[Fwd: LF: good signals - deaf receivers]

Andre' Kesteloot akestelo@bellatlantic.net
Fri, 16 Apr 1999 07:43:50 -0400

Rik Strobbe wrote:

> Another thing about the 'deaf receiver discussion' :
> I do not agree with the opninion that 100mW is not enough to work upto
> 1000km (and more) since I worked over 1600km (OH1TN) with an estimated ERP
> of about 70mW. I think that others (eg. G4GCV, GW4ALG) worked up to 1900km
> with ERP's arround 100 to 200mW.
> Now I am running about 140mW ERP and for the last weeks I have heard at
> least 4 stations regulary with 10 to 20dB S/N ('armchair copy') but I'm not
> able to attract their attention. Assuming that these stations run 1W ERP
> and that my 140mW ERP is 8.5dB below this, I should produce at least a 0dB
> S/N signal with them (sufficient for a CW QSO).

> So my pledge still is : work on your receiver-situation and don't be misled
> by S9+++ commercial stations that might give you the idea that your RX is
> OK. To my experience the keyword is 'intermodulation-surpression', so try
> to attenuate the incoming antenna-signal until the external noiselevel
> (normally caused by QRN) is just above the RX-noisefloor. You won't gain
> any sensitivity if the external noise is 10 or 20dB over the RX-noisefloor,
> it will only increase the IM-products. Remind that for every dB you can
> attenuate the incoming antenna-signal, the IM-products will be reduced by
> 2dB (so you may gain 1dB in absolute sensitivity).
> 73, Rik
> Rik Strobbe  ON7YD
> rik.strobbe@fys.kuleuven.ac.be
> Villadreef 14  B-3128 Baal  BELGIUM   (JO20IX)