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K3 vs 6700?

KY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
edited March 2017 in SmartSDR for Windows
Last weekend I participated in a farcical NON Scientific shootout between a IC-7800, KX3, K3 and a Flex 6700 during the CQ WW SSB Splatterfest.   The results at best were the 6700 having the edge to at worst the K3 having the edge.

The results were incredibly unreliable due to the biases of the observers and the random non scientific way variable were continually changed by the K3 Operator so that no true baseline for comparison could be established.

I wonder if anyone owns both a K3 and a 6700?

IF so, could you lets us have your HONEST Opinion on both radios...


  • Tom K3TF
    Tom K3TF Member
    edited March 2017
    I own a K3 and a 6500. I am a CW only guy and can give a perspective on both. I am a QRQ CW operator, a few of us left who QRQ at 50 wpm and faster.

    Both radios are very good. 

    I built my K3 a couple years ago and run the current firmware. My 6500 is only 1 month old.

    After comparing both rigs for QRQ CW, contesting, and DXing I prefer the 6500.

    I run the 6500 with a Quad Core processor PC and use a high end video gaming card. I still prefer to use windows CW Type driving a COM card with a one transistor keying circuit directly to the 6500 key jack rather than using CWT. 

    My issues with the K3:

    1. You can not send CW over 42 wpm while using the RIT or IF shift controls. The CW suddenly becomes garbled. Turning off RIT, IF shift, running QSK Fast mode, you are good to about 74 wpm before the signal distorts again. The 6500 will key over 100 wpm perfectly. Not a problem for SSB operators. 

    2. AGC. The K3 uses a simple full wave diode peak detect circuit for the first AGC loop (the analog portion) of the receiver with only one preset AGC decay time (about a half second) no fast or slow decay selection. AGC Fast/Slow only in the DSP portion of the IF. Any strong CW signals getting in the roofing filter passband will cause the AGC to pump. No way to turn this off with out modifying the RC time-constant. Makes it very difficult to work a CW signal close to a strong signal (<200hz.). Not a problem for SSB. 

    Everyone looks for different things in a rig and these are just my opinions. 

    73 & 161,

  • Steve N4LQ
    Steve N4LQ Member ✭✭
    edited September 2015
    Tom is right about CW. I still have the K3 and 6300. The 6300 is superior. The K3's hardware AGC is not  adjustable. There isn't any hardware AGC on the flex but you need to adjust AGC-T which requires some attention. And yes, the K3 is not too much fund with QRQ speeds.
    As for SSB...I've had the 7800, Omni 7, K3 and Flex 6300. As selectivity goes, it doesn't matter much since SSB is so broad anyway however I've found that with the Flex (any model) I can understand speech better when using narrow filters i.e. 2 khz or less.  I can't say exactly why that is but it can really make a difference. I would think all of this applies to your 6700 also.
    Steve N4LQ
  • Kent Hufford
    Kent Hufford Member ✭✭
    edited January 2017

    Both are good radios. Check the SHERWOOD Engineering web site. BUT, most important watch one of his videos where he talks about the differences, or lack of differences.

    Kent KQ4KK

  • KY6LA_Howard
    KY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited December 2014
    Where is a link to his talking about the differences?

    Nothing on his web site?
  • Kent Hufford
    Kent Hufford Member ✭✭
    edited October 2014
    I saw him at a Huntsville AL hamfest, and they had videos. And also at Dayton one year.
  • Kent Hufford
    Kent Hufford Member ✭✭
    edited October 2014


    CTU - Segment 9 - 2013 Contest Radio Performance

  • Kent Hufford
    Kent Hufford Member ✭✭
    edited October 2014
  • IW7DMH, Enzo
    IW7DMH, Enzo Member ✭✭
    edited January 2017
    I have owned a K3 before going for a 6300 and my impression is that the receiver in the 6300 is much quieter than the K3.
    I am mostly a cw operator and at 30 wpm I can't hear any difference between K3 and 6300. QSK is perfect.
    I find it amazing the way the 6300 AGC can be tuned, even closing the filter up to 50 Hz it eliminates whistling and ringing. Also APF is better on 6300.
    These are just my impressions and are not supported by any measurement.

    73' Enzo

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