K3 power drop

[Steve Reichlyn]

I noticed today when starting to transmit on RTTY in the WPX test, although the power out from the K3 was set on 60 W, the rig only put out about 30 W for the first several transmissions then the output gradually rose to 60 W as selected. The antenna SWR is 1.5.
Any ideas? S/n is 855 But has bEen updated to current specs.    Steve KH6/AA4V
Sent from my Verizon Wireless BlackBerry
______________________________________________________________
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

[Don Wilhelm-4]

  Steve,

Assuming you are operating RTTY in AFSK mode rather than FSK, my guess
is that you are not driving the audio input to the K3 sufficiently.

Use TX TEST and observe the ALC meter.  Bring the audio up until you
have at least 4 bars on solid and then increase it a bit more until you
just barely see the 5th bar illuminate.

Contrary to "classic" instructions, that say you should not have any ALC
indication, the K3 "ALC" meter is both a "VU" meter and an "ALC" meter.  
The onset of ALC does not occur until the 5th bar - below that it is an
indicator of audio drive.

The most common result of having the audio into the K3 too low is just
as you have stated - it takes a long time for the K3 power output to
come up to the requested level.

Bottom line, ignore the "classic" advice, and drive the audio as
instructed in the K3 manual, and adjust the power output with the K3
power control knob.  Attempts to control the power output by adjusting
the audio drive level will result in the "Power Creep" that you have
observed.

The way the K3 controls power output is different than that if most
other transceivers.  The K3 actually monitors the power output and
attempts to control the transmit gain accordingly.  Other transceivers
use their ALC mechanism to control the power output - the K3 does not
(for those listening, the K2 is similar).

73,
Don W3FPR

On 2/12/2011 11:41 PM, [hidden email] wrote:

> I noticed today when starting to transmit on RTTY in the WPX test, although the power out from the K3 was set on 60 W, the rig only put out about 30 W for the first several transmissions then the output gradually rose to 60 W as selected. The antenna SWR is 1.5.
> Any ideas? S/n is 855 But has bEen updated to current specs.    Steve KH6/AA4V
> Sent from my Verizon Wireless BlackBerry
> ______________________________________________________________
> 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

[Richard Ferch]

Are you using AFSK or FSK? If it's AFSK, when you set the meter to
display ALC, how many bars do you see when you transmit?

A possible cause of the symptoms you observe is too low audio input in
AFSK. The input level should be high enough to display 4-5 bars on the
ALC meter. With sufficient drive, the requested output power should be
reached immediately, but with lower drive, the K3's ALC will take some
time to bring the power up to the requested level. You can adjust the
audio drive with the MIC gain control (which controls LINE IN gain in
AFSK A and DATA A modes).

73,
Rich VE3KI



KH6/AA4V wrote:

> I noticed today when starting to transmit on RTTY in the WPX test,
> although the power out from the K3 was set on 60 W, the rig only put
> out about 30 W for the first several transmissions then the output
> gradually rose to 60 W as selected. The antenna SWR is 1.5.
>
> Any ideas? S/n is 855 But has bEen updated to current specs.
>
> Steve KH6/AA4V

______________________________________________________________
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