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  1. KD5PIV

    KD5PIV Guest

    My grandson was over yesterday and he ask about USB or LSB and how do we know which to use. He also asked, "Where in the rules does it say which sideband to use on which band?"

    I love that little brat, but he gives me a headache.:eek:

    OK, so where is the rule found? It's not in the band plan (that I could see).

    Conner is right where I want him to be so that he will ask the big question, "Can I become a Ham Grandpa?" Unfortunately Grandpa is a dummy. ;)

    Thanks for any help you can give an ODL (Old Dummy Load):eek:
  2. K2KLI

    K2KLI Banned QRZ Page

    It's not a rule, just a guideline.

    <10 mHz use LSB, >10 mHz use USB.

    The reasoning for it was the common use of 9 mHz filters for filtering out the sidebands, back in "the day."

    Hope that helps.
    Last edited: Jul 21, 2009
  3. AB1GA

    AB1GA Ham Member QRZ Page

    The standard operating practice for SSB is, as 'KLI says, to use LSB below 10 MHz, and USB above 10 MHz. This is not a regulation, nothing forbids you from using the "other" sideband, but then who would you talk to?

    The convention is, so I've heard, largely historical, based on the design of an early SSB rig. The IF was 9 MHz, which is 5 MHz below the bottom of 20 meters and 5 MHz above the top of 80 meters. When mixed with a 5-5.5 MHz VFO, the sum frequency was at 14.0-14.5 MHz, which covered 20 meters, and the difference frequency was at 4.0-3.5 MHz, which covered 80 meters.

    I wrote the 80 meter frequency range backward to indicate that with this approach the higher the VFO frequency, the lower the mixer output frequency. This also meant that if you started with an upper sideband signal on 9 MHz, you still had a USB signal on 20, but an LSB signal on 80, and thus the convention was born.

    Now, with the digital modes, all bets are off. I've heard old RTTY ops say that RTTY is LSB everywhere, and new PSK ops say that PSK is USB everywhere, and that if things don't work to just use the software "invert" switch. I'll leave it to someone else to enlighten us on that part.

  4. KD5PIV

    KD5PIV Guest


    Thanks for the great feedback!
  5. KL7AJ

    KL7AJ Ham Member QRZ Page

    Yip...the "standard" was actually all Swan's fault. They made the first multiband SSB transmitter uisng the heterodyne method, and everyone followed suit. :)

  6. SM0AOM

    SM0AOM Ham Member QRZ Page

  7. K0RGR

    K0RGR Premium Subscriber QRZ Page

    The 10 Mhz. convention has become blurred recently, anyway with the inclusion of the 5 Mhz. band, which is USB, only.

    I know that my father had an early SSB rig, which was centered on the 'Silver Sentry' mechanical filter, circa 1950, and as I recall it was designed to operate 20 meters and 75 meters using the single filter. I thought the IF was 9 Mhz. because he used a modified Command Set as a VFO and I believe it was a 5 Mhz. Command set. But, if we reverse that, with the IF at 5 Mhz. and the VFO at 9, the old story works. Perhaps, though, they shifted the 9 Mhz. IF carrier so that the lower sideband was selected for use on 75. I thought his exciter only had a single crystal, but my memories from 50 years ago are rather dim. I do think it's unlikely that they would have used a 9 Mhz. VFO, as VFO stability above 5 Mhz. was not great.
  8. AB1GA

    AB1GA Ham Member QRZ Page

    My apologies to all for my erroneous post, and thanks to Karl-Arne for the correction.
  9. NN4RH

    NN4RH Subscriber QRZ Page

    Would someone be considered a LID if they did use USB on 75 or 40m, or LSB on 20, 17, 15, 12, 10? Or is it merely frowned upon because of tradition?
  10. AC0GR

    AC0GR Ham Member QRZ Page

    You might be surprised at how many people you would find to talk to
    All of them telling you "YOU'RE DOING IT WRONG!" :D

  11. N5MOA

    N5MOA Subscriber QRZ Page

    Or you could do like the guy I heard two nights ago.

    He had a real nice signal around 14.182 on upper ssb, and a equally nice signal around 14.202 on lower ssb.
  12. ZL3GSL

    ZL3GSL Ham Member QRZ Page

    That isn't a problem. Just work USB at the bottom of the band, so you can tell them you are required by law to use USB at that frequency. :cool:
  13. K7JEM

    K7JEM Ham Member QRZ Page

    But you're not required to use USB at the bottom of the band. Why do people think these things?
  14. W0IS

    W0IS Ham Member QRZ Page

    If, for example, your VFO is on 7126, and you want to operate SSB, then you are, indeed, "required by law to use USB at that frequency."

    There is a better solution to the problem, but that statement is correct.
  15. K7JEM

    K7JEM Ham Member QRZ Page

    Well, I think some here don't understand how SSB works. An LSB signal contains exactly the same bandwidth as a USB signal. In most cases we call that 3KHz, but it could be more or less, depending on the radio. If you operate on 7126 USB, your signal is occupying 7126-7129 KHz. That spectrum is being used by your station. If you move your VFO to 7129, and switch to LSB, you will be occupying the exact same slice of spectrum. No additional benefit is gained by running either sideband, they are both just as effective. The only reason to choose one over another is to be compatible with others using the band. We don't have to "guess" which sideband a station will use, it's defined by convention. That convention is USB except on 160, 80 and 40. Pretty simple. We could change the convention and use USB everywhere, but it wouldn't gain anything.

  16. K9ZMD

    K9ZMD Subscriber QRZ Page

    Oh, Come On Now

    Yes, Joe, you stated the obvious, but changed the point of the discussion by changing the frequency. If you kept your VFO at 7126 and switched to LSB, you would be operating with a good portion of your signal below 7125 (out of band for phone operation). With the stipulated frequency of 7126, any phone operation would have to be USB, by law.
  17. K7JEM

    K7JEM Ham Member QRZ Page

    But we have no stipulated frequencies. When you "stipulate" a frequency on SSB, you are stipulating a "band" of frequencies, not just where the suppressed carrier is. The fact is, there is no advantage or reason to switch sidebands just because you are near a band edge. Nothing is "forcing" an individual to operate on 7126, and use USB. He could easily move to 7129 and use LSB, and use the same spectrum.

    The way I am reading these posts is that some feel that there will be some "lost" spectrum unless USB is used near the bottom of the band. That is not the case. New operators may not understand this, so it is foolish to suggest doing this, as you will get people doing it. "Oh, I saw on QRZ where we should use USB when down near 7125." Better that they should understand to just stay on LSB and not operate below 7128. That should be easy enough to understand. Their signal will occupy to down as close to the band edge as possible that way, and you don't confuse others, or make them think you're a lid.

  18. W0IS

    W0IS Ham Member QRZ Page

    And obviously you do understand how it works. That's why I was careful to say "if your VFO is on 7126" and not word it some other way.

    If your suppressed carrier frequency is 7126, then the quoted statement is true, because it's illegal to use LSB on that suppressed carrier frequency, for the reasons you stated.
  19. K7JEM

    K7JEM Ham Member QRZ Page

    I suppose that is correct. But what it does is to suggest to people that they have to operate USB when at the bottom of the band. My point is that we don't "have" to be on that particular frequency, in order to operate SSB. Park your VFO 3KHz up from there, and do LSB. You occupy the same amount of spectrum, and are a better neighbor.

    The subject of USB on 40 meters should not even come up. To do so confuses new ops and those who don't totally understand how things work. A person that operates USB on 7126 would be considered a "lid", since it is non conventional. We need to avoid any suggestions to people that would result in "lid like" behavior.

    So, while the above is technically correct, the better suggestion is just to stay on LSB and stay above 7128. That should make everyone happy.

  20. KI6ZIF

    KI6ZIF Ham Member QRZ Page

    Actually, if you were at the very bottom of the band "carrier" wise, suppressed or not.. Your LSB would fall outside of your band usage limits. :cool: As already mentioned. You could park at 7125 and use USB. Or qsy up to 7128 and use LSB.
    Last edited: Jul 26, 2009
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