MFJ-224 Instruction Manual
2-Meter FM Analyzer
14
Schematic
Page 1: ...s to read this manual A special orientation section is provided to help you get started Technical Specifications Frequency Coverage 143 5 148 5 MHz Selectivity 6 dB 20 kHz Receiver Type Dual Conversio...
Page 2: ...mance a few feet either way can make a big difference over difficult paths Aim yagis with absolute pin point accuracy Measure Preamp Gain Tune preamps for best gain and noise figure using your meter a...
Page 3: ...eter for the first time you must install a fresh 9 volt battery The MFJ 224 draws about 20 mA when in use and can operate for many hours between battery changes However we suggest you check battery st...
Page 4: ...a pick up probe or resistive attenuator For the purpose of this orientation connect a 2 Meter station antenna to monitor off air signals IMPORTANT NOTE Your MFJ 224 is a sensitive instrument To avoid...
Page 5: ...s FM carrier swing during modulation of signal RSSI dBm RSSI dBm Dev kHz Battery Displays battery voltage indicates if battery is okay Discriminator Tuning aid meter centers when signal is tuned in co...
Page 6: ...MFJ 224 Instruction Manual 2 Meter FM Analyzer 6 for the meter to read below 100 dBm with no signal present Check the repeater signals in your area and note the level differences between them in dB...
Page 7: ...librated in dBm a unit of RF power As previously mentioned calibrating the scale in dBm is convenient because it allows comparison of signal differences directly in dB Signal strength is also commonly...
Page 8: ...the base of your mast or a rotator with a control box so you can document degrees of rotation off axis from the signal source The primary specifications for directional antennas are Forward Gain dBd...
Page 9: ...t to Back Ratio 5 Coaxial Line Loss The Signal RSSI function when used in conjunction with a signal generator can provides accurate end to end loss measurements for 50 coaxial line With this test you...
Page 10: ...lly and follow the manufacturer s instructions closely The MFJ 224 is a sensitive instrument and you must take care not to overload it during transmitter deviation tests To limit ambient RF levels in...
Page 11: ...ignal being fed to your scope Scope readings taken with the meter switch in the Discriminator or Deviation position may be somewhat reduced in amplitude and will not conform to the calibration chart s...
Page 12: ...transmitter signals If you must copy extremely weak off air signals for diagnostic purposes you may install an external in line 2 Meter preamplifier to boost sensitivity Be sure to incorporate preamp...
Page 13: ...l Tuning Tune to a spot on the dial where no signal is present Connect a DVM to TP 1 test point Tune quad coil L3 for a reading of 2 45 volts dc 4 Discriminator Meter Zero Switch the meter selector to...
Page 14: ...MFJ 224 Instruction Manual 2 Meter FM Analyzer 14 Schematic...
