[UK-CONTEST] Receiver Question Slightly OT

[Bob Henderson]

Hi James

This could be useful but only if you were to want a single frequency 5kHz
b/w receiver.

Front-end xtal filters are sometimes used by contest stations wishing to
receive and transmit simultaneously on the same band.  In this situation the
two receivers in use would have input filters which don't overlap.  Inrad
market such filters.  You can view typical frequency/bandwidth combinations
here:

http://www.qth.com/inrad/

4O3A in Montenegro have gone even further:

http://www.4o3a.com/front-end-filters/multiple-crystal-front-end-filters.html

They must suffer some incredible levels of intermod to justify an approach
like this.

73

Bob, 5B4AGN

2009/10/28 James Thresher <James.Thresher at jaama.co.uk>

> Hi All,
>
> I realise this is slightly OT, but I wonder if any of you could shed some
> light on something I am working on.
>
> You will have to excuse my ignorance of receiver design, but If I was to
> place a receive band pass filter with say a 5Khz filter width and 70-80db
> attenuation between the antenna and the rig, would this have any significant
> impact on the performance of the receiver, or would it be no better than a
> decent roofing filter within the receiver itself? This is not the main goal
> of this project but my gut feeling is that there should be some performance
> increase in the receiver, although with my current level of understanding
> around receiver design i'm not sure if this would be the case or why.
>
> Thanks
>
> 73 James 2E0YOM
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