[1000mp] ARRL REVIEW ROOFING FILTER

[Earl W Cunningham]

Ron, WA0KDS wrote:

"There  is no  way that anyone can tell the difference between -69 and
-79 .  The ear is just not that good. Sorry.  A lot of hype out there to
sell radios and filters."
==========
Ron, on a quiet band (with no strong signals nearby in frequency) you'll
probably won't hear any difference.

The INRAD roofing filter vastly improves the IMDDR3 and BDR of the
receiver.  For example, when I use my FT-1000MP (without the INRAD
roofing filter) in a crowded band with many strong signals (especially
during contests), I have to crank in 6 dB of front panel attenuation to
get rid of the chirps and birdies caused by the IMDDR3 products produced
by two (or more) strong signals on the band (within the bandpass of the
stock roofing filter, which is 20 kHz, I believe).  But that 6 dB of
attenuation makes it more difficult to hear the weaker signals.

If I had the narrower INRAD roofing filter, that 10 dB of improvement in
IMDDR3 (at 2 kHz spacing) would negate the need to use any front panel
attenuation because I wouldn't hear the chirps and birdies I normally
would.

I've never had a problem with BDR, but the ARRL test results for that
parameter are also quite impressive.

No, I'm not going to buy the INRAD filter because I have a different
radio that I like better for contesting and DXing, but for you contesters
that prefer using the MP series of radios, it looks like a "must have".

73, de Earl, K6SE