NOTE:- PLEASE CHECK AND UNDERSTAND EVERYTHING.TAKE ALL THIS AS A GUIDE, I MAY BE WRONG SOMEWHERE.
CONTENTS OF THIS PAGE:-
Use one without a USB connection.
Interfacing to a Receiver for use as a Panadaptor My FT840 used as illustration.
Using the Ensemble without a USB connection.
The reason for doing this is to enable the frequency to be set, then remove the USB connection.
For data modes or other purposes a single frequency may be used for a long time.
If required CFGSR could be used to set a start frequency so no USB is needed at power-up.
This shows the RXTX Ensemble. It can also be applied to the RX version.
Below, an additional regulator for supplying power to the Si570 and USB AVR.
Looking from underneath the hole for the mounting bolt was drilled between the two ground planes.
I relieved the corner of the USB plane with a sharp knife and used an insulating washer under the bolt head.
I soldered 0.1uF capacitors across the pins. The 12 volts supplied by the enamelled wire from the top, 5 volts sent to the switch on the yellow wire. Centre pin grounded.
The wires to the left go to a frequency counter, connected to one of the QSD/E lines. This indicates the centre frequency. I find that on some frequencies spurii are picked up so be careful!
Below, the 12 volt tap and an extra resistor to feed a red TX LED. See lower down this page. TX and RX LED Indicators.
A track carrying 12 volts passes close to the bottom of R41. I just scraped it and connected there. Another place to pickup 12 volts is the hairpin of D4.
To keep the 7405 a little cooler a resistor of, maybe 33R 0.5 watts could be put in series. Use Ohms law, my 12.4 volt supply connected directly does not heat the regulator too much. Another alternative is to use a small heat sink. You may not think this necessary but I like to keep things cool.
Another option for the 5 volt supply is to replace the small 7805 with the larger version. R52 would need to be reduced, maybe 27 Ohms and 1 watt rating. A heat sink may be considered, if you use long leads to move the regulator then extra 0.1uF capacitors may be a good idea.
Careful consideration is required regarding switching between the two supplies. It would not be a good idea to connect this extra 5 volts to the USB 5 volt supply.
Where the USB power is cut depends on what you require.
I show two different ways, just one cut is required. The first one was a mistake but does allow the RXTX USB to be removed after frequency setting. You may think this cut is easier to make.
Another way has occurred to me. If you are ingenious a mechanical lock could be devised. I am thinking of a pivoted cover for the USB socket. This could be arranged so that a single pole slide switch could not be operated unless this covered the socket. Just a thought.... This would only work for presetting with CFGSR.
Here I have cut the track next to R5. This cuts the USB power input to the Si570 BUT leaves the AVR powered and controlled by USB. NOTE THIS METHOD CAN ONLY BE USED ON THE RXTX VERSIONS. Removing the USB leaves the Si570 on its set frequency. If power is removed in this state then the Si570 will start at its default frequency 56.32MHz. If USB is reapplied the Si570 is reset to the frequency set in the AVR.
The enamelled wire is soldered to C1, this point goes to the AVR and 3V3 regulator. The wire goes to the common of a two way two pole switch. This is common to both options.
Ignore the three other wires, parallel port control of the Si570.....
Here the USB power is cut to the left of R3 just behind the USB socket where there is a short track going to the bottom of R3. This is probably the best way, and must be used with the RX otherwise the ABPF selection will not work.
In this case when powered from the internal regulator the Si570 will start at the frequency preset in the AVR by CFGSR. As the AVR is powered by the internal 5 volts removing and reinserting the USB has no effect except that USB control is restored.
The orange wire is connected to the bottom of the USB socket, taking 5 volts USB to the switch.
The blue and green wires are the two ground planes, connected by the switch when internal power is selected.
Switch:- 2 pole 2 way.
One section. Centre:- Common to C1. Internal 5V/External USB 5V
Other section joins the two grounds in Internal position.
To use the RXTX without a USB connection a different PTT method is required. This method may be useful for other purposes. The normal USB control of PTT is not affected.
A transistor is soldered across the optoisolator.
Almost any NPN may be used. Here the collector is the centre pin soldered to the left (collector) of the optoisolator. The emitter to the right (ground connection).
The 47K is connected to the base. The hole drilled where nothing is under the board gives some mechanical strength for the connection to the green wire.
This goes to the COM port, usually DTR or RTS through a diode.
I use a 4 port USB adaptor with a FTDI chip. Plenty of COM ports for multiple Softrocks.
The additional 24K resistor seen on the picture near the top of this page is connected to the hairpin of R37, S12v. This goes to a red TX indicator LED.
Another 24K from the hairpin of D4 goes to a green power on indicator LED.
24K suits my LEDs and brightness requirement.
A similar subject, add a TX relay as well. http://groups.yahoo.com/group/softrock40/files/G8VOI/
Ensemble RXTX IQ Swap links http://groups.yahoo.com/group/softrock40/message/69627
My Ensembles have TX crossed, RX straight. I confirm that this works with all versions of PSDR and Rocky. CHECKED!!!
But it is always the responsibility of the user to check operation, understanding what effect these links have.
I usually make my own Softrock cases out of copper-clad PCB material. The best way is to isolate the Softrock using Tony's spacers and keep the connectors isolated. I then ground this case to the antenna ground.
Normally a KM5H aluminium case is not grounded. The supports Tony uses do not provide a ground path, indeed the copper around the PCB holes is not grounded.
It seems a shame to have an ungrounded metal box. Grounding is probably not necessary in most situations but seems to be desirable
and might sometimes cure a problem.
To do this with mine I removed the angle bracket for the top screw at the antenna socket end.
Both the top and bottom of the case will need the paint removing where this bracket contacts.
When replacing this bracket I put a solder tag under the fixing nut.
I removed the PCB, soldered a wire to the antenna socket ground and to the solder tag.
For best results remove the other angle bracket and similarly clean off the paint.
Leif, SM5BSZ suggests connecting both the Softrock ground and USB ground to the case with 0.1uF capacitors. He drills the case for the capacitor grounds. No direct connection to cause ground loops. To avoid common mode signals on the antenna cable another 0.1uF between antenna ground and Softrock ground.
A couple of boards I used to take 47.05MHz IF from my FT 840 for a Softrock panadapter. (https://sites.google.com/site/g4zfqradio/hdsdr-if-pano)
To avoid de-tuning the IF a buffer will be needed, a high impedance input and mounted very close to the tapping point. I used a JFET source follower.
Signal Levels:- I have roughly measured the signal level from my FT840 at the output of my source follower. The signal is taken just after the first mixer. It is at a low level, approximately the same as at the antenna input. (I measured 1dB more.) The Softrock is relatively insensitive at 47MHz, especially using "subharmonic" mixing. A MMIC amplifier was used. I also tried a RTL dongle, this worked with just the JFET buffer. A Funcube dongle also does not need amplifying. The Pro+ is needed for the FT840 but for rigs with 70MHz IFs then it could be a good use for the original Funcube dongle.
The boards are ordinary copper-clad, the lands made by cutting with a broken mini hacksaw blade.
Above, the JFET schematic. Almost any N channel depletion JFET may be used. Adjust the R bias so about 5-10mA flows. For the 2N4416A 270R is about correct.
The MMIC can also be almost any. Adjust R bias so the recommended current flows, maybe about 50mA.
The MMIC I used has about 20dB gain, that was about right for my usage. But may well be too much for other MMIC/SDR combinations, an attenuator after the MMIC may be needed.
FITTING TO MY FT840
I do not remember my selection of the tap point. It looks as if I drilled my hole to use the connection to the filter? But I am not certain if this is the best point.
G4HUP http://g4hup.com/Orders.html#PAT favours AFTER the filter. I have not tried this but I'm sure that 96KHz coverage will not be achieved satisfactorily.
I include the pictures below as a guide only.
"X" my hole for the 5pF capacitor.
Here is my 2nd IF tap at 8.25MHz. The plug I used has 3 contacts, the unused one hangs off the end. The two end pins of the FM unit connector are used, the yellow component is a series isolating capacitor. Remember this way will only give a narrow display as it comes after the roofing filter.
http://sites.google.com/site/g4zfqradio/add_lpf A way to install the additional LPF for RXTX models.
http://sites.google.com/site/g4zfqradio/srlitemod This shows how to add USB control to a Softrock Lite or early model. It also shows some of the crazy ways I've done that.
More Softrock related pages.