K3 losing RF

[Paul Ormandy ZL4PW]

Hi all,

My K3 has developed a problem...

Power output is down to 70W and the LCD back-light flickers on tx. The "Low Voltage" message flicked
up briefly once.

I suspect a DC power problem but so saying, the voltage at the rig is 13.9V on transmit at 70W and
the rig is drawing 13A. The problem seems worse on the 6mb.

If I reduce the output RF control to around 60W, there is no perceptible LCD flickering.

I will obtain another 20A power supply tomorrow and see if the problem persists.

In the mean time, (apart from running low power), can anyone suggest what I should start looking for
internally?

Kind regards,

Paul


--
Paul Ormandy ZL4PW ZM4M
www.radiodx.com
www.zl4pw.orcon.net.nz

______________________________________________________________
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

[Cookie]

Paul, look for voltage drop at the power poles.  Solder or crimping is critical
and proper assembly is as well.  A fraction of an ohm will cause an unworkable
voltage drop.  Look at the internal volt meter on the K3 display to identify
excess voltage drop at the connection.
 Willis 'Cookie' Cooke
K5EWJ




________________________________
From: Paul Ormandy ZL4PW <[hidden email]>
To: [hidden email]
Sent: Sat, January 1, 2011 11:22:39 PM
Subject: [Elecraft] K3 losing RF

Hi all,

My K3 has developed a problem...

Power output is down to 70W and the LCD back-light flickers on tx. The "Low
Voltage" message flicked

up briefly once.

I suspect a DC power problem but so saying, the voltage at the rig is 13.9V on
transmit at 70W and

the rig is drawing 13A. The problem seems worse on the 6mb.

If I reduce the output RF control to around 60W, there is no perceptible LCD
flickering.

I will obtain another 20A power supply tomorrow and see if the problem persists.

In the mean time, (apart from running low power), can anyone suggest what I
should start looking for

internally?

Kind regards,

Paul


--
Paul Ormandy ZL4PW ZM4M
www.radiodx.com
www.zl4pw.orcon.net.nz

______________________________________________________________
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



     
______________________________________________________________
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

[Paul Ormandy ZL4PW]

Hi all,

I was less flustered today and did some more checking...

Discovered the main fuse in the negative supply line from the PSU had blown.

I would like to know what reason it could have blown and at this point, presume it was something to
do with running 100W on 6M.

Thanks to all who e-mailed directly with suggestions.

Cheers,

Paul

> ----------------------------------------------------------------------------------------------------
> *From:* Paul Ormandy ZL4PW <[hidden email]>
> *To:* [hidden email]
> *Sent:* Sat, January 1, 2011 11:22:39 PM
> *Subject:* [Elecraft] K3 losing RF
>
> Hi all,
>
> My K3 has developed a problem...
>
> Power output is down to 70W and the LCD back-light flickers on tx. The "Low Voltage" message flicked
> up briefly once.
>
> I suspect a DC power problem but so saying, the voltage at the rig is 13.9V on transmit at 70W and
> the rig is drawing 13A. The problem seems worse on the 6mb.
>
> If I reduce the output RF control to around 60W, there is no perceptible LCD flickering.
>
> I will obtain another 20A power supply tomorrow and see if the problem persists.
>
> In the mean time, (apart from running low power), can anyone suggest what I should start looking for
> internally?
>
> Kind regards,
>
> Paul
>
>
> --
> Paul Ormandy ZL4PW ZM4M
> www.radiodx.com <http://www.radiodx.com/>
> www.zl4pw.orcon.net.nz <http://www.zl4pw.orcon.net.nz/>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email] <mailto:[hidden email]>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

--
Paul Ormandy ZL4PW ZM4M
www.radiodx.com
www.zl4pw.orcon.net.nz

______________________________________________________________
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