[Elecraft] LP Pan versus P3 Panadapters

[Alan Bloom]

No I didn't have to narrow the span to 2 kHz to see the -127 dBm signal.
Anything less than about 30 kHz was sufficient.

Also, remember I had the K3 preamp off and the attenuator on.  With the
attenuator off, the -127 dBm signal is visible all the way up to 200 kHz
span.

With the K3 preamp turned on I can see a -135 dB signal, even at 200 kHz
span.  (I had to use a 10 dB attenuator to get the signal generator to
go that low.)

Alan N1AL




On Tue, 2010-09-14 at 07:51 -1000, Merv Schweigert wrote:
> For some reason that goes against what I think many are looking for in the
> P3,  if one has to narrow the span to 2khz, then I see no use for the P3 
> at all,  I need
> to see what is on the band at -127DBm at 30 to 50khz or more span.  If 
> the signal is
> only seen at 2KHZ,  I can hear that by ear and dont need the P3.   I 
> think VHF
> operators are saying the same thing,  they need to look over a larger 
> portion of the
> band and spot weak signals and move to them,  not narrow to 2KHZ and sit 
> there
> and tune the radio hoping to find a weak signal,  thats what you do 
> without a P3. 
> Does the LP Pan also work that poorly that you cannot see weak signals 
> 30KHZ
> away? 
> I do notice that with all the P3 sales,  you do not see many LP Pans for 
> sale,  so either
> people who buy the P3 are just buying it to have another Elecraft 
> product,  or they are
> keeping both and not sure yet which is the best?   
> Most of my operation will be low band,  160 meters, and if I cannot see 
> the weak
> signals on the band and cover at least 30 KHZ then the P3 is of no use 
> at all. 
> Bill W4ZV are you seeing the weak signals on 160 that are 20 or 30KHZ away?
> Or do you have to narrow the span down to see a signal that is barely 
> audible?
> 160 ops would like to know.
> 73 Merv K9FD  /  KH7C
> 
> 
> > Hi Larry,
> >
> > It depends on the span.  Unlike some other panadapters, the P3
> > automatically reduces the sample rate as you narrow the span, which
> > improves the sensitivity.
> >
> > For example, I have my HP8656B signal generator set to 3640 kHz with the
> > amplitude as low as it will go (-127 dBm).  The K3 has the preamp off,
> > the attenuator on, and default CW shift and width.  Under those
> > conditions I can just barely hear the carrier.  It's weak enough that if
> > it were a modulated CW signal I don't think I could copy it.
> >
> > However the carrier is clearly visible on the waterfall if I set the P3
> > span to 2 kHz.  As I increase the span the signal gradually gets harder
> > and harder to see.  Above about 30 kHz or so the signal disappears into
> > the noise.
> >
> > So that's the trick.  Narrow the span to make those signals pop out of
> > the noise.
> >
> > 73,
> >
> > Alan N1AL
> >
> >
> > On Tue, 2010-09-14 at 06:03 -0700, Larry K1UO wrote:
> >   
> >> Bill,
> >>
> >>    I can tell you that just last night, on 160 meters, I copied 2 very weak
> >> stations perfectly Q5 that did not show on the P3 waterfall.  Now, Its
> >> entirely possible its my adjustment skills but I dont think so.  Yes..the K3
> >> IF Mod was factory installed.     This has happened more than once.  For
> >> some reason I was expecting the P3 to show these very weak signals better
> >> than I could find them myself while tuning but no amount of adjustment so
> >> far will do this.  I may be expecting too much?
> >> Just so you know what anothers experience has been so far.
> >> 73
> >>
> >>
> >>
> >>
> >>   I too would like to see details of the improvement over LPan etc. I am a
> >> long time user of SDR/computer panadapters for use in detecting very weak
> >> signals at UHF/VHF/microwave. I use a Softrock on the K3 IF port since I got
> >> my K3 a year ago.  I have yet to see one report regarding weak sig detection
> >> with the P3 after many requests to the initial testers of the P3. ANYONE out
> >> there looking for weak weak sigs with a P3??
> >>
> >> 73  Bill K0AWU  EN37ed
> >>
> >>
> >>     
> >
> >
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