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VHF Data Radio APRS (145.01 Mhz)

The MFJ-8621 was especially designed for packet-only operation. MFJ has eliminated costly circuitry that you don't need: such as squelch, repeater offsets, PL tones, DTMF pad, PLL synthesis, memory, and the speaker-amplifier. At the same time, we engineered in essential packet circuits like true-FM direct modulation, unsquelched AFSK, PIN-diode switching, data-passband IF filtering, and a tailored 0-Vu DC-coupled line driver to ensure top-notch performance. There are no user-adjustable controls to set incorrectly, and the MFJ-8621 works with most popular TNCs.

  • Packet-Only Performance: The MFJ-8621 is designed from the ground up for packet. This means you'll get uncompromising performance at all data rates--on AFSK or FSK-- for a fraction of what you'd pay for a converted voice radio. Cool Running: The MFJ-8621 draws only 25 mA on receive, and less than 1 A on transmit. Run it 24 hours a day 365 days a year, or pack it with yourlap-top and take it on the road.
  • Sensitive: Motorola-IC based receiver circuitry recovers data from weak signals for better throughput and fewer collisions.
  • Made-For-Data Filters: Optimize the receiver for wide 9600-baud signals or narrow 1200-baud signals. No other radio does this!
  • Rugged 5-Watt Transmitter: All the power you need to get the job done without creating needless interference at distant nodes.
  • Clean Unsquelched Data Output: The MFJ-8621 uses a wide-response DC-coupled line driver rather than a speaker amp for flawless signal recovery. Note: Your TNC must have full DCD (Data Carrier Detect) in order to work with radios that have full unsquelched AFSK output.
  • Lightning-Fast TXD: Set TXD low! PIN-diode switching, continuous-running receiver, and crystal control deliver ultra-fast switching.
  • Twin Modulators: Varactor-modulation for true-FM at 9600-baud and reactance modulation for mic-level signals at 1200 baud provide ultra-clean FSK and AFSK. Simple Setup: The MFJ-8621 is compatible with virtually all up-to-date TNC-2 modems.
  • Easy To Rechannel: Run the MFJ-8621 with supplied crystals on 145.01 MHz, or order custom crystals for the channel of your choice. Simple step-by-step instructions illustrate how to exchange crystals and set on frequency without expensive test equipment.
  • The Right Tool For The Job: The MFJ-8621 was designed from scratch for fast, clean packet communication and nothing else! Whether you are monitoring the local DX cluster or breaking new ground at 9600, you can look forward to years of hands-off service.


    Frequency: Coverage 144-148 MHz
    Sensitivity: 0.6 µV for 12 dB Quieting
    Image Rejection: -45 dB or better
    1st IF: 10.7 MHz
    2nd IF: 455 KHz
    1st LO: Crystal , 3rd overtone
    2nd LO: 10.245 MHz
    Selectivity: -6 dB at 20 KHz (data-passband filter)
    AFSK Output: Unsquelched, 0dBm @ 3.0-KHz deviation
    Current Drain: 25 mA


    Frequency Control: Crystal, 18-MHz x 8
    FSK/AFSK Input level: 150 mV p-p @ 1200 baud, .8 V p-p @ 9600
    Deviation: 0-5 KHz, adjustable at TNC
    RF Power Output: 4.0 - 5.0 Watts into 50 Ohms
    VSWR Tolerance: 3:1 Max.
    Current Drain: 1.0 Amp @ 13.8 Volts
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