Fast automatic antenan tuner with a wide tuning range.
Automatic antenna tuner MFJ-939 comes with control cable suitable for various radio manufacturers, depending on the model. This greatly simplifies the operation, because you only need to press the ' Tune ' on the radio.  the ' 939 ' is characterised by a wide tuning range from 6 to 1600 Ω. This is much more than most internal tuners can offer. The wide tuning range is supplied by a large number of capacitors and inductors, which translates into a very precise tuning with 256 combinations of C and L each.
Using more than 2500 tuner memories offers a tuning very fast, because once you find combinations of L and C are stored for each frequency, instead of calculating the combination every time. And the tuner offers various acoustic and optical protection signals and Diagnostics, eg against hi input ROS or power. In case of too much power over the main entrance of tuner sends ' LED ' in telegraphy, a QRT reports the error as well. But even in case of not enough power (2W is minimum) the tuner sends ' QRO ' in morse ...
Another feature is the sleep mode the tuner. In case no tuning needs to be done and while RX, the tuner will go into Sleep mode and turns off the microprocessor. This has the advantage of reducing the energy consumption and to avoid noises on HF. Also the MFJ-939 is ready for the future-in the event of a system change you can just use a different control cable and continue using the same tuner. MFJ offers different cables for different radio.
The maximum transmission power is 20 W = SSB or CW. Industrial grade switching relays are rated to 1000V/10A. Minimum power for tuning is 2W. Included in shipment is a control line, which is suitable for various most radios or the manufacturer selected. In some cases the control cable is also used to power the radio, in other cases require an external power supply (13.8 V, 750mA).
|Model||Control cable Inc.|
On an expedition
|to the transceiver|
|MFJ-939I||MFJ-5114I||All Icom tuner socket 4pin|
IC-703, IC-706, IC-718, IC-736, IC-746, IC-7400, IC-7410, IC-7600,
IC-756, IC-756Pro I/II/III, IC-765, IC-775, IC-7000, IC-7100 ua
|MFJ-939K||MFJ-5114K||All Kenwood with 6 pin socket tuner|
TS-50, TS-450, TS-480, TS-570, TS-590, TS-850, TS-950, TS-2000 ua
|MFJ-939Y||MFJ-5114Y||FT-100, FT-857, FT-897 FT-450, FT-950|
 Other transceivers can be used with other type interface cables "MFJ-5114x". On some radios the melody mechanism is initiated by a button on the tuner, not on the radio.
|Tuning range C||0-24||μh|
|Tuning range L||0-3900||PF|
|TX power min.||2||In|
|Power Max.||200||W (SSB, CW)|