ILER-DDS V2.1 VFO/DDS.
Page 22
The voltage output for "S-Meter" of our receiver will surely keep little proportionality with the previous
table (for example S9 could be 3V, but surely S8 will not be 1.5V or S7 will be 0.75V).
- If you have a professional RF generator, you can inject the signals from the previous table into the
receiver and perform the calibration of the S-Meter of the ILER-DDS.
- If you do not have an RF generator, then you can make comparisons with another receiver.
The strategy is very easy, let's give an example:
Plug the antenna into the "master" receiver and when the signal is for example from S-7, change the
antenna to your receiver, enter the configuration mode and move the encoder until the S-7 screen
appears. In the lower line appears the voltage that is arriving at the ILER-DDS input (this reading is
informative, it can’t exceed 4.9V and obviously you can’t change it from the ILER-DDS). Then press the
encoder and "S-7 SAVED" will appear on the screen (the ILER-DDS has saved that level as signal S-7).
This way you must continue successively until you save all the levels from S-0 to S-9. Once finished,
move the encoder until "EXIT" appears and press.
Important notes
:
- The voltage range at the input of the ILER-DDS must not exceed 4.9V
- In low HF bands, levels S-0, S-1, S2 or even more, are usually a "noise" signal, you can save them with
the background level of the antenna when there is no signal.
- Keep in mind that in urban or industrial environments, the background noise may represent a level of S-
4 or higher.
- It is not necessary to save all the levels in a single session. The levels can be saved and reviewed
independently at any time.
- When you make any adjustment in the "DIRECT S-METER" mode or in the "REVERSED S-METER"
mode, then the ILER-DDS will automatically work in that mode.
Annexes
CONNECT THE S-METER INPUT TO AN ILER TRANSCEIVER
The S-Meter output of the ILER transceivers (
www.ea3gcy.com
) is inversely proportional to the strength
of the reception signal.
The available ACG voltage is used on the right pin of the "S" terminals
(the
pin on the left is not used here).
This pin delivers a voltage of about 12V when there is no reception signal and decreases as the
reception signal increases.
Therefore, you must use the "REVERSED S-METER" mode
You must add a resistive / 3 divider with a 47K resistor and a 22K resistor plus a 1uF capacitor to filter
out fast variations in the audio signal. In this way we can send to the ILER-DDS a voltage margin of less
than 4.9V. The voltage input of the ILER-DDS for the S-METER is pin 10 (RA5 / AN4).
See the following images:
S -
7
S A V E D
S -
7
2
4
3
0
m V
