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Reviews For: FlexRadio FLEX-6400

Category: Transceivers: HF Amateur HF+6M+VHF+UHF models - non QRP <5W

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Review Summary For : FlexRadio FLEX-6400
Reviews: 28MSRP: 1999
Software Defined Radio Transceiver with 2 Independent
Band/Mode full performance receivers from 100khz to 55MHz
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
W4HTP Rating: 2023-09-17
worst purchase of my ham radio years Time Owned: more than 12 months.
Cutting straight to the point, these 6000 Signature Series radios are not reliable, and the company cannot provide competent support. They will actually withhold support if you don't constantly pat them on the back as radio gods. My experience in 1.5 years of owning a 6400M has been terrible. I see why Flex Radio seems to have a high turnover in ownership. If you feel the need to buy one, buy used - plenty available. You'll see. Be sure you have a backup traditional radio. #Truth

BTW, as a radio, the Flex receiver is very good when it works and the software problems aren't creating performance issues. It's a good remote radio when the company doesn't forget to renew important services that make the remote access work. The remote system, Smartlink, is prone to outage.

My recommendation - don't buy a Flex 6000 series radio or accessories. You've been warned.
NG0Z Rating: 2023-08-12
Amazing Technology Especially for Remote Operation Time Owned: more than 12 months.
The FlexRadio 6400 replaced my Icom 7610 when I went to a fully remote station after moving into a townhome with an HOA. I've owned it a little more than a year now.

Setting the Radio, Amp (PGXL), and Tuner (TGXL) for remote operation was quick and easy. The receiver's performance regarding sensitivity, adjacent signal rejection, RX audio, and TX audio are all on par with the 7610, which was the best radio I have ever owned.

I would give it an A+ if it weren't for a couple of minor issues.

1) Sometimes the SmartSDR software has to be shut down and restarted initially to recognize the audio input (v3.3.33) or otherwise operate properly. More of an inconvenience than a substantial flaw.

2) The NR and ANF are not on par with the 7610 but the WNB, when you get it to work, is pretty amazing.

Having said that (#2), I almost never need the NR as the AGCT is amazing, and perhaps why Flex hasn't spent as much effort on the NR.

I can tailor my audio for different input devices using Full Duplex and the built in EQ mode so you can hear your actual transmitted audio and I have received favorable audio reports.

The TNF (Tracking Notch Filter) is also amazing for finely eliminating birdies or other interference.

With the PGXL and the TGXL, the Flex acts seamlessly as an integrated full legal power radio just like my 7610 and PW1 (1KW) did in my prior station.

SmartSDR is fun and easy to operate, especially with the FlexRadio FlexControl. I haven't even read the manual as it's pretty intuitive.

The Flex CAT software integrates seamlessly and remotely with my logging program, N3FJP's ACL.

I operate remotely 100% of the time out of necessity and can't imagine a higher performing or more seamless way to be back on the air.

Support, including the Flex Community and YouTube channel, has been excellent.

I would recommend FlexRadio even if you don't operate remotely and perhaps want to keep your equipment in the basement or under the desk and have your operating position upstairs on a LAN. I operate with a gaming laptop on the LAN or on Wi-Fi - either way, it works great.


M1EGX Rating: 2023-06-30
Definitely not plug and play Time Owned: 0 to 3 months.
I bought the 6400 second hand,I already had a 3000 and 5000 which are both wonderful transceivers.I found that working the 6400 needs a lot of computer savvy,it is not plug and play also the manual over 200 pages long is written for the more knowledgeable computer operator it is not a well written manual or easy to read. The set is also prone to rfi much more than my other two flex radios.
My advice is unless you want to remote or have a high knowledge of computers leave 6400 alone
W3DDF Rating: 2022-01-10
Excellent for remote operations Time Owned: 6 to 12 months.
I purchased a 6400 to be my remote operations rig. It has worked flawlessly in that capacity. I am able to use either Smart Link or VPN into my remote computer. Set up was easy and virtually no latency. If you need a remote ham radio option the Flex is the way to go.
K1BJS Rating: 2022-01-09
my experience with the 6400 Time Owned: 6 to 12 months.
I have been hesitant to send this review. I have been a Flex owner since the beginning of Flex SDR radios. I now have the 6400 and must say that when it is working , it is probably the best Flex product that I have owned.. I have owned SDR radios from Flex since the beginning.
From the onset, I have had issues with the software, particularly when operating remote. My comment is that this software has been out for several years now and it still has problems. It is not a mature product that works out of the box. I would advise future purchasers to know that this is not a plug and play for all issues. You need to have knowledge about software, Internet, etc.
Being a remote user for 4 months out of the year, I find that there are times when I must go to a total factory reset. You cannot do this! You must be able to push the button on the front of the radio to do this. Am I going to keep this radio? Yes because it is the best SDR out there.
KK9H Rating: 2022-01-05
Remote operation is really fun Time Owned: more than 12 months.
Every year I like to try something new in our hobby. Toward the end of last year one of my friends bought a second Flex radio due to a deal he couldn't pass up and then immediately loaned it to me to try. I have been very interested in trying out remote HF operation, but I am not much of a computer guy. The first thing that impressed the heck out of me is how easy it was to get this 6400 operating remotely. I have the SmartSDR app on my iPhone which works great, but I prefer using the SmartSDR on my laptop where, with a little help, I have been able to integrate WSJT-X, DX Keeper and JTAlert-X to be able to operate FT8 from anywhere. The Flex 6400 itself is a wonderful radio. It has superb receiver characteristics, transmitter performance and the built-in antenna tuner works very reliably. I have the Flex 6400 connected directly to my Xfinity router via an ethernet cable and that has provided very reliable access from wherever I am. One thing I have been quite successful with is adding to my 160M DXCC total using the Flex on FT8 which I can do from anywhere I happen to be and that has proven to be very handy. I have been a ham for over 50 years and this rig is not my primary rig, but it has provided a tremendous amount of additional fun. One thing I love to do is show my non-ham friends what I refer to as "the ultimate in nerdom" by pulling out my iPhone and demonstrating the operation of the Flex by working someone on SSB for them. I hope my friend will let me keep it for a good while longer. Maybe I should make him an offer he can't refuse!

I have had no transmit audio problems on SSB using either my laptop with a headset or my iPhone. I am careful about setting my audio level to not overdrive it and I left the transmit audio frequencies at their flat (default) settings.
KE9ND Rating: 2022-01-05
I Sold It After A Few Months Time Owned: 6 to 12 months.
I owned a Flex 6400 for about 9 months. I wasn't very happy with it for various reasons. I still have a Flex 3000 that I enjoy very much. The SmartSDR software needs much improvement, it is very basic with a lot of importance leaning toward remote operation. I get much better audio reports with my Flex 3000 than the Flex 6400, the audio section needs improvement. I got the blinking red led on powering it on a few times and had to do a factory reset to clear it, then of course had to reconfigure the settings. I hope Flex works on their software (and hardware) before their next radio is introduced. I thought the 6400 would be better than my 3000, but that was not the case for me.
UA3LM Rating: 2022-01-04
Great radio Time Owned: more than 12 months.
I have been operating the 6400 for several years and during this time there are no glitches ! FlexRadio has a great transmitter ! I don't know why people complain about the transmitter, probably losers. A lot of people buy sdr radios after conventional transceivers and cannot cope with the new technology .That's why they write about problems, but it's not about the radio))). Thanks.
DL6EAT Rating: 2021-12-06
Not good at all! Time Owned: more than 12 months.
I owned a Flex 6400 (non M version) for more than one year - it was simply disappointing. Modulation is never distortion free.....the best result was achieved by using Marcus's iPhone/iPad-S/W. But again - all the time people told me that the sound was not "crystal clear".
Also 3 friends of mine purchased the very same radio - same results!
I really wonder why so many people are just fine with that bad modulation! Have you never used an ICOM 7700, 7800 or an ANAN 7000? I also tried several different microphones (USB, Sennheiser, Rode, dynamics and electret and finally the iPad and iPhone 12 with Air Pods....)
To me it appears that the Flex 6400 / 6600-series has general build-in rf inrush problems what so ever.
After many, many tests I have never heard a crystal clean signal from any Flex 6400 or Flex 6600...

At the end I sold the Flex 6400 and purchased a pre-loved Flex 6300 again with S/W version 3.2.39. No problems at all with this radio! Perfect modulation with any of my microphones - no rf inrush! All fine.....
WD1V Rating: 2021-10-12
SmartSDR Mac Version 1.9.14 (124) Time Owned: 0 to 3 months.
I was an early adopter of Flex SDRs back with the 1000 and 5000 series. Since I've owned Kenwood 990s and TS-2000, a few Elecraft K3s, and Icom 7300 and 7610. All had strong points that make them great radios. But I returned to the Flex 6400 wanting to try the Mac version of SmartSDR.

As I enter my second week I have 3 takeaways.

1) Flex radios sound the best and not by a little, by a lot. The filtering, DSP, AGC, and richness of sound quality perform where I can't imagine better for a ham radio experience.

2) The Mac SmartSDR is superb. On my 27" iMac I can easily see (panadapter) and click select, filter (choose and fine tune filter), and operate with great signals in and out. DSP noise reduction is incredible - no garbled result - just less to no noise. Memories and profiles let you return to same freq/same settings. I suggest external PC stereo driven by the Flex direct.

3) Flex has a community web site for newest software downloads, FAQs, and find specific answers to your questions and gain insight as to how others are Flexing.

Hope to meet you on the bands. 73