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Competitive comparison

Larry Benoit
Larry Benoit Member ✭✭
edited November 2019 in FLEX-6000 Signature Series

Pending arrival of the new 6000 series transceivers, I performed a preliminary competitive comparison of the “K3S Contester and DXer” package vs. a Flex-6600/Maestro package. I chose these packages to create a “knobbed vs knobbed” comparison among two of the best high performance transceivers on the market.  Neither package requires a separate computer for basic local and remote operations, but both need a computer to support some desirable capabilities.   

Elecraft offers the discounted package with dual receivers and several important options for $5900 ($300 discount) vs. $5200 for the Flex 6600/Maestro package (no discount).

While the K3S package is excellent, the Flex 6600/Maestro duo has several features and capabilities that are not included in the Elecraft package. Accordingly, I added extra cost options to match wherever possible the features of the Flex-6600/Maestro package and as a result the cost of the K3S package rose to $8090 vs. $5200 for the Flex package (rounded amounts to next $5).

I’ve avoided comparing raw performance specifications, leaving that to Mr. Sherwood and other experts to sort out and chose to focus mainly on operating features, options and capabilities. But, I couldn’t cover everything, so please pardon the absence of some distinctions between the two radios.   I’ve tried to carefully verify all of this information, however, should anyone discover an error, please let me know and it will be promptly corrected.

K3S “Contester and DXer” package includes the following:

·        K3S-F 160-6M, 100 W Transceiver

·         Digital Voice Recorder

·         100W Internal Autotuner

·         2.8 kHz High Perf. SSB/Data Filter

·         2.1 kHz High Perf. SSB/Data Filter

·         400 Hz High Perf. CW/Data Filter

·         200 Hz High Perf. CW/Data Filter

·         High Perf. Subreceiver

·         2.8 kHz High Perf. SSB/Data Filter (for Subreceiver)

·         400 Hz High Perf. CW/Data Filter (for Subreceiver)

·         MH2 Hand Mic

·         P3 Panadapter

·         P3SVGA Video Adapter

·         Elecraft Hat


The Flex-6600/Maestro package includes the following:

 ·         Flex-6600 transceiver

·         Maestro control console

·         Hand microphone


The Flex-6600 does nearly all RX/TX filtering in software (except RX preselectors and TX final bandpass) whereas the K3S employs conventional and crystal filters to perform the same tasks.  While the K3S package comes with a robust filter set, it does not include the AM/FM filter at $150. Narrow filter options for CW and SSB on the sub-receiver, will cost an additional $320. Also, for general coverage, you’ll need a bandpass filter for $180. Again, these filters are added to approximately match the capabilities of the Flex-6600.

Remote Operations

The Flex-6600/Maestro duo is designed for native remote LAN/WAN operations, supporting nearly all functions with tactile and touch-screen controls and a high resolution panadapter/spectrum display. The Maestro can connect to a network via Ethernet cable or Wifi, while the radio is connected with Ethernet cable only. Also, the 6600 can be operated remotely without the Maestro using SmartSDR 2.0 software (SmartLink) on a Windows or IOS computer connected to your LAN or the Internet.

The K3S requires a package of hardware for remote operations and provides no remote panadapter display support.  The equipment includes RemoteRig gear for $500, K3/0 mini control head for $700, plus cables and power supply, totaling $1320. Unfortunately, the RemoteRig control site box does not support WiFi.

Band Coverage

Both radios provide standard TX support for 160m-6m, while the K3S can support 2m with an optional board (not included in package).  Both radios have standard transverter I/O ports.

The K3S can monitor two bands and display spectrum for one band with the P3, while the 6600 can monitor up to four bands (slices) and display the spectrum for each on four separate panadapters (two on Maestro).  Both provide general coverage (includes 630m and 2200m bands), but this capability requires an optional filter with the K3S package. The Flex covers down to 30 khz while the K3S covers down to 100 khz.

Both radios have dual receivers with separate antenna inputs and support diversity reception.

Panadapter/Spectrum Display

The P3 display is small (4.5” approx.) with poor resolution (480x272) and limited 200 khz bandwidth, while the Maestro display is much larger (8”), has higher resolution (1280x800), numerous touch-screen controls and covers up to 14 mhz bandwidth.

The P3 as optioned supports an external monitor while the Maestro does not. Of course, the Flex provides native support for high resolution monitors at no extra cost when the radio is operated with a computer instead of the Maestro.

Digital Modes

The K3S has built-in, but limited support for PSK31 and RTTY modes (text displayed on the front panel) with no requirement for external hardware or software.  There is no provision for direct text input via a keyboard, so text is entered real-time with a CW key (code translated to text) or as macros in memory.  Full digital capability with keyboard input and GUI requires a computer and third party software.

The 6600, when operated with Maestro, does not support digital modes, however all digital modes are fully supported when operating the 6600 with a computer running SmartSDR, third party software, DAX and SmartCAT.   

No external sound card is necessary for either radio when operated with a computer.

The K3S does not support DSTAR while the 6600 provides support with an optional USB drive.  Also, Free DV support is included with the 6600 (waveform plug-in), but not the K3S.

Oscillator Stability

The Flex-6600 has a .5 ppm main TCXO (preliminary published spec) while the K3S is rated at 5 ppm.  An optional high stability TCXO for the K3S will nearly match the Flex-6600 at a cost of $120.  

The 6600 has a standard 10 mhz input for external oscillator reference control, while the K3S package needs an optional board for $100.

An optional internal GPSDO is available for the 6600, but not the K3S.

Digital Recorder

The KS3 digital voice recorder provides RX/TX recording capability (several recordings for TX), while the 6600 provides only a single RX recording, which can be played back in TX or RX mode.  The Elecraft DVR is more capable and there is no comparable option available for the 6600 (third party software solutions are feasible).   

Both radios provide CW recording, macros and TX playback.


The Flex 6600 provides support for SO2R in one radio and full duplex (cross band), while the KS3 provides neither.

Third Party Software Integration

With introduction of N1MM spectrum integration and spotting software into SmartSDR 2.0, Flex has taken another big step in exploiting the tremendous benefits of its networked architecture and sophisticated software APIs. Elecraft is significantly behind in this area, offering no native network interface for developers. It’s seems unlikely that the P3 will provide a robust graphical user interface for third party apps.


The K3S package comes with an Elecraft hat, while customers must purchase the Flex hat separately for $12 plus shipping.


The K3S “Contester and DXer” package is $5900. Additional K3S options to match or partially match the Flex-6600 standard features are as follows:

$ 1320 Remote operations package

$ 150   FM/AM filter

$ 170  Narrow CW filter for subRX

$ 150  Narrow SSB filter for subRX

$ 100   10 mhz external reference oscillator input board

$ 180   General coverage bandpass filter

$ 120   high stability TXCO (1 ppm)


$2190 total

These items bring the K3S package to $8090 vs. the Flex-6600/Maestro package at $5200. Again, this pricing was derived by matching features to the extent possible. Some features, such as full duplex, SO2R in one radio and native remote operation are currently not available from Elecraft.

I recognize that many of these "high" features may not be wanted or are affordable for some hams. However, eliminating all of them from the upgraded K3S package would still result in a cost difference of $700 in favor of the Flex 6600/Maestro while retaining all the standard high features in the Flex package. 

If traditional knobs are not essential and you already have a decent Windows or IOS laptop or tablet, the Maestro can be eliminated for a total savings of $1900 whilst retaining a peerless panadapter/spectrum display, native remote capability and several other features lacking in the K3S package.

Alternatively, the Flex-6600M alone would provide operational equivalency in combination with a laptop or tablet (specifically for remote ops) for $900 less than the K3S “Contester and DXer” package (with no add-ons).

I admire Elecraft and Flex and own quality products (6500 and KPA500) from both American companies. With the arrival of the 6600/6400 radios and SmartSDR 2.0 Flex has in my opinion taken the industry lead in value, features, operating ergonomics and software integration. Competition is a good thing for amateur radio and it inspires better and lower cost products for us to enjoy.


Larry KB1VFU


  • Mack
    Mack Member ✭✭
    edited March 2019
    Larry, That's a fantastic analysis! It seems very fair and balanced. Mack W4AX
  • Mark_WS7M
    Mark_WS7M Member ✭✭✭
    edited July 2019
    Outstanding analysis!  Thanks for posting.

    The other day I was talking with a local guy who just built a home built Windows computer and not being a computer person he needed help and was frustrated with how complex things where and what driver was needed for what thing.  He ended his diatribe saying he would never go through that experience again.

    I asked him why he built it and he said because I need a computer in my shack.  Almost in the same sentence he started to talk about how he'd never want a radio that would require a computer.  He went on and on about how he likes the older gear from the 90's because he just flips it on and it works.  No need to run any special software. etc.

    But then his very next statement was how much he loved having the SDR receiver running on his new shack computer and how he was using it constantly to see that his output signal was clean and to monitor incoming signals.

    So I told him that was why I love my flex.  I have my computer, my software, full time pan display and as soon as I let go of transmit he said, "Oh man I'd never own a radio that required a computer..."  I could not believe it.  He was so addicted to his computer and SDR display but simply could not conceive of having it all in one package so to speak.

    At one point he said, you know when your computer crashes and you are off the air I'll be on the air with my 90's gear.  I politely reminded him that I could use my phone, my iPad, my other computer, even my wife's computer to run my flex.

    Anyway the point is that regardless of how good the flex is there will always be someone to poke a hole in it even if they are trying to do so with a wet noodle.

  • Bill Roberts
    Bill Roberts Member ✭✭
    edited July 2018
    Sounds like the poor man is mightily confused.
  • Kevin
    Kevin Member
    edited August 2017
    Sounds like your friend is definitely in a transition period. :) At my age, I have to struggle with some computer concepts while others seem natural.
  • Kevin
    Kevin Member
    edited July 2019
    Larry, that is an outstanding analysis of the Flex 6600M vs. K3S. Lining them up side-by-side and feature-for-feature and cost-for-cost really helps put things into perspective. As it was when I bought the 6500, there's no doubt I would buy another (or the 6600x when available) again today.

    There was a short-lived thread on the Elecraft board with some wishlist items for the mythical K4 and beyond so in this industry it's probably best to keep an eye on the competition. Good things have come from that company.

    I own a KX3 and a 6500 (and also a KPA-100, KPA-500, KAT-500 and W2). Love them both. The KX3 is a natural outdoors while the 6500 is the cat's meow indoors and, for some, remote.

    You mentioned the peerless panadapter and I have to agree, there's nothing like it. Unfortunately (well fortunately for the consumer maybe) when there's nothing to compare to, it gets compared to itself. While the panadapter is the key wonderful feature of SSDR I contend SSDR is generally overdue for an overhaul. I won't repeat my comments from previous posts. I will say being at the top doesn't leave any room whatsoever for resting on one's laurels. SSDR needs help.

    Oh... and I notice you didn't compare the cost of fan replacements! ;)

    Excellent analysis. Thank you.

    Kev K4VD

    P.S. I guess it should be pointed out that the K3S is actually available and has been for a while. And another interesting note, the previous K3 is, I think, mostly upgradeable to a K3S.
  • Ria
    Ria Member ✭✭
    edited November 2019
    I like my Flex hat.

    Kudos on the comparison. Well written. 

    However, I tell people - buy what YOU want. I am not telling anyone that any radio is worse than the other because the K3S has strengths as well as weaknesses. However overall I would buy the Flex again if I was presented with the choice.

  • Varistor
    Varistor Member
    edited November 2019
    Or you can buy two Icom 7300s and have the ultimate flexibility to switch between SO2R, M/S, and M/2. Total investment of $2,600.
  • Ria
    Ria Member ✭✭
    edited August 2017
    Doesn't take into account the filters and SO2R interface necessary but that is always an option. 

  • Varistor
    Varistor Member
    edited August 2017
    It takes into consideration years of designing, building, and maintaining a contesting station that has broken records and earned plaques. Practice trumps theory every time.

    When it comes to managing intra-station interference, one of the most important components of the station is the filtering system. It all boils down to how much undesirable RX and TX signal suppression you can provide to each radio.

    The answer is you need in excess of 40 db for low power stations and well into the 70s db for high power station. If you are using triplexers to share antennas or the antennas are physically close to each other these numbers jump much higher.

    Here's some reading on the level of filtering one needs to achieve:


    In my case I use a combination of low and high power filters for total filtering of over 100 db between radios.

    To get to that point of undesirable signal suppression, you need filters that are quite large in size and where each filter is in its own metal enclosure. Size matters, folks, and the only viable way to effectively manage filtering is by using external filters, often larger than the Flex rig itself. Note that filters also belong AFTER the amplifier, not in front of the rig as you want to suppress the harmonics and phase noise created by the rig plus the amplifier.

    To illustrate my point, here's the type of filters I use after my amplifiers:


    and these are the filters before the rigs:


    DX Engineering has a similar solution, which is quite large in size as well:


    Notice that both filter sets are in fairly large enclosures. This is dictated by the basic requirements for high Q, heat dissipation, and avoiding RF leaks between components. Even the relatively low level of isolation Bandpasser is in a box that won't fit in any Flex.

    So the point I am making is that anyone considering building a SO2R station is facing the reality of using external filters to achieve the desired level of isolation between rigs. Flex filtering alone is insufficient, no matter what FRS is telling ya. Size matters.

  • John - K3MA
    John - K3MA Member ✭✭
    edited August 2019
    Umm.....nice price comparison.  I wonder what if any price comparisons Flex used before they priced the 6400/6600?  If the comparison presented here is a reflection of Flex's work over the last two years to break into the contesting market.  Then it would seem Flex left money on the table as well as pissing off existing owners of the Flex 6300/6500 when they priced the new models less than the current model they are replacing.
  • Ria
    Ria Member ✭✭
    edited August 2017
    Most contesters would disagree, most of us are not using high power filters after the amp. In fact a lot of stations are using stubs which are cheap and effective and work just as well at QRO levels. I use two 5B4AGN filters after the exciter. Works very well.
  • Varistor
    Varistor Member
    edited August 2017
    The original discussion was about "competitive" station design, not about what most people do. Most people don't proactively plan their station design, run HFTA to determine optimum antenna height, or think about intra-station interference. Most people don't break records or earn plaques and that's OK; the question was about being competitive.

    Ria, you tend to read a lot, but not take the time to read in depth. Or build what you read. Often the devil is in the details. For example, stubs are not as trivial as you think. For stubs to be effective they have to take into consideration the load they see on their output. In plain English, stubs' performance greatly depends on the distance between the stub and the antenna feed point. Obviously this becomes a major pain point and the vast majority of hams never bother actually tuning their stubs for that particular distance. To avoid the uncertainty of the distance to the feed point, the recommended approach is to use two identical stubs in sequence.

    The idea of using nothing but a Flex to combat intra-station interference in a competitive SO2R, M/S, or M/M environment is causa perduta.
  • Varistor
    Varistor Member
    edited November 2019
    The point was and still is that there are other very viable options to consider, including a pair of Icom 7300s. Such options could be better priced and more feature rich than a Flex. A pair of rigs allows you to enter in many more categories and have quite a lot of station reconfiguration flexibility.
  • Ria
    Ria Member ✭✭
    edited August 2017
    I can have a pair of 6600s for less than the price of two fully loaded K3Ses and I'll have double redundancy. Add a pair of power genius XL and I can have double redundancy at the amp stage, for just a bit more than two KPA1500s.

    This is an apples to apples comparison. The 7300 is not really an apples to apples comparison as it is a very basic SDR radio and has only one receiver/slice. If I really wanted to go cheaper using flex equipment I could get a pair of used 6300s.
  • Ria
    Ria Member ✭✭
    edited November 2019
    When I mean competitive, I mean SO2R ops from my club who place in the top 10. General consensus is that filters before the amplifier are usually sufficient, and many top 10 contest stations use cheaper solutions like coax stubs. The cost to benefit ratio for high power filters really isn't all that good, but if you're K3LR or K1LZ you'll have the money to spend to get that extra tightness in the filtering. But I know lots of top 10 placement who use simpler equipment and not expensive high power filters.
  • Bill -VA3WTB
    Bill -VA3WTB Member ✭✭✭
    edited February 2018
    Of course there are many options out there. Larry could not possibly list all the possibilities in his article. He was only using the K3S radio as a example, but a good one since there have been a lot of DX stations put together using the K3S, I don't know how many DX stations are using the 7300's

    Nice work Larry, a lot of work went into that.
  • Clay N9IO
    Clay N9IO Clay N9IO Member ✭✭
    edited August 2017

    John I respectfully disagree. 

    I made a choice to trade in my 6300 toward the 6600 as I see great value in the 6600 and 6400 models. The shift in pricing is (welcomed) by myself, I am not "**** off" whatsoever.  Had I chosen to keep my 6300 I would be equally as happy with that choice as the 6300 still is as it was pre 6600 (one fantastic radio).  Again my choice.
    Please don't put words in my mouth, speak for yourself, and I seriously do mean this respectfully.  You see it your way and I see it mine.

    This thread started off positive and quite to Larry's point.  Well done Larry.

  • Bill -VA3WTB
    Bill -VA3WTB Member ✭✭✭
    edited August 2017
    As every one knows. flex is a very progressive company, always going ahead.  They have found a way to make the new models with un- beaten performance, features, and price. Most companies when offering new products commonly up the price. So as Flex actually lowered the price it is a win for future customers as well as customers wishing to trade up.
  • Dan -- KC4GO
    Dan -- KC4GO Member
    edited October 2017
    I have placed an order for the 6600 trading in my 6500. I will gladly pay the difference to gain the dual SCU's and what comes with them.  I have a TS-480 Kenwood that I purchased in 2005, they still sell the same unit with the same serial connection. One would think at least they would up grade to USB. I'm glad to see that Flex is a progressive company bringing out new products.  I looked at the K3 before my 6500 purchase and I'm still glad I made the choice I made. 
  • Joe N3HEE
    Joe N3HEE Member ✭✭
    edited February 2019

    I just ordered a certified pre-owned (demo unit) Flex 6600M.  It was discounted $500 and shipped the same day I placed my order!  I am coming from an older Elecraft K3. It made no sense financially to persue a new Elecraft K3S.  I love my K3 though and it has been a great radio.  I truly hope for the same performance, features trouble free operating from the Flex.  -Joe N3HEE

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