21Mar01
Digital Operations, General
The FT-847 is designed to accommodate a variety of digital modes. There are two jacks on the back of the rig for
digital operations. One, the Data In/Out port, is for RTTY, PSK, MFSK, 300 bps Packet, AMTOR, and the like. This
port will only work on the HF bands. This port uses a 1/8" stereo plug carrying Data In to the rig, Data Out,
and PTT control.
The second port is for FM Packet on both 1200 and 9600 bps, and this port only works on VHF/UHF. Some have had a challenging time getting their rigs set up for digital operations. Pages 16 and 17 in the operating manual do explain many of the things you have to watch for, so you need to read these pages carefully. I do not have much experience in packet or with TNCs (just got on packet in November 1999), so some of the following discussions are directly from hams who have personal knowledge on how to set up digital operations properly.
Please note that the FT-847 does not have FSK capability; only AFSK.
03Jan00 Update: Jerry W4UK reported that he was having problems getting his automated mailbox (MBO) to work with Pactor on his PK-232. He had set up the interface as shown in the manual, but could not connect properly. Billy WA5RZQ wrote to say he had a similar problem with a KAM+, and he solved it by changing the Yaesu-recommended 10 mfd capacitor to a 0.1 mfd capacitor. Jerry wrote back to say that he swapped in a 0.2 mfd capacitor and now everything was working well. I have seen other references to a 0.1 mfd cap as well (but not specifically to the FT-847). Apparently Kim WB4LZQ suggested the same thing. Those having trouble using this port may want to consider this experimentation.
Open Mike Problem When in digital mode (and mike audio is supposed to be cut off)
Back in the beginning of 2000, there was a thread running where at least three hams reported that the mike audio is not muted when TXing via the Data In/Out port. In October, Andy M1MOD reported that he tested his mike audio when under data control and his mike was not muted. Stan K8SRB, on the other hand, reported that his mike audio is muted when under data control. Coincidentally, their serial numbers are very close to each other and begin with 9I25. Unless all the other rigs reporting on live mikes have the same production run, I'd guess the problem is spread across multiple runs. Al reported that he sent his rig to Yaesu to fix this problem and it came back with an added transistor, SMT chip, and a jumper wire.
Now we have the answer from Yaesu on the open mike problem when sending data. Evidently some radios do not respond properly when TXing via the Data In/Out port. Others seem to work properly. Thanks to Reid MI0BOT for sharing the jpg file he got from Yaesu on the fix. Basically, the fix involves adding a switching transistor to the circuit to force the mike audio cutoff when TXing via the Data In/Out port. I have included two JPG files. The first, courtesy of Gary N5IXI, is a nice digital photo showing where and how to install the fix on your AF-CTRL board. Click here for Gary's picture; it's 440 KBytes big. The second is an image from a Yaesu technical data sheet showing the fix both schematically and graphically. Be advised that this file is 886 KBytes large, though, and will take some time to load. Click here to view the image of the data sheet.
Finally, Andy M1MOD, sends along the following, describing the actual fix. Note that the transistor used appears to be a bit unusual. Yaesu UK sent Andy the transistor he needed; perhaps your Yaesu HQ will do the same. Andy said:
"Reid got a diagram of the fix from Yaesu and I contacted them and they sent it to me too along with the one component needed, a BA1A4M-T. Well done Yaesu - my rig is not within waranty but they sent me the part and a diagram so I could do it myself.
"I'm no expert on working on SMD components but I managed the fix by using my smallest soldering bit and looking very carefully. It is fairly simple as you just need to solder the emmiter and base of the transistor to two pins on opposite sides of the same chip and then a flying lead going around to a capacitor a few inches away. The only thing I had to do (apart form having to rework my soldering several times, was to undo a connector (J1029 I think) and move it and it's wires out of the way whilst I soldered.
"I bent the E and B pins to 90 degrees so the transistor stays flat (parallel with the board) and just clear of the board, and soldered these vertically bent bits to the legs of the chip. I finished of with a piece of insulating tape round the transistor and exposed leads just to make sure it doesn't touch anything conductive once the lid is back on.
"After I finished the MIC is fully muted when the rig is keyed via the data in/out jack - so the fix seems
to be 100% effective.
One thing to be wary of - I tried to find the component from a couple of the popular component sources in the UK
and it was not stocked - it seems to be a specialist item. I did check the specs on the web and it is not just
a regular transistor as it has two biasing resistors built in. When I had problems finding it I called Yaesu UK
and they where quite happy to send me one FREE along with a copy of the circuit diagram.
"All in all I'm very pleased to have fixed this problem without too much effort - I think if I'd had warranty I'd have thought again about doing it myself as the soldering is very tricky but then I'm not used to these tiny SMD type components - still I did it and it worked and the rig does not seem to have been too sensitive to static or heat."
Interfacing with Various Controllers
This section contains reports on using the FT-847 with various controllers for digital operations. Be sure to check out the Digital Operations, General FAQ as well. There are discussions for the following controllers: SCS-PTC IIe, PK-232, MFJ-1270, MFJ-1276, MFJ-1278, KPC-9612. Click on the one you want to read about. You can come back to this mini-menu by clicking your browser's Back key.
Hank K9LZJ reports that you will need to make some component changes to interface your SCS-PTC IIe to the FT-847. See the figure on p. 16 in the FT-847 Operating Manual; it shows a 2k resistor and a 10 mfd capacitor. He says that you will need to change the value of the 10 mfd. capacitor when using the AFSK interface with the SCS controller. Hank found that a 0.22 mfd, with a 2.7k resistor works well. He also suggests setting both the PSKA and FSKA levels to 120 mv.
Interfacing with the MFJ-1276 (and 1270)
I recently acquired this model. It's a 1200 baud VHF and 300 baud HF packet controller with PACTOR included. I installed both the VHF and HF features, one cable to the Packet Port and one to the Data In/Out Port. I used the setup as described in the FT-847 Operating Manual (10 mfd & 2k resistor) and everything works like it should on both bands.
At Mike KF6SWI's suggestion, I have reproduced two postings from Howard G6LVB on interfacing the MFJ-1278 to the FT-847. Perhaps you'll find them useful if you're trying to interface this popular controller. The postings are reproduced verbatim, with thanks to Howard.
"Sorry, by p-p I mean peak to peak voltage. Having re-read your original post I realised that you probably
don't have an (oscillo)scope.
Setting the Transmit Level voltage accurately without a scope may be a bit harder, but is still not too tough.
OK, I'm going to set up the MFJ 1278 _without_ a scope this time...
Assumptions:
o You're using the RADIO 1 port only for now
o You have your terminal or computer communicating OK with the MFJ1278, with a 'cmd:' prompt.
Procedure:
o Run the command MODE VP,1200
o Run the command RADIO 1
o Plug in the 5 Pin Din into the MFJ RADIO 1 socket and the 6 Pin mini-Din into the FT847 PKT socket
o Set your FT847 to a frequency that's not in use (or use a dummy load) on 2m or 70cm
o Put the FT847 is in FM mode
o Turn the RF Power on the FT847 right down to minimum
o Turn the RADIO 1 Transmit Audio Level (accessible with a small screwdriver on the left side of the MFJ 1278)
right down to the minimum (fully counter clockwise).
o Send the command CALIBRA to the MFJ.
o Press 'K' on your keyboard. The MFJ PTT should light. And the FT847 should transmit, with the DATA icon on the
display. If your FT847 doesn't transmit, check that your cable's OK on the GND and PTT connections. Having a Multimeter
or continuity tester will really help here.
o Keep in mind there's a 40 second or so timeout on the PTT from the MFJ, so if the MFJ PTT light turns off during
this procedure for no apparent reason, you need to press 'K' twice to get back into transmit mode.
o Each time you press 'K', the MFJ and FT847 should alternate between transmit and receive.
o Whilst in transmit, adjust the RADIO 1 TRANSMIT AUDIO LEVEL slowly upwards until the FT847 stops transmitting.
For mine this is only about 1/10th of a turn or so.
o Now turn the level back down _very_ slowly until the radio transmits again. You'll probably see there's a time
when the DATA and TX icons on the radio display flicker as you're just on the edge of the radio's acceptance level.
You want the setting _just_ slightly less than this 'acceptance' level.
o Press 'K' a few times to check that the radio switched between transmit and receive correctly.
o Whilst in receive mode, press the space bar once. This switches to the second packet tone.
o Press 'K' a few times again to check that the radio correctly switches between transmit and receive.
o Press Q to return to the MFJ command mode, and remember to turn your RF Power back up if necessary."
...And the second posting...
"You may want to try a couple of other ideas I discovered whilst playing with the MFJ/FT847 combo today:
o Check menu setting 23 on the FT847 (PKT RATE) is set to 1200. Although you'll be able key the FT847 transmitter,
the unit will not transmit any audio at 1200bps packet unless the PKT RATE is set to 1200.
o Connect to yourself, listening to your 3rd harmonic signal using full duplex:
- Switch to the SAT mode, set the TX freqency on 2m to, say, 144.950 and the RX frequency to 434.850 (this is the
3rd harmonic of 144.950). These frequencies are OK in the UK, but you may want to check your local bandplans, or
use a dummy load.
- Turn the RF Power right down
- Switch both RX & TX to FM
- Set the MFJ to MODE VP,1200
- Set the MFJ to FULLDUP ON
- Try connecting to yourself, eg 'C G6LVB'
- You should hear the tones being transmitted, and you should be connected.
- Disconnect by pressing Ctrl-C and then enter the D command
- Switch off full duplex with FULLDUP OFF
- Reinstate you RF Power if necessary and then try for real.
o Try the digital loopback technique on P38 of the MFJ manual if the above didn't work."
Mike KF6SWI sent along a schematic for interfacing the FT-847 with the KPC9612. You can click here to see Mike's schematic and some notes about how to connect the KPC9612.
22Feb00 Update: See also the discussion Operating Packet Port at 9600 bps for some hints on interfacing 9600 bps modems.
Issues hooking up 9600 bps and 1200 bps TNCs
A number of people have faced a challenging time getting the rig and their modems to operate easily at 9600 bps. In some cases, the required signal levels to drive the FT-847 at 9600 bps have been difficult to set up. Alan WA4SCA has helped me considerably to understand the issues. He, in turn, was reporting on the work of Jon KE9NA, Mike N1JEZ, and Dave ZL2AMD, as well as others. Thanks to all these hams!
Basically, here is the information. On receive, the incoming (RX) signal is routed to both the 1200 bps and the 9600 bps pins on the packet jack on the back of the FT-847. Before they get to these pins, they are massaged by the FT-847 so they present the appropriate signal levels and bandwidth. So, to receive 9600 bps, you would connect your TNC or modem to pin 4 on the packet jack, and to receive 1200 bps signals, use pin 5 on the packet jack. It does not matter what you set Menu #23 PKT RATE to in order to receive! The pin you use determines which speed you will get. Menu #23 does nothing!
On TX is where things get more interesting. If you set Menu #23 PKT RATE to 1200, then the modem's TX signal coming into Pin 1 on the FT-847 packet jack goes right into the TX circuitry where it is amplified 18 times, per David. On the other hand, if you set Menu #23 PKT RATE to 9600, then the signal coming into Pin 1 is fed through an attenuator/buffer before going into the TX circuitry. Alan reports that there is as much as 50 times attenuation of the signal when Menu #23 PKT RATE is set to 9600. So, all signals are connected to Pin #1 and they're attenuated and buffered if you have Menu #23 PKT RATE set to 9600 and they're not attenuated and buffered if you have Menu #23 PKT RATE set to 1200.
Depending on your modem or TNC, you have the option of feeding the FT-847 a fairly high signal level (so, set Menu #23 PKT RATE to 9600 to attenuate it) or a much lower signal level (so, set Menu #23 PKT RATE to 1200). According to Alan, the only function of the Menu #23 PKT RATE is to switch the attenuator/buffer in or out of the circuit. Dave reported that there is circuitry in the buffer that will inhibit TX if there is too much drive into the FT-847 when "in 1200 mode" (Menu #23 PKT RATE set to 1200). You will want to keep this in mind when trying to use the 1200 setting to reduce the drive requirements from your modem. You definitely do not want a high level signal when you have Menu #23 PKT RATE set to 1200.
There is still balancing that must be done, of course, but I hope this will make it easier for people to hook up 9600 bps with their FT-847. Keep in mind that the rig is apparently performing to spec for both speeds, but individual modems and TNCs sometimes have other requirements or users want different settings for other purposes.
Anyone with additional information or hints is invited to send them along to me. k1uc@amsat.org.
In order to use your sound cards for many of the HF digital operations, you will have to build or buy a simple interface between the rig and the PC's sound card. Essentially, you need a means of getting RX audio to your PC, TX audio to your FT-847, and a means of keying the rig for TX. There are two general approaches for an interface.
1. Interface to Data In/Out port. This interface connects your sound card to the FT-847 via the rig's Data In/Out port. It also provides for PTT control via the Data In/Out port. This port is intended for this purpose and has one key advantage: the input and output levels do not vary as you adjust mike gain or volume control. The interface for this method consists of proper isolation between the PC and the rig to prevent ground loops, as well as providing a means to key the rig from your PC. One "feature" of the Data In/Out port is that you must use the PTT on the Data In/Out port for keying your rig or no data will be passed through for TX. Also, when you use the PTT on the Data In/Out port, the mike audio is cut off (but see the Open Mike discussion above). Once you set up this interface, you can leave it in place and continue to use your rig for voice or CW.
The interface is something you can buy or build with a small number of parts available from most Radio Shack stores. You can see a schematic for an interface that I've built twice and works fine with a Soundblaster AWE64 (and 16) and the FT-847. I have used the interface for PSK31, SSTV, MFSK, and RTTY modes, and it works fine. I built the units up on perf board or one of the small boards that Radio Shack sells. Update 21Mar01: Some hams have found that they need to replace the 10 mf capacitor on the schematic with a 0.1 mf capacitor to avoid relay chattering when releasing from TX in PSK31. I assume this is related to the properties of the RS-232 port.
There is another type of interface, that involves using an optoisolator instead of a transistor for the PTT (as in the schematic link mentioned above). You can see the diagram at http://www.packetradio.com/sb16rads/ft847dio.gif and it is done with a "pictorial" schematic that's very clear.
One commercial unit is the RASCAL from BuxComm (aka Packetradio). Ray W8RD has provided pictures of the Rascal, both the kit as delivered as well as assembled. This unit uses the Data In/Out port for the interface. The unit is sold primarily as a kit, although you can get it assembled, in some cases. The price of this unit is quite inexpensive and it comes with all the cables you will need to hook it up.
Also, see also David AD6KI's schematic for an interface that does not require a dedicated COMM port for keying the rig when using the Data In/Out port. Click here to go to this discussion.
2. Interface to Mike & Headphone jacks. This type of interface avoids use of the Data In/Out port completely.
Transmit audio goes into the FT-847 via the mike jack on the front panel and receive audio leaves the FT-847 via
the headphone jack or some other audio output from the FT-847. The main plus for this interface method is that
at least one commercial unit is available that will get you going quickly. Some drawbacks to this method are: you
will need to carefully manage your mike gain and volume control so the interface works properly.
The Rigblaster, from West Mountain Radio, is one of the commercially available interfaces. It provides the level controls you need as well as an extra mike jack that you can (permanently) plug your mike into. The unit does not come with all the cables you need, just the custom cable that goes from the Rigblaster to your mike jack. The remaining cables are typically common 1/8" stereo patch cables with male plugs on the ends. You can get these from West Mountain Radio or from Radio Shack. This unit seems to me to be a bit on the expensive side, but reports from users have been enthusiastic. "Easy to set up," they say.
Setting proper levels on your sound card is challenging but important to a good implementation. There's no easy
way to instruct how to do that other then to suggest that people learn about the sound card's features and request
feedback from other hams you communicate with using digital modes. One caution: most people have been surprised
at how low they have to set the sound card settings to avoid overdriving in PSK.
"DOX" (Data operated Transmit Control) Interface by David AD6KI
David AD6KI, the author of the "DOX" interface in the September 2000 QST, has kindly provided the schematic and a discussion for the interface. Click here to see the schematic in PDF format (you must have Adobe Acrobat Reader to view it) or click here to read the discussion from QST (also in PDF format). Note that the schematic as shown in the QST article is incorrect for the Speaker Out Tip & Ring; the schematic shown here is correct. This interface is interesting because it doesn't require a dedicated COMM port to key the rig; it uses the audio signal to key the rig. Thanks to David for providing this and to QST for permission to reproduce it.
This interface uses the energy in the TX audio to trigger the rig into transmit, and saves having to build the little 1 transistor connection to a COMM port. Of course, it also saves a COMM port, which are always in short supply.
Interfacing FT-847 to IBM ThinkPad with no RS-232 port
Chuck W5USJ wrote to say he successfully hooked up his FT-847 to an IBM ThinkPad model that had no RS-232 port and minimal sound controls. He sent in a schematic of how he hooked up the two units; click here to see a pictorial of how he did it. I'll reproduce what Chuck said about his installation.
"The ThinkPad I have has minimal features for doing things with sound interface and it has no RS-232 port.
I used a converter from USB to RS232 that is working OK. I think I could have made a better choice of laptops but
this one was available at a good price 8^)...
"I'm using it with DigiPan and doing all the volume adjustments with the 847 headphone volume. The headphone
output jack on the TP is stereo but I connected both sides together. With all the isolation in the 847 there is
no loading problem. I use the monitor on the 847 to hear myself when I need to and can connect a speaker or headphones
to listen to the band when needed also.
"If you would like more details, let me know. I think most ops could figure it out OK though." Email
Chuck, if needed.
PSK31 on the FT-847
PSK31 is a new communications mode introduced in its current form by Peter Martinez G3PLX. It uses your PC in combination
with a radio to provide keyboard-to-keyboard communications. Please see http://aintel.bi.ehu.es/psk31.html
if you would like to learn more about the PSK31 mode.
The FT-847 is well suited for use with PSK31. You will need to build an interface first to use the Data
In/Out port for PSK31 (you can't use the VOX method of interfacing because there is none on the FT-847). Click
here to see a schematic on one way to construct the interface for use with a sound
card. Also, click here to read about an alternative interface which does not require the use
of a dedicated COMM port to key the rig.
There is one very nice feature available (and which may be unique to the FT-847) for this mode, which is the
0.1 Hz tuning rate. You can adjust this tuning rate on Menu #2 MIN-FREQ. PSK31 signals are very narrow and it's
very easy to tune right past them, plus a bit challenging to tune right on them. I find it hard to tune signals
properly on a 1 Hz rate, but the 0.1 Hz rate is easy.
Once you have built the interface, you can get right on the air.
Update 01Jan01: All of this discussion applies to MFSK and other narrow band digital modes as well as PSK (of which there are now some variants).
| 1. | Set your main VFO to USB (PSK31 is typically used on the upper sideband on all bands, while MFSK follows the usual conventions for USB/LSB) and tune in the signal you want to copy. |
| 2. | Press and hold for 0.5 seconds the A-B button to load the frequency and mode into your sub VFO. |
| 3. | Now press the SPLIT button. The display will show a small RX-TX image on the display. (If this shows, instead, a TX-RX, simply press the REV button to turn it around.) You are now ready to TX on the sub-VFO. |
| 4. | Press the CW button and the main VFO will be tuned to the receive frequency. Now you're receiving in the CW mode and can press the NAR button to insert your narrow CW filter. Note that you do not change either VFO at any time in this process; everything's automatically matched for frequency. |
That's it. Note that you cannot change any VFO setting; if you do, you will then be "unsynched" on
your RX and TX frequencies. Also, don't forget to disable split operations (by pressing the SPLIT button again)
or the next time you transmit, you will be on the frequency and mode on your sub-VFO, not the frequency/mode
on your main VFO!
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