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Discussion in 'Amateur Radio News' started by HB9NBG, Jun 29, 2021.

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  1. SM0AOM

    SM0AOM Ham Member QRZ Page

    It is fundamentally impossible to observe any differences between high-grade receivers when the receivers are much better than the transmitters which form the actual interferers.

    When Rob Sherwood measures receiver performance he uses unmodulated CW signal sources which are at least 50 dB "cleaner" at "close-in" spacings than any fielded SSB transmitter.

    The first adjacent channel IMD spectral density of a medium-grade SSB transmitter corresponds to a sideband noise level of about - 80 or 85 dBc/Hz, which can be compared to the at least -140 dBc/Hz which
    is required to measure a 2 kHz receiver spaced dynamic range in excess of 100 dB.


    This would also enter the picture in the CW or A1A usage context.

    The plot below, from K9YC, illustrates this.

    If all transmitters were K3:s, a 2 kHz spaced receiver dynamic range of perhaps 90 dB could be used in practice.


    If you do not believe me, suggest that you locate the proceedings of the 2019 Nordic HF Conference and repeat for yourself the measurements made in preparing the presentation

    "Performance limitations in HF communication systems composed of practical realisable hardware".

    Last edited: Jul 4, 2021
    HB9PJT, N3AWS, KA4FIX and 5 others like this.
  2. KO4CES

    KO4CES Ham Member QRZ Page

    Fahrvergnügen. Well done!
    M1WML likes this.
  3. KA2K

    KA2K XML Subscriber QRZ Page

    I was able to translate it in my head more accurately, and I speak no German. Youtube auto translate is worthless.
    M1WML, K0UO and PU2OZT like this.
  4. AJ4GQ

    AJ4GQ XML Subscriber QRZ Page

    Du meintest ausgezeichnet. Nicht wahr?
    M1WML likes this.
  5. KO4CES

    KO4CES Ham Member QRZ Page

    No, not necessarily. I meant the pleasure of driving a new DX radio. But ausgezeichnet is good, too.
    M1WML and AJ4GQ like this.
  6. M0MNE

    M0MNE Ham Member QRZ Page

    Who told you English was The International Language? It's a popular language yes, but no one is under any obligation to use it as a second language. Only 1 billion people can speak English. That's only 12 per cent of the World's population.
    M1WML and N3AWS like this.
  7. US7IGN

    US7IGN Ham Member QRZ Page

    Quantity and quality matter. In third world countries, one who knows the same English or another foreign language usually also has more knowledge in other areas, more money and more power than others.
    Have you ever wondered why we hear so few local radio amateurs on the air from the same Africa?
    Personally, I associate the rapid decrease in the number of new radio amateurs in the post-Soviet space precisely with the rapid decline in the literacy level among young people.
    M1WML, AJ4GQ and PU2OZT like this.
  8. W9YW

    W9YW Premium Subscriber Volunteer Moderator QRZ Page

    Thread warning: The thread is not about English, it's about the K4D.
    K5SLO, M1WML, K0UO and 2 others like this.
  9. IV3DDJ

    IV3DDJ Premium Subscriber QRZ Page

    Interesting machine, hope it's good as the price! But leds just above the tuning knob seem to be a DIY made,
    not accettable for "that" value!
    M1WML likes this.
  10. US7IGN

    US7IGN Ham Member QRZ Page

    This is a trick. A recognizable design is very important for a brand.
    M1WML and HB9NBG like this.

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