48
14 TROUBLESHOOTING
OPERATION NOTICES
The transceiver has been designed and engineered
to avoid possible hardware glitches. However, you
may notice the following symptoms when you operate
the transceiver. These symptoms are not
malfunctions.
OPERATING VOLTAGE
As stated in “SPECIFICATIONS” {page 53}, this
transceiver operates on a DC voltage from 5.5 V ~
7.5 V DC (battery terminal) or 12.0 V ~ 16.0 V DC
(
DC IN
jack). If you find that the transceiver cannot
be switched ON, or “VOLTAGE ERROR” appears, the
supplied power source may be outside of the
specified range.
In such a case, remove the DC power cable from the
transceiver immediately and confirm that the supplied
voltage is within the specified range.
If you are using a variable DC power supply to
operate the transceiver, adjust the DC power supply
voltage to 12.0 V DC. Considering the output power
efficiency and thermal characteristics of the
transceiver, this is the optimal voltage to operate the
transceiver.
TUNING IN SSB/ CW MODE
The transceiver uses a general purpose IF filter to
receive signals in LSB, USB, CW and AM modes.
So, when you receive signals in LSB or USB mode,
the opposite side band signal is not fully attenuated.
At the same time, since the same filter is used for CW
reception, you may have difficulties seperating the
CW signal from other signals in the crowded band.
To best tune in to a SSB signal, follow the instruction
below.
When you receive signals in USB mode:
1
Turn the Fine Tuning function ON {page 33}.
2
Tune to the target signal while starting at a lower
frequency, using the
Tuning
control.
When you receive signals in LSB mode:
1
Turn the Fine Tuning function ON {page 33}.
2
Tune to the target signal while starting at a higher
frequency, using the
Tuning
control.
RECEIVING IN AM BAND
If you receive a weak signal in AM band, you may
notice a high pitched squealing noise in the
background. This noise is generated by the internal
DC/DC converter and it cannot be removed.
RECEIVING SIGNALS IN CITIES
When you receive signals in cities, the receiver’s entire
S-meter may light up without receiving any strong
signals. This happens when the RF amplifier in the
receiver is overloaded by strong interference signals
that are nearby. In this case, turn the Attenuator
function ON {page 34} to reduce the interference
signal level. You may further have to adjust the
volume level while receiving the target signal.
BEAT AND NOISE
When you have the same 2 m and 70 cm band
frequencies for both A and B-band receivers, the
Visual Scan may indicate the signals on the bar-
graph display even if no signal is monitored on the
A-band receiver. This error occurs due to the
internal spurious harmonics that are generated by
the B-band-receiver. Refer to “INTERNAL BEATS”
{below} for the frequencies.
You may also hear some noise in the receiving signal
in the following cases.
•
You perform any scan on the other receiver.
•
You perform the Visual Scan on the B-band
receiver.
TRANSMISSION
If you continuously transmit for more than 3 minutes
at high power (5 W), the transceiver becomes warm.
If you continue or repeat the transmission before the
transceiver cools down, the thermal protector
automatically decreases the output power to 0.5 W.
“H” also blinks at the same time. If this happens, let
the transceiver cool down for a while before
transmitting again.
If you continuously transmit for an extended period at
high power (5 W) using the
DC IN
jack, the
transceiver becomes warm. If you continue or repeat
the transmission before the transceiver cools down,
the thermal protector automatically decreases the
output power to 0.5 W. “H” will blink at this time. For
the 70 cm band, the thermal protector activates in
about 2 ~ 5 minutes at high power, depending on the
ambient temperature. In these cases, let the
transceiver cool down for a while or use the “L” (low
power) position before transmitting again.
SUPPLIED ANTENNA
The supplied antenna is designed to give you the
best transmission and reception performance on the
2 m and 70 cm amateur radio bands. So, it may not
be suitable for the frequency that you want to receive.
Use an appropriate antenna for the frequency if the
sensitivity is low.
INTERNAL BEATS
If one of the formulas on the next page is true, the
S-meter moves without receiving any signals or you
cannot receive any signals. This is inevitable when
you use superheterodyne receivers.
Summary of Contents for TH-F7A
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