[1000mp] INRAD IF Amp vs. Roofing Filter wrt rcvr noise

[Pete Smith]

Inrad says "The amplifier (on the roofing filter board) provides enough 
gain to override the filter insertion loss plus a dB or 2.

Further down, they discuss replacing the IF mod with the filter, and 
suggest turning the IF gain (menu 9-1) back up two integers from the 
setting used with the IF mod.  I turned mine back up 1, and it seems as 
sensitive as before, but I haven't measured the MDS.  Are there any 
measured numbers out there?

73, Pete N4ZR



At 03:34 PM 11/29/2004, you wrote:

>Lately I've been very active on 12M. There have been several very nice 
>openings and many weak openings. Since 9/15 my 12M country count has gone 
>from 50 to 125. Many of the stations I've been working are just barely out 
>of the noise on CW, and I have the AF gain cranked all the way up and 
>still need to really concentrate to copy them.
>
>I know the INRAD IF amp is intended to reduce the amount of white noise 
>for improved readability of weak signals, but I know it also degrades the 
>receiver in strong signal situations. How does the roofing filter mod 
>compare to an unmodified radio where weak signals are concerned? Does it 
>add any gain at all? The INRAD web page doesn't address this, and I didn't 
>find anything about it on VA3CR's site either. I'm only using an inverted 
>Vee for the WARC bands, so I need all the sensitivity I can get for these 
>weak stations on 12M.
>
>73,
>
>John, K9MM
>
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