84 ELECRAFT
Calibration Functions
The C A L menu provides the following functions:
F C T R frequency counter
C U R programmable transmit current limit
T P A PA temperature set (see KPA100 manual)
S L O S-meter zero set
S H I S-meter full-scale sensitivity set
P L L VFO linearization
F I L filter settings (see next page)
After selecting a C A L function, hold
E D I T to activate it.
Frequency Counter (CAL FCTR)
C A L F C T R displays the frequency of the signal at P6 on the
Control board during alignment (see page 57).
Transmit Current Limit (CAL CUR)
C A L C U R allows you to set a safe maximum transmit current.
The recommended setting is 3.50 A. A lower setting may be
appropriate if you're using 5 watts or less, or if your power supply
has a lower current rating.
S-meter Calibration (CAL S LO, CAL S HI)
To set the S-meter zero level:
1. disconnect the antenna
2. make sure the RF GAIN control is fully clockwise (max gain)
3. select C A L S L O in the menu
4. turn the VFO knob until the left-most bargraph segment is just
barely turned off
5. exit C A L mode by tapping
M E N U
To set the S-meter sensitivity:
1. disconnect the antenna
2. turn the RF GAIN control fully counter-clockwise (minimum
gain)
3. select C A L S H I in the menu
4. turn the VFO knob until the right-most bargraph segment is just
barely turned off
5. exit C A L mode by tapping
M E N U
Note: The S-meter must be recalibrated anytime the AGC threshold
is changed. The AGC threshold adjustment is described on page 46.
VFO Linearization (CAL PLL)
The C A L P L L function automatically calibrates VFO fine-tuning
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.
You can repeat C A L P L L at any time, although this should not
normally be necessary. One reason you might re-run C A L P L L is
after calibrating the frequency counter (see Advanced Operating
Features, page 98). In general, you'll need to re-run C A L P L L and
C A L F I L anytime you change the setting of C22 (Control board),
which is used to align the 4 MHz crystal oscillator.
To Linearize the VFO:
1. Remove the top cover. The bottom cover must be installed
2. Allow a 10-minute warm-up period at room temperature.
3. Connect the internal frequency counter cable to TP1 (VCO).
4. Exit the menu if you were using it.
5. Switch to 40 meters and set the VFO anywhere in the 7000-7100
kHz range.
6. Use the menu to activate C A L P L L .
7. When calibration is completed (4-8 minutes), you'll hear a short
alert tone and see E n d on the LCD. You can then tap any
switch to return to normal operation.
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What you're actually calibrating is the relationship between the PLL (phase-
locked loop) divider and the crystal reference oscillator. (See Circuit Details.)
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