no was RF output (the
> meter said "0 watts with two dashed lines above it), The radio keyed (the
> TX LED went on and the meter showed audio which could be heard via the
> radio MON), and the meter said "0 watts with two dashed lines above it. I
> disconnected everything but the antenna, and still... no change. I did a
> system reset. Again, no change.
> >
> > I quit for he evening and came back in the morning, On a lark, I hooked
> it all back up, and lo and behold, everything worked as if nothing had gone
> wrong.
> >
> > I'm stumped. I've never opened up the radio -- the only time it was
> opened was at Elecraft last year.
> >
> > Any advice is appreciated!
> >
> > 73,
> > Eric W3DQ
> >
> > ______________________________________________________________
> > 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]
>
>
>