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K3 FSD-D (RTTY) power-control bug fixed

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wayne burdick

K3 FSD-D (RTTY) power-control bug fixed

Administrator

Hi all,

It appears that I've fixed the reported bug in FSK-D mode (RTTY) where power could not be increased while transmitting. I know some of you are in the middle of an RTTY contest as we speak, and if you'd like to try the new firmware, please email me directly.

73,
Wayne
N6KR

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Joe Subich, W4TV-4

Re: K3 FSD-D (RTTY) power-control bug fixed

Sorry, Wayne. It's not fixed. Although the power adjusts now it still
comes up more than 1 dB low (65 to 75 Watts for 110W commanded) and
takes more than five seconds to reach set output. These tests in
FSK_D. For comparison, in CW power output comes up at more than 90%
of the commanded level and reaches full output in 1 second or less.

I've performed wattmeter and power calibration - they have little
if any impact on the issue.

73,

... Joe, W4TV

On 2/8/2014 12:23 PM, Wayne Burdick wrote:

> Hi all,
>
> It appears that I've fixed the reported bug in FSK-D mode (RTTY) where power could not be increased while transmitting. I know some of you are in the middle of an RTTY contest as we speak, and if you'd like to try the new firmware, please email me directly.
>
> 73,
> Wayne
> N6KR
>
> ______________________________________________________________
> 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
>

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Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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wayne burdick

Re: K3 FSD-D (RTTY) power-control bug fixed

Administrator

Hi Joe,

I reduced the power ramp-up rate in FSK-D in conjunction with other changes. I'll improve this in the next beta release. Meanwhile it lags a little in this mode, which is hopefully just a minor inconvenience.

73,
Wayne
N6KR

On Feb 8, 2014, at 3:27 PM, "Joe Subich, W4TV" <[hidden email]> wrote:

>
> Sorry, Wayne. It's not fixed. Although the power adjusts now it still
> comes up more than 1 dB low (65 to 75 Watts for 110W commanded) and
> takes more than five seconds to reach set output. These tests in
> FSK_D. For comparison, in CW power output comes up at more than 90%
> of the commanded level and reaches full output in 1 second or less.
>
> I've performed wattmeter and power calibration - they have little
> if any impact on the issue.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2/8/2014 12:23 PM, Wayne Burdick wrote:
>> Hi all,
>>
>> It appears that I've fixed the reported bug in FSK-D mode (RTTY) where power could not be increased while transmitting. I know some of you are in the middle of an RTTY contest as we speak, and if you'd like to try the new firmware, please email me directly.
>>
>> 73,
>> Wayne
>> N6KR

Joe Subich, W4TV-4

Re: K3 FSD-D (RTTY) power-control bug fixed

> Meanwhile it lags a little in this mode, which is hopefully just a
> minor inconvenience.

It's more than a little lag <G> - particularly on those occasions the
lower level is nearly 3 dB low to start. I'm looking forward to the
next one. Perhaps the update rate should be adaptive - fast for the
first couple seconds of a transmission and then slowing down after the
power has had a chance to stabilize ...

73,

... Joe, W4TV

On 2/8/2014 7:35 PM, Wayne Burdick wrote:

> Hi Joe,
>
> I reduced the power ramp-up rate in FSK-D in conjunction with other changes. I'll improve this in the next beta release. Meanwhile it lags a little in this mode, which is hopefully just a minor inconvenience.
>
> 73,
> Wayne
> N6KR
>
>
> On Feb 8, 2014, at 3:27 PM, "Joe Subich, W4TV" <[hidden email]> wrote:
>
>>
>> Sorry, Wayne. It's not fixed. Although the power adjusts now it still
>> comes up more than 1 dB low (65 to 75 Watts for 110W commanded) and
>> takes more than five seconds to reach set output. These tests in
>> FSK_D. For comparison, in CW power output comes up at more than 90%
>> of the commanded level and reaches full output in 1 second or less.
>>
>> I've performed wattmeter and power calibration - they have little
>> if any impact on the issue.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 2/8/2014 12:23 PM, Wayne Burdick wrote:
>>> Hi all,
>>>
>>> It appears that I've fixed the reported bug in FSK-D mode (RTTY) where power could not be increased while transmitting. I know some of you are in the middle of an RTTY contest as we speak, and if you'd like to try the new firmware, please email me directly.
>>>
>>> 73,
>>> Wayne
>>> N6KR
>

Don Wilhelm-4

Re: K3 FSD-D (RTTY) power-control bug fixed

The K3 power control is a closed loop system, and the loop gain will
vary a bit with variations in the K3 RF chain gain.

While it would be ideal if the control loop could be critically damped
for all K3s, I don't think that is practical because of component
tolerances giving rise to variations in the RF TX gain.

IMHO it is better to make the loop gain be a bit overdamped than to
allow it to be underdamped which would permit power spikes which drive
some modern amplifiers 'wild'.

Yes, too much overdamping is not good - unfortunately the response time
varies with the mode. Hopefully a compromise can be found that will
satisfy all K3s.

73,
Don W3FPR

On 2/8/2014 7:49 PM, Joe Subich, W4TV wrote:

>
> > Meanwhile it lags a little in this mode, which is hopefully just a
> > minor inconvenience.
>
> It's more than a little lag <G> - particularly on those occasions the
> lower level is nearly 3 dB low to start. I'm looking forward to the
> next one. Perhaps the update rate should be adaptive - fast for the
> first couple seconds of a transmission and then slowing down after the
> power has had a chance to stabilize ...
>
> 73,
>
> ... Joe, W4TV
>