MLA-T PRO v.7 + CB4M UNI
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MLA-T PRO v.7 + CB4M UNI
The new MLA-T PRO v.7 replaces a well-known model of magnetic loop antennas – MLA-T PRO v.4, v.5, v.6, with approximately 100 units sold during the last years. The CB4M UNI control unit is the latest version of the control box for magnetic loop antennas.
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Description
The new MLA-T PRO v.7 replaces a well-known model of magnetic loop antennas – MLA-T PRO v.4, v.5, v.6, with approximately 100 units sold during the last years. The MLA-T PRO is a commercial magnetic loop antenna that was used and enjoyed by many HAMs. During the production period, the MLA-T PRO antenna was upgraded several times. The common advantage of all MLA-Ts is that with a relatively small diameter of the four loops, at only 0.8 m, the antenna also works on the 160 m band. Although the efficiency at a low antenna diameter to lambda ratio is not ideal on the 160 m band, the robust construction, the use of copper tubes and high voltage capacitors allows you to use the full power of 100 W, which most HF TRXs have. Because of this, the lower efficiency of the MLA-T PRO at 160 m is partially compensated. The external design of the MLA-T PRO v.7 remains identical to the MLA-T PRO v.4 model, the internals of the antenna are upgraded.
The main advantage of the new MLA-T PRO v.7 is the addition of a new usable band – 30 m band, and new tuning motor, that allows the use of rechargeable battery pack to power the CB4M control unit. Thanks to the use of rechargeable battery back we eliminated interference of "unknown origin" caused by most wall plugs. The previously used linear power supplies with a transformer were gradually pushed out of the market by smaller and cheaper adapters (switching power supplies), which bring new unpleasant phenomenon to the HF – QRM. Reduction of QRM when using AKU pack can be heard immediately.
IMPORTANT WARNING
MLA-T is for indoor usable with maximum power of 10W. For healthy: higher powers than 10W don't use it as indoor antenna nearer than 5 m. Operators with a pacemaker; best not to use it.
Caution: High frequency magnetic field passes through walls with low loss!
CB4M UNI for MLA-T PRO
The CB4M UNI control unit was developed not only to increase the tuning comfort of magnetic loop antennas, but mainly to eliminate the complicated power supply of the original CB4M and CB4M DUO units, which required a separate (galvanically isolated) external 12V power supply. The rechargeable battery pack is integrated directly into the control unit, which was originally developed to control the two motors of the MLA-S (RT/R) antenna. Experience has shown that the CB4M UNI is useful not only for antenna tuning and rotation of the MLA-S (RT/R), but also for single-motor systems such as the MLA-S (RT) as well as for the MLA-T PRO v.7 By switching the CB4M UNI to the "ROTATOR" function, where the blue light on the top panel is permanently illuminated, it speeds up the fast re-tuning, which was originally handled by the CB4M in a much more complex, time-spaced PWM. Fast re-tuning of both MLA-S (RT) and MLA-T PRO v.7 single motor antennas can be achieved very easily with the CB4M UNI. If the black button on the panel is switched to the "TUNING" function, (the green light is on), it is switched to spread tuning.
But the CB4M DUO controller has one other significant advantage, automatic switching to standby mode when the residual current drops to just hundreds of microamps. The standby mode automatically switches on after approximately ten minutes of inactivity of the CB4M UNI control unit, thus saving internal battery power. This is indicated by no light being on. The CB4M UNI switches to standard operating mode by quickly turning the knob on the top of the box. The reason for using the CB4M UNI battery power supply is that conventional 230 V/12 V 50 Hz linear power supplies have been phased out by smaller and lighter pulsed power supplies, but these tend to cause very high pulsed QRM/noise. The difference between the original and the upgraded solution is unmistakable.
Instructions for use CB4M UNI
The CB4M UNI is the latest version of the control box for magnetic loop antennas. In its essence, it is a major innovation of the CB4M DUO, which allows control over one coaxial cable of two motors. The major improvement of the CB4M UNI over the CB4M DUO is that:
1. it eliminates the need for an external 12V power supply to power the control box, as the CB4M UNI has an integrated internal Lion rechargeable battery. Due to the former necessity of using only linear mains power supplies and the exclusion of using switching power supplies/power supplies to power all previous versions of control boxes (with with regard to causing strong pulsed QRM), the new internal ACU power supply is a significant advantage.
2. The original method of controlling the motor(s) by pushbuttons using PWM is replaced by the CB4M UNI by an analogue solution based on the idea of the Japanese radio amateur 7N3WVM, which has been modified and modified to improve user comfort. The author of the final solution is BTV (Czech Republic).
FUNCTIONS
Charging of Lion battery is solved by USB C connector on the side of the box. To indicate the status of the battery (discharge/charge) is indicated by the LED next to the USB connector. Colour fillet/red, see Figs. 1 and 2. charging, red - charged.
To indicate functions, the middle LED is used, which when green indicates switching to debug mode, light nodré colour indicates switching to antenna rotation mode. If this middle LED is red, it means that it is the battery needs to be recharged first, see previous paragraph.
The CB4M UNI has an intelligent solution for putting the electronics to sleep in a microampere mode, which below the self-discharge level of the battery. Starting the CB into operating mode occurs after a quick turn knob to either side. The central LED will then illuminate, with the option of blue, green or red, see previous paragraph. The black button on the front panel. If the CB4M UNI is idle for approximately 3 minutes, it will automatically fall asleep and must be reset to restart it, see above.
Rotation of the MLA capacitor left/right (the capacitor does not have an extreme position) and likewise for rotating the antenna clockwise/counterclockwise, use the rotary knob on the top of the cabinet. Due to the low friction bearings and the weight of the knob, a single mechanical multiple 360-degree rotations can be achieved with a single impulse. In this way, the MLA can be repositioned relatively quickly over the entire the capacity range of the tuning capacitor. In the antenna rotation mode, the knob must be turned fast enough, because the micro-motion of the rotary knob (with the blue LED lit) can cause a small amount of detuning tuned frequency. In the rotator function, therefore, very slow knob movements should be avoided when the electronics may misunderstand/misjudge the targeted function of the control box mode. This is only a short practice to avoid this "double" mode.
Technical parameters
- Number of loop turns: 4
- Loop diameter: 0,8 m
- Antenna dimensions: 83 x 30 x 100 cm
- Antenna weight: 7,3 kg
- Shipping dimensions: 85 x 28 x 105 cm
- Shipping weight: 12 kg
- Maximum usable power: 100 W
- Bands: 160m, 80m, 60m, 40m, 30m