Flex Radio 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.

Ham Radio Audio


W2IHY EQplus and Iplus.

With some things I have a tendency to go overboard. OK, probably with most things. But honestly with audio I try to keep things to the minimum as I dislike the processed audio you hear coming from a lot of stations these days.

I run two microphones. A Heil PR-780 which was my original HF rig mic which has now been demoted to the 2 meter FM rig. I replaced it with a Electrovoice RE320 that I now use for both the Flex and Icom which improved the detail of my audio greatly.

Electrovoice RE320

Electrovoice RE320

The system is pretty simple. The Electrovoice is on a Heil PL2T boom with shock-mount. This feeds into the W2IHY EQplus. The EQplus output goes to the W2IHY iPlus input which switches the mic between my Flex and Icom and has one available position left for a future radio.

It also switches the 2 channel audio output from my rigs to a pair of Palstar SP30H speakers as well as changes the keying line to my amp. And added benefit to the iPlus is it has an audio isolation device internally that helps eliminates issues when running external audio equipment.

The 2 meter Heil PR-780 Microphone is mounted on a Heil SB2 short boom and is of course wired direct.

This setup works pretty well except I am considering adding a preamp as my controls are close to maxed out with the Electrovoice. I am also debating my decision to switch the receive audio with the iPlus and not use a mixer.


SteppIR Big IR what do I think?


SteppIR mounting location (before radial install)

I have to say I am pretty happy with my BigIR installation. Most of this can be contributed to the fact it’s the polar opposite of my other antenna’s I have installed which are typically supported at low elevations (wavelength speaking). The angle of radiation on my dipoles are quite high and provide excellent signals state side but are lacking when it comes to DX. The SteppIR does much better for long distance and on the high bands where you can switch between 1/4 and 3/4 mode you can play the gain vs angle of radiation game. 3/4 mode actually works quite well in MOST situations as the additional gain seems to usually offset the loss in the lower angle radiation areas.

Also where one antenna seems to have noise any given day, the other one seems to be quiet. On the first night after installing radials we had a storm coming in and during my evening 160 rag chew I used the BigIR as a receiving antenna and it worked quite well.

Executive Summary

To give an summary of how it compares I would say that on 10, 15, 17 and 20 meters the SteppIR will beat out my other antennas 90% of the time. The fact I can choose 1/4 or 3/4 mode on two of those bands gives it an additional edge since I can tailor the antenna to the station I am working. On 40 meters its about 50/50 compared to my 270′ long balanced fed dipole. Stateside contacts are stronger on the Dipole and DX on the BigIR is noticeably better. On 80 meters the dipole pretty much wins hands down but in all fairness the 80 meter add-on coil for the BigIR does work and if you are confined to a small lot the thing will do a decent job.

You may have noticed I left out 6 meters. Well to be honest I have not had a chance to play with it and I am confident it will always be a crappy 1/4 wave antenna on 6 meters however may work a little better in the 3/4 wave mode. Why do I say this? Well a 1/4 wave on 6 meters is only a little over 4′ long. When you install the 80 meter add-on coil it shortens the antenna to the point where its only about 2 feet tall. How do you think this will work? I personally don’t have a lot of faith in a 2′ antenna mounted at ground level. Running 3/4 mode the antenna is about 105″ long in my particular installation. Still not great but better than nothing. My guess is if you are serious about 6 meters, you might want to use something else.

I also have a zero-five antenna and 200 watt SGC remote tuner that I purchased used and decided not to install. I have 4 friends locally that have or have had the zero-five 43′ multi-band vertical using the un-un transformer and the remote tuners. So my “observations” on the pro’s and cons are based on that, my cost research and the modeling I have created for a 43′ vertical. My personal zero-five is sitting on a shelf in my shed with dust on it so do not consider me THE authority on the 43′ vertical.

At first glance the cost difference between the zero-five vertical and SteppIR seems huge. It is significant however by time you consider all the other required cost associated with BOTH antennas it is not as bad as one might think. In my option for the antenna to be truly omni directional you need 360 degrees of radials. Depending on what theory you follow the radials need to be a certain length. In my case I felt 60′ was the number for the longest radials. This means your antenna needs to be at minimum of 60′ away from your house. There is also something to be said about the performance of an antenna shielded by your house. Remember the current point is at ground level on a 1/4″ wave ground mounted antenna and that is where most of your signal comes from. So if you get away from your house you have cost for coax and control cable (which is even higher if you get the bury kind).

The cost of radials is expensive. Copper is not cheap. If you have not looked lately a 500′ roll of 14 gauge will run you between $40 and $50. In my case I used 7 rolls. So the cost of coax, control cable and radials is going to be a constant no matter which way you go. Add in turf staples and a radial plate (optional) and that is going to run the bill up another $125.00.

The Zero-five works pretty well with an un-un at the base of antenna on 10 to 40 meters and is a legal limit antenna for those bands. It will “work” on 80 and 160 meters with the un-un however the line loss with coax is so extreme you really can’t get much performance out of it. The only option is to add a remote tuner at the base. If you want something legal limit like the Palstar you need to be prepared to spend a small fortune on a tuner. SGC has a couple nice tuners that work very well but with 100 and 200 watt power limits don’t think about turning on your amp. Not to mention they are $360 and $595 respectively.

I modeled out both antennas with EZNEC and the performance of the SteppIR vs 43′ vertical are similar as a whole. The SteppIR kills the zero-five on 10 meters for DX angles of radiation and on one of the lower bands the Zero-five beats the SteppIR. One thing to note is the 43′ Zero-Five has a higher current point on some bands which can help getting your signal away from near bye objects.

So the pro’s and con’s.

SteppIR BigIR

-Initial cost
-Much more assembly required
-Theoretically more maintenance (it does have a motor in it).
-Requires more conductors in control cable (compared to 43″ if you choose remote tuner)
-Will not do 160 meters.
– Lacking on 6 meters compared to a real antenna

-Legal limit
-It literally will tune any frequency between 6 meters and 80 meters and not just the ham bands.
-You can play with the 1/4 and 3/4 mode from the comfort of your shack on the higher bands.
-Its is literally resonant where you transmit.
-You have another cool gadget (control box) for shack 🙂
-Green and black and blends with tree’s

43′ Zero-Five Vertical

– Not resonant on any band.
-Require un-un or remote tuner.
-Higher loss with un-un and some bands unusable loss with un-un.
-Bad DX antenna for 10 meters
– Shiny and screams hello to neighbors. Could be a Pro to some neighbors.
– Requires tuner for 80 and 160 really. Cost from $350 to $1800 depending on what power limits you want.

– Cheaper initial cost
– Will do 10 meters where BigIR wont
– No maintenance really. Its just a stick of aluminum.
– Easier to knock down and move.
– Higher current point on some bands may perform better


General BigIR

BigIR assembly

BigIR installation