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

[Ian White, G3SEK]

kr6c at juno.com wrote:
>
>Hi,
>
>I just installed the roofing filter but sure dont seem to notice any 
>difference when tuning around the band.  Should the rolloff or 
>"Bandpass" difference be noticeable between the main and the aux VFO's 
>when listening or is this something that will be noticable in pileups 
>and contests?  I used an oscillator and tuned thru the frequency with 
>both VFO's (S0 to S20 to S0).  Theres about a 2 kHz wider passband on 
>the aux receiver then the main.
>
>I didnt check to see if there was 5V on the pins after I removed the 
>70MHz mod.  Did I miss something or should I have heard a big 
>difference??

You shouldn't have heard any significant difference under "peacetime" 
conditions.

The difference should only appear in pileups and contests; and even 
then, it will only help at certain moments when there are several very 
strong stations on frequencies close by. With the unmodified FT-1000, 
intermodulation inside your own receiver will make it sound like there's 
more QRM on the frequency than really exists. That extra IMD makes it 
very tough to copy a weak station.

The key question is: what do you normally do, at moments like that?

If your normal operating habit is to QSY away from such situations, you 
will never see any benefit from the INRAD filter - in fact you're 
actively avoiding situations where it could help.

But if you're the kind who grits his teeth and hangs in there - because 
you really need that new country, or you really want to hold your run 
frequency in a contest - then the INRAD filter *will* help. Not every 
time, of course, but it will definitely improve the odds in your favor.


-- 
73 from Ian G3SEK