IC-756Pro II S-Meter & Spectrum Scope Calibration Curves

by Adam M. Farson VA7OJ/AB4OJ

Introduction:

Figure 1 is a curve showing S-meter reading vs. input signal power in dBm. Figure 2 is a curve showing the relationship between the Spectrum Scope vertical amplitude in dBr (0 dBr = top of scale)  and input signal power in dBm. Table 1 gives RF ATT setting vs. actual attenuation.

Test Setup: 

IC-756Pro II S/N 26XX. Freq.: 14500.000 kHz CW. BW = 500Hz (BPF lit), Preamp off, ATT off, NR off, NB off, AGC FAST, Twin PBT neutral (SFT = 0), RF Gain at 100%. HP8640B signal generator (checked against R&S URV4 RF millivoltmeter), set to CW, 14500.000 kHz, LOCK on, and connected to ANT 2. ANT 1 terminated in 50Ω. Note: -73 dBm = 50 µV in 50Ω.

Figure 1: S-meter reading (X) vs. RF input power (Y).
Figure 1: S-meter reading (X) vs. RF input power in dBm (Y).

 

Figure 2: Spectrum Scope relative vertical amplitude (X)  vs. RF input power (Y).
Figure 2: Spectrum Scope relative vertical amplitude (X)  vs. RF input power (Y)

 

Table 1: RF ATT  values.
ATT setting dB Atten. dB
0 0
6 7
12 13
18 19.5
Copyright  2005 A. Farson VA7OJ/AB4OJ (including images & data). All rights reserved.
Last updated: 09/30/2018

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