[1000mp] ARRL REVIEW ROOFING FILTER

[Ron]

Yes going from 12 MHz to 4 MHz will indeed be a big  improvement  but 
lowering  a beat in the bandpass from  a -69 level to a -79 dB level I 
would really have to question  if  you could tell the difference.

I believe where the problem is is that we are not talking actual level 
but a difference.  If -69 dB is the beat below the  signal you are 
trying to copy you will not know the difference if it was -69 dBor -79 
dB.   Now if the signal you are trying to copy is at a level that is 
equal with the  -69 db signal  then yes I expect it would make a 
difference. 

Lets but some names on these numbers.  -69 db is a relative number and 
-69 dBuV is a real level. 

Now what are we talking about ? 

Ron 

.

 
D. J. wrote:

> Ten db is quite a bit.  Like going from 100 watts to 1000 watts.
>
> If you understand what the roofing filter does then it's easy to see 
> how going from a 12 khz wide roofing filter to a 4 khz wide one will 
> improve receiver performance in the pileups and contests.  If you are 
> a rag chewer weekday afternoons then save your money.
>
> Dale
>
>
> On Dec 23, 2004, at 13:01, Ron wrote:
>
>> Come on now  I have been there.   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.   
>> You spent the money and wanted to hear and improvement so did.  The 
>> mind work wonders to do what you want it to do.
>> Ron   WA0KDS
>>
>>
>>
>> D. J. wrote:
>>
>>> Dirk,
>>>
>>> Here are some numbers:
>>>
>>> MKV noise floor before the INRAD roofing -123 and after -130
>>>
>>> Blocking at 20 khz spacing before 130 db   after 146 db
>>> 5 khz spacing before 105 db after 130 db
>>> 1 khz spacing before 104 db after 106 db
>>>
>>> IMD dynamic range 20 khz spacing before 88 db after 93
>>> 2 khz spacing before 69 after 79
>>> On Dec 23, 2004, at 10:51, ON4ADZ wrote:
>>>
>>> The report says "improvement is notable".
>>>
>>>  I have it installed in my own MKV and It's a noticeable improvement 
>>> without affecting the normal SSB audio.  AM even sounds ok to my old 
>>> ears.  I highly recommend it.
>>>
>>> 73
>>> Dale, K9VUJ
>>>
>>>
>>>> Dear
>>>>
>>>> I am intrested in a summary of this arrl only member review.
>>>>
>>>>
>>>> With thanks,
>>>>
>>>> ON4ADZ
>>>> dirk
>>>> on4adz at skynet.be
>>>>
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>>
>>
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