Pan-adapter screen shows small peaks on either side of freq when using FT8

  • 1
  • Question
  • Updated 4 days ago
When using the Maestro on FT8, when in the TX mode, I see several smaller peaks along each side of the carrier.  The level meter on the DAX screen shows about 95% on TX peaks.  So, as a test, I turned it down and the smaller side peaks went away so show a perfect TX peak with nice sloping sides. So, supposedly, this gives me a nice FT8 carrier without overshoot and spurs, however, I had to turn the power knob all the way up to 100 watts, to convince the Maestro to provide just 40 watts. So, to get a clean carrier, I have to reduce power. My question is, is the TX pan-adapter accurately showing spurs when the DAX level approaches 100% or is that a bug? Do I really have those spurs?  (My SWR is very low... antenna is a log periodic.)
Photo of Doug K0DV

Doug K0DV

  • 142 Posts
  • 17 Reply Likes

Posted 5 days ago

  • 1
Photo of Geoff - W8GNM

Geoff - W8GNM

  • 49 Posts
  • 6 Reply Likes

Doug, 

Try turning down or turning off the receiver pre-amplifiers.  The display you see on transmit is the received spectrum from leakage between the transmitter output and the receiver input. Too many preamp stages will overload producing IMD products in the transmit spectrum display and make the spectrum look worse than it actually is.

73,

Geoff-W8GNM