On Mon,8/31/2015 4:37 AM, Larry via Topband wrote:
I have been following the discussion on front end relays with
interest, and I was wondering
what sorts of bandpass filters folks are using for receive antennas.
Bandpass filters do nothing for in-band signals -- their only function
is to reject OUT OF BAND signals. The primary reason for using bandpass
filters IS for RX. A good 160M bandpass filter would be effective at
reducing overload from AM broadcast stations. So would a high pass
filter. There is a survey of bandpass filters for contesting at this
link. http://k9yc.com/BandpassFilterSurvey.pdf
Most bandpass filters are designed for low power -- 200W or less, and
some for only 100W. This means that they must be installed between the
rig and the power amp, so they are of no help with killing harmonics
generated in the power amp. This is a great application for stubs -- if
placed after the power amp, they can significantly reduce the level of
harmonics. Here's an applications note that appears in the most recent
National Contest Journal. http://k9yc.com/LocatingStubs.pdf
73, Jim K9YC
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|