Friday, May 28, 2021

Elecraft K4 added to Sherwood Engineering's list

The new Elecraft K4 has been added to Rob Sherwood's much-vaunted list and many will be surprised at the placement at #13 of this new flagship radio.

Above it are the K3S and KX3.

Also above it are direct-sampling SDR radios from Flex (from 2014 and still #2 on the list!) and Apache Labs.

Two things about Sherwood's list: if your favorite radio ranks high, you use this fact to brag about your rig and your astute purchase decision. If your radio is low on the list, you dismiss the criteria used to rank the radios and talk up the other specs that don't contribute to the radio's placement.

This if, then interpretation allows any radio to be Awesome! no matter where it is on the list.

Elecraft's official position on the K4's placement on Sherwood's list: "We're quite pleased with his test results...".

I'll admit to being surprised at the K4's position on the list but I'm even more surprised that Elecraft has chosen to be a one-radio company, no longer offering the higher-performing K3S.

The K3 became the rig of choice, not just for top contesters and DXers, but for DXpeditioners too. It was small, lightweight and reliable. I seriously doubt the K4 will be as reliable to take along on a DXpedition to some remote location. Added complexity = reduced reliablity.

  • Will the K3S make a return to Elecraft's line-up? 
  • Will Elecrafters be happy knowing that the latest offering from Elecraft is, in a big respect, a step down from what had been available?
  • Will the flexibility of the K4's SDR architecture compensate for its lower performance and higher price?

My prediction: Yes (well, hopefully). Maybe. No.




From Rob Sherwood regarding his data on the K4:

Comparing laboratory receiver measurements is a complex subject.

My recent post of Elecraft K4 lab measurements has resulted in some inaccurate conclusions by some readers of my long form report and my web table. The “notes” portion of my report made some comparisons to the Icom IC-7610 and Flex 6000 series transceivers. All three have similar architecture. One must first realize that the measured values for dynamic range, ADC overrange (overload) and RMDR (reciprocal mixing dynamic range)/ phase noise values (as listed on my web table) are all relative to the noise floor of a given radio. All transceivers currently in production have adequate sensitivity on 10 meters, let alone 6 meters. All direct sampling transceivers have a similar dynamic range. This is simply physics. An ADC by itself has a given noise floor, and a maximum signal voltage it can handle without overload. This dynamic range is about the same for all ADCs in amateur radio equipment. The ADC in the K4 is the same one used in the IC-7610. The Flex ADC chip is different, but it has similar performance.

The main difference among these three brands (Elecraft, Flex and Icom) is the gain between the antenna and the input to the ADC chip. With no preamp enabled on a Flex or the K4, there is no gain stage driving the ADC. In the case of the Icom 7610 (and the 7300), there is a 20 dB ADC driver chip in the circuit all the time. Note: All these transceivers have preamps and attenuators that should be used to set the “net gain” that is driving the ADC chip. This chosen net gain should be different on 10 meters compared to 160 meters. Band noise on 10 meters is typically 30 dB lower than band noise on 160 meters. The operator of any radio should take this into account when deciding to enable a preamp or an attenuator.

Let’s look at the receiver noise floor of three different brands and models to understand why each should be operated differently. Noise floors are normally published in a 500-Hz CW bandwidth for consistency. Also listed is dynamic range.

Receiver noise floor on 20 meters, no preamp:

Radio     Model    Noise floor    Dynamic Range

Flex      6600      -111 dBm           99 dB

Elecraft   K4       -121 dBm          101 dB

Icom      7610      -132 dBm           98 dB

The noise floor difference is 21 dB and all are direct sampling radios. The dynamic range values are virtually identical. No one on the air could possibly tell the difference as far as dynamic range. It should be clear that these radios need different amounts of preamp gain or attenuation depending on which band it is being operated. Flex transceivers will need preamp gain on 10 meters, and the Icom should be operated with attenuation on 160 and 80 meters (and likely 40 meters). The K4 is in the middle, and remember these numbers are with NO PREAMP at all.

I made the following statement in my long form report. “If the 7610 is adjusted for 12 dB of attenuation, the noise floor of the 7610 will be the same as the K4.

In this case the K4 will over-range (overload) the ADC at a level 6 dB higher (better) than the Icom. (I added the comments in parentheses for clarity.) When comparing radios they should be adjusted for the same noise floor or the overload level is meaningless. I believe many hams are reluctant to use an attenuator when they should, and tend to use a preamp when it is inappropriate.

Remember: Band noise varies by 30 dB from 10m to 160m, and receiver noise floor with no preamp varies by 21 dB in these three examples. Another subject that exists is there are two main architectures in current product offerings: Superhet with roofing filters and direct sampling, which by definition can NEVER have a roofing filter.

In very difficult RF environments, the superhet with a roofing filter has an advantage when dealing with VERY strong out-of-passband signals such as those line-of-sight or Field Day. The K3S has a blocking level at least 20 dB higher than direct sampling radios. The K4HD will likely be similar to a K3S. Most of us most of the time do not have to deal with extremely strong signals. I have never seen a skip signal overload a direct sampling radio at my contest station in rural Colorado. With a 7610 with no preamp, overload would be at S9+64 dB. With no preamp a K4 would overload at S9+82 dB, but that is with a different receiver noise floor.

Let’s quickly look at three different Elecraft radios, the K3S, the KX3 and the K4. The K3S is a superhet, and its gain with no preamp is similar to the Icom 7610. The KX3 is a completely different architecture, and it has a very wide range of preamp gain. Its limitation, as identified in the footnotes on my web page, is its opposite sideband rejection at around 65 dB. The K4 is direct sampling, and on the lower bands, where no preamp is needed, will handle very strong signals better than the 7610 with no attenuation.

Rev A


  1. I couldn't agree more, John: "I'm even more surprised that Elecraft has chosen to be a one-radio company, no longer offering the higher-performing K3S.

    Sverre LA3ZA

    1. Hello Sverre,

      I regret selling my K3 - it was such a fantastic radio for a lot of reasons and I learned a lot from it regarding how a receiver should behave. My prior (mis)conceptions were due to the inferior radios I could afford before finally buying the K3. Hopefully, it will make a return to Elecraft's line-up.


  2. Equally surprising to me (I hadn't looked at Rob's list in awhile) was the high placement of the Yaesu FTdx10. That's a LOT of receiver performance for under $2k and I almost never hear anyone talk about it.

    But yeah, I can almost hear hearts breaking in the Elecraft world over that K4 review...

    Jeff KE9V

    1. The FTdx10 was also very favorably reviewed in the June QST. The reviewer stated that its performance was only slightly less than that of the FTdx-101D, which is Numero Uno on the list.

    2. I waited a long, long time for the K4 to be released. I started with a KX3 as a first time ham and must say it is a hell of a radio especially given it's "QRP", portable, camping, and hiking status. For this and many other reasons I was completely hooked on the Elecraft brand. But alas reality multiplied by politics did a number on life as we know it and the K4 hit the brick wall from Hell. I had decided that a K3S would be radio that would make me a happy Ham camper but found when I went to order one of those bad boys I was a day late and a dollar short. Extremely poor planning on my part I must admit. I even had a very nice chap from Elecraft ( One of the reasons why Elecraft is so high on my list is the service and support. Just superb.) STRONGLY recommend that I purchase a K3S immediately as I would not be able to for much longer. Did I listen? Of course not.

      I am very surprised that Elecraft made the decision to stop the K3 line. Per normal there are things I'm not privy to that I'm certain made perfect sense to the brass at Elecraft. From an old fart with a fair amount of common sense I'd have to say that I wouldn't have gone the "Cancel the K3 line" route. But Monday morning quarter backing is usually pretty good. I still doubt I would have stopped the K3 radios though. Again, I sure there was very good reason to do so. It's just not obvious or on an intuitive level clear what this reason was. And since it's not my dime in the pile I can still even recommend to Elecraft that they go ahead and Re-Release those radios anyhow. Unless they completely destroyed all the necessary tooling and infrastructure to do so.

      Elecraft owners are a pretty loyal bunch, and, I believe Elecraft will do some serious tweaking with the K4 that will bring it up to top seller status. Provided somebody doesn't come up with something new that everyone just must have in the near future.

      I finally pulled the trigger on the Yaesu FTdx101MP and I'm quite happy with it. After the KX3 though it does seem a little too easy to use often times. The ability of the RX to bring a signal out of horrific noise to end up sounding like a wired phone call amazes me every time. And I get great sound reports on almost every contact. I can't complain other than I do seem to have a thing about the Flex and Anon radios regarding their panadaptors. I simply prefer the way they look. It's that simple.

      I'm not one to attribute God like status to any radio or manufacturer the way some folks might. Competition just makes it too hard to be that much better than anyone else. I do think that too much is based on the Sherwood reports but seeing as how I ended up buying the radio that was number one on the list I guess I don't have much room to criticize do I?

      With that admission I'll sign off. Here's to Elecraft. They took one hell of a left hook and I think they're still not sure the canvas isn't moving, but I think given their history they'll finally come back very strong. And, I have not ruled out buying a K4 in the future.

      Kirk WC6T

  3. I have two early K3 models. Very, I say VERY happy with these, a huge improvement coming from TS-850 radios.
    The K4 looks nice, and my K3 are 13 & 14 years old already (if I recall right).
    Note: back then the Euro-Dollar ratio was obnoxiously favoring EU (1.65:1).

    When announced I wondered: will this K4 be an improvement over my K3, and if so: by how much to justify the purchase?
    These measured numbers tell me: stick with the K3. Last weekend (WPX CW) I worked all my antennas let me hear, and then some. Even some obscure AE5 prefix from TX...

    By all means I would never be an early adopter again. My low S/N Elecrafts needed hardware mods that got incorporated in later revisions. Some mods have never been done at all. I hate messing with this hi tech micro stuff.

    For now, the K3 setup will have to serve another few tours of duty on the contest battle field. They have so much combat experience by now, and have a chest full of medals to show for it.

    Don't get me started on the Seven Oh Five. As much as it's tempting me I'm afraid I will never be a low-power-low-rate-in-the-field kinda guy. So I'd regret buying it. And it's hard to get rid of these things around here.

    Franki ON5ZO / OQ5M

    1. Thanks for the call during WPX, Franki. I was a bit overwhelmed at times at the intensity of stations calling and only had 2 hours to participate this time. Glad you were one of those I worked.

      It will be interesting to see how the K4 develops - I think we will see fewer K3's for sale on the used market than what many previously might have thought. Gerald Youngblood (of Flex) needs to monitor the Elecraft list to see how to sell radios. Wayne Burdick is a master at that skill; Flex, with higher rankings in the numbers department - not so much.


  4. Very dissapointed. K4 release was delayed, with the 2nd RX and panadapter introducted, costs seemed to high, compared with a K3s and upgrade with these options. Well after the only comparision tests available from Sherwood the games over. Keep the K3s and buy higher up the list(Yaesu,Icom) "IC705 from Icom says it all 160-432 10 watts" $1200 US add KPA500 and your there.

    1. Even if the K4 had been released on time (not Elecraft's fault, I know) it is still a radio that is playing catch-up to other rigs on the market.

      Elecraft soared to popularity by consistently developing innovative radios like the K2, then the K3. At the time of their release there was nothing else like them. The K2 - a high-performing HF kit; the K3 - a modular kit with receiver specs nothing else could touch.

      But now, the K4. There are already several rigs on the market that already do what it will do in terms of ergonomics, receiver specs and SDR FLEXibility. Icom, primarily, with Yaesu hot on their heels. Say what you want about the K4 but it is not innovative - it's nothing more than another player in an already-occupied field, running on momentum of Elecraft's past.

  5. I had a 2009 model K3 (at that point, it was pretty stable, and ended up only needed a couple of hardware tweaks while I had it), then 'traded up' to a K3S (and glad I did, since they are no longer available) by selling a stripped down (2.8 kHz filter, 100W PA, ATU, upgraded LO board) K3 to a new General in the local club (he's very happy with it), and then moving all the other filters, 2nd RX, general coverage RX boards, etc. to the new K3S. So, I ended up with a fully tricked-out K3S for the price of the base 100W K3S, and most of that was covered by the price I sold the used K3 for.

    So, now comes the K4. Like some others, I'm waiting for the K4HD, and for the early issues to iron themselves out, before even considering taking the plunge. I do like the modular design, which promises to allow an upgrade to the RF ADC boards if/when new and improved (and affordable) ADC's come out.

    I'm also quite curious about the K4's NR (Noise Reduction) algorithm, which I've been told is currently based on the legacy Elecraft gear, but is slated to be re-done based on newer/better 'improved' NR algorithms that can run on the far faster processor(s) in the K4. Right now, I've heard that the K4's NR beats the K3/K3S hands down, which interests me, because my experience with the K3/K3S NR has been disappointing.

    The Yaesu FTdx10/dx100 are interesting, and a couple of folks on the weekly Sunday Elecraft Zoom call, have actually cancelled their K4 orders, and instead purchased either an FTdx100D or FTdx100MP (the 200W version). One ham on the call, insists that the Yaseu-proprietary "VC Tune" feature makes all the difference (and apparently VT Tune is NOT available on the FTdx10). As near as I can tell, it is an automatic tuning RF pre-selector. Those of us that remember the Drake 4-line back in the day will remember touching up the RF pre-selector as they tuned across the band. It peaked the receiver sensitivity, but also added some needed front-end selectivity, a kind of broad, tunable roofing filter if you will.

    So, in the FTdx100d/100mp, the VC Tune forms a poor-man's tunable roofing filter, as it tracks across the band following the receiver tuning. I'm not sure just how narrow the filter is, from folks that have used it, they swear by it, saying that it cleans up even adjacent strong signals (not sure just how adjacent, though).

    Anyone else have better information on VC Tune?


    -- Dave, N8SBE

    1. It's too bad we can't test drive rigs before deciding to purchase. $3000 now seems to be the entry-level price for a rig with a set of specs that will allow it to perform well in harsh RF environments.

      I had an early deposit on a K4 myself but cancelled it when I saw the writing on the wall. My operating style has changed with the diminishment of CW in general and CW-operating DXpeditions. Regardless though, I do like to follow developments of the K4 and look forward to the modular kit version being available, if only to enjoy it vicariously.

      I had not heard of Yaesu's VC Tune - maybe someone will post a demonstrative video to YouTube.


  6. These wild Yaesu with antenna relay making noise like gramdma's 1904 sewing machine. Definitely not good radio for a CW-only guy...

  7. Hi all was very supprised by the Sherwood Engineering results of the Elecraft K4, good luck I keeped my KX3/K3 up grade. I also noticed Sherwoods results on Icom's new range has followed in the same manner IC705/9700/9100 have struggled to out pace the oldies IC756 etc and holding their own on the HF rigs. Yaesu on the other hand has well, wiped the floor with their latest offerings and the opposition with their FTdx10 series,(not a fan but go figure)

  8. TL;DR: Knowing how to use your receiver properly for conditions is more important than what radio you have.

    Great info—thanks.

  9. have now K4 #430 (K3 and K3s also)
    i am very disappointed that after 24 Month (since K4 announcement) the software is far behind from SW of K3
    dont know what elcraft has done last 2 years

  10. I am very happy with my K4D.I am somewhat limited as I DO NOT buy 'Rice BOXES". I was Collins for years and never regretted it. After that it was Ten-TEC until my Orion I took a strike in 2011. That's when I got the K3. It was upgraded about 6 months ago and it still works great!!

    Being a three time GA Tech graduate I fully understand the numbers. Rice boxes are never long lasting, and become obselete quick. Also, service is always an issue. I want nothing to do with them...

    Using a K4D in Diversity RX with the Hi-Z 8 and the Waller FLAG. I hear stuff I never heard before.

    Merry XMAS es HNY to all.

    My best 73,

    John, W4NU
    (K4JAG 1959 to 1998)

    1. I've owned a number of Elecraft, Ten-Tec and Flex radios but don't limit myself to them. My IC-705 beats the hell out of any KX-prefix radio and my FT-891 is a better mobile rig than anything US-offered. I wish the K3 was still available - owned one for 11 years and sold it - a mistake on my part.

      John AE5X

  11. Good morning John. I found your blog through VE9KK's blog - and I'm glad I did. Love your content!

    As a relative newcomer, I was of course, initially influenced by the Sherwood Table and considered it to be the absolute reference, but I sure do feel differently about it now - almost to the point where I ignore it.

    Most of the technical data listed on the table is way beyond the processing power of my wee brain, so I have had to rely on my intuition and guts when judging a radio. The Yaesu FT-DX101D is a great case in point - it's #1 on Rob's table and I sold my 7610 to buy one - and then went back to a 7610 when I realised that there's SO MUCH MORE to radios than data on a chart and positions on a league table.

    I have a KX3 and a 705 and love them both for different reasons. The 705 is around 20 spots lower down the table than the KX3 but out there in the field, there's virtually nothing to part the receivers.

    73, Tom, M7MCQ

  12. Good morning, Tom - been looking at your blog this morning over coffee and have you added to my blogroll. Similar interests with radio and motorcycling!

    I think many of us pay to much attention to Sherwood's list - I've had radios that would be in the lower half of his list but were a pure joy to operate and created many fond memories. Also, the list doesn't take versatility of a radio into account - as you know, the IC-705 is amazing in that non-Sherwood-rated spec.

    Be careful on that moto of yours...73!

    John AE5X