The development progress of the new NTS series SSB/CW handheld tranceiver(A start in June, 1999 - completion in January, 2000)
1.The outline of the development
Frequency : each single band portable machine of 144MHz and the 430MHz band
Transmitting output : 1W
An appearance is based on NTS 200,700.
Modulation forms are SSB and CW (with the side tone and the semi breake-in function).
Settlement of frequency : a miniature thumb wheel switch and 5kHzUP-switch and FINE-TUNE (type PLL built-in)
A frequency cover range is extended to 1MHz, and a level of stability is improved.
2. Development time
3. NTS210 development progress
3.1 PLL circuit
The photograph of the bottom is a trial production circuit board for the PLL experiment.It is used for the 120MHz band (local ocillator for 144MHz) and the 200MHz band (2 multiple is done, lacal ocillator for 430MHz).
PLL experiment circuit board
3.2 Frequency control
A PLL-IC is controlled with a PIC microcomputer in accordance with the indication of the thumb wheel switch.
A PLL circuit was combined with the microcomputer software, and an experiment was made.
It worked properly in the frequency of the purpose.
3.3 modulation sound monitor experiment (144MHz)
A shielding board was put on the PLL circuit, and connected to NTS-200, and the reception of the transmitting voice was done.
When transmitting output power was 1W, it found that a voice warped greatly by the change in the power supply voltage.
The ripple filter was made from a transister on the power supply line of PLL and added.
A level of stability improved with this.
3.4 PLL circuit output spectrum (for 144MHz)
As for the figure of the bottom, the signal outputted from PLL was measured with spectrum analyzer.
The spurious in the neighborhood can get good property in the -70dB following for handheld.
(SPAN=200MHz,CENTER FREQ.=100MHz)
3.5 Circuit (September, 99)
A foundation experiment was finished, and the circuit figure of the transceiver occurred.
A circuit adds a part PLL to the old model.It is put on the chip part, and many parts take their place.
A main circuit follows the high frequency SSB generator of the voice reversal IC use by the development which is characteristic of our company.
As for 430MHz as well, single conversion is being made possible by this.
It enters the pattern design of the print circuit board from now.
3.6 Print circuit board design (October, 99)
3.9 Battery holder
The board of the nickel plating is used from the viewpoint of the life and the cost.
NTS710 Aphotograph inside the trial production machine
4. The summary of the development of the NTS series SSB/CW handheld
The summary of the development of the NTS series SSB/CW handheld
The development of the new model started in last June.
Though it took about eight months, it is supported by everyone's encouragement, and it is reported that the development of the new NTS series was completed.
The most important theme is to build in PLL by this development.
Then, the range that it is covered is extended, and it is to improve a level of frequency stability.
It could get the data which could stand up to utility by the independent circuit movement in the foundation experiment.
It proceeded with the development in earnest from about August.
A goal for the development was attained.
(January 23, 2000)
