[1000mp] Improving the Close Spaced IM3 DR on the Mark V with Inrad Roofing Filter Mod

[Mike Schatzberg]

Hello 1000MP Fans:

I came across an interesting posting on the Contest Group of Quebec website.
The posting is from November 26, 2007, from Gilles, VE2TZT.

Although written in French, it appears that Gilles had quite a problem
during contesting with the new Inrad Roofing Filter installed in his Mark V.
You can see his posting here:

http://contestgroupduquebec.com/index.php?option=com_simpleboard&Itemid=41&func=view&id=528&catid=2

My rough translation of his problem is as follows:

"For the last WPX CW, I had installed the roofing filter INRAD (other
modifications Noise Blanker and key clicks already carried out with by
before) and I had been rather disappointed by the results (not found an
unspecified improvement, to see even a degradation of intermodulation on
strong close signals in particular on 40m where I have a good antenna). This
observation appeared to me in contradiction with the measurements taken by
the ARRL in the QST of February 2005."

So basically he says that he didn't see any improvement advantage after
installing the Inrad filter, and he even experienced a degradation of the
resistance to intermodulation products on 40 meters where he has a
particularly good antenna.

His article concludes that performing the simple modification to the Inrad
Roofing Filter board as suggested on the VA3CR website, fixed the problem,
and he has now no issues while contesting.

For those of you that are interested in addressing the same issue, you may
read about this modification here:

http://www.va3cr.net/mods/roofingfiltermodmarkV.htm

73 and Happy DXing,

Mike
W2AJI