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HF
Transceiver and Receiver VFO Calibration
The following methods enable accurate
field check of receiver and transceiver
calibration on receive,
within 1 Hz by ear, without the need for special RF
equipment.
| METHOD #1
may
be used only with HF SSB transceivers or receivers
that have variable
selectivity filters, passband tuning, IF tuning
offset, or Twin
Passband Tuning. Many modern ham radio
transceivers have these features. |
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METHOD #2 may
be used with any HF SSB transceiver or receiver,
but it requires a
second shortwave receiver capable of AM reception.
This method is the
most accurate. |
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METHOD #1
Note: only for HF SSB transceivers or receivers that
have variable
selectivity filters, passband tuning, IF Tuning offset, or
Twin
Passband Tuning.
- Stop or pause all software controlling the radio.
- Select manual VFO.
- Select USB Upper Sideband.
- Select widest bandpass filter.
- Turn off Clarifier or RIT.
- Turn off Notch.
- Turn off DSP Noise Reduction.
- Set Passband Tuning to -1.5kHz (toward the left as
possible), this should enable you to hear both USB and
LSB simultaneously.
- Tune to the highest Standard Frequency Time Signal,
such as WWV on 10MHz, 15MHz, or 20MHz.
- Select 1Hz tuning speed of VFO.
- Wait for a minute when the standard audio tone is
broadcast.
- While listening to the tone, tune VFO slightly
above/below.
- Listen as you tune the VFO knob, for zero beat
frequency. Zero beat is a point with the clearest pure
musical sound,
without rumble or slow vibration.
- Read the dial VFO frequency.
- The difference between the standard frequency and your
dial VFO frequency is the calibration error.
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METHOD #2
Notes:
This method of calibrating Radio
A requires a second shortwave receiver (Receiver
B).
Receiver B is the
reference audio receiver.
Receiver B does
not need to be an accurately calibrated receiver.
Receiver B must be
set up before Radio A
calibration is started.
Radio
A calibration:
- Stop or pause all software controlling Radio A
while it is being calibrated.
- Select manual VFO.
- Select USB Upper Sideband.
- Turn off Clarifier or RIT.
- Turn off Notch.
- Turn off DSP Noise Reduction.
- Tune to the same Standard Frequency Time
Signal as you are listening to "WWV" with Receiver B .
- Select 1Hz tuning speed of VFO.
- Wait for a minute when the standard audio tone
is broadcast.
- While listening to the tone, tune Radio
A VFO slightly above/below.
- Listen to both Receiver
B and Radio
A at approximately the same
volume level, as you tune the Radio
A
VFO knob, for zero beat frequency. Zero beat is
a point when the sound
and tone pitch of both radios match. It is the
clearest pure musical
sound, without rumble or slow vibration.
- Read the dial VFO frequency of Radio
A .
- The difference between the Standard Frequency
Broadcast and Radio
A dial VFO frequency is the
calibration error.
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Receiver
B set up:
Set up a common shortwave receiver Receiver
B tuned to AM mode,
on the Standard Time Frequency broadcast you will
use to calibrate,
such as WWV 10, 15, or 20MHz. Turn up the volume to
a normal listening level. The accurate calibration
of Receiver B
in not necessary. |
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