Pactor Primer

A Pactor Primer

Getting Started with Ham Radio Email
1997, 98 Jim Corenman KE6RK
Revised 16 Jan '98 15z

This document is intended as a guide for the mobile ham who is new to the world of message forwarding via the ham radio HF Pactor network. It is written by the author of the AirMail personal mailbox program, primarily for cruising sailors and RV travelers that want to stay in touch via amateur radio and email. Subjects covered include advice on equipment selection and installation, getting started with the AirMail program and getting connected to the Pactor network. The last section also covers doing it the hard way, using a dumb terminal program.

The biggest problem with getting started with Pactor is documentation. The Pactor controllers all come with thick manuals which cover a multitude of operating modes, but by the time you painfully extract the part that is relevant to Pactor you find the documentation to be pretty thin. Our advice is to treat the controller manuals as highly valued reference documents, sort of like unabridged dictionaries, and don’t attempt to actually read them unless absolutely necessary.

A further note on this document: Parts of it are full of fluff and can be skimmed quickly, but when we get to the step-by-step instructions on how to get your station on the air, then you need to slow down and read each word carefully.

Contents:
1. Overview of the network
2. Choice of Equipment
3. Installation Basics
4. Getting Connected with Airmail
5. Using a Terminal Program
6. Glossary
7. Links

Overview of the Network

Sending digital communications over radio is nothing new, but recent advances in technology and software have made it easier than ever before for mobile hams to stay in touch via ham radio. Email is almost universal these days, and is ideal for exchanging messages between mobile hams and their contacts at home. All that is needed is some method to get messages to a fixed station and from there to the internet. Thanks to the efforts of a bunch of dedicated system operators (sysops) and a few software developers, the pieces are all in place.

In order to exchange email messages with the folks back home, you will need a suitable radio setup to access a Mailbox (MBO) station via HF radio, and your contacts will of course need email access (you don’t need an account yourself). While there are VHF and satellite packet stations in use, most long-distance traffic is sent via HF Pactor stations and that is what we are going to focus on here.

There are literally dozens of HF MBO stations world-wide, most running the WinLink software package originally written by Vic Poor W5SMM and rewritten and developed by Hans Kessler N8PGR. WinLink stations are designed for automatic message forwarding, either to other WinLink stations via Pactor on the HF bands, or via the VHF packet network. The real breakthrough for mobile users to be able to keep in touch with the folks back home was the development of internet email gateways, and many WinLink stations now also operate internet gateways using the NetLink software package developed by Jim Jennings W5EUT.

Pactor is a method of sending digital information via radio, and was developed around 1990 by a small group of German hams who formed the company SCS. Pactor is an Frequency-Shift Keying (FSK) based system that incorporates longer blocks than the earlier Amtor system, robust error checking and automatic switching from 100 baud to 200 baud when conditions permit. The first Pactor controller was developed by SCS and the protocol was adopted by most other manufacturers of TNC's (Terminal Node Controllers, or radio modems), but often without the analog memory error correction scheme developed by SCS.

The Pactor team at SCS went on to develop Pactor-2, a two-tone phase-shift encoding (PSK) scheme. Their Pactor-2 controller is the PTC-II, with the modem implemented by a powerful DSP (Digital Signal Processor) chip and incorporating a fast 32-bit microprocessor to move the data. The original Pactor mode is also included (and in fact Pactor-2 operates as a "turbo" mode once contact is established via Pactor). Amtor, RTTY, Morse and weather fax modes are also provided, plus plug-in options for VHF/UHF packet.

A message on the digital ham network looks a lot like an email message, with a "From" and a "To" address, a subject line and a message body. Addresses are hierarchical and geographic. For example KE6RK@OE4XBU.AUT.EU indicates station KE6RK who can be reached at mailbox station OE4XBU in Austria in Europe. In Theory, a message can be entered into any BBS or MBO station, addressed to any other, and will get there by whatever route the MBO stations decide. Similar to email, the message is not generally delivered to the end user automatically, they must connect to the BBS or MBO station and collect it.

Passing messages between the ham radio network and the Internet requires a gateway between an email service and a ham radio MBO. Each message must carry two addresses, one for the ham network and a second one for the internet. The NetLink program handles polling the email server, reformatting the messages, and handing them off to the WinLink MBO program. There are limitations on the messages that can be handled, due to the relatively low bandwidth of the ham radio network and the regulatory limitations associated with ham radio communications. For ordinary email messages the bandwidth is not a problem and messages up to 5-10KB are commonly forwarded, and longer messages are possible with direct links to certain gateways.

The regulatory issues result from the international agreements that grant amateur radio some prime HF real estate, on a non-compete basis with commercial carriers. All of the various national regulatory bodies have implemented prohibitions on commercial messages, which in the U.S. prohibits any communication in which either party has a "pecuniary interest" (Part 97.113 of the FCC regulations, revised in 1993). So you can order a pizza via ham radio as long as neither party works for the pizza parlor. This language applies to U.S. hams operating /MM in international waters also, but different language may apply in other countries.

A second issue is non-ham third-party traffic, that is messages originated by or addressed to someone who is not a ham. For mobile hams in international waters or connecting to a U.S. MBO there are no restrictions and messages may be freely passed, but in other countries other rules may apply so it pays to check.

Choice of Equipment

The only difficult part of setting up a Pactor station is the variety of equipment that is available, none of which uses compatible connections. This means that cables need to be made up especially for each installation, which is the number one source of problems. (Number two is figuring out the correct transmit frequency).

Three components are needed to set up a Pactor station: a radio transceiver (and antenna), a data controller (also known as a terminal note controller or TNC), and a computer with some appropriate software. The controller is the only specialized piece of equipment, and is essentially a radio modem, similar in concept to the ubiquitous computer modem used for telephone connections. The controller generates the audio signals that are sent via the radio transmitter, and decodes the incoming audio signals from the radio receiver. So the primary connection between the controller and the radio is two audio signals (audio in and audio out), plus a PTT (push-to-talk) signal to tell the radio when to transmit.

Transceivers

Transmitting and receiving digital signals is similar to voice, and most modern SSB radios will do the job just fine. Ideally, the audio signals to and from the controller will be line-level (500mv) signals to a rear-panel connector, allowing the radio to be interchangeably used for digital and voice communications. Some older radios do not provide a rear-panel "accessory" connector, however, and the speaker and microphone connectors must be used. The audio level from the speaker jack will be adequate (although the volume cannot be turned down too far), but the controller's normal transmit audio may overload the microphone jack. Depending on the controller there will be a some way to reduce the transmit level if required.

The second issue is the transmitter's ability to transmit a continuous full-power signal without melting. Again, most recent transceivers can do this without a problem, but some older transmitters will have to be operated at a reduced power setting. This is generally no big deal, as even 25 watts is enough when conditions are good and many /MM's (Maritime Mobiles) routinely operate at 25 or 50 watts just to save the poor batteries.

Two less important issues relating to the transceiver are filters and a TCXO. A narrow-band (500 Hz) filter can be handy for reducing interference on the sometimes-crowded ham bands, but the controllers themselves are very good at ignoring adjacent-channel interference. The only time it becomes an issue is the rare case when a strong adjacent signal activates the receiver's AGC and reduces the level of all signals. Bottom line, if you have a narrow filter that works in SSB mode then use it, otherwise don't worry about it.

The TCXO issue relates to the accuracy of the transceiver's crystal oscillator. With digital signals operating with only a 200 Hz frequency shift, transmitting and listening on the correct frequency is a significant issue. Without a temperature-controller crystal oscillator (TCXO), a typical ham transceiver will drift 50 Hz or more as it warms up. This is not enough to be detectable on a SSB voice transmission, but for a digital connection would be significant. Pactor will operate up to 100 Hz off frequency but is happier (fewer errors) if within half of that, and Pactor-2 needs to be within 50 Hz. If a TCXO is available for your transceiver, then we would recommend installing it.

The Controller:

There are a number of controllers or TNC's on the market, although the SCS PTC-II and the Kantronics KAM+ are the most popular with mobile users (and currently the only ones supported by AirMail). Both are small and relatively low-powered (about 1/3 amp at 12 volts). The KAM+ is a second-generation controller, with a simple micro-controller and programmable analog filters, and does a good job with all of the basic modes including Pactor. The SCS PTC-II is a third-generation controller with a powerful DSP (digital signal processor) to handle the modem functions plus a 32-bit microprocessor for the digital chores. All the basic modes are supported plus the new Pactor-2 mode. The choice is economic, with the PTC-II offering much faster and more robust connections at a significantly higher cost. There are other controllers that support Pactor also, such as the PK-232 and MFJ-1278, so if you've got one then use it (AirMail will shortly support the PK family, plans for the MFJ are uncertain).

The Computer:

Almost any sort of computer will do the job. The controllers all have a pretty reasonable command set, and at the basic level any sort of "dumb terminal" program can be used effectively, so even the simplest computer is capable of handling digital communications. For sending more than the occasional message, however, cutting and pasting messages with a dumb terminal program gets pretty tedious and some sort of specialized terminal program such as Airmail will make things much easier.

There are lots of terminal programs available for DOS, Windows and Mac computers, but most are focused on making the multiplicity of controller modes easier to use, and are not oriented toward any specific application. So the value of a conventional terminal program for the job of sending email via Pactor mailboxes is, in our opinion, of little value over typing commands directly to the controller with a dumb terminal program. Being able to cut and paste message text for incoming and outgoing messages is very handy, so being able to run Windows or having a Mac is a significant advantage.

The key to making software programs easier to use is to focus on doing one application well and not try to do everything. And that is why we wrote AirMail. It is a Windows-95 program with a good set of email-style tools for sending and receiving messages via HF Pactor using the PTC-II or KAM controllers (and soon the PK-232), and that's about all.

Installation Basics

There are three cables required to get a controller hooked up: a data cable to the computer, an audio cable to the radio, and a power cable to a 12-volt supply. The data cable sometimes comes with the controller or can be purchased at the computer store. The PTC-II box has a 9-pin female connector with the same pin-out as the 9-pin male found on most PC's, and the KAM has a 25-pin female connector, so both of those are standard computer-store cables. The PK-232 cable is weird and will probably have to be made up special.

The audio cable will have four wires: transmit audio from the controller to the transceiver, receive audio from the transceiver to the controller, a push-to-talk (actually "ground-to-transmit") connection, and ground. The cable must shielded, with the shield connected to the connector shell at each end. The pin connections are different for each controller and each radio, so generally a cable must be made up specially for each configuration. If the radio has a rear-panel "Accessory" connector then that should be the first choice, otherwise the front-panel microphone connector can be used. An accessory jack provides line-level input and outputs and (on most radios) disables the microphone when the rear-panel "PTT" connection is activated.

If you use the microphone connector, you might find a speaker or audio-out connection on same connector, otherwise a rear-panel speaker or audio-out connector can be used. You do not want to disable the speaker completely, however, as it is very important to be able to listen on a frrequency before transmitting. Also consider the TNC/microphone switch (http://www.mfjenterprises.com/mfj/switches/tncmic.html) and thanks to W2WJY for this hint.

And whatever connection you use, be sure that the transmitter audio is not being over-driven, particularly with Pactor-2 (a PTC-II controller). The audio distortion will dramatically reduce the effectiveness of the signal as well as making you a very bad neighbor on the ham bands. The way to check is with the ALC meter, you want it well into the "green", towards the bottom of the dial. Also be sure that any speech compression is turned off for the same reason. You may be able to adjust the transmit audio with the Mic gain control, sometimes there in an internal adjustment, or you can adjust it at the controller (The PTC-II uses the PKSA and FSKA commands, the KAM has a jumper, and the PK-232 has a rear-panel trim pot).

The PTC-II controller uses an 8-pin DIN connector for its HF audio connections, although all of the interesting signals are on pins 1 to 5 so a 5-pin DIN connector will work just fine. And in fact the German pin layout for an 8-pin connector does not match the geometry of the American pin layout, so if you melted the original connector trying to solder it then a 5-pin connector is the safe replacement. The 5-pin connectors from Radio Shack also don’t melt as easily as the German ones.

The relevant PTC-II pin connections are as follows:
Pin 1 Transmit audio (TxD) from the controller to the transmitter
Pin 2 Ground (audio signal return)
Pin 3 Push-to-Talk (PTT), connect to ground to transmit
Pin 4 Receive audio (RxD) from the receiver to the controller
These signals, or something equivalent, will be present on the transceiver's rear-panel accessory connector or front-panel mike and speaker jacks, so simply match up equivalent signals (and keep a drawing of how you did it!).

The KAM also uses a 8-pin DIN connector for its HF audio connections, with pin connections that are almost, but not quite, the same. Either use the pigtail that comes with the KAM or a USA-style 8-pin connector from Radio Shack, a 5-pin connector will fit but will not include pin 6. The KAM pin connections are as follows:
Pin 1 Transmit audio (TxD) from the controller to the transmitter
Pin 2 Ground (audio signal return)
Pin 3 Push-to-Talk (PTT), connect to ground to transmit
Pin 6 Receive audio (RxD) from the receiver to the controller
The pin numbering for DIN connectors is goofy, so check the manual carefully for the pin locations. Some DIN connectors are also prone to melting while being soldered, so use a clip-in heatsink (or hemostat) on the other end of the pin while soldering, and work quickly.

The power connector used by the PTC-II, KAM and PK-232 controllers is a 5.5mm x 2.1mm coaxial-pin connector (the only thing they all agreed on), also available from Radio Shack (if the controller did not come with one). The center pin is positive, not negative, and the penalty for wiring it backwards is severe. (Note that the PTC-II has an alternate 12V input on its HF audio connector but no corresponding ground return, so we would recommend using the separate power connection for RFI reasons).

A few comments on RFI: A transmitter pumping out 100 watts in digital modes can generate a quite a bit of stray RF, which often finds its way into the controller and computer cables and raises all sort of havoc. The PK-232 seems particularly sensitive to RF, and the PTC-II is pretty immune. A good ground system and shielded cables are a must, and if either of those are deficient then that's a place to start. But beyond that it is usually necessary to add some clip-on ferrites or a coax line isolator to provide RF blocking.

Clip-on ferrite chokes are about 1" long with a 1/4" hole through the middle and act as RF blocks, allowing normal bi-directional signal flow but blocking any common mode (unidirectional) RF current such as stray RF flowing on a ground wire or shield. Their primary function is to break up ground loops and keep the ground currents off of the signal cables where it will couple into everything. Ferrite chokes can be particularly useful clipped onto the audio connection between the PTC-II and the transceiver, ideally one at each end. They are available from Radio Shack, but a better choice is Fair-Rite p/n 0443164251, available from Newark Electronics as their part# 95F763. Another choice is the MFJ-701 from MFJ, an open-frame core which allows multiple turns of cable but which we don't think is as effective as the Fair-Rite choke.

Clip-on ferrites or a ferrite Line Isolator is also highly recommended between the transceiver and the tuner (or between the transceiver and antenna if no tuner is fitted). A line isolator is a much beefier version of a clip-on ferrite choke, and blocks the stray RF path to ground via the coax shield and transceiver ground, forcing the antenna currents to use the proper ground strap. An excellent Line Isolator is model T-4 from The Radio Works, Portsmouth VA (and their web site also has an excellent discussion on grounding and RF interference).

Getting Connected with AirMail

Once things are hooked up and checked, it is time to try out AirMail. (We're also assuming you have a compatable controller and are running Windows-95). AirMail is downloaded as a self-extracting .exe file, so simply double-click the download file from Windows (file) Explorer to install it. AirMail by default installs in the directory Program Files\AirMail and prompts for a path with the default "C:\". The easiest way to install the program elsewhere is to first accept the default and then move the AirMail folder (and sub-folders) and re-do the shortcuts from the start menu and the desktop - the program itself is a self-contained .exe file and is highly portable.

Start the program, answer the callsign question (no /MM here) and before doing anything else go to Tools/Options on the menu and check the settings. On the first page be sure the appropriate controller is selected and the baud rate is correct (we recommend 38400 or 57600 for the PTC-II and 4800 or 9600 for the KAM). Also check "Show Link Messages" for now (and un-check it later after things get going). In the radio section, check "none", "LSB", set the Center Frequency to "2100" and check the "Set Decoder Tones" box. On the next page make sure your callsign is correct and don't worry about the ID string unless you want to identify as a "/mm" for example. Click the OK button (not cancel) to close the Options Window and save the settings.

Now select View/Frequency List from the menu, that will show the list of all available MBO stations. The check boxes mark the stations that will appear in the Station list, and don't forget to save if you made any changes. If you said "What check marks?" then you need to update the Windows Common Controls Driver (comctl32.dll). There is a Microsoft update for that called com32upd.exe available at http://www.microsoft.com or wherever you found the Airmail download. (This update used to be bundled with Internet Explorer, but is now available separately at the suggestion of the Justice Department).

Now open the Terminal Window (F6 or Window/Terminal on the menu or click the right-most "Terminal Window" button). Watch the upper screen - after 2-3 seconds it should show a list of setup commands in red - these are the "Link Messages" that you elected to show in the Options Window. The status bar at the bottom should also show "Init OK", but the message is a bit elusive as the same box gets used for hints. If all that worked then you should be ready to connect.

AirMail can communicate with the MBO station in three different modes: BBS mode ("Handshake" button down) is the default and provides automatic message forwarding both ways, you don't have to do a thing except make the initial connection; Keyboard mode ("Keyboard" button down) allows you to enter commands manuall, read bulletins, etc.; and Unprompted mode (neither button down) is completely manual. There are also buttons that allow you to get or send messages in Keyboard mode, but we strongly recommend that you use BBS mode for transferring messages, as it will save time and allow others more access.

If you are new to WinLink MBO's, there are two things we would suggest: First, start with an MBO that isn't particulary busy. K4CJX runs a geat MBO but is very busy, instead try N8PGR or K7SLI. Secondly, make your first contact in "Keyboard" mode so you will have a chance to read the help files and check for bulletins. Once you are up and running, however, you will want to use BBS mode most of the time.

The next step is to select a station from the Station pull-down list (on Terminal Window's Toolbar), that chooses the station that AirMail will try to connect to. (If you don’t pick one first, AirMail will ask when you try to connect). If you don;t see the station you want on this list, then close the Terminal Window and go back up three paragraphs and put a checkmark next to the stations you want to access.

Once you have selected a station from the Station List then click the Frequency List to the right access a list of frequencies scanned by that MBO station. As you move up and down the list, the dial frequency will be calculated and displayed in the status bar at the lower-right (and if you had a remote control cable connected to the transceiver then the frequency would be set automatically - that's a great feature but one to worry about later). For now you may want to put the dial frequencies for your favorite MBO into the transceiver's memory (and remember that the frequency list at the top of AirMail's Terminal Window shows center frequencies, and the selected dial frequency will be displayed in the bottom status bar).

Check all of the frequencies for the selected MBO, listen carefully and choose a clear frequency on an appropriate band, and then try connecting to the MBO. If you are trying to connect to a busy MBO like K4CJX, then you will likely find him busy on another frequency. In this case either find a less-busy MBO, or wait untill he signs off with a "SK" message. When you are ready to connect click the left-most "Green-light" button or select Control/Connect) from the menu). The controller will call for about a minute before timing out, that is usually plenty if the propagation is good and the station is not busy on another frequency. If the MBO doesn't answer then try another frequency or try some other time - the station may be busy on a another frequency or there may be no propagation.

When you get connected to a WinLink MBO, you will see the welcome message and then a command prompt ending with a "", that means "Go Ahead". In Keyboard mode you will be in a semi-automatic mode where you can type commands manually (into the lower keyboard box) but AirMail will hold each command until it sees the next prompt from WinLink. Each command is followed by the Enter key, and WinLink will take care of turning the link around - there is no need for you to initiate a change-over (and doing so will just confuse everyone).

Enter the H (Help) command into the lower keyboard box, and WinLink will return a list of commands and their use. Also try the I (info) command, and enter LB to get a current list of bulletins. If you want to read any of the listed bulletins, enter R and the bulletin number, i.e. R 1234 to read bulletin number 1234. If all that works then logoff (enter a B for Bye) and WinLink will disconnect. If you got this far, then all of the technical stuff is working, the wires are all hooked right and you got the frequencies figured out correctly. If the controller isn't working correctly, then skip ahead to the Terminal Program section and check it out step-by-step.

If you got this far then try composing a test message. Do this by going back to AirMail's main window (F6 to switch or close the Terminal Window) and click the "New Message" button (or File/New from the menu). For now, close the Address Book by pressing the Esc key and then enter "SP CALLSIGN@MBO" on the first line of the new message, where "CALLSIGN" is your callsign and "MBO" is the callsign of the MBO that you want to connect to. ("SP" means Send Private and is the send-message command). The second line is the subject, and the third line starts the message. Don't worry about adding the "/EX" terminator at the end, AirMail will do that. When you are done composing the message, click the "Post" button (or menu File/Post) - that will save the message and mark it for sending, and return you to the index. Your new message should be in the index with a "mailbox" icon next to it indicating it waiting to be sent.

Now go back to the Terminal Window (F6 again), and this time click the "BBS mode" button (the handshake icon). Reconnect to the MBO as before, and this time AirMail and WinLink will exchange system ID's (the square-bracket codes) and handle the transfer automatically (the keyboard is disabled). Uploads go first in BBS mode, so your message should first be uploaded to the MBO, and then should immediately download again (if you addressed it to yourself). WinLink will disconnect automatically when done. Now go back to the Main Window (F6 again) and check your new message.

Sending a message to an email gateway is just as easy. Messages addressed to "Nexus" are routed to the NetLink internet gate, so start a new message with "SP NEXUS@MBO" on the first line, where MBO in this case is the nearest WinLink station that has a Nexus/NetLink gateway. The email address goes on the second line, and the message subject on the third line. Follow that with the message text and post it as before. If the gateway is not at the same station that you normally connect to, then it will be forwarded automatically but you will be prompted for which MBO you want to send the message to (the "Post-to MBO"). AirMail's "Post-to" MBO is where the message will first be sent, and the "@MBO" is where the message will eventually wind up after being forward.

If that all works then it is time to grab your favorite beverage, sit down with the Help files, and start reading. If none of this works, try it with a Terminal Program and then come back here. If the controller didn’t initialize properly then the baud rate may be wrong, or there may be a setting that is incompatible with AirMail. It may also be necessary to restore the default settings if you have been trying other programs, but in general that should not be necessary more than once (if it is, we would really like to hear about it so we can fix it). If all else fails write us with a careful chronology and we'll try to help.

Using a Terminal Program

The first thing to establish is that the controller is communicating with the computer and that the baud rate is set to what you think it is. Windows HyperTerminal is a good choice, it is found under Programs/Accessories in the Start menu, open the HyperTerm folder and double-click "Hypertrm.exe". You will be prompted for a new connection, give it a name like "PTC-II" or whatever and click OK. On the next window change "Connect using" to "Direct to Com 1" or wherever you have the controller connected and click "OK". The next window is Port Settings, set the baud rate to 38400 or 57600 for a PTC-II (4800 or 9600 for a KAM or PK-232, or whatever the controller is set to), 8 data bits, no parity, 1 stop bit and click "OK". Now go to the File menu and select Save to save the settings, and then exit HyperTerminal and restart it. This time you will see an icon in the HyperTerminal folder for your controller settings, double-click that and you should be ready.

One very important thing about HyperTerminal: if you change the port settings (baud rate, etc.) with the File/Properties menu, you must save the settings, exit the program and re-start it before your changes will take effect. This "feature" drove us crazy before a compassionate friend pointed the problem out.

When you power-on a PTC-II it goes into a "quiet" auto-baud state and you need to hit the "Enter" key to set the baud rate and wake it up, you will then see some start-up text and a "cmd:" prompt. The KAM and PK-232 start right up with the pre-set baud rate so you should see the start-up message and the "cmd:" prompt - if it doesn't then you probably have the wrong baud rate. You won’t be able to set a new baud rate (with the KAM's ABaud command or the PK-232's TBaud command) until you can communicate using the old rate (sort of a Catch-22) so some experimentation might be required. A brand-new KAM will come up in an auto-baud mode, so watch the screen and enter a "*" when prompted.

If you can communicate with the controller using HyperTerminal, then you might be up to a basic working level. Unless you are sure the controller is reset to the default defaults (i.e. it is brand new), give it a hard reset command just to make sure. And be sure that the terminal program is set to 8 data bits and no parity (HyperTerminal like to default to 7 bits/even parity - to change it, select File/Properties from the menu, then click Configure and check the settings, and then restart the program before doing anything else).

One very important thing about the KAM: If you start up a new KAM (or one that you gave a Restore Defaults command), and you have not set 8 bits/no parity, then nothing else will ever work. Trust us on this one. (We think the same is true for the PK-232).

To reset a PTC-II to the factory defaults, use the RESTART command. The controller will reset and go back to its auto-baud routine so hit the Enter key and you should see the start-up text and a "cmd:" prompt. For the KAM, use the RESTORE DEFAULTS command (spelled out). The controller will then start its "Auto-baud" thing, so give it an asterisk (*) when it prompts. The PK-232 requires a RESET command to restore its defaults.

Once you see a cmd: prompt, you should be able to enter controller commands. Commands can be upper or lower case, and usually only the first few letters need to be typed. We will indicate the part of the command that is required with capital letters, and the optional letters with lower case. When you enter the command, however, you can use either case. Each command is followed with the Enter key, and (depending on the command) you will usually get an acknowledgement of some sort and a new cmd: prompt.

The next task is to figure out the offset between the advertised frequency of the WinLink MBO stations and your radio dial. We're recommending that you use the radio's lower-sideband (LSB) mode and set the controller's audio tones to a mark and space frequency of 2000 and 2200 respectively, that's an audio center frequency of 2100 Hz. (The PK-232 is fixed at a center frequency of 2210 Hz). In SSB mode the transceiver's dial always reads out the carrier frequency, not the actual transmitted frequency. The difference is the audio frequency, so for tones of 2000/2200 and LSB mode, the transceiver dial must be set 2.1 KHz above the center frequency of the other station. For most MBO's this works out to be an even kilohertz. For example K4CJX (a popular WinLink MBO in the U.S.) operates on an advertised center frequency of 14071.9 (among many others), so you would set your dial to 14074.00. Simple, no? Of course there are lots of other possible tone and offset combinations, and you can also operate USB or RTTY modes (the latter in Pactor-1 mode only), and once you figure out what you are doing there might be good reasons for doing so. But for now, that's an unpaved road.

At this point we are going to split out the PTC-II users for a few paragraphs while we talk about the commands appropriate for that controller, so KAM users should skip down a a couple of paragraphs.

If you have a PTC-II, there are a few commands that you probably want to change from the default settings: Enter the command REMote 0 to turn off remote-control access, CWid 0 to turn off the CW (Morse) auto-ID (which is not required in most countries), and CHOBell 0 to turn off the change-over beeper (it will make you crazy). The way to set the tones to 2000/2200 is by entering the commands TOnes 2, MARk 2000, and SPAce 2200. You will also need to enter your callsign with the Mycall command.

The PTC-II is already in Pactor Standby mode when it powers on, so you are ready to tune around the band and listen for signals (14065-14080 kHz is prime Pactor real estate). To call another station, set the frequency and enter the command C N8PGR (for example). If the other station responds you will see a "link" message from the controller and then a welcome message and a prompt like "KE6RK de N8PGR>" and the link will turn around so that you become the sending station.. Proceed as outlined below "Communicating with WinLink".

For the KAM, the first thing we need to do after a hard reset is get the unit out of the "New User" mode. We may be, but it won’t let us set the tones so it's got to go. Enter the command INtface Term, then set the tones with the commands SHift Modem, then SPace 3000, MARk 2000, SPace 2200. (With the KAM the space tone must always be higher than Mark, even when being set, so setting Space first to a silly-high tone avoids a possible error message). To get into Pactor Standby mode, enter the command PACTOr (with no argument). You can monitor traffic on the air, get the frequency offsets figured out, etc. To get back to the KAM's cmd: prompt, type <ctrl-C> X (i.e. control and "C" keys together, then the "X" key alone). With the KAM, before calling another station, you first need to return to the cmd: prompt by doing a <ctrl-C> X. Next, find a WinLink MBO frequency, type <ctrl-C X to get a cmd: prompt, then enter the command PACTOR N8PGR (for example) to call the MBO station. If you connect, you will see a welcome message and then a prompt like "KE6RK de N8PGR>" and the link will turn around so that you become the sending station.

Communicating with WinLink: The best place to start is by typing the H command (plus Enter after each command), and WinLink will send back a command list. (Also in AirMail's directory as WinLink.txt if you want to study ahead). WinLink handles all changeovers, you don't need to do anything except type commands and text. LB lists bulletins on file, another handy command. To send a message, for example to your own email address, type SP NEXUS, wait for the prompt for "email address:", type your email address, wait for the prompt for "Subj/Msg:" then type a message subject followed by the text of your short test message. End the message with /EX on a separate line. When you are finished or bored type B (Bye) to quit. (Note that these are all WinLink commands - if you want to send a command to a PTC-II controller, hit the Esc key first to get a cmd: prompt (<ctrl-C> for a KAM). But once linked to WinLink, you don’t want to be sending commands to the controller).

If you need to initiate a disconnect (something WinLink normally takes care of when you enter the Bye command), for a PTC-II enter a <ctrl D> (or type Esc to get a cmd: prompt, then DD to force a disconnect). For a KAM, enter <ctrl-C> X to get a command prompt and then A <Enter> to abort the link.

If all that works then your controller is wired right and your transceiver is working. If there are troubles then there's a couple of things to check: If the transmit power level is too high (ALC off the scale) or too low then the transmit audio level needs adjusting. The PTC-II transmit level is adjusted with the FSKA and PSKA commands and KAM has a jumper (it's OK to check the manual on this). Also, stray RF sometimes gets into the computer serial cable or the audio cable to the transceiver. Adding one or more clip-on ferrites helps a lot as we outlined above.

 

Glossary
 
 
Amtor Amateur Teletype Over Radio, the first popular digital communication protocol which included direct linking between two stations with data acknowledgement and error checking. It is the same mode as commercial Sitor, and has largely been replaced by Pactor on the ham bands. 
APLink An acronym for Amtor/Packet Link, a DOS-based mailbox program by Vic Poor W5SMM and the predecessor to WinLink.
AX.25 A version of the X.25 protocol adapted by hams for VHF Packet radio, which allows multiple stations to share the same radio frequency. Data is broken up into blocks, or packets, which are transmitted and acknowledged independently. AX.25 packet is sometimes used at 300 baud on the HF bands but not with any particular success. 
Clover A higher-speed HF protocol developed by HAL communications, utilizing multiple-tone phase-shift encoding. Effective throughputs are similar to Pactor-II, and it will be long debated which is the better protocol although Pactor-II has clearly won the popularity contest.
DMB (See MBO) Digital Mailbox - An HF mailbox station for storing and forwarding messages, generally running WinLink software. 
DSP Digital Signal Processor, a specialized microprocessor for processing analog signals. Signals are converted to digital form and processed using various mathematical transformations before being converted back to analog form if required for output. 
FSK Frequency Shift Keying. A simple method of sending digital information over radio, where a binary "1" is assigned one tone and a "0" a second tone. These tones are called "Mark" and "Space" after RTTY practice, and are typically separated by 200 hertz on the HF ham bands. 
KAM A popular multi-mode controller manufactured by Kantronics. The current model is the KAM-plus (KAM+), and an enhancement board can be added to older KAM's to make them KAM-E's with the same functionality. The KAM includes all the basic digital modes plus Pactor and G-TOR, a proprietary 300-baud protocol that was never adopted as a standard by the MBO operators.
MBO Mailbox station - same as DMB - An HF mailbox station for storing and forwarding messages, generally running WinLink software.
NetLink A program written by Jim Jennings W5EUT that provides a gateway between a WinLink MBO and Internet email. 
Packet (See AX.25) The protocol used by digital VHF/UHF stations. A few HF stations operate Packet at 300 baud, but it is not considered reliable (at least by Pactor enthusiasts) and is not supported by WinLink.
 Pactor Pactor A digital radio protocol developed by a group of German hams in the early 80's, allowing faster and more reliable communications than Amtor. The name comes from Latin for the "Mediator". Pactor operates at 100 or 200 baud depending on conditions, with net throughput of up to 18 characters per second.
Pactor-II An improved version of the original Pactor protocol, also designed by SCS, the same group that did the original Pactor protocol. Pactor-II is a two-tone phase-shift system rather than FSK, and operates at basic rates from 100-800 baud depending on conditions. Net throughput is up to 140 characters per second depending on conditions.
PSK Phase-shift keying, the encoding method used by Pactor-II and Clover. Multiple frequencies (tones) can be used to transmit more information, and the phase of each tone is shifted to encode a binary "1" or "0".
PTC-II The Pactor-II controller from SCS, a powerful DSP-based controller that also supports all of the basic digital modes (including gray-scale weather fax).
RTTY Radio Teletype. Originally designed for electro-mechanical teleprinters, RTTY generally uses a 5-bit Baudot code and operates around 45 baud. There is no acknowledgement (except from the operator at the other end) and no error checking.
WinLink A Windows program for MBO's which allows simultaneous operation on VHF packet and HF Amtor, Pactor and Clover (with suitable controllers), and provides store-and-forward message handling. WinLink was originally written by Vic Poor W5SMM as a development of his APLink (Amtor/Packet Link) program, and has been extensively rewritten and developed by Hans Kessler N8PGR. 

References

For further browsing, check the following:

KE6RK's AirMail Home Page (News and downloads for "The Best Little Terminal Program in Texas", at least according to N8PGR)

The K4CJX Home Page (Steve's is one of the busiest WinLink MBO's in the U.S.)
 
The N0ZO Home Page (A WinLink/NetLink MBO in Lady Lake, FL)

The W4NPX Home Page (A WinLink/NetLink MBO in Charlottesville and a clever on-screen frequency calculator)

The W5EUT Home Page (Jim Jennings is author of the NetLink email gateway software)

The ZS5S Home Page (Joost's Radio Page is the home of the MBO Directories and Chirping MM lists, and his MBO in South Africa is a major player in the world-wide network)

The SCS Home Page (These are the guys who invented Pactor and Pactor-2 and have posted a lot of information about it)
 

(c) 1997, 1998 by Jim Corenman, KE6RK