[TrunkCom] BC 780XLT Sensitivity

[Dave Emery]

On Sat, Jan 18, 2003 at 04:11:11PM -0500, W0rw@aol.com wrote:
> i was checking the sensitivity of my BC 780XLT and it really is bad
> on 1296 MHz. Is mine broken ?
> It is 0.2 uV on 150 and 450 MHz,
> 0.8 uV on 956 MHz,
> and about 3000 uV on 1296
> for 12 db quieting,
> using my  HP 8640B sig gen.
> i noticed they left it off of the specification sheet.
> No the channel attenuator was not on.

	By way of curiousity - I thought the 8640B only went up to a
little over a ghz (with option 3 or whatever)  ?   You could, I guess be
using harmonics or a doubler - but how sure of your calibration are
you ?   -  3000 uv seems a bit extreme, I would bet 3 uv might be
more realistic if it is really really bad...

	However - it would not surprise me that the 780 is pretty
deaf up there.  The rf front end filtering required by the FCC NPRM that
limits image response at cell frequencies probably kills performance
at 23 cms unless they actually bothered to add another bandpass filter
for that band - which is unlikely considering the number of users.

	I know that years and years ago ICOM made the downcoverter
for the R-7000 narrow band so sensitivity over the 1.3-2.0 ghz band
on more recent R-7000s is very poor.    So manufacturers do limit
performance in little used regions of the spectrum.



> 
> Paul  w0rw@aol.com
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-- 
	Dave Emery N1PRE,  die@die.com  DIE Consulting, Weston, Mass. 
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