FlexRadio 6500

FlexRadio model 6500

FlexRadio model 6500

Let me start off by saying I am an IT guy so having a radio without knobs is not a problem for me.  As a matter of fact I helped Mike Cobuccio WA1EYP get Callsign Software started. Mikes first products were software control for the Ten Tec Pegasus and RX-320 so I have been dabbling with mouse radio control for years.

I will admit I lost interest for a while with software control and strictly ran the Icom, but in all fairness this was partly because the Pegasus/RX320 are entry level performers.  I have kept an eye on Flex over the years but never had serious interest because of their heavy reliance on a high end perfectly functioning PC. As if there is such a thing right?

Enter the Flex Radio 6000 series which does the majority of processing in the radio thanks to some components available in recent years. So how does it perform?  In a word. Great.

In my opinion  most modern top of the line radios are to the point you are splitting hairs when it comes to specifications and performance. In my experience the difference shows up in the form of dynamic blocking range which the Flex 6500/6700 tops the chart on the Sherwood Engineering site.

Software with 4 slices

Software with 4 slices

So on a crowded band the Flex 6500 stands tall. The pan-adapter and waterfall “panafall” are in a class by themselves. As a matter of fact I feel blind when operating the 7800 and it has one of the best scope/waterfalls available on HF rigs.

Now the downside is the new SmartSDR software that replaced the previous PowerSDR is for lack of a better term still underdeveloped.  The Noise Blanker and Noise reduction is for the most part useless, there are no memories at this point, no FM and really not many bells and whistles if you are into that kind of thing. Unfortunately, I am.  In its defense, the radio has what is called an AGC threshold adjustment which more than makes up for the lack of quality noise reduction on my Icom. That said, this threshold works so well for making a quite radio I don’t care if they ever fix the noise reduction/blanker. It is nothing short of amazing.

There are a few terms you will hear people throwing around when the talk about The Flex 6000. They are slices, SCU and direct sampling.  Lets start at the back. Flex has a spectral capture unit (SCU) that listens to every transmitted signal across the (0-74 mhz) spectrum at once. It’s hard for me to even comprehend the amount of signals that are being received and ready for listening on a Flex 6000.  In front of that Flex adds a slice which in layman’s terms is a section with a VFO, Demodulator and all the necessary circuitry to allow you to choose frequency, mode, etc and includes a panafall for each slice.  Depending on what model you choose dictates the amount of slices “receivers” and SCU’s you receive.

  • 6300 – 2 slices, 1 SCU
  • 6500 – 4 slices, 1 SCU
  • 6700 – 8 slices, 2 SCU’s

The final term is direct sampling.  In the old days a radio was multi-conversion also known as “superheterodyne”.  Without going into details with conversion comes noise and distortion at each stage. So a triple conversion radio has more places to add distortion than a dual conversion radio and dramatically more than the single conversion direct sampling radio. This kind of design was not previously possible as the hardware architectural required for this kind of processing power has not been available.

Since I do not have the knowledge to test this kind of performance I will summarize by saying  the Flex 6500 is as good of receiver as far as sensitivity goes compared to any other radio I have owned and the dynamic blocking range is better. I will leave it to the experts to measure and argue how good.