[Elecraft] K3: General Coverage Receive Filter

[Iain MacDonnell - K6IAM]

I'd been meaning to ask for a while; what is the motivation for those
of you who have ordered the general coverage receiver option? i.e. what
makes it worth the extra $129 ??

     ~Iain


Ron D'Eau Claire wrote on 07/28/08 07:35:
> Joe asked:
> 
> What is the General Coverage Receive Filter, how does it work? If it is
> just
> another roofing filters, why not just use the 6.0 filter?
> 
> -------------------------------------------------------
> 
> It's not, Joe. The KBPF3 provides additional receiver input bandpass
> filters. 
> The input bandpass filters are L/C filters that are switched
> automatically according to the frequency band selected to protect the
> receiver from strong out-of-band signals hundreds of kilohertz or even a
> few megahertz away from the desired signal.
> 
> The first I.F. "roofing" filters follow later in the signal path to
> provide selectivity within a few kHz or a few hundred Hz of the desired
> signal. 
> 
> The basic K3 is equipped with input filters covering the 160-6 meter Ham
> bands. These filters also allow reception near the Ham bands but, as you
> tune farther from a Ham band, the sensitivity will drop off as you move
> beyond the edge of the filter bandpass. This is most apparent when
> trying to listen to AM broadcast band stations below 1,000 kHz without
> the KBPF3, but a significant loss of sensitivity occurs whenever the
> basic K3 is tuned far from a Ham band. 
> 
> The KBPF3 provides additional input filters that are switched in
> automatically to cover the out-of-Ham-band frequencies between 500 kHz
> and 30 MHz. 
> 
> Ron AC7AC
> 
> 
> 
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