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Reviews For: FlexRadio FLEX-1500

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

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Review Summary For : FlexRadio FLEX-1500
Reviews: 83MSRP: 649
The FLEX-1500 is a low-cost, QRP SDR that is positioned to allow ham radio operators the ability to experience the incredible capabilities and just plain fun of operating an actual software defined radio without breaking the budget. It comes packed with features that make it ideally positioned to be the ultimate low cost, high performance QRP rig and IF deck for VHF-microwave transverter operation.

* Two-tone, 2 KHz spacing third order dynamic range measured @ 14 MHz of greater than 80 dB
* Full HF/6m transmit capability - General coverage receiver
* Built In Test Equipment (BITE) for hassle free calibration
* Multiple RF outputs for transverter IF or "full gallon" QRP operation
* Dedicated Receive only antenna selection for use with the transverter IF or the 5W PA Transceiver port
* Simple USB interface to the computer eliminates messy cabling that plagues other QRP software defined radios.
* External connectors for band data, asserting PTT, headphones, key and microphone
* Simple USB interface to the computer eliminates messy cabling that plagues other QRP software defined radios
Product is in production
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
VE3INH Rating: 2023-09-03
Some good features but dated by todays standards. Time Owned: more than 12 months.
I have owned the Flex 1500 for over 5 years now and had the opportunity to use it under both good and bad band conditions. Although the multiple manual notch filters and variable brick wall bandwidth skirts are truly amazing, the noise reduction (NR) and noise blanker (NB) functions in the power sdr software are abysmal.

I was truly saddened and felt quite betrayed as a Flex Radio customer when software development and updates were dropped like a hot potato upon Flex's introduction of their new 6000 series and associated smart sdr software.

KE9NS has done a stellar job of updating the old smart sdr graphical interface and offering it for free. Mind you; in my humble opinion; it would have been far better to have seen an improvement in the noise reduction and noise blanker segments of software; if that indeed was possible. Quite honestly; I would have been happy to have paid a nominal fee for such upgrades.
VE3TMT Rating: 2022-12-23
I really like it Time Owned: 0 to 3 months.
I recently took delivery of a Flex 1500 after deciding to downsize the station a little bit. This was my first SDR radio, although I have been using SDR receivers for years. I had the opportunity to play with the demo version of PowerSDR before the Flex arrived, but it is much easier to learn the in's and out's with the radio actually hooked up.

Once I learned how virtual audio cables and virtual serial ports work, I started adding my external programs. I use WSJT-X for FTx modes, MMTTY for AKSF RTTY (the Flex doesn't support true FSK) and MixW for CW and PSK31. I now have full control over all modes and CW works like a charm, no problem running 40WPM in a recent contest.

Without repeating everything else that has been said, I'll only comment that I find the receiver very versatile and offers plenty of QRM fighting functions at its disposal. I have three TX profiles set up, one for digital, one for rag chew and one for ESSB. Changing from one to another is as quick as a mouse click. I run the receive audio through a Logitech 5.1 system with sub and the audio sounds phenomenal. Currently I am feeding the Flex into my Yaesu FL-2100B amp which yields about 50W out. I have a 50W solid state amp on the way from which will serve as a driver amp for the Yaesu if needed, but I am making plenty of contacts with just 50W. For SSB I use either a Koss SB40 headset or Behringer XM8500 boom mic. With the TX EQ in the Flex, they both sound really nice.

So far I am really happy with the Flex.
KD8OPI Rating: 2022-05-08
Can't believe Flex discontinued it. Time Owned: 6 to 12 months.
I found an eBay unicorn. A NIB Flex 1500 that sat unopened/unused since 2010 (made in the 29th week of 2010 per the serial number) in a storage unit allegedly owned by an electrical engineer. He stopped making payments, the unit went for auction, and my radio (along with a SECOND NIB Flex 1500) were obtained by someone who paid $50 for the unit. It arrived in its original shrink-wrap last year.

My experience?

I paid $400 for mine. IMHO, it is worth 2-3x that.

I installed the latest KE9NS version of Powersdr (how awesome is that guy?), and was on the air without much hassle.

In a word, the radio is fantastic. The software/interface is impressive and easy to use. I don't need to go into how easy SDR interfaces are to operate, but suffice it to say I prefer using this radio to my loaded K3 - its just so easy. Is my K3 a "better rig"? Absolutely - but the FLEX 1500 is a powerhouse in its own right.

My set-up: I've moved, and most of my high power gear is in storage. I was using an Elecraft KX2 and Yaesu 817nd at my new house with an end-fed half wave for 40m. I got the cheap 35w MFJ version - but it works great - no tune on 40/20/15/10, SWR all the way down to 1.01 on 40. The antenna is up 50' in some huge oak trees, and NE/SW broadside.

Using this set up, I've casually worked well over 1000 stations in a year with 5w on the FLEX 1500. With it, I won my state's (TN) QSO party, QRP division (N9GX, my vanity call, look it up on qrz), setting a new record of about 240 SSB contacts (previous was 25% of this). I've hunted nearly 500 unique POTA activations, made about 100 FT8 contacts (I don't FT8 a ton), and occasionally set up a 200 mW WSPR beacon with it.

Its all about the interface. I can move and hunt up and down the bands crazy fast, pull my filters in/out as I need as I "see" the QRM to get rid of, and adjust noise-blankers/notch filters crazy fast. I can hunt through a list of spotted POTA activators crazy fast, switch over to FT8 in a click, and then monitor traffic for DX. I also get amazing, entirely unsolicited compliments on audio.

Are there some negatives? Sure. No SWR meter/bridge means you need to check your SWR with another device. No built-in tuner (not unusual). The filtering isn't as sharp as I'd like (sometimes) , and while the NB is AMAZING, full NB and NB2 activation tends to reduce selectivity and strong adjacent signals overpower the one you want to hear (but otherwise reduce annoying noise in my neighborhood almost to the point of something akin to magic). This is where a the K3 and its Elecraft goodness shine - but its supposed to. The K3 and 1500 were contemporaries, with the K3 being 3x or more the cost BEFORE adding a pan-adapter.

Yup, you need a computer to use it - but an el-cheapo Microsoft Surface Go can run power SDR with 30% CPU burden cleanly, and a powerful laptop in 2022 will run it at only 3% cpu burden. Any modern computer can run this rig to the point you will set up the 1500 to what are "optimal" settings for sampling, latency, and filters.

But, overall this is an amazing radio. As good or better than a lot of QRP rigs sold today, and as large as a paper-back book.

You have to question the decision making at FLEX to discontinue the 1500 a few years ago. This qrp rig is so "powerful" with 12 year old SDR tech and was so affordable (like $700-800 )compared to their "entry level" 6400 today (now selling for $2100 before tax), it was essentially a "gateway drug" for hams to their line-up. I dismissed FLEX products for their price and nebulous benefits in terms of Sherwood receive stats. No more. This rig has sold me on the power of SDR's, and if I buy a new full-power rig in the future, as much as I love Elecraft, it will be hard for me to swallow the K4's pricing after using the FLEX 1500, winning a contest with it first-go, and enjoying the heck out of it.

Flex! You took the one rig every ham could afford out of your line-up!! Silly decision.

GM8GIQ Rating: 2020-12-16
Nothing at the price can come close in RX performance Time Owned: 3 to 6 months.
My Sunsdr2 Pro had to go back for warranty repair and I bought the Flex as a standby while it was away.

Use it with the excellent KE9NS version of Powersdr and amazed by the RX performance.
It may be old but has the same dynamic range as the IC705 88dB at 2khz spacing and it has a 16 bit ADC.
Had more fun with this rig on FT8 than anything I have had in the past.

Nothing comes close in performance at the price.

If you see one grab it, it's a classic and a keeper.
DF9CY Rating: 2020-12-16
Still a fine Radio (for almost 10 years now) Time Owned: more than 12 months.
Still a fine Radio

(This is an update of my earlier reviews / 5th version)

UPDATE 12/2020

After playing with the Flex-1500 since 10 years now, here are some words from me:

Using the Flex 1500 with the KE9NS PowerSDR now on 2m with a HA1YA ME2 Transverter. I am using it with the WSJT-X and MSHV for the digital modes, but microphone and morse keyer are in use as well. This combination outperforms my other "old" IC820H on VHF by far.

Love it ;-)

Nothing to add or cut on the old text below.

AT FIRST: A fast and a well configured computer is a MUST HAVE !! After trying a number of more than 15 different notebooks and desktops I can say, that as soon as the PC is too slow you will not have ANY fun at least when using CW ! So if your Flex-1500 suffers from delays your computer is slow - nothing else. The manufacturer of the radio (FlexRadio in this case) tells you clearly what is required.

CW: My favourite mode in Shortwave is CW - At least since the latest release PowerSDR 2.0.22 is here, I can indeed use the rig in CW. I did not upgrade from this version until now, as it is running ultra-stable. Now it is possible to speed up to 30 .. 40 wpm. I have made a big number of QSOs on 40m which is the only short wave band where I have a good antenna.

Digital Modes - PSK31: Running HRD5 via VAC I made about 30 contacts so far in PSK31. This is working great. I see some delay when switching from RX to TX; I have not found the reason so far.

Digital Modes - WSPR: I ran the Flex-1500 in the WSPR mode (using DIGU) for about 100 full days now with great success. I set power output to 2w and transmit/receive ratio to 20%. The signal is copied worldwide and the RX is good especially with all these filtering possibilities.

Voice: I made an adapter (as described in the Flex support) and use a Sennheiser headset, which sounds good so far. I made a good number VHF SSB QSOs in the last IARU contest - nobody did complain ... good audio quality was confirmed. There was a hum on the signal at first, but this was easily eliminated.

10 MHz Reference: The internal oscillator is very good. My rig shows an offset of 6Hz on 7 MHz after warming up for one hour. I switched to an external GPSDO (Trimble Thunderbolt) and I am on frequency (hopefully) exactly now.

VHF: The Flex-1500 is connected to my SSB LT2S transverter now. RX and TX lines are separate. I get full power output through the transverter out. RX is fine too. Indeed I split up the RX line from the transverter into the Flex-1500 and my RFSpace SDR-IQ. I very successfully use the setup for EME on 144 MHz in CW and WSJT/JT65B. With the RF splitter on RX I run JT65B on the Flex-1500 and MAP65 on the SDR-IQ giving me an overview of the entire 2m digital EME band (144.100 .. 144.160 MHz). The transverters' oscillator is GPSDO locked too.

VHF 2m EME: The combination above is VERY sensitive and I must say somewhat "sensational" for me. It does a very good job.

50 MHz: I made a few Meteor Scatter tests with WSJT by end of 2010. I also tried to receive EME on 6m. I both cases I ran my TS-690s in parallel. Everything ran successful - W7GJ was received via EME as strong as through the TS-690s.

The Software: I believe the rig is quite well designed from the hardware side which is of course a trade off between performance and cost efficiency for the manufacturer. I rate the Flex-1500 with *4* now even after the PowerSDR 2.0.22 appeared. This here is my major drawback: In the moment I experience that image rejection fails after a while forcing me to switch band or mode to reset it. This may be after seconds from the last reset to half an hour or so. This is a known bug and it is indeed very, very annoying. I am a bit frustrated it has not been solved so far.
Once the software will be in an acceptable performance, the Flex-1500 will be a very good performer I believe.
Already now my VHF setup (see above) outperforms any of my other 2m rigs (ICOMs) by far.
I "extracted" from the mail list postings that the mentioned open items were not yet solved even with the latest beta-version of PowerSDR.

By the way: the software always installed flawlessly on my machines on WinXP or Win7. No problems ever seen with it - unless there was a bad configuration. Then of course other stuff did not work correctly too - which you may not see immediately.

Other problems - i.e. crackling noise, delays and so on - are definitely computer related. The nature of software (PowerSDR) with all the FFTs and other signal processing is that it generates a high load on the PC. Hopefully Flex can optimize some routines in the future; perhaps there is some margin because I see other software which seems to be operating somewhat more effectively. (i.e. running Winrad or SpectraVue on my SDR-IQ). But I really cannot judge as I do not know anything about the "inside" of the software.

While reading the reviews here I sometimes get the impression some guys do not really know what Software Defined Radio does mean. After having built myself so many radios from diode receivers, direct conversion stuff and superhets up to to several softrocks in the past years I found myself being confronted with something revolutionary. I went digging through a lot of SDR theory and found it fascinating. Now of course I like turning the knobs on my TS-690s but the Flex-1500 or even better the tiny 40m Softrock open up another world.

Some of my wishes to Flexradio:
* The front screen of PowerSDR is a bit overloaded.
* I do not like the Average function on Waterfall display and so on at all. Software like Winrad or SpectraVue have a kind of MaxHold where the signal "pops-up" quickly and declines slowly. Way much better.
* Make a kind of Flex-1550 with ethernet IP interface.

So for me it was so a *good* decision of putting the Flex-1500 onto my operating desk

Christoph DF9CY
VA3SQ Rating: 2020-10-23
Great Little QRP Time Owned: more than 12 months.
I purchased this radio from Radio World 6yrs ago, and never had an issue with it. This is my main rig and use it mostly for Digital work. I have a lot of QRP rigs, but this is my favorite. I found it has good sensitive receiver for my use and have received good reports with 5 Watts.
EI7HFB Rating: 2020-01-06
Surprisingly good shack for the money Time Owned: more than 12 months.
I use occasionally this radio as have another radio
i have compared this flex 1500 with my primary radio for receiving that is IC 7610 .
I must say im amazed how good reception it got .
small footprint, great reception and easy software,
level of flexibility with filter adjustment - outstanding
i would recommend this radio for any QRP and IT enthusiast
WB0FDJ Rating: 2018-01-02
Still a great QRP rig Time Owned: more than 12 months.
Had the rig 6 years now and have no regrets. I'm still finding things I can do with the receiver, which is, along the the 3000, the best I own. On digi its fantastic, I use it to WSPR and some PSK, flawlessly. Very good SSB if you want. I've never had a glitch that resulted in having to reset, ever. (My Flex 3000 has needed this a very few times) The reason for this follow up post is to share what I've done to reduce latency as much as possible. If you are thinking of buying one of these used, the info might be helpful.

I have an old Acer desktop that runs an Athlon II quad core 645 chip, not the latest thing. Just used a free trial of AVG PC tune up to eliminate all but the most essential backround programs. This has resulted in CPU usage of 5-10%, often less than 5%

I plug the radio's USB into the front port of the computer which is shared with nothing else. Buffer size under audio settings: 128. Display FPS 10. Process priority Above Normal. USB driver buffer and Process priority are set mid range but might be worth a look if you need to. The result is I can reliably work up to 20 WPM with the internal keyer, as well as use a straight key. Out of the box, using default settings, this was not possible. Added bonus: with an external keyer there is no choppiness or dropped characters at all. Make no mistake, my other regular rigs are a TT Jupiter, Argo V, etc. At 100 ms delay it's not full break in and not quite as smooth as those but I've used this rig in events, such as SKCC, and it did the job well.

So for digi and SSB it's a great radio with multiple ways to enhance performance. (i.e. when running PSK set AGC to fixed and you won't have the problem of strong stations blanking out the receiver). For CW work to reduce latency and it's a very useful, if not perfect, machine. Why consider it at all? Digging out small signals with S5-7 noise is what this radio does all day long. I'll take a less-than-perfect but quite usable CW experience to do that.

I am listed on QRZ and will be happy to answer questions if needed.

Earlier 5-star review posted by WB0FDJ on 2012-09-05

This is an update. I bought a Flex3000 and have been using it, off and on, for months. A great radio but it is now, for the time being, retired to the shelf and I am using the 1500. I thought I needed something with 100W but rarely used it at that power level. And the clattering relay got on my one last nerve. I am finding that I like this radio a little more every time I turn it on. I am using an external keyer with the 1500 and that eliminates all of the CW issues, with the added advantage of being able to easily adjust speed without trying to find the mouse. I find myself using all of the incredible features that come in the SDR software. WSPR runs smoothly. I own the usual suspects for QRP (817, 703 and a bunch of kits) but this is my day to day radio. If you do QRP you should get one of these. Seriously. Earlier review follows:

I am a long time QRP op so I already know the "only 5 watt" issue is a non issue. About 3 years ago I bought a new IC-703 which is a very nice QRP radio, with great features, for the same dollar investment. There is no comparison between the two.

Like so many others who have shared comments here I come for the hollow state era, my first station being a Heathkit HR-10B and Hallicrafters HT-40. This new SDR is so many light years ahead of that I am astounded. Yes, for big knob guys like me there is a learning curve but it is not at all difficult. I'd never done anything with SDR but within 2 days of receiving the rig I had it up and running fldigi and JT-65. If I can do it anyone can.

This offers (as you've already heard) the best receiver for the money. My Ten Tec Jupiter is popular with it's owners because of its nice receive audio. In my opinion, based on A/B comparison, the 1500 gets the edge. Very easy to listen to for long periods of time. And you can do things, easily that either cannot be done on other radios (like dragging a filter edge away from QRM) or can only be done with effort. I recently have used it in the SKCC sprint and during the Flying Pigs Sunday night QRP event and found that it allowed me to work stations that would have difficult-to-impossible with my other radios. Digging out QRP sig's with S-6 backround on 40 meters is something that this kind of radio is made for. The filtering is superb and very flexible.

I'm a CW op mostly and I am now happy with it. The default settings were a little "off" as others have pointed out but tweaking the software has allowed me to run 20 WPM without disaster. It's not Ten Tec break in but it lets me QSO and have fun. For digi modes and SSB it's really slick. 5 watts on JT65 has netted me a fair amount of dx.

As with any SDR there are, well, quirks. I knew that going into this. Day to day though I find myself using this radio and enjoying the hobby a little more. I've also set it up to run as a panadaptor with my Jupiter and the excellent N4PY software. But I find that, since I run QRP anyway, I am not using that as much as I had expected. It's good to have the option.

For the cost you cannot find a radio that will do what this one does. It's a QRP op's dream. And fun!
K5AV Rating: 2017-12-01
Amp and Flex 1500 Time Owned: 0 to 3 months.
I recently bought my FLEX 1500 used from a friend (im late to the SDR game) and ran it through my Expert AMP 1.3k FA. With the Flex at 5 watts or 100% drive, all bands are 500 watts out with a few that just dip below. My amp runs on 110v setting and could probably do a little better if I went to 220. I have 3 other non SDR radios that now gather dust (which is a shame) as this radio makes the others somewhat boring. The Panafall setting along with mixed receiver output(hear tx and rx from either L or R speaker), lotsa of filter settings and a great receiver make it fun to operate.

There are a few small takeaways but non that cannot be corrected. Ie the CWX or internal keying is delayed. Not cool if you are in the heat of the DX moment and want instant tx response time. So I use my win keyer and bencher direct to the radio. I have seen it go into the 'oscillation mode' a few times on boot up only but never during operation. A quick restart and all is resolved.

Once your learning curve flattens, band change, set up split operation ect are quick and easy. The mouse wheel allows my hand to stay flat on the table which seems trivial but not after you go back and tune with the Big main knob of a hardware radio. With the Panafall zoomed out, I can view the entire CW spectrum and see any action from say 14000 to 14050 in just seconds.

I realize most of this is old hat to most but really wanted to mention my results with the amp…

Regards, John K5AV
K0INN Rating: 2016-11-01
For CW - highly dependent on your computer hardware Time Owned: 0 to 3 months.
I purchased the rig used from another ham. My operating mode is almost 100% CW. I like to operate 20-25 WPM casual QSOs. I'm using a 1 year old business class HP i5 desktop with 8GB RAM.

First off, the receiver and pan-adapter are great. This makes me really want to use the rig.

For CW with the internal keyer, the problem is delay. It is impossible to key when you are hearing the sound trailing by a second. There is a lot of material on the web about making changes to buffer sizes in the software. I tweaked on those and but never could get rid of that delay. But - then I discovered the secret. The audio was being carried from the flex by the usb through my computer to the speakers. I changed and ran a 3.5mm plug cable from the headphone jack on the flex directly to the input on the computer speakers. Voila! Delay gone.

So now - different issue. About 10-15 minutes into the QSO the keyer locks up and keeps sending dits. I have to close the program to stop it. This happens every time I use the internal keyer. I do some research and there are others with this same issue. The explanation is that it is likely a USB or computer glitch causing the problem. It is probably not the rigs problem.

OK. So I give in and use an external keyer. Everything is good now. I've been operating this way for a while and everything is working AOK.

One thing I've learned - software setting tweaking could result in there appearing to be a rig hardware problem. For folks experiencing what might be hardware issues - in the software there is an option to restore default settings. At one point I was convinced I had a hardware problem when there was an intermittent loud hum when transmitting. I restored to default settings and that was gone.