[AMRadio] ARRL reply to mod Q's

StephenTetorka at cs.com StephenTetorka at cs.com
Thu Dec 23 16:08:45 EST 2004

Hello Fellow AMers:

Following is a reply from Zac Lau in the Technical Services group at ARRL to these questions:

1.  How much Frequency Modulation is permitted in Amplitude Modulation mode?...on bands 160 thru 20.

1a. How is this quantity measured.

2.  Is it illegal to modulation the oscillator in a transmitter?..even if its a one-tube rig?

Hi Steve,
   Your first question appears simple, but in practice is difficult to answer,
because it depends on precisely how AM and FM are defined. The FCC doesn't care
exactly what definitions you use, as long as the signal meets good engineering practice.
97.101a.  Typically, if the bandwidth is less than 6kHz, you shouldn't run into problems.
The bandwidth is typically measured with a spectrum analyzer by the FCC. No, it is not
illegal to modulate the oscillator of a one tube rig, as long as you can meet the
"good engineering" practice standard.

73--Zack Lau W1VT

Happy (hiccccup) Hodilays,

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