[CQ-Contest] Bandpass filter

Jukka Klemola jpklemola at gmail.com
Tue Jul 3 10:38:13 PDT 2012

Some work with luck .. usually not for more than a contest or two.

Then they realize they need to design the station and use the station
to the specifications they created.

Making a station capable of all that is very rewarding and sure is a
lot of Fun !
Yes .. the smell of some burnt electronics is Fun.

In case you buy everything ready from a bunch of shops, you can do it.
But I write you it is less fun than building + experimenting = experiencing.

Jukka OH6LI

2012/7/3 Joe <nss at mwt.net>:
> Never have run this mode,  if this IS a large problem,  then how do SO2R
> stations work without blowing everything up?
> Joe WB9SBD
> Sig
> The Original Rolling Ball Clock
> Idle Tyme
> Idle-Tyme.com
> http://www.idle-tyme.com
> 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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