[Lf] Use of Spectogram

[Andre' Kesteloot]

Rik Strobbe wrote:

> John wrote>I'm  not good at Spectrogram.   I need all the help i can get.
> Question

> >I have been leaving my AGC on in fast mode Is this a mistake?
>
> Hello John,
>
> If you have strong signals within the RX bandwidth it is best to switch the
> AGC off (otherwise the AGC triggered by the strong signal might 'modulate'
> weaker signals. If you cannot switch the AGC off then the second best
> solution is to attenuate the incoming signal, as long as the band-noise
> (QRM/QRN) is stronger than the receiver noisefloor you will not loose
> sensitivity.
> Even if you can switch off the AGC it can be worth adding some attenuation
> to the incoming signal in order to improve the IM behaviour. I am using a
> 11.5m high and 23m long inverted-L (tuned to 137kHz) as antenna and a
> Kenwood TS440 as RX. I found out that I have best results with a 20dB
> attenuator, the external noiselevel is still far above the RX-noisefloor
> and I got rid of a lot of 'birdies'.
>
> 73, Rik  ON7YD
>
> (hpe to work u 2nite .... ..)