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[K3] Transmitter Calibration Procedure

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w8fn

[K3] Transmitter Calibration Procedure

During SS I noticed that my K3 transmitter seemed to be in need of
calibration, as the output power measured by my LP-100A (which I trust)
seemed to be a bit higher than expected from the radio's setting and I
was also observing some power "creep".

This afternoon I finally got an opportunity to look into this and indeed
the transmit output is slightly high. 5W setting produces about 5.7W and
50W setting produces around 60-62 watts. I used the K3 utility to do a
TX gain calibration and this seemed to only level the power on a band to
band basis. 50W requested now gets me about 62W on every band.

It looks as if the calibration is (understandably) using the internal
wattmeter to set the power. Therefore, I concluded that I needed to do
the wattmeter calibration first to see if that corrected the power set
error. Unfortunately, the procedure in the manual doesn't seem to work.
Firstly, it says something about calibrating in Tune mode. I tried doing
the cal with both the front panel Power set to 5W and 50W and with the
Tune power set to these values. The procedure tells me to hold the Tune
button in the adjust menu and appears to say I should be able to adjust
the output power with the VFO A knob. This doesn't work. As soon as the
Tune button is held the rig drops out of Menu display and I just get the
normal Tune mode behavior.

Am I reading the instructions wrong? They seem pretty ambiguous to me,
and no variant of what I think they could say seems to work. Has anyone
successfully done a TX Cal in the field? If so, how did you proceed?

73...
Randy, W8FN
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w8fn

Re: [K3] Transmitter Calibration Procedure

An update:

I did a power cycle and carefully repeated the TX calibration
procedure. This time I caught the requirement to set CONFIG: TUN PWR and
CONFIG: PWR SET to NOR. This instruction appears at the beginning of the
entire Calibration Procedures section of the manual. This time, things
behaved better but the instruction to "adjust menu parameter" for the
proper reading on the external wattmeter was still puzzling. Adjusting
the VFO A knob had no effect. Finally, I turned the PWR knob on the
front panel of the K3 and the output power changed. I was able to do the
5W and 50W wattmeter calibration using this technique. I then
re-executed the Transmitter Gain calibration using the K3 utility.

The PWR knob adjustment value still is incorrect. Setting the Tune power
for 30W delivers about 36W and to get 100W out of the radio I need to
back the power setting down to around 91. The level is pretty consistent
from band to band.

This is no big deal, but I'm still not sure why the wattmeter
calibration didn't affect the power control set accuracy. Am I just
misunderstanding what's being accomplished in the calibration or is
there still something wrong with the way I'm doing it?

73...
Randy, W8FN
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Mike Harris

Re: [K3] Transmitter Calibration Procedure

In reply to this post by w8fn

The procedure in the handbook is incomplete and misleading. This has
been mentioned before.

First set CONFIG: TUN PWR to nor with the VFO A knob.
Next follow the procedure.

When you get to "Hold TUNE" etc you will notice that the display changes
from the CONFIG:WMTR display to what looks like the normal TUNE display
and you lose the parameter reading. At this point you can still turn
the VFO A knob and the output power will change and you can match it to
your external LP-100. When you exit TUNE you will note that the
parameter value has probably changed.

Regards,

Mike VP8NO

On 09/11/2012 21:09, Randy Farmer wrote:

> During SS I noticed that my K3 transmitter seemed to be in need of
> calibration, as the output power measured by my LP-100A (which I trust)
> seemed to be a bit higher than expected from the radio's setting and I
> was also observing some power "creep".
>
> This afternoon I finally got an opportunity to look into this and indeed
> the transmit output is slightly high. 5W setting produces about 5.7W and
> 50W setting produces around 60-62 watts. I used the K3 utility to do a
> TX gain calibration and this seemed to only level the power on a band to
> band basis. 50W requested now gets me about 62W on every band.
>
> It looks as if the calibration is (understandably) using the internal
> wattmeter to set the power. Therefore, I concluded that I needed to do
> the wattmeter calibration first to see if that corrected the power set
> error. Unfortunately, the procedure in the manual doesn't seem to work.
> Firstly, it says something about calibrating in Tune mode. I tried doing
> the cal with both the front panel Power set to 5W and 50W and with the
> Tune power set to these values. The procedure tells me to hold the Tune
> button in the adjust menu and appears to say I should be able to adjust
> the output power with the VFO A knob. This doesn't work. As soon as the
> Tune button is held the rig drops out of Menu display and I just get the
> normal Tune mode behavior.
>
> Am I reading the instructions wrong? They seem pretty ambiguous to me,
> and no variant of what I think they could say seems to work. Has anyone
> successfully done a TX Cal in the field? If so, how did you proceed?
>
> 73...
> Randy, W8FN

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Don Wilhelm-4

Re: [K3] Transmitter Calibration Procedure

In reply to this post by w8fn

Randy,

If during the wattmeter calibration procedure you could not adjust the
menu parameter something is wrong and your wattmeter is still not
properly calibrated.

73,
Don W3FPR

On 11/9/2012 10:34 PM, Randy Farmer wrote:

> An update:
>
> I did a power cycle and carefully repeated the TX calibration
> procedure. This time I caught the requirement to set CONFIG: TUN PWR and
> CONFIG: PWR SET to NOR. This instruction appears at the beginning of the
> entire Calibration Procedures section of the manual. This time, things
> behaved better but the instruction to "adjust menu parameter" for the
> proper reading on the external wattmeter was still puzzling. Adjusting
> the VFO A knob had no effect. Finally, I turned the PWR knob on the
> front panel of the K3 and the output power changed. I was able to do the
> 5W and 50W wattmeter calibration using this technique. I then
> re-executed the Transmitter Gain calibration using the K3 utility.
>
> The PWR knob adjustment value still is incorrect. Setting the Tune power
> for 30W delivers about 36W and to get 100W out of the radio I need to
> back the power setting down to around 91. The level is pretty consistent
> from band to band.
>
> This is no big deal, but I'm still not sure why the wattmeter
> calibration didn't affect the power control set accuracy. Am I just
> misunderstanding what's being accomplished in the calibration or is
> there still something wrong with the way I'm doing it?
>
>

Mike Reublin

Re: [K3] Transmitter Calibration Procedure

In reply to this post by Mike Harris

Mike,

I thought I'd re-do my calibration. It took a LOT of turns to get from 4 watts to 5 watts on the Bird. I don't have a CONFIG:WTMR HP, only LP. I do have the 100W PA.

73, Mike NF4L

On Nov 10, 2012, at 8:09 AM, Mike Harris <[hidden email]> wrote:

> The procedure in the handbook is incomplete and misleading. This has
> been mentioned before.
>
> First set CONFIG: TUN PWR to nor with the VFO A knob.
> Next follow the procedure.
>
> When you get to "Hold TUNE" etc you will notice that the display changes
> from the CONFIG:WMTR display to what looks like the normal TUNE display
> and you lose the parameter reading. At this point you can still turn
> the VFO A knob and the output power will change and you can match it to
> your external LP-100. When you exit TUNE you will note that the
> parameter value has probably changed.
>
> Regards,
>
> Mike VP8NO
>
>
> On 09/11/2012 21:09, Randy Farmer wrote:
>> During SS I noticed that my K3 transmitter seemed to be in need of
>> calibration, as the output power measured by my LP-100A (which I trust)
>> seemed to be a bit higher than expected from the radio's setting and I
>> was also observing some power "creep".
>>
>> This afternoon I finally got an opportunity to look into this and indeed
>> the transmit output is slightly high. 5W setting produces about 5.7W and
>> 50W setting produces around 60-62 watts. I used the K3 utility to do a
>> TX gain calibration and this seemed to only level the power on a band to
>> band basis. 50W requested now gets me about 62W on every band.
>>
>> It looks as if the calibration is (understandably) using the internal
>> wattmeter to set the power. Therefore, I concluded that I needed to do
>> the wattmeter calibration first to see if that corrected the power set
>> error. Unfortunately, the procedure in the manual doesn't seem to work.
>> Firstly, it says something about calibrating in Tune mode. I tried doing
>> the cal with both the front panel Power set to 5W and 50W and with the
>> Tune power set to these values. The procedure tells me to hold the Tune
>> button in the adjust menu and appears to say I should be able to adjust
>> the output power with the VFO A knob. This doesn't work. As soon as the
>> Tune button is held the rig drops out of Menu display and I just get the
>> normal Tune mode behavior.
>>
>> Am I reading the instructions wrong? They seem pretty ambiguous to me,
>> and no variant of what I think they could say seems to work. Has anyone
>> successfully done a TX Cal in the field? If so, how did you proceed?
>>
>> 73...
>> Randy, W8FN
> ______________________________________________________________
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html