Various Technical Notes on S-Com products:
- Power connectors:
The 5K, 6K and 7K all use a common coaxial power connector that can be found at any number
of suppliers, until they closed you could find it at Radio Shack.
The 7330 uses 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. Mouser sells it
as a 651-1757019.
- 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
this table:
| 7K Rx1 |
U27 Pin 11 |
| 7K Rx2 |
U27 Pin 8 |
|
|
| 6K Rx1 |
U15 Pin 4 |
| 6K Rx2 |
U15 Pin 3 |
|
|
|
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.
Pin 5
COS Sense |
Switch Setting |
| S5 |
S6 |
| High True |
ON |
OFF |
| Low True |
OFF |
ON |
- On the 7K autopatch... These points were made in a comment thread on the Scom mailing list:
Audio levels vary in an autopatch... composite DTMF power should be -4 dBm whereas voice
mean should be limited to -10 dBm. Modem tones, call progress, etc. are lower yet.
The 7Ks TIM (telephone module) was designed so it could be marketed as a standalone product
that could be used with other uncertified equipment. To get Part 68 certification, we had
to demonstrate that that landline couldn't be overdriven no matter what was fed into the TIM.
The TIM schematic shows a power limiter circuit to prevent the 7K from overdriving the landline
(and violating Part 68). Part 68 allows a higher drive level for DTMF dialing (known as
"addressing" by the phone company). So, the 7K activates "AL" (Address Level) only during DTMF
dialing, and that temporarily increases the output of the landline audio driver.
The OFF HOOK output from the 7K controls the loop relay (actually a solid-state switch) in the
TIM. When the relay activates, loop current flows and initiates the telephone company's dial
tone. It also interrupts the loop current for pulse dialing, and it momentarily opens the
loop for "hook flash" features.
When the 7K BUSY IN is active, the 7K will not allow a call to be made. When the 7K
does make a call, BUSY OUT stays continuously active for the duration of the call.
Those two lines were put into the 7K design to handle specific issues. Some customers had
multiple 7Ks at a site that had only one phone line. They could tie all the 7Ks' BUSY INs
and BUSY OUTs together such that an autopatch call on one repeater would lock out the
others, so no call collisions. And, if a club used a site maintenance phone line for autopatches,
they could install a Teltone line relay coil in series with the maintenance phone. The contacts
were connected to BUSY IN so that a maintenance call wouldn't be interfered with by a
pesky ham autopatch (good neighbor policy).
- 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 volts
of DC 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 volts 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 Vyex 7K DAB and on the 7330 are common RS232.
I have two laptops dedicated to radio programming, both of them are Panasonic Toughbook CF-series.
Why Toughbooks? The CF-series all have a hardware COM1 on the back of the laptop. There are ZERO
issues with USB when you use a CF-series Toughbook for radio programming.
The one I use most is a CF-30 that I set up with 32-bit Windows 7sp1. Why 32 bit?
There is a lot of Motorola and Kenwood software that absolutely will NOT run on a 64 bit
operating system. When I need to do serial communications on the CF-30 I use TeraTerm, it is
available as a free download from
https://ttssh2.osdn.jp/index.html.en
or from
https://github.com/TeraTermProject/osdn-download/releases.
TeraTerm has two ways to send a file, "Transfer" is only used for binary files using XMODEM
or other serial transfer protocols. The "Send File" command sends a text file, line by line,
just as if you were typing it. TeraTerm offers two Transmit Delay settings on the
Setup / Serial Port menu to avoid input buffer overflow on the system that
you are connected to: one is a milliseconds per character and the second is
a milliseconds per line. For the 7330 you will wan to set the first to 6 milliseconds
and the second to 50 milliseconds. More details is in the 7330 manual on page 8-7.
PuTTY is another alternative and is also a
free download.
It is a free (MIT-licensed) Win32 Telnet, Rlogin and SSH client that also
happens to do plain serial.
I have a CF-27 only because it was given to me after I was overheard complaining about trying to
program older radios like Maxtracs and GM300s. I use it only about twice a year...
It runs a 233 MHz Pentium II, has 640K of memory and was shipped with MSDOS / Win98).
I updated it to Win98se. I dislike the Hyperterminal that comes with Win98 so whe i have to use
the CF-27 as a serial communicator I use the old "Terminal.exe" that was shipped with
Windows 3.0 and 3.11. It runs just fine on Windows 95 and 98.
Contact Information:
The author can be contacted at: his-callsign // at // repeater-builder // dot // com.
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