SDR-1000 Notes

About a year and a half back, Tom (W0IVJ) did a remote presentation for the Four Lakes Amateur Radio Club on the SDR-1000.  I immediately knew I had to have one of them because it was what I had thought a radio should be for for several years.  But, I didn't jump in with reckless abandoned.  First I got a couple of Softrock kits, then an Edirol FA-66 sound card interface, and finally the SDR-1000.

Nothing stays the same around here, but this is what the set up looks like at the moment.

The radio and sound card unit fit nicely behind the flat screen monitor.  It presently drives an old SB220 amplifier which is standing in for a TL922 while I scope out a problem.  The computer is a home assembled 3ghz P4 with 2gbt of memory.  Not visible is a homebrew solid state PTT interface and the optional USB to parallel adapter.  This unit does not have the ATU.

Going straight to the bottom line, I really like the radio and prefer to use it over my IC 756PRO.  Not only is the performance as good as or better, but the display is outstanding and a real plus in pile-ups, CW or phone.

Here are some notes from my experience getting it up and running.

It's been said that the SDR-1000 is not a beginners radio.  I'd have to modify that a bit in that anyone stepping into the world of a software defined radio is a beginner.  My take on it is that if you follow directions and proceed thoughtfully you could have the radio from shipping carton to on the air in a few hours.  The problem with a SDR is that if a problem occurs, it could be a radio problem, computer problem or sound card problem and the support for each item comes from a different source.   A good knowledge of radios and computers will certainly help in analyzing what to fix.  The FlexRadio people are very helpful, the Flex reflector is great and there are plenty of Flexers around who are willing to help out.

The question of what is needed for a computer is often heard.  I first set the SDR-1000 up an an Intel 2.4ghz Celeron.  The audio had breaks in it and the CPU usage was well over 50%.  I purchased a $75 3.0ghz P4 CPU and plugged it in.  The CPU usage now hovers between 10 and 25%.  It's not a difference in advertised speed, it's a difference in how it works.  No more Celerons in this shack!  My other computer that periodically hosts the SDR-1000 is a dual core 1.8ghz AMD.  CPU usage on that machine ranges between 5 and 20%.

I received reports that my signal was splattering well out of my desired bandwidth.  W0IVJ put me onto the publication ECO-027 which describes a needed bias adjustment on some SDR-1000 radios.  It is a simple procedure and might be worthwhile checking out regardless of if your radio seems to be working OK.

The filters didn't seem as sharp as I expected.  Some reading of the manual (can you imagine that!) suggested that when using a 192k sample rate the slope of the filters suffers.  I changed to a 96k sample rate and it is a lot better.  I might experiment with 48k on CW in the future.

I've noticed an anomaly with using the "Sub Receiver" and Split functions.  The sub-receiver frequency frequency will arbitrarily change from where you put it and you can't get it to go back or get it to stay put.  I need to determine the specific sequence of events, but it seems to relate to the second frequency being out of the pan adapter (sample rate) range.  I experienced this the other day when Martti was at 14.195mhz and listening above 14.250mhz.

Full range audio amplifier/speakers really show what the SDR can do.  However, for SSB or CW a quality set of simple amplified speakers is better (Those speakers usually have a headset jack in them which is a plus).  It is a case that sometimes what you can't hear is better.  There are some folks out there hitting the low end pretty hard and it adds a bass drum effect to their voice.  Of course, the electronics only play back what they hear, but ....

W0IVJ put me on to setting my amplifier levels using a reliable watt meter and dummy load as opposed to using the automatic set up in the radio software.  I felt more comfortable doing that his way.  In fact, my radio wants to blow fuses when it tries to do the automatic set up on the 160 meter band.

I thought the radio really could stand an indicator light to let me know it was on.  A quarter inch hole in the panel and a snap-in LED connected in parallel to the fan took care of that.  The fan is very quiet so when the fuse blew as previously described it took quite a while before I realized what was wrong ( I thought I had somehow really messed things up).

Perhaps it is not the most accurate way, but I found that tuning in WWV in the DSB mode and listening to the resulting two 1000hz tones while adjusting the clock offset in the calibrate screen works very well.  One simply adjusts the offset so that the two tones sound like a single tone.  You can't do that with most radios. 

You may note in the picture that N1MM logging software is running with the PWRSDR.  This requires the use of virtual ports within the computer.  The N8VB driver is required and described in Q10068 in the Flex data base.  Don't forget that after installing the driver you need to go in and set the configuration and active it.  For me the first time through was a breeze because I was following the directions.  The second time I thought I knew it, and didn't.  BTW, Device Manager lists those connections under Multi-Port Serial Adapters.

If you use the USB to parallel adapter you must install the USBIO driver from Flex.  Don't be surprised if this doesn't appear the way you would expect.  In Device Manager you will now find LibUSB-WIN32 Devices and in that you will find the SDR-1000 USB adapter.  It's been my experience that if you plug into a different USB port, the computer will find new hardware and needs to install the driver again.  I'm not a byte-head so that seems a bit odd.

So the USB/parallel adapter was indeed a problem.  I got a bad one and at first Flex didn't think so.  But, Eric went out of his way to help me determine the problem was the adapter and authorized sending me a new one.  But, that wasn't the end of the issue.  The new one worked as advertised on one computer, but not the other.  Adding a powered USB hub to the problem computer made it work.  The voltages from the problem computer are the proper value so it appears the real problem is a timing/buffering issue with data flow.  That is interesting because several other USB devices work fine on that machine.   To me that issue isn't resolved, but since it is working I have lost interest in figuring out what is wrong.

EST/N9MW 12/29/07