NUE-PSK Digital Modem
Answers to your Frequency Asked Questions!
How many Hz are
represented by each vertical line on the display?? How many lines wide
would represent an "ideal" signal? How many lines wide would be enough to
indicate that the transmitting station might be overdriving their radio?
The display covers from 500Hz to 2500Hz in 128 steps. This equates to 15.625Hz per vertical line. An ideal signal (idle) would be 2 lines wide. When sending data, the width is greater since additional sidebands are generated. However, since the vertical scale is logarithmic, the width can be even wider yet just above the baseline. When the peak is several lines wide, the signal is probably being overdriven at the transmitter (or possibly in the receiving stations receiver).
Some of my contacts are asking how I'm copying their signal and what the IMD is, etc. I was told mine was 19. I assume they meant -19 but how are they measuring it? Is 19 good or bad?
An IMD of -20 is
generally considered good. -30 is excellent. An IMD of -19 could mean that
you are slightly overdriving the transmitter audio input. Try turning down
the TX Audio control slightly. On the other hand, an IMD may not be
accurate when significant noise is present. IMD is calculated using the
strength of the idle signal (ignoring any sidebands) as a reference. The
ratio of the strength of the first pair of sidebands outside the desired
idle signal to the desired idle signal, in dB is the usual quoted IMD. -20
dB means that the undesired sidebands have a power level that is one
percent of the desired signal. -30 dB means that the undesired sidebands
are one-tenth of a percent of the desired signal.
At -10 dB, the undesired sidebands are 10 percent of the desired. If the noise level is significant, it may be impossible to determine accurately the level of the undesired sidebands. Instead, the software may be reading the noise level (at the frequency where the undesired sidebands are expected to be found) instead of the undesired sidebands. If the noise at that frequency is stronger than the "undesired sidebands", an erroneous IMD will be calculated. For example, it might report -19, when the actual IMD should be -25.
The measured IMD at the TX Audio output of the NUE-PSK modem is about -50 dB. To achieve a transmitted IMD of -20 to -30 dB requires a "linear" transmitter. Overdrive of either the audio, or rf, portion of the transmitter can result in nonlinearity and a reduction in the IMD of the transmitted signal. On most rigs this means that there should be little or no ALC indication when transmitting. ALC readings usually indicate that the peaks of the transmitted signal are being reduced to control the transmit power level--this can lead to nonlinearity. Consequently, it is recommended that PSK power levels be set below 40 percent of the rated power of the rig. I usually tune my rig for normal rated power on CW/SSB with the power control set for 100%. I then adjust the audio level from the modem to obtain a power level that is 10 to 25% of the rated power. For example, with my 5W FT-817, I set the audio level to obtain a power of about 1 watt when using F12, or 2 watts when using F8. (F12, with no keyboard or macros, transmits the "idle" signal. F8 transmits a CW signal. The CW power is about twice that of the PSK idle signal)
Missing callsign in the
macro? Having entered various macros containing my callsign, I
toggled to TX to send my macro, and I got a reply from a Dutch station. I
then noticed that I had still my portable callsign stored under Ctrl-M.
I changed this entry Ctrl-M, but now there is no callsign appearing
when the macro is run. This applies to both savings Ctrl-M and Ctrl-T.
(I type hb9zap and close it with < CTRL-M >. The ALT-M and Alt-T remains
Is the modem in receive mode when you type the callsign, followed by Ctrl-M? You cannot save a callsign, either your own, or "theirs" while in transmit mode. Your callsign is saved in EEPROM (using Ctrl-M), while "theirs" (using Ctrl-T) is in data memory. This means that "theirs" will be lost when cycling power. However, your callsign should remain in EEPROM when the power to the modem is removed.
RF getting into the modem and causing problems?
You might have RF
getting into the keyboard controller via the keyboard cable. Some
keyboards have cables that are not shielded. If this is the case, you
might try a Radio Shack clamp on RFI choke (Split ferrite toroid--not
exactly round--it's square).
If you don't have a good counterpoise, you may have excessive RF voltage near the transmitter and modem.
My IC-706 doesn't have a 6-pin mini DIN jack on the back for the data connection!
If you have one of
the earlier 706's (not the MkIIG) you must use a 13 pin DIN connector for
the modem data connection to the rig. The IIG has both 6-pin miniDIN and
13-pin DIN connectors. So it sounds like you need a cable with a 13-pin
connector on it if you have an early model 706.
TS-440 radio connectors
The 6-pin DIN (not
mini-DIN) ACC1 on the TS-440 is for computer control (basically
RS232/TTL), not for connecting an AFSK modem or TNC. You must use the
13-pin DIN connector to connect to the NUE-PSK modem. (The connections to
the 6-pin ACC1 are shown on one of the schematic pages.)
The newer TS-480 uses a 6-pin mini-DIN connector that uses the same hookup as the Yaesu FT-817/857/897 rigs.
I'm not getting the correct responses when I run the prog program for connecting to the modem serial port
Which interface are
you using? Sparkfun? Wulfden? other? And if you are using the Sparkfun
CP2102/3, do you have the driver installed?
Did you verify that the com port you are using (com3) shows up in the Port information in Device Manager? And, is it the port that you have the programmer attached to?
The error message that you report is because the bootloader code could not establish a connection to the serial port you specified. You can download Application Note AN1094 from the Microchip website. It lists all of the error messages that the bootloader software can generate.
What is the "Prog" program for the PC? Can it run on Linux?
"Prog" is a special
program that knows how to read Intel Hex files and to handshake with the
bootloader that is programmed into the NUE-PSK modem, while transmitting
the hex file to the UART in the modem. It supports a few commands such as
Read from a selected location in the dsPIC Flash program memory space, and
Read from EEPROM (our dsPIC does not have internal EEPROM). Since it runs
in a "DOS Window" on the PC, if the Linux system can emulate the DOS
Window, it will likely run on that system.
"Prog.exe" is "16-Bit Flash Programmer.exe" that may be found on the Microchip Website. It is described in Application Note AN1094. Source code for both the host (PC) and dsPIC are available from the website. Note, however, that the application note describes a bootloader placed in dsPIC program memory just about the interrupt vector tables. In the NUE-PSK modem, the bootloader code is placed at address 0x15000 and above. In addition, the dsPIC bootloader code has been modified to test for the presence of a button push before launching the bootloader. If a button press is detected, the bootloader is launched. The bootloader then waits for UART activity, for up to 10 seconds. If no activity is found, the Modem application is launched. If there is activity, the dsPIC bootloader and the PC host software "handshake" and establish communications between the two (at a 115.2kbps baud rate).
The program "16-Bit Flash Programmer.exe" can be run without modification. However, since the source code is available, it can be modified and recompiled. The windows code is in Visual C and C++. This code can likely be converted to be compiled with some of the Linux based development tools. Since I am not a Windows program developer, I have not attempted to anything with the host code. Instead, I used the compiled .exe code for this project.
In addition, the bootloader and the NUE-PSK code are treated as two separate "projects" in MPLAB, but in a single "workspace". This requires a non-standard method for generating code that will be loaded with an ICD2 (simultaneous loading of both the bootloader and the NUE-PSK application)
I hope that this answers some of the questions about "prog.exe". I can not claim ownership of this code as it was obtained from Microchip.
In the near future, we will provide a "Developer's Toolkit" that will have more information for those that wish to develop their own code for the Modem.
Making the Serial Cable
For all of you that are anxious to download new
software to the NUE-PSK modem--PLEASE DO NOT USE THE NUEPSK112A.HEX file
that is contained in the dsPIC Source Code zip file on the NUE-PSK
BEWARE! This file was not intended for use with the field programmer, but instead with the Microchip ICD2 programmer. If this file is used, you will wipe out the bootloader memory and will render the modem inoperable until it is reprogrammed with an ICD2.
We apologize for any inconvenience this may cause. If anyone has already tried this and found that the modem no longer works, please let us know.
Signals are not appearing on the modem as received from my transceiver
I suspect a
connection problem. Are you sure that the connector is fully inserted into
the Radio connector at the modem. These connectors are a tight fit and, if
not fully seated, may not have a good connection.
If you are sure that this is not the problem, can you try patching a signal from the earphone or speaker output of your rig to the radio connector on the modem? Connect the audio signal to pin 7 of the 8 pin miniDin receptacle on the side of the modem. Pin 7 is the middle one on the top row, when looking at the right end of the modem. Connect the ground of the rig to the ground of the modem. Pin 6 of the modem connector is ground. Pin 6 is the top left on the connector. Or, if you remove the cover of the modem, there is a ground test point near the upper right corner of the PCB. If you set your rig for a normal listening level, you should see the spectral display on the modem.
You need to have Modem Audio In connected to Radio Audio Out. Likewise, Modem Audio Out must be connected to Radio Audio In.
Recommendations for a nice, portable keyboard?
I have purchased a
BTC9118 PS2 keyboard from Fry's Electronics. It measures about 6" x 12".
Cost about $18. It works fine with the NUE-PSK Modem.
I also purchased the 2366 keyboard on EBay (from Hongkong). Cost $3 plus $10 shipping. It is a combo USB/PS2. Since it requires at USB/PS2 adapter (which comes with it), I decided to transplant the cable from an old mouse to the keyboard. This eliminates the need for the adapter. I have had no problems with this keyboard. However, there have been a few messages about possible problems.
The 2366 keyboard measures about 4" x 8.75". If you Google on "2366 Keyboard", you should find the eBay ads.
In addition to these two, I have used the Roll-Up keyboard from All Electronics, and another larger roll-up that I purchased from Discount Electronics in Austin, TX. The All Electronics keyboard is also a combo USB/PS2. It does work with the modem.
If you purchase a keyboard, and experience problems with it, please notify George, N2APB via the NUE-PSK website (www.nue-psk.
DIP socket. It is not soldered in.)
I also purchased and
regularly use the Parallax PS/2 keyboard (p/n 32351 at
The Cherry keyboard is small enough (not as small as the 2366), the key spacing/size is great and it comes with a moisture resistant shield. It's PS/2 only, inexpensive, and has been tested with the NUE-PSK.
Activating the modem's "Boot Loader" program
Turn on the modem
power switch while pressing the Select button. Hold the Select
button in only as long as it takes to turn on the modem power. Then,
within 10 seconds, press Enter on the PC keyboard to launch the programmer
code on the PC.
Holding the Select button, while powering up the modem, starts the bootloader code in the modem. It has a built in 10 second timer that will launch the modem application if no data is received on the serial programming port of the modem. Perhaps you held the Select button too long. The programming code that is run on the PC can also timeout if something prevents the modem from acknowledging the attempts to send info to it, such as no electrical connection, or the modem may not be running the bootloader code.
Holding the modem up at an angle for easier viewing
You might also want
to look at the "Clam Shell Mounting Bracket" at All Electronics. They are
adjustable, cost $1.50. www.allelectronics.
Now for all you cheapskates out there there's another business card holder stand also at Staples for $2.99 its made of painted folded sheet metal, and doesn't look anywhere as nice but does the job equally well.
Differences in keyboard current requirements
Most of the mini-keyboards that I have tested draw less than 5mA. Some of the early IBM keyboards could draw 100mA or more. It has been a while since I checked the current on my BTC9118 (6" x 12"), but as I recall, it was about 3mA. Of course, if the LEDs were illuminated, this current would be 30mA (or more) higher.
Please note that the
capacity of standard alkaline 9V batteries range from about 400mAhr to
625mAhr, depending on manufacturer. In addition, the terminal voltage of
alkaline batteries drops nearly linearly as they are depleted. If one uses
these in the NUE-PSK modem, and leave the backlight turned ON, the initial
discharge rate with fresh batteries will be about 60mA. As the terminal
voltage of the batteries drops to 12, the discharge rate increases to
about 85mA. Further depletion of the battery voltage causes additional
increases in the discharge rate to about 100mA when the terminal voltage
of the two batteries in series drops to about 9V.
Note also that rechargeable 9V batteries typically have a much lower capacity--<250mAhr.
If we assume a rate of 60mA, a 500mAhr battery could conceivably run for a bit over 8 hrs. However, at a discharge rate of 100mA, the best that could be expected would be 5 hrs. Therefore, I would expect that something close to 5 hrs for fresh batteries could be achieved.
Please refer to the QEX article for a chart showing the modem power requirement versus terminal voltage of the battery. Note that the current is significantly less when the backlight is turned off. If you are operating with internal 9V batteries, this is the recommended mode. If you want to run with the backlight turned ON, it is recommended that you run with an external Gel cell.
In addition, there are 9V lithium cells available (Ultralife) that have a much higher capacity, if internal batteries are required, especially if the backlight will be left ON.
Desire for keyboard-generated CW
If you want to run keyboard CW, you might want to take a look at what John Fisher, K5JHF, has done with his Morse Code Device. This little beauty, converts keystrokes into perfect on/off keying. John's board is only about 2" x 3" and uses a small Freescale microcontroller. It has a standard PS2 jack for the keyboard, and a few pushbuttons to control speed, etc. It also allows recording and playback of macros and runs for hours on a coin cell. I have used one for Field Day. It's an excellent device for the CW operator. One of the fellows in our local QRP club even installed one inside a keyboard. For information, check the AQRP yahoo group and John's files.
Caps Lock, Num Lock and Scroll Lock functions do not work on the keyboard
These are not
supported functions for the keyboard when used in the NUE-PSK modem. It is
up to the host (in our case the dsPIC) to determine whether to act on
those key presses. At this time, we have chosen to NOT implement these
features. During the "Power On Self Test-POST" of the keyboard you will
see the corresponding LEDs flash on and then off. This is part of the POST
for the keyboard. It takes a command from the host to make these LEDs stay
on. It is also up to the host to decide what to do when one of these keys
have been pressed. Since PSK actually sends faster (due to Varicode) when
using lower case characters, we chose to not implement Caps Lock. For the
few times when a Cap is needed, you can use Shift.
My battery gets hot!!!
How can I tell if the pcb mods were made at the factory?
A quick way to verify
the battery modification -
The modem loses the custom changes I make in Configuration whenever I turn off the power ... is this right?
This is expected. We are considering saving all user selected parameters in a future software update. At present, these settings are lost (except for the defaults) whenever power is cycled.
Can't seem to get my callsign entered into the modem memory.
While in RX, enter your callsign and then press Ctrl-M. Now press F11. You should see "de AB7OC" displayed on the screen.
Does the pre-fab "modem cable" you guys sell work with multiple radios?
Yes, the pre-made cable we sell works with Yaesu FT-817, FT-857, FT-897; Icom IC-706, IC-706, IC-7000; and the Kenwood TS-480 transceivers. We are considering making cables for use with other popular transceivers as well.
The Select pushbutton is too close to the edge of the hole in the top half of the case, and sometimes it binds.
You can adjust the position of the pc board within the enclosure, and hence the distance of the Select pushbutton to the hole in the case. First, remove the top half of the enclosure and loosen the nickel-plated screws on the bottom of the enclosure. While pushing the pcb toward the lower left direction, re-tighten those screws on the bottom shell. Next, loosen the screws holding the pcb to the standoffs on the top of the pc board. While pushing the pc board to the lower left, re-tighten those screws on the pc board. Put the top half of the enclosure on again and attach the four black anodized screws, while simultaneously biasing the top shell as far to the right as possible while re-tightening the screws. These actions will give enough clearance to the Select pushbutton to the edge of the enclosure hole, thus eliminating the binding condition.
Pressing the Pause-Break key on the keyboard causes the modem to reset.
Yes, this is a small bug in the modem software and it will be fixed in the next software update. Until then, refrain from pressing the Pause key - there is no related function for this key.
What is the PGA setting used for in the Configuration menu?
PGA stands for Programmable Gain Amplifier, which happens to be U7 in the schematic. This device can be set to different levels of amplification to better handle either low-level or high-level audio signals coming into the modem from the transceiver. Normally there is no need to change the setting of the PGA. The default setting is a voltage gain of 16. The PgUp key can increase the gain to a maximum of 32. The PgDn key can decrease the gain to a minimum of 1. In some cases, with a very strong signal near a weaker signal that you are trying to copy, reducing the gain may help in decoding the PSK signal. An alternative (which I frequently use) is to reduce the RF gain of the receiver, so that there is little AGC action due to the very strong signal. Because of the limited dynamic range of the electronics, reducing the gain, or the signal level of the input, can prevent "clipping" of the audio signal in the Modem. Generally, you will find that the Modem will demodulate signals that are barely visible on the spectral display.
When should the Hi-Drive jumper be used on the pc board?
The modem ships with the little red jumper only on one of the pins at the small 2-position P1 pinheader in the upper corner of the modem pc board. In this "off" position, the Tx Audio signal generated by the modem goes through an internal 10K resistor, thus lowering the audio levels delivered to the transmitter, making the drive level more appropriate for a transmitter's "mic" input. Jumpering the two Hi-Driver pins with the little red jumper effectively removes the 10K resistor from the audio path, thus raising the driver level to "line" input levels (~1V RMS).
How do I enter an F11 or F12 function key when using the "2366" keyboard?
Look at the bottom left corner of your 2366 keyboard. There should be a key with a Green "Fn" label. Notice that on the F1 and F2 keys there are Green F11 and F12 labels, respectively. Press the Green Fn key and the F1 key for F11. Press the Green Fn key and the F2 key for F12.
Why don't you provide the serial interface adapter by default with the modem?
None of the adapters
are made specifically for the NUE-PSK modem. Most have solder pads for
+3.3v, Ground, Transmit Data and Receive Data. A cable would have to be
soldered to these pads. The other end of the cable needs to have a 4
conductor plug on it that connects to the 4 conductor header in the
battery compartment of the modem. The Ground pad of the programming
adapter must be connected to the ground of the modem. The TxD line of the
programming adapter must be connected to the RxD pin of the modem. The RxD
line of the programming adapter must be connected to the TxD line of the
modem. If using the homebrew adapter show in the QEX article, the 3.3V
line of the adapter is connected to the 3.3V line of the modem. If using
one of the commercial adapters, the 3.3V connection to the modem can
usually be left unconnected. In fact, if the programming adapter receives
its power from a USB connection, or RS232 connection, then the trace
labeled "X" on the schematic in the Operators Manual should be cut.
If you don't have a background in electronics, I would suggest that you solicit help from a local ham that has experience in making up cables for connecting pieces of electronics together.
How does the AFC function work? When should I use it?
Here is a brief note
regarding AFC on the NUE-PSK Digital Modem. This should be of
particular interest to those that want to leave the Modem frequency fixed,
and tune the rig. AFC (Automatic Frequency Control) consists of two
parts: Capture and Tracking.
Capture is part of the Acquire routine. It is initiated whenever tuning has ceased for a fraction of a second, or when the Select button is tapped, or the "End" key on the keyboard is pressed. This reduces the initial error in frequency between the internal numerically controlled oscillator, and the audio frequency of the signal you wish to decode. Since many rigs can tune only in steps of 10Hz or greater, it is nearly impossible to set the frequency close enough for decoding to occur. The Acquire routine "captures" the desired signal by adjusting the numerically controlled oscillator to within a few Hz of desired signal. For this reason, the frequency displayed on the modem may not stay at 1500Hz. It may differ by several Hz. (Also note that the cursor can move only in discrete steps-- 128 to be precise-- representing the audio frequency range from 500Hz to 2500Hz. The frequency of the numerically controlled oscillator can, however, be set with much greater precision). If you are lucky enough to have a rig that tunes in 1Hz steps, it would be possible to turn off Capture, but it would likely take more time to get sufficiently close to the desired signal frequency for decoding to occur. Capture reduces the initial time delay before decoded characters begin appearing on the LCD.
Tracking is an optional feature. When AFC ON is selected (the default), the numerically controlled oscillator continues to track slow changes in the desired signal frequency. This allows for slow drifting, in either your rig, or the rig at the other end. If both rigs are "stable" then AFC OFF may be selected. I prefer to leave AFC ON.
Selecting AFC OFF does not disable the Capture operation.
German keyboard generate some swapped characters when displayed
I believe that the
problem is due to the keyboards generating a particular scan code based on
the position of the key, not the label on the key. Consequently the German
keyboard generates the same scan code, when pressing the Z key, as the US
keyboard does when pressing the Y key--and vice versa.
A table is used in the modem to convert the scan codes to characters displayed on the LCD. This table could be modified, but we would then have to keep up with multiple versions of the software. The simplest solution is to use the US keyboard. Modification of the table would require that you reprogram the modem with another version of the software. Do you plan on obtaining a serial interface to allow software upgrades? If so, we can consider providing a special version of the code.
If your keyboard "doesn't work"
The "basics" for expected keyboard operation
Software Developer's Kit ... coming soon
I need another standard (unterminated) cable like what you guys send with the modems by default
It's easy to get more
cables just like what we ship standard with each modem order. You can
order a 6' cable with the 6-pin connector on each end for about
$3.50+shipping, straight from the supplier we use: Jameco (http://www.jameco.
Connecting the modem to the Elecraft K2 transceiver
Right side of LCD display sometimes "goes blank"
We believe we have a fix for the "disappearing right half" of the display. It is a timing issue that comes about in the control of the chip selects for the left and right sides of the display. (The LCD has two controllers and we need to access each in quick succession when drawing a line or when writing text that crosses the midpoint boundary.) The fix is being tested, and if it works it will be included in the first software update that will be issued soon.
Checking out the keyboard and PTT line to the transceiver
Caution for using the +V wire in the modem cable
The +V line on the J3
"Radio" connector of the modem is intended to either:
1) provide the supply voltage of the modem to the transceiver, or
2) to accept supply voltage from the receiver (or external supply in the same radio cable.)
So in the case you describe of wanting the modem to supply power to an SSB transceiver, the main limiting factor of "how much current can be supplied" is the power switch S1, which is rated for 100ma at (30V). I suspect that S1 could safely handle perhaps about 300ma without problems at 12V, but I probably wouldn't want to go higher than that.
Now the good news is that the PSK-xx transceivers from Small Wonder Labs take about 100ma in receiver and 250ma in transmit. Or at least that's what my particular PSK-xx boards need when properly tuned and driven from the NUE-PSK.
The power could legitimately go "either way" in such a set-up. Since the whole idea of providing the +V line at the connector and in the cable is to eliminate one power cable in the portable station. That is, instead of having a power cord going from your external battery to *both* the transceiver and the modem, you just have *one* power cable going to the modem and have the modem cable supply power to the PSK-xx transceiver. Or you could have the power cord going to the transceiver and have the modem cable carry the supply voltage over to the modem.
Frankly, the second way is what I am set up to do if/when my two 9V batteries in the modem are exhausted. I use these the PSK-xx in my own portable PSK station and have the gel cell powering the PSK-20, and then have the modem cable supply the battery power over to the modem. This way, there's no concern about exceeding the current rating of the modem power switch, or any pins/wires in the cable. Plus this configuration also reduces the possibility of any "digital hash" from the modem from getting into the transceiver signals, although it's unproven (to me) that it's even a valid worry.
Two things to remember, though ...
1) You cannot have a power cord going to *both* the modem and the transceiver if you have the +V line in the cable connected. (Or if you do, just cut the "y" jumper on the modem pcb by J3.)
2) You ought not try powering anything from the modem when using the internal batteries. There's not enough current capacity in the batts to do anything except power the modem.
Is there a faster way to tune around the spectrum on the modem LCD?
My pre-fab cable seems bad - I don't get any signals to/from the rig
What is my actual transmit frequency when using the modem?
Popular PSK Frequencies"
Making the Serial Cable
You'll recall from our literature that the NUE-PSK Digital Modem may be upgraded to newer software in the field (that is, by *you*) simply by connecting the serial port of your PC to an adapter, which in turn plugs into the "Field Upgrade" connector in the battery compartment of the modem. Then with the proper program running on your PC (available for free download from the NUE-PSK website) you can send the modem the latest-and-greatest software we supply on this NUE-PSK website. This is a great way to keep your modem up to date with the latest features and bug fixes!
The USB or RS-232
serial interface adapter that you do get will probably need a cable to
connect it to the modem's "Field Programming" port -- the 4-pos'n, 0.1"
pinheader "P5" on the bottom side of the modem pcb, as accessed from the
battery compartment. You can fabricate a simple four-wire ribbon
cable terminated on one end in a mating SIP connector (Mouser
p/n 517-974-01-04, as shown on catalog page
Where do I get one of those serial interfaces?
Again from the QST and QEX articles, we mentioned that we do not provide a serial interface with the modem purchase because everyone's computer and way of operating are different. There are some great products out there and you can purchase specifically just what you need for about $20 from a number of good vendors. Based on what kind of serial port you have on your computer, you will want to purchase a USB-to-TTL interface or an RS232-to_TTL interface. Of course you could instead homebrew a simple one-IC version of the interface right from the schematic we provide in the manual and in the articles, thus saving you the purchase of the adapter.
Any way you get there, the interface adapters are available from ...
1) Wulfden at Hawk's Mountain -- http://www.wulfden.org/pa/index.shtml
2) SparkFun Electronics -- http://www.sparkfun.com/commerce/product_info.php?products_id=198 (USB)
3) HVW Technologies -- http://www.hvwtech.com/products_view.asp?ProductID=409 (USB), http://www.hvwtech.com/products_view.asp?ProductID=289 (RS-232)
Transmitter Settings Guidance for Digital Mode Operation on the FT-817
(May be similar on FT-857 and FT-897.)
1) Set the rig to a PSK31area of the band (e.g., 14.070 MHz) and set the rig operating mode to DIG (use arrow buttons above the display).
2) Set the rig's power level to be full 5W output. (Tap the F key, dial to the PWR MTR screen and tap A button repeatedly until you see the 3 bars blinking. Tap the F key again to exit.)
3) Select "PSK31-U" in rig menu #26 DIG MODE. (See the "Note" paragraph at bottom.)
4) Set the "Digital Mic" level to 50 in rig menu #25 DIG MIC.
5) Connect the rig RF output to a power meter with a dummy load attached.
6) Put the modem into TUNE (press F8) and adjust the TX Audio control to obtain about 3 watts of output power. Press F8 again to turn off the modem TUNE mode. (Since TUNE produces a CW signal, the BPSK signal will be somewhat lower on average, but will peak to this level at times.)
7) Use the CONFIGURE menu of the modem (press-hold the Select pushbutton) to read the Tx Audio level. It should be in the range of 15-20% at the default, power-on modem frequency of 1500 Hz.
If You Don't Have a Power Meter - You can also adjust the Tx Audio output to the proper level by viewing the ALC meter bars when the modem is in TUNE mode. Starting with the Tx Audio control fully counter-clockwise, turn it up slowly until you just barely see the first ALC bar appear, then back it off slightly until it just disappears. This should also yield the same 15-20% Tx Audio reading in Configuration as obtained in step 7. (Make sure you are still using a dummy load.)
Determining Signal Quality -- If you have an additional receiver, you could use Digipan on it to view the waterfall and get an IMD reading on your modem-generated signal. (Use an attenuator or disconnected the receive antenna to ensure that you are not overloading the receiver.) A reading below -25dB indicates a good setup of the modem and transmitter. You might try adjusting for great power output in step 3 above if you can verify that the signal has an IMD reading of least -20dB and set up to monitor the quality of the BPSK signal, you should not try to go much higher than 3 to 4 watts in TUNE. It might be possible to run higher power, say up to 4 watts in the TUNE set above, but only if you can verify an IMD of -20dB or less.
Note: Convention seems to suggest using "PSK31-U", as recommended in step 2. This way the actual operating frequency is just the sum of the audio frequency as shown on the modem, and the frequency shown on the dial of the 817. If you use xxx-L, you have to subtract the modem displayed frequency from the frequency on the 817 to get the "true" frequency.
The batteries won't fit!!!???
The standard 9V
batteries do indeed fit, although admittedly it's a tight fit and you need
to angle them into place -- no force required (and no hack saw!), but just
a little trial and error. We've put together two resources that might help
you and others in the future when it comes to installing the batteries.
1) Web Page -- Description and close-up photos showing the technique. Even has a little bit of the background on our unusual choice of batteries for this project.
2) Instructional Video -- A highly trained and NUE-certified professional is shown installing batteries to the NUE-PSK Digital Modem.
Good luck, and Power On!
Programming the Macros
The Macros section in the manual might be a
little confusing to the uninitiated. Here is some simple guidance on
programming macros into the modem ...
Turn off the modem.
Turn on the modem.
Enter your callsign on the keyboard.
Press Ctrl-M to record your call sign.
Hopefully you will see "de [your callsign]" without the extra callsign.
F11 displays the CWId string (assuming that you have recorded your callsign as noted above).
When you record your callsign, using Ctrl-M, it adds the "null" character to the EEPROM after your callsign.
If you have previously recorded your callsign, at Powerup, the modem copies that callsign, along with "de" into a RAM location for use as the CWId string.
If the above works, you should be able to re-record your Macros
Use Alt-Fn to erase the Macro.
Ctrl-Fn to start recording a new Macro.
F9 to stop recording.
A note about the EEPROM. Once it is recorded, it stays until overwritten. When you "erase" a Macro, you are really just writing a "null" character in the first location allocated for that Macro. The "null" character is used as an "End of Macro" signal. Ending Macro recording with F9, simply writes a "null" character after the last recorded character.
Page last updated: May 2, 2008