OK, in my continuing saga with my ICE filters, I have spoken in detail to
the folks at ICE. It appears that the "200 Watt" rating is really an
intermittent PEP rating (SSB service perhaps) and not a CW rating. I
stated that they need to clear this up in their literature. For keydown
type purposes, the units should be used at 100 Watts or less. He said
that was their intended application.
The guy at ICE suggested putting the filter between the transceiver and
the brick. He said that it would still filter the spurious output of the
radio and provide a clean signal to the amplifier. While I agree, I
don't think it is as effective as putting the filter after the amplifier.
All amplifiers have some non-linearity - particularly ham bricks.
Therefore, they will generate spurious products internally. I am
concerned that even with a clean signal going in, a dirty signal may go
out. He also said that putting the filter between rig and amp will
create a buffer effect between the two. I don't really buy that benefit.
Another thing I am concerned is from a receive point of view. The
bricks typically have preamps. If a very strong out of band signal is
present on receive, a filter prior to the preamp will remove that signal.
On the other hand, with the filter after the preamp, that signal could
overload the preamp and cause IM. Some of that IM could be in the band
of the filter and this would make the filter worthless.
So my question is: Am I overconcerned by the placement of the band pass
filter? Is putting it between rig and amplifier sufficient? Is the
benefit of placing it after the amplifier really not all the great?
Thanks es 73,
Jon
KE9NA
ps: I have more technical info on the filters and stuff for those who
want it.
--------------------------------------------------------------------------
The Second Amendment is NOT about duck hunting!
Jon Ogden
jono@enteract.com
www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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