SDU5500 bulletin page

SDU5500 / AR5000 DIRECT COMMANDS

If you are using an AR5000 as a companion radio, it is possible to send command strings to the AR5000 via the SDU5500 by prefixing them with an asterisk (*). Transfer to the AR5000 takes place only after the SDU5500 has completed its latest command sequence, at which point it will wait for a response from the radio and report it back over the RS232 link. The SDU5500 firmware version number must be 1.010 or higher to support direct commands.

Example:

*MD<CR><LF>

will produce the response in the form

*AU0 MD3<CR><LF>

A few units toward the beginning of production have suffered from loss of contrast when the SDU5500 is first switched on. A technical bulletin has been generated on the subject and is available as a small Acrobat PDF file (22kb) - click here.

The problem is basically a capacitor, which will need to be replaced with one of high quality (details are given in the bulletin). One customer in the Canada has offered the following part numbers for local supply:

Quote:
It comes from DigiKey the biggest mail/phone/internet order in US and
Canada which deliver overnight.

You know in North America if you can give us a part number from Radio Shack
of Digi Key the problem is 90% solved as anybody will be able to find the
exactly same part in a couple of hours.

He used:

BC (Beyschlag Centralab Components) from Denmark
Serie AHT 118 Axial High Temperature Electrolytic Capacitor
47 uF 40 Volts (safer for 24 volts than a 25 volts one)
Part # 222 118 37479
DIGI KEY Parts # 4137PHCT-ND
Marked 47µF 40V 125ºC 63V 85ºC

One customer had problems in configuring the IC-R8500/SDU5500 so that the 'connected' message could be displayed on the SDU5500, there were two problems:

1) A 9-25 way connector was in use on the RS232 and not all the pins were connected (common with serial mice). A replacement lead was provided to correct this, please confirm that the following connection are used:

2) The 'default' settings in the IC-R8500 menu had been unwittingly altered, please confirm the following items in the SELECT INITIAL SET MODE menu (refer to page 30 of the IC-R8500 operating menu for the procedures to access, change and save the settings):

With the SDU5500 operating at its widest sweep range (10MHz) when coupled to an AR5000, an unwanted spurious signal can be observed approximately 4.8MHz away from the centre frequency (moves slightly with AR5000 frequency).

This is present at all frequencies although it will jump to the other side of the screen when the AR5000 is tuned above 1.4GHz.

The spurii appears to be leakage of the 2nd local oscillator DDS signal at 5.8MHz to 6.7MHz (hence when viewed from the IF frequency of 10.7MHz becomes 4.9 to 4.0MHz away).

This is not a problem during normal receive with the AR5000 as the 10.7MHz filter removes any signal but is present at the IF output taken before the filter. It is also not a problem if the sweep width on the SDU5500 is reduced slightly.

It is however a problem to the customer who wants to use the full scan width with the AR5000 at VHF and UHF frequencies with the 'peak' facility selected AND FULL BANDWIDTH. The 'peak' just goes to the unwanted
signal as this is usually at a larger level than the wanted signals.

To address this, select a bandwidth of about 9.8MHz rather than 10MHz, so the spurii drops off the edge of the display.

The spurii is usually in the area of -70dBm although one customer reported it as high as -58dBm on certain bands.

This report was passed to AOR Japan (by AOR UK) in November 2001. It is acknowledged by AOR Japan but is a necessary compromise in design... it cannot be easily or cost effectively addressed.

Of course all electrical equipment produces some noise, especially where large displays are involved. Connecting a good RF earth to the equipment can help with general low level spurii.

Due to continuous developments, AOR reserves the right to make design and specification changes for product improvement without prior notice. The performance specification figures indicated are nominal values of production units. There may be some deviation from these values in individual units.

CIV ADDR default	4AH
CIV BAUD	9600
CIV TRAN default	ON
CIV 731 default	OFF

IC-R8500 25-pin male	SDU5500 9-pin male
2	3
3	2
5	7 GROUND
7	4
8	5

SDU5500 Bulletin Page