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  • Two Tone Question

    From Ron H@rnh@no.spamm.net to alt.ham-radio.ssb on Wed Mar 15 07:48:29 2006
    From Newsgroup: alt.ham-radio.ssb

    I am confused over the "ideal" frequencies to use for a two tone test of a
    SSB transmitter. Art Collins' book states that using two tones with a 3 to
    5 relationship will make it easier to identify intermod products and
    harmonics and in fact Collins used 3 and 5 KHz as the two tones. Modern SSB rigs only have about 2.7 to 3 KHZ audio passbands so 3 and 5 are not much help. I see articles using evrything from 400 & 1900 Hz to 1.1 & 2.2 KHz..
    Is there a "best" pair for testing modern rigs, or is this all a lot of hype and any two tones inside the passband wil work?

    Ron H.


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  • From jawod@jawod@fuse.net to alt.ham-radio.ssb on Fri Mar 17 08:53:37 2006
    From Newsgroup: alt.ham-radio.ssb

    Ron H wrote:
    I am confused over the "ideal" frequencies to use for a two tone test of a SSB transmitter. Art Collins' book states that using two tones with a 3 to
    5 relationship will make it easier to identify intermod products and harmonics and in fact Collins used 3 and 5 KHz as the two tones. Modern SSB rigs only have about 2.7 to 3 KHZ audio passbands so 3 and 5 are not much help. I see articles using evrything from 400 & 1900 Hz to 1.1 & 2.2 KHz..
    Is there a "best" pair for testing modern rigs, or is this all a lot of hype and any two tones inside the passband wil work?

    Ron H.


    Ron,

    According to ARRL, the two tones should be about 1 KHZ apart and not harmonically related. They use 700 and 1900 Hz.

    John
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  • From chuck@nospam@nospam.net to alt.ham-radio.ssb on Mon Apr 3 16:05:31 2006
    From Newsgroup: alt.ham-radio.ssb

    Ron H wrote:
    I am confused over the "ideal" frequencies to use for a two tone test of a SSB transmitter. Art Collins' book states that using two tones with a 3 to
    5 relationship will make it easier to identify intermod products and harmonics and in fact Collins used 3 and 5 KHz as the two tones. Modern SSB rigs only have about 2.7 to 3 KHZ audio passbands so 3 and 5 are not much help. I see articles using evrything from 400 & 1900 Hz to 1.1 & 2.2 KHz..
    Is there a "best" pair for testing modern rigs, or is this all a lot of hype and any two tones inside the passband wil work?

    Ron H.


    Hi Ron,

    There is no single "best pair" of tone frequencies, but it doesn't
    follow from that that any two tones will work well.

    You want to choose tones with the following characteristics;

    1.) Not harmonically related (e.g., 3 and 5)
    2.) Within the passband of the rig (better to stay clear of the passband edges)
    3.) Sufficiently far apart to allow whatever spectrum analyzer you are
    using to distinguish between them.

    If you are not attempting to measure distortion products but are only performing a subjective RF waveform analysis with an oscilloscope, #3 is
    less of an issue.

    Good luck.

    Chuck
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