[1000mp] Roofing filter observation, A=B test

[Jim W7RY]

Make that a pair of 250Hz filters!  Sorry. (BTW they are also INRAD).

73
Jim

At 03:34 PM 1/14/2005, Jim W7RY wrote:
>I too noticed the same great performance. I did operate in the ARRL RTTY 
>Roundup contest last weekend and listening on the bands with a pair of 
>125Hz filters centered at 2200 Hz was a pleasure to listen to without all 
>the noise.
>
>
>My MK-V did not have the INRAD 70 MHz IF mod installed. To get the same 
>s-meter reading with a calibrated signal generator after installation of 
>the roofing filter I had to turn down the IF gain to about 9. I think I 
>finally setteled on a setting of 10. Originally it was set at 13.
>
>I you listening to a quite band... I would highly recommend it!
>
>73
>Jim W7RY
>
>At 08:30 AM 1/14/2005, =?iso-8859-4?B?VPVubm8gVuRoaw==?= wrote:
>>Just a quick note on my roofing filter observations:
>>
>>I have two MPs both so far with IF mods. All filters in and mostly 
>>identical in all measurements.
>>
>>So I had the opprotunity to install roofing filter into one instead of IF 
>>mod and do A=B testing.
>>
>>1. I did not notice signal strength change. I think I have both set to 12 
>>in 9.x menu and they were still identical.
>>2. I did not find any strong enough signals close enough to cause any 3rd 
>>order IMD products so I did not see any difference in signal clarity, 
>>cutting splatters or anyhing like this. I guess I have to wait for 
>>contest for that.
>>3. What I did notice for sure was remarkable HISS REDUCTION. The 
>>backround noise was constantly about 1-2 S-units lower on all bands. 
>>Quite remarkable. The receiver is more quiet. What actually seems like an 
>>ordinary band noise was noticably lower.
>>
>>I am satisfied:)
>>
>>73
>>tonno
>>es5tv
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