[1000mp] On-Air test for Roofing Filter check

[Bill Tippett]

KR6C wrote:
 >Thanks for the inputs.  I know the Inrad info said casual ops would not 
notice any difference but thats not why I bought it.  Im down to my last 5 
countries, I like chasing DX during Contests and I am determined to work 
DXCC on 160 with my 40' tower ( only 25 more to go ;-) ).

         Nice going...especially with that antenna and
from California to boot!

 >The reason I decided to try the roofing filter is because everything on 
160 is weak to me and I live 2 miles from K6SE. I notice bad desensing from 
the strong stations during pileups and hoping it will also cut down on the 
wide keyclicks I hear during these conditions.

         There are 2 separate issues the roofing filter
will help...3rd order IMD products are the phantom
"bleeps and bloops" that two strong signals spaced
just right will cause on your listening frequency.
The desense issue (BDR) is caused when one very strong
signal causes blocking and desense of your receiver.
ARRL measured 25 dB improvement in BDR at 5 kHz spacings
for the Mark V and 17 dB for the MP they tested.  That's
a significant improvement.  Note:  the Inrad new filter
does not help nearly as much for signals spaced 2 kHz
and under (either BDR or IMD) since the interfering
signals thenl fall within the 4 kHz bandwidth of the
new filter.

         Bottom line...the new filter will improve both
issues for you as long as the interfering signals
are about 5 kHz away.  Unfortunately there is not
much of anything that will help keyclicks except for
the offending station to fix them.

                                         73,  Bill  W4ZV