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Miscellaneous S-Com Information Written, HTML'd and Maintained by Mike Morris WA6ILQ

Various Technical Notes on S-Com products:

• DC Power connectors:        (all of the links in this paragraph are off-site pointers and each opens in a new browser tab)
  
  The 5K, 6K and 7K all use a common 2.5mm 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 most convenient source of small quantities of a 7330 power connector just might be eBay as Kurt Meltzer, KC4NX / WB9KNX / Meltzer Radio Engineering.
  He sells all kinds of radio (and other) connectors, cable kits and cables on ebay as seller "mre1032".
  
  
• Inside 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 (the DADM board requires +9.0 Vdc to +12.0 Vdc at 25 mA)
  5 = Audio mute logic level 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 audio delay circuitry. That connection 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. That line is also dipswitch selectable for either high-true or low-true control.
  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

  5K Rx1 IC7 Pin 6

  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, Scom 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 firmware 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). Among other neat features the firmware for the 7K DAB allowed reassigning BUSY IN as an additional Logic Input and the BUSY OUT as an additional Logic Output.
  

• 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 audio 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 (inside the 7330 there is a three-pin two-position push-on jumper for each port). 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 / DCS version of a TS-64) - about $60 (late 2011 price). They show up on eBay occasionally.

Controller Programming: The serial ports on both the Vyex 7K DAB and on the 7330 are common RS232 9-pin "D" connectors. If your radio programming computer does not have a 9-pin serial port then you can use an FTDI-based USB to serial converter like this one or if you like blinkenlights then use this one. (both are off-site pointers and open in a new browser tab)

Personally, I have three laptops dedicated to radio programming, all of them are Panasonic Toughbook CF-series. Why Toughbooks? The CF-series are designed from the beginning as a Japanese Military field computer and as a result can take a lot more abuse than your regular plastic laptop. Plus they all have a hardware 9-pin COM1 on the back. There are ZERO issues with USB when you use a 9-pin cable for radio programming.
The Toughbook 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. I also have a CF-31 that runs 64-bit Windows 10. Someday I'll spend a day and configure the CF-31 for dual booting of 64-bit Win10, 32-bit Win7.

I have a third Toughbook, 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 that use MS-DOS based programming software. That is happening less and less these days. The CF-27 runs a 233 MHz Pentium II, has 640K of memory and was shipped with MSDOS / Windows 3.0. I updated it to Win98SE as I'm more comfortable in that over 3.0. There was a version of TeraTerm for Win98SE and I'll add that when I get around to it.
And maybe I'll add a 3rd boot option to the CF-31: MS-DOS 6.22...

For the 7K DAB or the 7330 I use the TeraTerm program on either the CF-30 or the CF-31, 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  / YMODEM ZMODEM / Kermit and more. On the other hand the "Send File" command sends a text file, line by line, just as if you were typing it, which is ideal for controller programming. 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 want 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.

Contact Information:

The author can be contacted here.

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This page split from the index page 25-Jan-2014.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.