Tenma 72-7390 User manual

72-7390
Smart R.F. Counter
lntroduqtion
The Tenma 72-7390 hand-held radio frequency counter is ccrmpact, truty pocfet-sized, versatile test instrument designed
for measuring any digital,. on/off keying or analog signal on frequencies between 30 MHz and 2.8 GHz. Supplied Ls a
ccmplete with internal rechargeable battery pack, AC wall chbrger and 7 section telescopic antenna"
$pecifications
lmpedance:
Frequency range:
Sensitivity:
Max. input:
Resolution:
Timebase:
Weight:
Size:
Case:
Battery:
Power:
50 Ohms (BNC Socke| VSWR less than 2:1
30 MHz - 2.8 GHz
less than 5 mV
15 dBm
10 KHz for digital Signals or On/Off Keying
1 KHz forAnalog Signals
Less than 1 PPM at room temperature
210 g
80 mm high x 68 mm wide x 31 mm deep
Stamped aluminum with black anodized finish
lnternal 4 x AA 600 mAH rechargeable battery pack
I VDC 300 mA
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f-eatures-
7 digit Liquid Crystal Disptay
Frequency counter fordigital, on/off keying and analcg signals with a minimum pulse width of 250 uS.
Ultra sensitive synchronous detector - 16 section bargraph to show RF signal sfrength (-35dBm to 0 dBm)
Two range positions - _t!" t. GHz position for frequencies between 30 MHt and 1 GHz and the 2.g GHz position for
frequencies between 500 MHz and 2.8 GHz.
Squelch adjustment for input signals
Hold switch to lock display
Low battery indicator
Vibrating alert
Low power consumption (Average 5 hour bat$ery life)
Supplied with rechargeable battery pack. AC wall charger and telescopic antenna (143 MHz to 460 MHz)
SQL Knob - This knob turns the RF counter on and tunes the squelch up or down to set the signal strength for
reception.
Range Switch - This should be switched to the 1 GHz position for frequencies between 30 MHz and 0.8 GHz and
switched to the 2.8 GHz position for frequencies between 500 MHz and 2.9 GHz.
Hold Bufton - This holds the current display and stops the counter from counting.
Calibration - The calibration adjustment opening is located on the front panel of the counter. This allows access to
the trimmer capacilorthat provides about a 10 PPM adjustment range of the time base oscillator. This is not usually
necessary but to do so read a signal of a known frequency before adjusting the trimmer for correct frequency
display. lf you calibrate at 4.1943 MHz or above then the counter will be more accurate.
Warrantv
Tenma Test Equipment guarantees the RF counter and its accessories for one year against defects in manufacture. This
warranty does not cover items that have been modified, subject to unauthorized repairs, misuse or abuse. This warranty
does not cover damage caused by excessive power levels applied to the signal input.
Never make any kind of connection between the RF counter and a transmitter.

Hints and Tips
i. Battery Operation
This RF counter can operate for up to six hours from its fully charged batteries. They are charged when the unit is
plugged into the supplied AC/DC adapter. Full recharge will oCcur over 12 to 16 hours. Before recharging the batteries
yoriinouto be deepcycled occasionaliy by allowing them to completely discharge to maintain maximum battery capacity
The batteries should iast for several years. However, it is a good idea to check them every twelve months for signs of
corrosion or leakage. Always replace the whole set if any one cell fails.
2. Signal lnPut
when using the RF counter with an antenna for signal pick up, random frequencies may appear on the display. This is
quiie normll and is caused by the high gain of the receiver circuits, which amplify noise in the abgence of a strong
readable signal. Never get the unit too close to a transmitter as internal damage will result'
3" Antenna Selection
The supplied telescopic antenna is best for general purpose use. This is because its length can be adjusted to suit the
frequency required. Usually you will want a shorter antenna for UHF and a fully extended one for VHF / HF.
4. Reception Distance from Transmitter
The distance from which you will be able to receive frequencies will depend upon the type and location of the transmitting
antenna, transmitter output power and the frequency in use'
SC-1 RF Signol Strength BorgroPh i --" lst segment
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