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Re: Pre-amp question



Stan wrote:
> 
> Hello Al,
> 
> Your technical decision should be based on the electromagnetic
> environment that you are in. If you are out in the rural county
> with no other 2M operators and a radio wise quiet area the
> Mirage/MFJ mast mount preamplifier would be a cost effective solution.
> 
> If you are in a dense electromagnetic environment with many 2M
> legal limit operators, strong 136 Mhz FAA transmitters, and many
> pagers at 152 Mhz, then you need a a low noise preamplifier
> with 2M bandpass selectivity to reject all of the strong
> signals NOT of any interest.
> 
> The Mirage/MFJ units DO NOT provide significant 2M bandpass
> capabilities and should be considered as broad. The SSB mast
> mount preamplifier is multi stage with helical filters after the first
> low noise stage. (as I recall)....
> 
> If you are in a really HOT RF area.... consider the DCI, 4-cavity
> bandpass filter, ahead of any preamplifier.
> I use them on 6M, 2M and 222 Mhz.......
> 
> Keep in mind that all of the passive insertion losses between
> the antenna and the first active device (preamplifier) add directly
> to the system noise figure. If you have 10 dB of losses ahead
> of your 0.1 dB low noise preamplifier,  your system noise figure
> will be no better than 10.1 dB......
> 
> Stan, WA1ECF   Cape Cod, MA   FN41sr
> 
> Allen Emer wrote:
> 
> > I'm looking to install either an SSB SP2000 preamp or a Mirage KP2 (VHF)
> > anyone have experience with these units? I'd hate to spend the extra bucks
> > on the SSB if
> > they both perform the same.
> >
> > Al Emer N2YAC
> >
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> 
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I agree with the DCI filter usage... I wouldn't be without them on 2
,222 and 432... they increase loss by around .8dB , but they drop the
noise floor by 4 or 5 dB... well worth the loss... gets rid of all the
intermod and TV spurs ,computer spurs and noise... 73 de Jordan...
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