Elecraft K4

Discussion in 'Ham Radio Discussions' started by W6RZ, May 16, 2019.

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  1. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    I learned many years ago never to kindly notify "alligators" that their signal is distorted and wide. One might as well tell them that their manhood is teeny-tiny and get the same belligerent response!
     
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  2. KM1H

    KM1H Ham Member QRZ Page

    Absolutely! Anything to hold a run frequency:eek: When I was using 4 high 4 el stacks 10-20M (and 4/4 KLM's on 40), I (or the guest op) would often turn the lower one to a USA area that was annoying me and automatically switched to the others on RX.
    Some went as far as to modify rigs to TX on wider filters and open up the audio bandwidth. The TS 890 allows up to 4000 Hz audio:D Soon to be a contesters dream rig:rolleyes:
     
    K2XT likes this.
  3. KM1H

    KM1H Ham Member QRZ Page

    That could also apply on various forums:p:eek:
     
  4. WA6MHZ

    WA6MHZ Subscriber QRZ Page

  5. N2EY

    N2EY Premium Subscriber QRZ Page

    The "12 dB or more" recommendation is NOT "nonsense" at all, Carl.

    I think you proved something that didn't need to be proven.

    The "12 dB noise figure is more than adequate on HF" recommendation IS good advice for MOST radio amateurs, because they don't have really good locations or very directional antennas. That recommendation is for the great unwashed masses of us in "average/typical" situations. And the rigmakers learned, decades ago, that the way to sell rigs was to design for the reality of the average/typical situation. There have always been exceptions, but to spend large amounts of resources for a small market wasn't the way to success for them.
     
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  6. SM0AOM

    SM0AOM Ham Member QRZ Page

    Depending of what receiver manufacturers are considered, at least sub-octave filters could be standard.

    The ITT-Standard Radio CR1000, CR300 and CR90 series had front-end selectivity built in form of 12 sub-octave filters, as well as the more expensive offerings from Racal, Rohde&Schwarz, Telefunken and Skanti.

    However, most other receiver manufacturers offered RF selectivity or a tracking preselector only as a quite expensive add-on.

    The Collins HF-8064 and the quite common R&S FK101 were good enough to handle receiver/transmitter co-location situations.

    Multicouplers also form part of the receiver system. The most common here were the R&S NV14 which had good enough performance (IP3 = 40 dBm, IP2 almost 90 dBm) not to degrade the R&S EK07 receiver that had several tuned circuits before the RF amplifier and consequently a very good IP2. It also was better than the EK70, but on par with the EK085.

    If an NV14 became defective, it was immediately evident from the mess of IP2 products created by the imbalance in the feedback amplifiers.

    Today, the reduced dynamic range requirements in the HF range has made life somewhat easier for the systems designer, but it remains a depressing fact that the progression in amateur transmitter spectral purity has gone backwards.

    It is quite some time since I listened to a fully open HF
    band when a contest was going on, but it appears that a mess of IMD products extends quite far around the major players.

    As "dirty" signals also appear to give a competitive advantage it would be a difficult endeavour to "sell" clean signals to this group.

    Creating and maintaining "clean" signals also is an engimeering challenge, and will become more and more difficult when we OT:s that know about characterising and adjusting an ISB quality transmitter system are becoming fewer and fewer.

    73/
    Karl-Arne
    SM0AOM
     
    Last edited: May 25, 2019
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  7. SM0AOM

    SM0AOM Ham Member QRZ Page

    Actually, several decades of noise measurements point in the direction that for full-size antennas in temperate climates the antenna noise figures very seldom g0 below 15 dB, which makes receiver noise figures much below 10 dB quite moot.

    My own measurements on full-size antennas made since the mid-80s in both civilian and military HF stations up to about 20 MHz have not netted a single measurement of antenna noise figure below 18 dB, except in one case where one branch of the feedline to a horizontal 8-30 MHz LP had been disconnected.

    This resulted in an indicated NF of about 6 dB which really was an outlier.

    One cause for using low-noise HF receivers is however when ionospheric disturbances block both atmospheric and galactic noise (as well as signals) from reaching the antennas. Such occasions are so rare that it is not worth-while to design whole systems for them.

    In QST for 1970, receiver designer at Collins Bill Sabin W0IYH wrote a seminal article which addressed this general question in a very clear and understandable way.

    73/
    Karl-Arne
    SM0AOM
     
    Last edited: May 25, 2019
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  8. KM1H

    KM1H Ham Member QRZ Page

    Of course it is and long obsolete.

    Sour grapes as many on here can clearly see.

    Joe Average is not the sole user aimed at in many rigs, especially the higher performing ones. There is no extra money involved in 2019 to include a great 2 stage preamp (as compared to average or less in many) as in the TS-890S and allow new levels of stations to be heard especially now at near the bottom of the sunspot cycle. There is no extra money involved these days in 2019 to provide exceptional phase noise performance on RX and TX. Everybody benefits without paying a premium.
    I dont know what the final K4 spec will be.

    Even with poor antennas and a noisy location the low NF preamp lets especially the FT8/FT4 users to dig deeper and even the SSB only crowd on 10M to benefit at no extra cost.

    Of course someone without anything even remotely close to a modern rig or antenna that works on the higher HF bands by his own admittance....or any actual and current all band experience with the necessary test equipment isnt one to talk for Joe Average by any stretch.
    OTOH a 6EH7 and 7360 front end would be called overkill even by myself for a RX that doesnt go above 20M. A 20M NF of ~ 6dB would be the worst expected....I do that on 10M with a 6GM6/7360 in my 75A4 that was modded in 1965 and still in use.
     
  9. KM1H

    KM1H Ham Member QRZ Page

    Perhaps Riley Hollingsworth, K4ZDH, who retired as FCC Special Counsel....Translation: Active Ham Band Enforcer to head up the new joint FCC/ARRL Volunteer Monitor program will include contesters when he swings his club. It is long overdue as is enforcement of the 1500W rule.

    Carl
     
  10. SM0AOM

    SM0AOM Ham Member QRZ Page

    This would be nice, but is certainly nothing I would hold my breath for.

    The contesters have a political influence in organised amateur radio that vastly exceeds their numbers, and any enforcement against those would be seen as an attack on the core values of organised amateur radio, which by the way is run like a "banana republic dictatorship", with zero transparency and zero accountability of the rulers.

    "All animals are equal, but some are more equal than others..."
    - George Orwell

    73/
    Karl-Arne
    SM0AOM
     
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