Building filters able to handle a consistent amount of power is not
expecially difficult, unless a couple of parameters has to be taken
in account.
The first one is that components (mainly capacitors) has to be that
type able to manage high currents and high voltages and not to change
substantially their value because of heating.
The second is that insertion loss could be significant in term of
heathing.
This last drives to the need of low insertion loss design (typ -.5db)
to prevent excessive heating, currents and voltages and critical
component values (i.e. too small inductances)
Of course this goes in contrast with filter sharpness and building
semplicity and tells, when possible, to use filters on receiving
section only expecially on higher HF bands.
About practical approaches, it's a number of years that Arrl HANDBOOK
gives a full set of normalized values and calculating examples about
filters.
Concerning how to split one antenna to a couple of receivers, the
easiest way is to use an inductive directional coupler that gives
two outputs of typically -4db but with some 30-50db isolation
between ports.
73,
Mauri, I4JMY (one of IR4T)
-----Original Message-----
From: owner-cq-contest@contesting.com
[mailto:owner-cq-contest@contesting.com]On Behalf Of Peter
Sent: Thursday, February 18, 1999 8:22 AM
To: CQ-Contest@contesting.com
Cc: topband@contesting.com
Subject: [CQ-Contest] Bandpass filtering
Hi,
Has anybody out there some experience with homemade band pass filters
for the 200 watt level?
yes I kwon there are dunstarr and ice filters, but howebrew is still my
favourite way!
Second are there any drawings for the use of 1 berverage and two rigs
e.g. 80 and 160?
How does the group handle this?
Peter
PB0AIU
--
CQ-Contest on WWW: http://www.contesting.com/_cq-contest/
Administrative requests: cq-contest-REQUEST@contesting.com
|