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## Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!

 To: amps@contesting.com Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY! "Roger (K8RI)" Wed, 28 Dec 2011 18:48:54 -0500 mailto:amps@contesting.com>
 ```On 12/27/2011 1:23 PM, Commander John wrote: > > > That is about what I said. But it doesn't make the signal any wider. > please read the previous posts as to what I was commenting on. > john W9ZY Let me take a shot at this: I'm sure some one else can do this more clearly than I but... First, lets separate the lower stages from the driver and final. Lets say your transceiver has an audio pass band of 0.3 to 2.8 KHz or 2.5 KHz. Now lets hit it with two tones. One at 300 Hz and one at 2.8 KHz and make the foolish assumption that this is still a clean 2.8 KHz wide signal when it gets to the final. We now have two tones that on upper side band are your carrier frequency plus 300 Hz and plus 2.8 KHz or still 2.5 KHz wide if all went well. Now that final can not only pass and amplify these two signals at 750 watts each, but if it has only - 20 db 3rd order IM we also now have signals at 2.8 KHz +/- 300 Hz or 2.5 Khz and 3.1 KHz. 20 db down (If I understand this correctly) we also have 300 Hz +/- 2.8 KHz or 3.1 KHz and a - 2.5 KHz 3.1 and a - 2.5 KHz below the carrier for 5.6 KHz band width instead of 2.5. The signal is over twice as wide. What if we have 2KHz and 2.8 KHz. Now we have 800 Hz (still in the pass band) and 4.8 KHz but we also have 2 KHz - 2.8 KHz or a - 2 Khz (below the carrier) and we are now up to 6.8 KHz wide. IOW in a two tone test we have the sum and difference between *both* frequencies. In the latter example both sums fall on the same frequency while but the differences fall on different frequencies. Those that fall on the same frequency depend on the phase as to whether they add, subtract, or fall some where in between. In either case the IM does cause the signal transmitted to be wider than we'd hear from an amp with -50 db IMD products and I think they'd be 30 db stronger. You can keep taking the results and running the sum and difference on all of those and then repeat with all of those results with diminishing strengths each time. I'll leave it to others to correct my work as I've never gone through a math problem without making a mistake yet even though I have a minor in it. It may not be correct but it should convey the general idea. 73 Roger (K8RI) > _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps ```
 Current Thread [Amps] Fwd: Re: Fwd: Linear Amplifier Tuning---PROPERLY!, (continued) Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Commander John Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Gary Schafer Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Commander John Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Roger (K8RI) <= Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Fuqua, Bill L Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Roger (K8RI) Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, jeff millar [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Jim Thomson [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Jim Thomson Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY!, Fuqua, Bill L [Amps] FW: Fwd: Linear Amplifier Tuning---PROPERLY!, Fuqua, Bill L