Here is a question for the collective wisdom of the contributors
to this reflector:
Background: I operate almost exclusively HF CW and RTTY. Much of
my operating time is during contests, the rest being mainly DX
hunting. My suburban lot has little room for antennas, and I
have never had a rotatable antenna. At present my only antenna
is a trap vertical. (Before last week's ice storm brought it down,
I also had a G5RV mounted above the roof as a bent inverted V,
but it was hardly any more directional than the vertical anyway.)
There are several other hams living within a few blocks of here,
at least one of whom likes to operate during many of the same
CW contests as I do.
Given this situation, rejection by my receiver of strong signals
within a few kHz of my frequency (whether from a nearby ham, or
simply to compensate for my inability to reject strong signals
by rotating a beam antenna) is an important attribute to me.
I am using a TS-850S equipped with the Kenwood 500-Hz filter
in the first IF, but only the stock SSB filter in the 2nd IF.
I also have an audio DSP filter, which I use mainly on RTTY,
where I find it can improve the readability of signals once they
are tuned in. Otherwise, I have found audio filtering to be of
limited help as compared with the receiver's IF filtering, and
of course it can do nothing to mitigate the effect of strong
signals on the receiver's AGC.
Question: How cost-effective would a CW filter in the 2nd
(455-kHz) IF be for me? Would it have any significant effect on
signals outside (but near) the bandpass of the first IF filter?
Related questions: 1. Would a 2nd IF CW filter make alignment
more critical than at present? 2. Would it make the slope tune
controls any more effective? With my present setup, the tuning
steps on these controls are obviously designed for the 2700-Hz
filters. In the normal CW position, the high-cut control very
quickly moves the narrow filter to the wrong side of zero-beat,
and even in the CW reverse position the useful range of the
low-cut control is only two or three switch positions. 3.
Would a narrower (250-Hz) 2nd IF filter be a better choice
than a second 500-Hz filter, and what effect would this choice
have on the answers to questions 1 and 2?
I look forward with interest to any response, particularly
from anyone with experience with 2nd-IF CW filters.
73,
Rich (VE3IAY)
--
CQ-Contest on WWW: http://www.contesting.com/_cq-contest/
Administrative requests: cq-contest-REQUEST@contesting.com
|