Re: [RFI] Power Line Noise in Indonesia

[Pete Smith <n4zr@contesting.com>]

At 02:07 PM 7/20/2004, Tom Rauch wrote:
> I haven't looked at what you are talking about, but I expect
> it is a tunable noise receiver that you place on a clear
> frequency with only noise, and the receiver drives a blanker
> for signals in the main receiver system.
>
> If so, it cannot be a phased system or a noise subtraction
> system. It has to be a blanker.
>
> The problem is it would be a level threshold trigger for a
> gate that turns of the receiver system. In effect this
> punches a hole in the signal.
>
> It is useful only for short sharp pulses like ignition,
> ringing noises or multiple noises cannot blanked without
> degrading desired signals. The noise duty cycle has to be
> low, and peaks sharply defined.
>
> I did suggest to MFJ that I would design one if they built
> it, but it never happened. I did have just such a system in
> my old diesel truck, to blank sharp pulses from the injector
> solenoids. I'm not sue how it would work with power line
> noise.

As I recall, this is what Collins offered at one point as an add-on for the 
KWM2A -- it attached to the underside of the hatch in the cabinet and, from 
memory, operated at ~46 MHz.  We had one of these radios in the old State 
Department club station next to the elevator motors of a 9-story building 
in downtown DC.  I don't recall that the blanker was particularly effective 
on most of the urban noise environment.


73, Pete N4ZR
The World HF Contest Station Database
was updated on June 5, 2004
2728 contest stations at
www.pvrc.org/WCSD/WCSDsearch.htm  

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