Topband: 160 noise and receiver NB.

[Giulio Scaroni]

Hi to all,
here i have a little question about the utility of noise blanker on 160 =
meters band.
Here during my experiment with the all the type of man made noise, i =
have discovered that for noise produced by dimmer, elettronic =
transformer (like use my wife on the table on the kitchen) the NB of the =
Icom radio is totally ineffective, i tried with IC 737, IC 738, IC 775 =
DSP, but nothing to do, the noise is 10 over 9 and not change using the =
NB, so i have tried with the old Drake R-4C, that i have in the shack, =
but never i use (is a museum piece, hi), well with its NB the noise drop =
of about 5 to 6 S points!!!!!
Why this happen??
So i have checked the schematic diagram of all the Icom RX and also the =
R-4C, the circuit seems the same, except that the Drake make a =
conversion on the NB gate and the Icom not, its using only a series of =
fet for amplifier the noise on the same IF frequency.
So wich is the difference, and why with the old R-4C the performance is =
better than all the Icom that i have in the shack??
The Icom is working very very well for short and high rise time impulse =
like ignition spark, they can delete a ignition spark signal from 20 /30 =
over 9 signal to 0 S, but not for the not so high rise time impulse.
Is possible made some modification on the Icom NB?
I hope that this may help also someone else that have my problem.
73 to all and see you on the band, yes the 160 shure !!
Giulio IK2DED.


PS I'll be in Las Vegas at the end of April, from 23 to 29 for visit =
like usual the N.A.B. exibition, if some topbanders will be also there, =
i'll be very happy to meet some guy's!!
Pse reply for this at my private e-mail  scaroni@phoenix.it  tnx.



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