Kenwood TS-590S Manual Do Utilizador

TS-590S

19

In the first local oscillator, instead of the conventional PLL/VCO system, a 14-bit DDS (direct digital 
synthesizer) is adopted to provide the output signal directly to the mixer.  During the down 
conversion, the oscillator frequency is lower than that in up-conversion operation, and, therefore, the 
output has far better C/N (carrier-to-noise ratio) characteristics that contribute to superior reciprocal 
mixing

*1

 characteristics.

*1

Reciprocal mixing: First, the signal sourced from a signal generator (SG) at a frequency far from the receive frequency is 

injected.  Then, the output level of the signal generator is changed to measure the level at which the signal is detected as 

noise.  The higher the value, the lower the noise that is produced due to adjacent undesired signals occurring and therefore 

quieter reception is possible.

Figure 3-1 is a graph to compare the measurement results of TS-590S and of TS-480S at 14.200 MHz.
For example, at the 10 kHz point, if the receive frequency is 14.200 MHz, an unmodulated carrier 
signal of 14.210 MHz is supplied from a signal generator to the antenna terminal of the transceiver.
In the TS-480S, if the output level from the signal generator reaches -45 dBm, the noise level starts to 
rise.  However, in the TS-590S, you can see the noise level goes up if the signal sourced from the 
signal generator is raised to -25 dBm.
Figure 3-2 shows a graph of C/N characteristics plotting the data measured at the TS-590S’s first 
local oscillator.

C/N characteristics of the first local oscillator 
when receiving 14.2 MHz
1 kHz      -116.5 dBc/ Hz
10 kHz    -134.4 dBc/ Hz
100 kHz  -142.5 dBc/ Hz