[CQ-Contest] Bandpass filter

Joe nss at mwt.net
Tue Jul 3 06:37:23 PDT 2012

Never have run this mode,  if this IS a large problem,  then how do SO2R 
stations work without blowing everything up?

The Original Rolling Ball Clock
Idle Tyme
On 7/2/2012 8:53 PM, Tom W8JI wrote:
>> Assuming it is not just in the receive line, a bandpass filter may help
>> you keep peace with any neighbors who are on the same band and others in
>> the contest - as it will cut down on any extra "crud" your transmitter
>> produces.    It even works with "clean" transmitters.
> A traditional bandpass filter does nothing for same-band overload or
> interference, because by definition it passes the entire band.
> The exception would be crystal or other very high Q narrow bandwidth
> filters, but they are generally unsuitable for transmitting or very
> expensive. I've experimented with high-Q filters on 160 meters, to allow
> duplex operation on 160 with two radios at the same time, and it is a very
> difficult filter to build. It would be much worse for something like 40
> meters.
> A bandpass filter will help clean up stuff outside of the band it is
> designed for. This can make it safer to have a receiver running on one radio
> through a bandpass (say on 40 meters with a 40 bandpass filter), while
> transmitting on another radio on a different band (say 80m or 20M).
> If a transmitter needs a bandpass, it might be time for an upgrade or
> repair, or more antenna spacing. :-) Usually the receiver is the big worry.
> 73 Tom
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