Elecraft CW Net Announcement

[Kevin Rock]

Good Evening, (very late)
   I just got my power turned back on and they don't know how long it will last so I better be quick.  Weather has turned back to chilly and wet after a few days of summer.  Propagation was good this week on twenty meters hopefully it will continue improving.

Please join us tomorrow evening.
 
1) Hail signs  (first letter or two of the suffix of your call)
2) NCS help (as well as QSP/QNP <relay> help)
 
Sunday 2300z (Sunday 4 PM PDT) 14050 kHz
Monday 0200z (Sunday 7 PM PDT)  7045 kHz
 
   Stay well,
      Kevin.  KD5ONS

ecn.visionseer.com

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[list1]

Hi all,
I decided to realign my ole trusty KAT2.

Adjusting the bridge null seemed to go OK.  However, when I adjust the power knob to give 15.8 Volts (5 Watts) at my precision dummy load (50.3 Ohms), turning R1 clockwise to the maximum position only shows 4.4 Watts on the CAL S readout.

Any suggestions?

Thanks,
Steve, W2MY

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[Don Wilhelm-4]

Steve,

Set the menu ATU parameter to CAL P when adjusting R1 for the power
reading.  CAL S is the setting used to align the SWR (use a dummy load
which will provide a known SWR such as a 25 ohm or 100 ohm load which
give a 2.0 SWR).

Also, be certain that your RF Probe is a type that provides RMS
readings.  Some (those with the diode connected in series with the meter
probe) will indicate peak voltage.  At 5 watts, 15.8 volts is the
correct voltage for an RMS reading probe across a 50 ohm load, but if
your probe indicates peak voltage, you must adjust for 22.36 volts minus
the diode voltage drop.  If you are looking at an oscilloscope, you will
see a peak to peak voltage and that should be 44.72 volts for 5 watts.

Consider how you checked your dummy load?  If you checked it with an
ohmmeter, that is the value at DC, but the value at any given frequency
may be different - check it with an antenna analyzer to be certain.

73,
Don W3FPR

list1 wrote:
> Hi all,
> I decided to realign my ole trusty KAT2.
>
> Adjusting the bridge null seemed to go OK.  However, when I adjust the power knob to give 15.8 Volts (5 Watts) at my precision dummy load (50.3 Ohms), turning R1 clockwise to the maximum position only shows 4.4 Watts on the CAL S readout.
>
> Any suggestions?
>
>  
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[David Woolley (E.L)]

Don Wilhelm wrote:

> Also, be certain that your RF Probe is a type that provides RMS
> readings.  Some (those with the diode connected in series with the meter
> probe) will indicate peak voltage.  At 5 watts, 15.8 volts is the

Surely any simple diode based design is peak reading, whether the diode
is series or parallel.  To get true RMS, you either have to assume a
sine wave, and use a voltage divider, or you need to integrate the
square of the instantaneous voltage, by using thermal effects, using
square law detectors, or by integrating digitally.


--
David Woolley
"The Elecraft list is a forum for the discussion of topics related to
Elecraft products and more general topics related ham radio"
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