Discrete frequency setting with a step of 1 kHz in the radio R complicates its use in Amateur radio purposes. To obtain the possibility of continuously tuning the frequency up to ±4 kHz about the frequency settings on the digital scale radio is quite simple. It is enough to replace the signal frequency of 10 MHz supplied from the frequency synthesizer radio station (unit 2-1) through the multiplier unit 3-3 on the mixer unit 3-1, the tunable signal to ±500 Hz crystal oscillator at 10 MHz in the circuit shown in Fig.1.
Fig.1
Since the mixer unit 3-1 is used eighth harmonic oscillator, the operating frequency of the radio station will change within ±4 kHz, which is enough. The resistor R7 in the circuit selected in the range of 0.5-2 ohms, depending on the activity applied to quartz, to obtain the nominal signal level at the output of the radio is pressed and key-mode at-T. Coil L is made on the annular magnetic core of the brand WC size CHH wire PELSHO 0.1 mm and has 15 turns. Using well a calibrated receiver, it is desirable to select the number of turns of the coil with an accuracy of up to one to obtain the oscillator frequency is 10 MHz±50 Hz in the middle position of the regulator R4, wherein the working frequency to match the frequency on the digital scale. Quartz resonator is preferably used in the vacuum performance. Power generator voltage +12.6 V from capacitor C2...C6 filter decoupling in the power supply circuit unit 2, which can be accessed when removing the upper block N9 radio station.
The printed circuit Board of the device shown in Fig.2, the location of parts on it - in Fig.3.
Charge conveniently placed in a shielded unit-cassette sizes HH mm, mounted on the transceiver to the left of the operator. On the face of the block, in addition handles the tuning frequency of the radio station from the resistor R4, it is convenient to place the Jack for phones, toggle enable tone generator and a toggle switch that duplicates the work of the PTT button radio mode "transfer".
Author: B. Pavlov (EW1BB), Minsk; Publication: N. Bolshakov, rf.atnn.ru