Fw: Re: Fw: Re: [Test-Equipment] Spectrum Analyzer BW measurement

[Dave Emery]

On Sat, Jan 31, 2004 at 08:53:45AM -0600, windy10605@juno.com wrote:
> That, I understand. Thanks Dave. 
> 
> Just for curiosity what do you read with your SA when you look at a
> signal at the -55dB points using the "few %" RBW vs 10x that RBW. I
> realize actual filter passbands are going to be different, today's
> spectrum analyzers probably compensate, etc. but I'm interested if you
> see something around 5x-10x BW at -55dB.


	I measured my antique IFR A-7550 (it being the one that
was handiest and not needing work)...

	300 hz 		300 hz  @ 3db	1600 hz  @ 50 db   2000 hz  @ 60 db
        3   khz		3.2 khz @ 3db	11.6 khz @ 50 db   12.8 khz @ 60 db
	30  khz		30  khz @ 3db	68   khz @ 50 db   80   khz @ 60 db
	300 khz		380 khz @ 3db   710  khz @ 50 db   820  khz @ 60 db

	I think its 300 hz and maybe 3 khz values were possibly somewhat
contaminated by its inherent LO phase noise (incidental FM).   It
ain't all that wonderful compared to better instruments, and its noise
floor was about -78 dbC in this case.

	I tried a couple of different signals including a precision
GPS derived 10 mhz from a standard and they gave similar results.


-- 
   Dave Emery N1PRE,  die@dieconsulting.com  DIE Consulting, Weston, Mass 02493