Why are hams selling their Heathkit radios?

Discussion in 'Ham Radio Discussions' started by KR2C, Feb 5, 2020.

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  1. W1VT

    W1VT Ham Member QRZ Page

    ....
    Joe Riesert W1JR said something similar many years ago. That he would work for the League if he somehow got paid the salary to which he was accustomed.
     
  2. KM1H

    KM1H Ham Member QRZ Page

    The last time I saw him he was being escorted by Security down the back stairs of Tower 1 at Wang Labs after he got canned....screaming and fighting all the way. What a gem!
     
  3. KM1H

    KM1H Ham Member QRZ Page


    They couldnt agree what measurement standard to use to mark the string.
     
  4. KM1H

    KM1H Ham Member QRZ Page

    It sure doesnt look like it has been accessed much, another best kept secret even from the membership.

    BTW, the manual section about IMD is very unclear to anyone not already aware of the procedure and 6dB ruse.

    A case of actual honesty by the ARRL would include a clear explanation of the ARRL method and the real standard. Im not holding my breath.
     
  5. KM1H

    KM1H Ham Member QRZ Page

    I should include: The last time I saw him in a work environment etc etc
     
  6. N2EY

    N2EY Premium Subscriber QRZ Page

    To set the record straight:

    I don't "hate" anyone here. Nor do I "hate" any company that made or makes ham gear, nor any particular product they made.

    However, it does seem that some folks take personal offense when I or someone like me points out design deficiencies and other problems in various products and company policies. Or, worse, when I or someone like me points out errors in what people post, complete with proof and examples.

    Like this:

    There is a persistent urban myth that the tradition of LSB on the amateur bands below 10 MHz and USB on those above came from the use of SSB transmitters which generated SSB on 9 MHz and then heterodyned it to 75 and 20 meters by mixing with a 5 MHz VFO or crystal oscillator. The urban myth says this results in LSB on 75 and USB on 20, and so was the origin of the tradition. Sometimes a specific rig is mentioned.

    The story is plausible and seems correct to those who don't get into the details. But it's completely wrong, because heterodyning of SSB doesn't work that way. If you use a 9 MHz SSB generator and a 5 MHz VFO, you get the same sideband on both 20 and 75 that you started with. Only if you use a 5 MHz SSB generator and 9 MHz VFO does the sideband inversion happen.

    This plain and simple fact is easily proved mathematically. It is also verified by the design of rigs that use the scheme - just read the manuals. It's basic radio theory. The only way you get sideband inversion is if the local oscillator frequency is higher than both the mixer input and output frequencies.

    Yet when the subject comes up, there is often someone who claims the old myth is true, and gets very angry when proved wrong. Sometimes the person will just reject all proof, even though it's just basic arithmetic. Sometimes the person is insulted by the facts. Sometimes the person will say their Elmer told them the story decades ago, and ol' Elmer knew everything there was to know on the subject. Etc. Often the person who gives an accurate account (ahem) is insulted and denigrated for being right!

    Why that is, I don't know. One would think that people would want the facts.

    There are lots of other examples.

    73 de Jim, N2EY
     
    N2SR likes this.
  7. WD4IGX

    WD4IGX Premium Subscriber QRZ Page

    I get that it's a myth and have no problem with accepting that it isn't so.

    But - and I'm sure this has been mentioned before but I don't recall - since that is NOT the origin of the LSB on 40 and lower bands and USB on higher bands, what IS the reason for that convention?
     
  8. N2EY

    N2EY Premium Subscriber QRZ Page

    Thanks!

    I don't know for sure.

    The best explanation I have seen is that it was copied from commercial standards of the time (late 1940s/early 1950s).

    The tradition dates back to at least the early 1950s. Here's proof:

    The Central Electronics 20A was introduced in 1953. (It is reviewed in the New Apparatus section of QST for January 1954).

    The manual for the 20A can be found here:

    http://bama.edebris.com/manuals/ce/20a/

    On Page 1 of the PDF is "condensed instructions" for operating the 20A. One of them is where to set the sideband switch - SB1 or SB2 - for each band, and what sideband will be produced (it's different on different bands).

    The "traditional" sideband is indicated in the manual, with LSB on 160, 75 and 40, USB on 20, 15 and 10.

    Note that when you change from 75 to 20 the switch position must be changed to get the "right" sideband.

    So the tradition was in place when the 2oA manual was written.

    ---

    If the SSB is generated at around 5 MHz, and a 9 MHz VFO is used, both 20 and 75 can be reached by additive/subtractive heterodyning, and the sideband DOES invert on 75 but not 20. If a 12 MHz VFO is used, 40 is covered, getting the same sideband as 75.

    This heterodyne scheme was used in several popular amateur rigs of the 1960s - the Swan 240, the National NCX-3, the Hallicrafters SR-160 and SR-500, the Eico 753, among others. The tradition was in place first, then the rigs were designed to match it.

    73 de Jim, N2EY
     
    Last edited: Feb 13, 2020 at 2:31 AM
    WD4IGX likes this.
  9. SM0AOM

    SM0AOM Ham Member QRZ Page

    Retirement has given me some more time for archive research.

    In the professional world, this started out as "Question 46" at the CCIR Study Groups in the late 40s:

    upload_2020-2-13_11-14-57.png
    This was in the heyday of the international ISB radiotelephone and radiotelegraph circuits.

    After some deliberations, the Recommendation 91 was issued in 1953,
    where this table summarised the sideband usage for various ISB channeling arrangements;
    upload_2020-2-13_11-19-14.png

    Note the cases e) and f) which depict SSB, or single channel ISB, transmissions.

    Not having the actual minutes of the working party discussions, it is difficult to have any views of what came first, amateur radio de facto standardisation of sideband usage, or national and international professional practices.

    However, considering that in this era many influential figures in the radio business also were amateurs, it is very likely that there were many cross-influences.

    As noted in earlier posts on this subject, the actual sideband usage had some regional variations, and did not become "universal" with LSB on 160,80 and 40 and USB above, until DX working using SSB became more commonplace during the mid/late 50s.

    73/
    Karl-Arne
    SM0AOM
     
    Last edited: Feb 13, 2020 at 10:51 AM
    N2EY likes this.
  10. N2EY

    N2EY Premium Subscriber QRZ Page

    Thanks, Karl-Arne!

    Given the dates involved, it's quite possible that amateurs followed commercial practice....or the reverse.

    Here's one more data point:

    About 1948, there was an article in QST giving the basics of SSB transmitter design, in very general, block-diagram terms. One of the block diagrams showed a transmitter where the SSB was generated at a low frequency and then heterodyned up to about 5 MHz, where it was then mixed with a 9 MHz VFO or crystal oscillator to get to either 75 or 20 meters. That heterodyne scheme results in USB/LSB inversion on 75 but not 20. Whether anybody actually built such a transmitter that far back is unknown. (In those days, in the USA, hams had very little access to 160 due to LORAN, 40 was all CW, and 15 wasn't a ham band yet. So, practically all US 'phone activity below 25 MHz was concentrated on 75 and 20, and the 'phone subbands were much narrower than today. )

    ---

    Fun fact: SSB was first described theoretically about 1915, and was first used for telephone carrier circuits (wired) about 1918. The first use of SSB on radio was for the transatlantic telephone service, which went into commercial operation in 1927. That first service was on LF (around 5000 meters) and SSB was used in part because of narrow antenna bandwidth.

    73 es TNX de Jim, N2EY
     

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