Various Technical Notes on S-Com products:
- Power connectors:
The 5K, 6K and 7K all used a common coaxial power connector that can be found at any number
of suppliers, even Radio Shack.
The 7330 used a much more sturdy locking connector that is a bit uncommon. It is made by
Phoenix Contact company and is their part number 1757019. It's second sourced by Tyco as
their part number 796634-2. Digikey sells it as part number 277-1011-ND. If it's in the Mouser
catalog I couldn't find it.
- The 5K, 6K and 7K DADM:
The connectors on the DADM board and in the controller are not keyed, and
depending which end is plugged into the controller (5K, 6K, or 7K) versus
the DADM, and depending on whether you chose to have the right angle plug
point away from the DADM or towards it, will all be factors in determining
which color on the ribbon cable is associated with which signal and pin
function. Therefore, you can ignore the wire colors...
If you look at the DADM's silk screen, between the connector and the
board edge you will see "1 2 G + 5". Pin 1 is closest to the centerline
of the DADM board, and Pin 5 is not installed (but can be).
If you accidentally reverse the 4 pin connector, power is applied to the
(AC coupled) audio input. You won't damage anything, it just won't work.
So just flip over one end.
1 = Audio Into the DADM
2 = Audio Out
G = Ground (negative)
+ = Positive Power
5 = Audio mute input (optional, see note below on driving it with the receiver unsquelched signal)
- Another point about the 5K, 6K and 7K DADM:
Note that there are 5 pins on the schematic, but only 4 on the connector that is
soldered to the DADM board. The extra pin is the "erase" line from the digital
delay circuitry. It functions as an audio gate function that defaults to the
"pass audio" mode. It can be hooked up to the COR line to provide positive audio muting.
If you present unsquelched audio to the 7K, then Pin 5 should be connected per
When you assert the COR input whatever is being held in the digital delay is erased. The
signal is dipswitch selectable for either high-true or low-true control. If pin 5 is
unused then use the "High True" setting.
||U27 Pin 11
||U27 Pin 8
||U15 Pin 4
||U15 Pin 3
- 7330 audio: The audio output circuit of the 7330 is designed to feed almost any transmitter.
It's not balanced, it's single-ended. But it is 600 ohms. The output coupling caps are
10 µF, 25vDC, nonpolarized ceramic caps. Their main purpose is to block the 2.5 V bias
on the op amp's output but they will also block any DC that might be on the transmitter's mic
input. The designers specifically selected nonpolarized caps because the voltage across them
can be one way if the transmitter circuit they are driving has no bias voltage, but the other
way if the mic input has more than 2.5 V of bias. Almost all Motorola microphone circuits bias
the microphone line to +8 to +10vDC to power the preamp inside the microphone.
- The 7330 has a separate CTCSS encoder on each port, but it can't do
Digital CTCSS / DCS / DPL / DCG (pick your appropriate name). The CTCSS
output pin can be either the encoder audio output, or a logic output level
to control an extenal encoder (it's a three-pin two-position push-on jumper).
If you need DPL just set the jumper to the logic output mode and use
that to key a Com-Spec DCS-23 board (it's a DPL version of a TS-64) - about
$60 (late 2011 price).
- 7330: The serial ports on the 7330 are common RS232. The old Windows
3.0 and 3.11 had "Terminal.exe" (which I've copied to and used
on Windows 98, 2000 and XP), the 95, 98, NT, 2000 and XP all come with
"Hyperterminal.exe". It doesn't seem to be installed by default
on Vista or Windows 7 but you can copy the binaries from an XP system
and they work fine. Just make sure you get all four files:
1) C:\Program Files\Windows NT\hypertrm.exe
(the "Windows NT" section of the path to hypertrm.exe may be different
on your system).
Create a C:\Program Files\HyperTerminal directory in Windows 7 then add
the four files mentioned above. Create a shortcut to
"C:\Program Files\HyperTerminal\hypertrm.exe" and put it on the desktop,
or in the programs menu, or both. Set the file suffix associations to
open all "*.ht" files with ""C:\Program Files\HyperTerminal\hypertrm.exe"
%1". Note that there are two " characters at the front of the path.
Opinionated personal comment: I've never liked Hyperterminal and used Terminal.exe
on Windows 2000 and XP until I discovered Tera Term.
The latest version can be downloaded for free; click the Tera Term link.
PuTTY is another option and is also a
It is a free (MIT-licensed) Win32 Telnet, Rlogin and SSH client that also
happens to do plain serial.
The author can be contacted at: his-callsign // at // repeater-builder // dot // com.
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