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[AMPS] 6146 splatter help? IFR overload

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Subject: [AMPS] 6146 splatter help? IFR overload
From: W8JI@contesting.com (Tom Rauch)
Date: Wed, 3 Jan 2001 06:38:31 -0500
Hi Jim,

> Correct me if I am wrong but splatter is energy outside the intended 3kHz
> occupied bandwidth of the signal caused by over-modulation.  If there was
> splatter "up and down the band" surely it would show.  If I can see a CW

Not when the analyzer is sweeping and the spatter is off and on, 
and the peak energy is not stored. in the display system so the 
highest peaks are display even if they appear while the analyzer is 
sweeping by just for one sweep out of a hundred. 

You are playing luck-of-the-draw if you are talking and trying to see 
the real peaks as a non-storage analyzer sweeps by.

> signal, it means I can see energy is there even though I can't properly
> analyze it.  In fact, energy beyond +_ 15kHz and above -100 dbm IS

CW is a different game. Any spurs are there continuously. The 
analyzer passes by the spur on every sweep. Not so on SSB. 

> noticeable although it leaves you to wonder.   The spectrum analyzer
> module has a 25kHz filter.  The 1200 and 1300 series IFR's are a little
> better and can actually resolve individual Bessel nulls in an FM signal. 
> The old Motorola R-2000 and Cushman CE-6's are "has-beens" (and thousands
> of amateurs dream).  

The analyzers in these units are good for their intended job, looking 
for parasitics and harmonics far removed from the carriers of FM 
(and AM) transmitters or SSB transmitters modulated to produce 
steady output. You can't even see the fifth order products from a 
SSB voice signal on them.  

They also have poor dynamic range, and like most analyzers you 
have to be very very careful to not overload them. 
 
> This is definitely a "service" instrument rather than an "engineering lab"
> instrument.  Most of the two way shops these days seem to be more
> concerned with sales and political concerns and all the equipment is junk.
>  They wanted to borrow mine all the time.  Fat chance!

They are OK for FM service work, but are not a good SSB test set. 
73, Tom W8JI
w8ji@contesting.com

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