SoftRock RXTX V6.3 Construction                                           Last 5/9/2011

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This page was created to document my project to build and operate a SoftRock RXTX Version 6.3 Software Defined Radio. Extensive construction details are available from the various SoftRock user sites and Yahoo reflector.

The SoftRock began as a winter project, I've built a number of rigs both from scratch and kit with good results.  When the SoftRock 40 receiver first appeared on the scene I didn't react fast enough to get one of the originals.  The RXTX Version 6.3 was the next model that drew my interest so an order to Tony Parks KB9YIG was quickly mailed off.  In the end it was turned out to be a great project, complex but the build instructions are very good so it worked on power up, well not that easy  because numerous sound card issues and software experience had to be overcome. 

The following paragraphs describe some of my experiences, not all and not always in detail. 

Although the bare module with switch controlled center frequencies will work on CW, PSK and SSB the frequency range is limited. Adding the I2C USB connection to control the SI570 DDS (see Note-1) and modifying ROCKY.INI adds vast frequency flexibility.  Other additional modules include a FCC-1 digital frequency meter to monitor the output frequency and power, a Tony Parks I2C USB interface to control the SR SI570 frequency base, a HFProjects PA-100 5-15 watt HF amplifier, and an external USB Audigy 2NX to process the I-Q signals. The Audigy is updated with Creative Labs 2004 firmware for better operation.  After weeks of learning how to use  ROCKY and PowerSDR software,  10 contacts from Asiatic Russia to the Eastern Canada were completed within a few days.

May 24, 2011: To date over 60 PSK31 and CW contacts have been completed on 40, 30 and 20 meters with output from the HFProjects PA-100 from 5 to 12 watts.  Rocky SDR software seems best for my operation as it works fine on CW and PSK31.  At first it seems features in Rocky are pretty slim but read the Rocky documentation a couple of times to find how to use the A/B VFO and filter bandwidth.  Simon Browns SDR-Console for Receive works fine, installs almost instantly too.  PowerSDR SR40 and PowerSDR I-Q work fine with VAC and Simon Brown's Ham Radio Deluxe and DM780.  Setting up VAC was not too hard but it messes up the internal sound card for normal Windows functions.  DM780 digital and SSB require 3 sound cards; one for transmit and Receive IQ, one for the loud speaker and Mic, one for DM780.  I use a Logitec USB Headset for the human side , it works without additional drivers and gives very good audio.

I suggest watching for the transmit version of Simon Browns SDR-Console assuming that is in the works. PowerSDR has too much CW latency or delay time for my liking.   Also if you have a SoftRock with the original Tony Parks I2C / USB SI-570 interface I recommend updating to the latest version to improve tuning control.  

If anyone knows where I can find a fully isolated 12VDC to 5VDC 1 amp convertor I would appreciate a note from you.

October 9, 2009: Not much new to add as my time was diverted to working on my classic VW, building a really nice TinyTrak4 and working at my new appointment as ARRL Club Coordinator for the Orange Section.  Otherwise I just continue to hone my skills with SDR and dream about a slick cabinet. I did find a Push On/Push Off Switch and found a online service to mill front panels. I'm kinda hoping for more PowerSDR SR-40 upgrades or a ROCKY upgrade.

June 15, 2009: Everything is working great on ROCKY and PowerSDR SR-40 as I've completed about 25 PSK31 and CW contacts on 80/40/30 & 20 meters.  I'm learning to work with a few software Quarks in PowerSDR and managed to download the purchased version of VAC (Virtual Audio Cable) version 4.09 and VCOM (Virtual Com Ports) so that Ham Radio Deluxe-DM780 can be operated with all of its Digital Modes.  Really nice.  I finished hand forming a air duct from a 1 inch fan across the PA-100 Power FETs to keep those components cool during the Digital Modes.  Remember the duty cycle for digital is almost 100 percent, far more than 20-30% for SSB operation.  A fan controller from K5OOR HFProjects was added to activate off of the PA-100 PTT relay and run about 1 minute longer than the TX session.  The Power FETs are running cool now as opposed to the almost "OUCH" level heat prior to this latest change.

Setting up VAC and VCOM was not too hard once some guidelines were found, I'll add the step by step details here after I setup this software a few more times and iron out my procedures.  However it does work fine on this 2.2Ghz Core2Duo Lenovo X61 laptop.  So what we are finding is that the SoftRock really works fine, the software is pretty good, RX operation is Good but no its not going to replace my FT1000MKV Field but maybe my oldest IC706 ....

The DDS-60 arrived after a very long wait and so I kinda lost interest in it.  Now that NORCAL is taking orders again ( June 2009) I placed orders for the FCC-1 & FCC-2 with the reasoning that the pair has the shaft transducer and the DDS-VFO firmware loaded and ready to go.  If it doesn't work out then I'll return to the DDS-60 and the HC908 controller and purchase all the parts necessary to complete a DDS-VFO.  See the AMQRP.ORG web site for details.

June 5, 2009: PA-100 output levels: CW output is close to 15 watts, PSK31 output is from 8 to 12 watts.  A Fan and Air Duct are added to the PA-100 power FETs to reduce heat during extended PSK operation.  The 12V fan has 30 ohms in series to reduce both noise and speed as the little fan duct efficiently directs air across the amplifier heat sinks.

May 22, 2009:  A significantly larger heat sink was added to the 7805 5VDC regulator powering the external Audigy 2NX sound card.  This regulator is dropping 8 volts at 5 watts and gets HOT fast and even with this larger heat sink a tiny Laptop CPU fan will be added to aid cooling.  

After 15 or more CW contacts it appears the PA-100 heat sinks are not as hot as the 7805 regulator but there is significant additional heat running PSK31, a 100% duty cycle mode.  At this time PSK operation is limited to 15 minutes until a air manifold and small fan can be constructed over the PA-100.

About May 5 a AMQRP Club DDS-60 was ordered but I'm still waiting 17 days later for delivery.  Very slow for sure.  I had hoped to have the DDS-60 installed as a free standing VFO in a remote box so the PC can be put out of site during Softrock operation. More on that when its installed.

May 14, 2009:: I've learned that the RF output power drops off rapidly at the edges of the sound card band width, something that a newbie might think that his RXTX is not working, be mindful of the sound card!! If in Doubt, use a transmit frequency within 5-10Khz of the center frequency. Experiment! When transmitting with PowerSDR SR-40, Before transmitting, key in the transmit freq minus 600 hertz so the SI570 is set to the correct frequency and the side tone is 600 hertz. If the Sidetone is very high/very low and the power output is low, thats the problem!!!!

May 12, 2009: After testing CW and PSK31 into a dummy load the antenna was attached for my regular QSO with WB6W on 80 meters and a PSK31 contact on 40 meters.  I'll add notes about setting the drive level in ROCKY for CW and PSK for 200-300 milliwatts output instead of the maximum 1 watt in order to help insure clean output from the SoftRock and and not over drive the PA-100 amplifier at 10-12 watts output.  I'll add notes for setting the transmit frequency in both ROCKY and PowerSDR.  Note the output could be ZERO if the transmit frequency is too far from the DDS / Center frequency defined in ROCKY.INI or the DDS Frequency steps in PowerSDR. 

April 8, 2009:  I want to use USB printer and Scanner cables to the SoftRock, thats the USB-A connector at the PC and B recepticle at the SoftRock chassis. These can be ordered but I made mine since the desired length is just a few inches.  Also in progress is a bypass and filtered 12VDC buss to each module on the base plate.  Drawing and etching the circuit boards by hand takes time.

March 21, 2009: The HFProjects PA-100 5 watt is now complete.  Rated at 1/10 watt drive for 5 watts output, more depending on drive. The SoftRock output is 1 watt CW but I feel for the cleanest signal possible the drive is reduced 6db by the drive setting in Rocky, thats about 500mw output and less on PSK where a very clean signal is desired.  Working with 35 watt HFPack amplifier at these input levels gives 8 watts output on PSK and 15 watts output on CW.  I hope to see about the same levels with the PA-100 even if a cooling fan is required.  The HFProjects switchable band pass filter board will control harmonic output.

I'm looking for USB panel mount B-recepticle to B-Plug to connect from the rig front panel to the Audigy USB-B and the I2C USB-B ... sometimes it seems like making these parts would be easy but a commercial product would look so much better.

The copper boxes will be secured to the base using 4-40 screws bent at right angles to attach to the side of the box and down to the base.  Those little screws don't bend so easy.

March 11, 2009:  Packaging the various modules is now a work in progress, each module will be enclosed in a shielded enclosure and external connections will be filtered, all in the attempt to minimize noise and RFI when transmitting.  As it stands now, 10-15 watts of power has not been a problem with the various SoftRock modules spread around my desk and only a few inches from the HFPack amplifier.   Instead of buying commercial aluminum boxes that are not exactly the right dimensions, I made my own from 1/8" pine hobby board and will cover each with .002 copper.  The main base is a copper covered 1/4" pine hobby board.   .

For Details, Contact  Bill K6ACJ

NOTE-1: The si570 is not a dds, I used a generic term, it is a microwave pll using a dco followed by a series of dividers.  Thanks to Alex Brown M0GJR for this information.

NOTE-2: Its a good idea to perform the voltage and current checks in the Build documentation and especially the currant drain by each PA Final .  I found 2 cases where the PA current draw was badly out of balance and replaced the FETs in each case.  Afterwards the drain current was nearly exact and the Final current drain was right on specs.

CLICK PHOTOS FOR A FULL SIZE IMAGE.  USE YOUR BACK ARROW ICON TO RETURN TO THE HOME PAGE

Sorry the good photos disappeared but here are a few showing the SoftRock, and HFProjects PA-100 Kit placed on the copper base.

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Clockwise from the Bottom Left: SR, Pa-100 band pass filter, PA-100 Amp, Audigy Sound , NORCAL FCC-1 frequency meter

Under Construction

 

Testing RF output. before final assembly