Easily Heard Signals

Flex 1500 Update 10/06/15

DSC05970This little QRP fig is testing out to be a very capable transceiver. I have only made about a half dozen contacts with the radio on CW and SSB.  However, I find it very sensitive and selective and great fun to operate. It is intended to be my front end for up conversion into microwaves but I see it can easily be used on any HF band.

The real joy is the PowerSDR computer display. On a $700 radio it is a killer feature. I can run 5 watts on my Ten-Tec Omni VII but I can’t enjoy all the display features of the PowerSDR software.


I have discovered what is an issue with some owners. It is the audio latency through the computer processing. A high speed multi core processor is a prerequisite for sure. I have a quad processor 3.4 MHz computer but I do experience the problem in CW when using the built in keyer with side tone and using the audio from the computer speakers. There is enough audio delay to mess up the brain / hand timing.

I didn’t discover this latency at first as I began using the audio from the “Phones” jack on the front of the radio case. There are no delay issues there. When I started using the internal AC1 computer audio, I see where the fuss is coming from. It is only noticed with the keyer side tone.

I personally do not find it a serious issue to use the phones jack for CW audio. I have a powered set of computer speakers plugged into the jack. Headphones are a usual CW operators friend and can be used here. There is some computer sound processing that may be missing using the hardware speaker jack, but not noticeable when operating CW.

Another work around would be to use an external keyer with its own side tone. Either case the operator will have an extra but not unusual piece of hardware for CW operation.

Latency is a quirk of SDR and I don’t see a perfect fix because of the USB limitations. It’s not a bug but a limitation. A limitation easily overcome by getting CW audio from the radio hardware.


DSC05867I found out how to do a Windows 10 registry edit so I can see the entire panel of the PowerSDR display. Super simple and the computer doesn’t complain at all. The native resolution of the netbook was set at 1024 x 600 which is quite too short for the 1024x768 display of the SDR panel. The bottom 2 inches were cut off and the display would not scroll. The bottom was unreachable and not viewable.

Now I have 1024 x 768 available as well as 1152 x 864. WIN10 actually says the 1152 x 864 is “recommended” resolution but it does make things a bit “squished”

I am still running at 1024 x 600 normal screen but the screen will now automatically expand for the 1024 x 768 of the radio panel display. You can see the example in the picture. I see the entire panel. I don’t need to scroll around. It’s a pretty wonderful improvement on this skimpy screened netbook.

As you can see the video quality is excellent.

That’s about the end of the good news. The SDR definitely will run on this netbook and looks good doing it. However radio performance sucks. Take a good look at the very bottom left corner of the screen. That is a display of the CPU activity.

When I first powered on the SDR it was at 100% for about ten minutes. I did some buffer enlarging and other adjustments that spoils the radio performance and probably is the cause of the response issues other authors have commented on. It is not the FLEX radio, it is a computer issue.

In the picture you should be able to realize I am monitoring WWV at 10 MHz. I have left it just set on the frequency for over an hour and you can see the CPU is running at 77%. It swings between 70% and 80%. The radio and computer is doing nothing but listening to WWV. The swings are probably background computer housekeeping going on. I can only guess.

When I am actively tuning and making adjustments CPU activity sometimes is back up to 100% I tried brief SSB transmissions and the CPU activity didn’t change much for the 70-80 range. So perhaps it is useable, but the netbook and the Atom processor is working very hard. Netbook battery life is probably horrible.

So as the Myth Busters say, I rate it as a plausible combination, but not highly recommended.

As I have said previously the CPU activity with the FLEX-1500 running on “office”, my big quad processor machine, the CPU activity is 5 to 10%, just loafing along. That means the is a lot of processor overhead available for multitasking with Feldigi and log books and all sorts of nice-to-have things going on.

SDR First Look

DSC05863 DSC05864 DSC05865

The future is here. Maybe that is not quite right. Software Defined Radio (SDR) has been around probably long enough to drink legally in all 50 states. But then I have never seen a radio take a drink, ever.

It's a FlexRadio Systems, “FLEX-1500” SDR which is the baby of their product line. It is a 5 watt output QRP transceiver that (must) uses a personal computer as its basis of operation. I won't get into the theory of SDR here but suffice to say they are equally important system partnership.

My out-of-the-future radio has arrived on my ham desk. Actually half of it has been there for many years. The radio part seems futuristic to me so I will leave it at that. It is a ham transceiver that has only one control on the case, the on/off push button. Everything else is a hardwire I/O (In/Out) connector of many variations except for the ground post which I hope doesn't need to be an I/O.

The only indicator on the case is a blue LED in the middle of the On/Off push button. It's one of those blinding light laser beam like devices that I don't like to look straight into. I am sure it is NOT dangerous but most of us know how penetrating a blue LED appears. No issue, just a comment. I think it looks cool.

I have one on my electric tooth brush that I use as a night light at 3:00 AM in the morning.

The Computers

I have connected the FLEX-1500 to two of my personal computers.

The most powerful is my office computer. It's a home assembled unit built by myself and has been rebuilt once after it suffered heavy damage in a home lightning strike. As did everything electronic in my home office including all my ham radio gear.

Currently this computer (I call “Office”) has a 64 bit quad AMD processor running at 3.5 MHZ, a decent independent (non motherboard) PCI video card and 8 Gigabytes of RAM. The OS is Windows 7. I don't consider exact hardware detailed specs important here. Let me just say it can carry any load quite well. With SDR it is running 5% to 10% CPU load.

The second computer (rover) I tried is my little low powered ASUS Eee PC1005HAB Netbook 1.6 MHz Atom 270 processor (32 bit), single core but 2 logical (hyperthreading) I upped system to 2 GB RAM, OS was WIN 7 Starter. I just upgraded to free to WIN 10 OS so will test again with new OS.

My Linux (sandbox) could not be used as there is no software from FlexRadio Systems for Linux. (I'd vote for that!)

The Software

PowerSDR v2.7.2 is the current software for the FLEX-1500. It will run as either 32 bit or 64 bit as it contains drivers for both. FlexRadio Systems has other (and newer) software for its larger SDR systems but they are not compatible with the FLEX-1500 and its USB computer interface. (The others use Firewire).

I am sure Firewire was chosen because of its increased speed which looked good at the time of design. I have Firewire I/O on my “Office” computer and used it for my old video camera, but it is seldom available on laptops these days. USB3 is now most favored… Just a personal comment about the other FLEX SDR systems)

The spec for the Flex-1500 is USB1.2 and it seems adequate for the purpose. I would think USB 2 or even 3 would be a logical upgrade. I have read comments about the “slow” USB1 interface with the FLEX-1500 but I haven't experienced any yet. (It IS just out of the box…)

The issue I think is there are a lot of reasons communications to the FLEX-1500 over USB1 may be slow in any particular case and that (now) slow standard is an easy target. I suspect there are many other contributing issues. I will be looking…

I had terrible problems loading the software on my “Office” computer. It starts to load, the green “progress” bar moves fully to the right, and it says, “Standby while the system is configured.” That standby never ends. It would stall out there, lock up the computer and never finish. I spent probably 16 hours installing and trouble shooting the software install on “Office”.

The install on ROVER went perfectly. No issues at all. Thankfully I had a good install I could reference to trouble shoot the “Office” install. It ended up that I found .bat (batch) files that were not executing in in rather obscure directories in “Office” Even the “skins” needed a batch file run to configure. I had to rename the batch files to “.cmd” files so they would manually execute at my command (then name them back). There is obviously a software issue in my WIN7 Ultimate OS that killed the .bat files from executing. Some day I may go figure why, but PowerSDR v.272 is installed and running fine now.

First Impression

The FLEX-1500 is a REAL radio. WOW! Superior weak signal reception. The displays are a spoiler to going back to my TenTec Omni VII but I can compensate. The OMNI is a great radio…

I am going to have to spend a lot of time with all the settings and variations of those settings. But honestly, the FLEX setup is NOTHING compared to setting up my MACH3 CNC machining control software.

The bands were all down with very little activity. I messed with CW and my keyer and found no problems (yet) of latency issues with running the built in keyer at 20 wpm. I can't stand full break-in (and have never needed it) so maybe that is the issue. In any case I will be investigating that in much more detail. No contacts made on CW yet.

I heard a very weak special event station N9Q on 20 meters sideband (14.267 Mhz). I could hear him and see light traces in the waterfall but no bumps in the panadapter display. He was calling CQ but no activity. I picked up the mike, cranked the transmit up to 100% (5 watts) and gave him a call. He heard me the second attempt and called my back with my correct call sign. He even called my by my name as he looked me up in QRZ. He was also named Dan and located in Elkhart, Indiana. N9Q is still being received in the pictures above. I worked him yesterday.

Not bad for 5 watts sideband and an R7 vertical antenna at my end.

SDR Radio

FLEX 1500 angle PSDR 660x350 ARCI have been doing extensive research in where the state of the art is in Software Defined Radio (SDR) these days. It has been actively around for over 15 years. I had taken some interest in the systems when I was a participating member in Tucson Amateur Packet Radio activities. I was more interested in packet radio than SDR, but did take an interest in all the radio modules with the funny names.

My recent investigations reveal the system is still quite popular but mostly with receivers and not so much with complete deliverance systems. The system that TAPR was supplying kits for is still very much alive. I see where someone is still building complete systems.

I can't find anything that says SDR is a bad idea. It is however a ton of work to scratch build.

The FlexRadio Systems folks are the big exception for delivering a real product. There are a few lesser know commercial and military SDR systems that appear to be outside the USA. Most are very high priced as are the FlexRadio systems, except for their FLEX-1500 QRP version.

I see a crop of low cost DSR receiver modules are flooding the market in the sub $100 range. I don't know enough to have an opinion on these USB stick devices, but they do seem to be less than serious for real two way communication use. Probably interesting and low cost way to experiment and do SWL (Short Wave Listening) Most extend far into the UHF frequencies.

One very big issue is see is almost no solid recomendation on the computer half of the SDR radio. I had to dig very deep into the FlexRadio Systems website to even get a hint of what the specifications needed to be on the computer hardware for their systems. It is certainly a very critical part of how well a SDR system will perform.

I have read a lot of user reports on various SDR equipment and the folks that struggle the most probably are trying to use an inferior computer. The best computer information I could find was posted in a BLOG on the FlexRadio website. Nothing is mentioned about a target computer spec in any of their literature or specification pages. In fact I can't find that same reference again.

FlexRadio is now building a complete computer display front end for their premium Flex-6xxx radio systems called Maestro. I saw the new Maestro terminal running at the Arlington Hamfest this summer and it definitely was impressive.

So as I suspected, the SDR does need a good computer and very high powered data processing CPU system to perform the best. $400 laptops will not cut the mustard. Laptops are actually not generally recommended by FlexRadio. Desktop multi core processors with powerful and non-motherboard GPU's are what they say is really required.

I have discovered some laptops that will do the job, with the lowest cost I could find being around the $800 range. They are often called minimal “gaming” laptops and have very good NVIDIA or ATI GPU boards. Separate GPU's take a lot of graphic load off the main CPU cores.

At that price, they are really not top notch gaming machines. They would be excellent for rover microwave systems with a Flex 1500 and not too much multitasking.

So the rule is, “don't try to marry a good SDR to a basic PC and then complain about poor radio performance." It needs to be a lopsided marriage where the computer system carries most of the work load.

I have intentionally been vague in this posting about specific brands and models except Flex Radio Systems. It's because the Flex-1500 has my attention as a good first IF radio for VHF/UHF/Micro Wave use and an affordable rig for general coverage receive and QRP ham use. The hard part for me is the initial cost for both the SDR and a suitable computer (for rover use) is $1500. It's not a free ride.

I have taken the plunge and I have a Flex-1500 on order! I will have much more to say...