NOTES for the SDU5000
(Rev 1.3)
First ensure that the receiver is switched On and connected to the SDU5000. The SDU ROM will
permit operation with the AOR AR3000A, ICOM IC-R7000, IC-R7100, IC-R9000 and as a band scope
with other receivers with a 10.7 MHz I.F. output such as the AOR AR3000 (a small modification is
required to the AOR receivers in order to provide compatibility).
If using an ICOM receiver, the CT17 optional interface will be required. The ICOM receiver must be
configured for remote control, refer to the ICOM operating manual. The following setup is required:
Baud rate
Frequency data
Address default
9600 bps
5 Byte
Example setup for the ICOM IC-R7100 receiver
Step 1.
For transceive ON
On the ICOM receiver, press and hold both "3" and "ENT" keys and switch the power switch ON.
Then switch the receiver OFF.
Step 2.
For baud rate of 9600
On the ICOM receiver, press and hold both the "5" and "ENT" keys and switch the power switch ON.
Then switch the receiver OFF.
The receiver must be configured and switched On before the SDU5000 in order to guarantee a valid
connection via the RS232.
Note: The output level of the ICOM receiver(s) is about 10 - 15dB below that of the AOR receiver(s).
Should the connection be lost, use “CONF” to confirm that the correct receiver had been selected.
If a connection cannot be established, switch Off the SDU5000, unplug the 12V DC feed and leave
the unit for 10 seconds. Reconnect and try again.
It is possible to get false indications below 0 MHz !! (minus figures will appear in front of the
frequency readout).
A small false signal may appear on some bands to the right (or left) of the centre in a constant
position (455kHz), this is normal and due to an internal 455 kHz I.F. of the receiver.
When tuning in channelised bands ensure the correct STEP size is selected (i.e. 9kHz for medium
Depending upon the step size, resolution and span a frequency (say 198 kHz) way appear up to 5
or 6 kHz off frequency. Reset the centre frequency and the error will be reduced. This effect is
MOST noticeable when using the "marker" and is explained here.
Each division of the graticule has 16 steps so dividing the entire screen into 160 steps. To work out
the frequency shift for each movement of the marker take the chosen bandwidth (SPAN), divide
this kHz bandwidth by 10 then by 16... the answer will be in kHz.
i.e. for a bandwidth of 10 MHz, each shift will be 10000 / 10 / 16 = 62.5 kHz
Of course you can work the formulae backwards too! If you require a 5kHz step:
5 x 16 x 10 = 800 kHz - you may note a quick way: simply divide or multiply by 160
(the total number of increments)
The following relative table may be of assistance:
Each marker movement
1 kHz
5 kHz
6.26 kHz
9 kHz
10 kHz
12.5 kHz
20 kHz
25 kHz
50 kHz
62.5 kHz (maximum span)
Bandwidth (span)
160 kHz
800 kHz
1000 kHz
1440 kHz
1600 kHz
2000 kHz
3200 kHz
4000 kHz
8000 kHz
10000 kHz
Due to the AGC effect of the host receiver, the peak trace may reduce as it is tuned toward the centre
of the display. As a result measurements may be more accurate when measured away from the
centre frequency. The level of change may be in the order of 10 - 15 dB but will depend on AGC
(the larger the signal then the greater the change).
To help with this, the modified AR3000A/3000 is fitted with an SDU AGC/mute switch. For best
accuracy, switch the AGC "off" when taking measurements on the centre frequency.
Set the R8500 up as an ICR7100 by accessing the ICOM initial set mode as per page 30 of the ICOM operating manual. Set the baud rate to 9600 and address to 34h. The supplied RS232 is ready to go without
Remember, although not a low cost product the SDU5000 is a
fraction of the price of a dedicated spectrum analyser.
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