[Elecraft] P3 S meter variance

Sun Jan 16 02:42:05 EST 2011

I have quoted Shakespeare in my ECN notes as well as other authors.  Many  
times an apt quote can say what we cannot say.  Or, more often, say it  
much better than we ever could.
    Kevin.  KD5ONS


On Sat, 15 Jan 2011 23:32:58 -0800, Don Wilhelm <w3fpr at embarqmail.com>  
wrote:

>   Alan,
>
> WARNING - I am leading this thread Off-Topic.  Delete immediately if you
> object,- some parts are personal.
>
> Quoting Shakespeare on the reflector may be as good or better than some
> of the other "OT" posts that have appeared here in the past (no specific
> examples cited nor intended).
>
> I just might add a few of my favorite Mike Cross (and Tom Paxton) quotes
> to the melay in due time!
> (OK, you can Google if you are not familiar with those artists).  The
> humor and sentimentality of Mike Cross's songwriting helped me stay
> grounded through 3 bouts with cancer - he gave me hope and a new
> perspective on life, and I thouroughly enjoy the political satire that
> Tom Paxton has provided me with both a laugh at politics and a deep
> sorrow at the beauracracy that has developed.
>
>  From Mike Cross (who does not have an apparent active political agenda
> -- the serious side is embodied in songs like "Red Tailed Hawk",  while
> the funny side is characterized by "Elma Turl",or "Granny's Milk  
> Cartons".
>
> Tom Paxton does have a political agenda, but has composed and performed
> music ranging from "Ramblin' Boy" to "Lyndon Johnson told the Nation"
> (use Google).  Yes, this is stuff from the 1960s and the 1970s, and some
> is anti-war., but the time of Lyndon Johnson and Vietnam are past, so
> just enjoy the music and forget the politics that made that music so
> close to home.
>
> 73,
> Don W3FPR
>
> .1/16/2011 1:20 AM, Alan Bloom wrote:
>> Don,
>>
>>> The manual suggests that you calibrate the S-meter with the preamp ON.
>>> If you do that, and set the S-meter to ABS, you will find that the
>>> S-meter response is about 2 S-units lower than what you may expect.
>> Interesting.  I assumed that in ABS mode it didn't matter if the preamp
>> was on or not.  I sheepishly admit I have never bothered to calibrate my
>> K3 S meter.  No excuse - I have an HP8656B signal generator sitting
>> right next to the K3 - I just never got around to it.  I'd do it right
>> now but it's time to go to bed.  :=)
>>
>>> The K3 has re-vitalized the old Collins 50
>>> uV equal S-9 "standard".  That standard is not a standard at all,
>> Actually IARU Region 1 has published Technical Recommendation R.1 which
>> specifies S9 = -73 dBm (50 uV into 50 ohms) and 6 dB per S-unit.
>> http://en.wikipedia.org/wiki/S_meter#IARU_Region_1_Technical_Recommendation_R.1
>>
>> But you're right, that recommendation is more honored in the breach than
>> the observance.  (Gosh, quoting Shakespeare on the reflector - what are
>> we coming to? :=)
>>
>> Alan N1AL
>>
>>
>>
>> On Sun, 2011-01-16 at 00:43 -0500, Don Wilhelm wrote:
>>> Alan,
>>>
>>> I might add about the K3 CONFIG: SMTR MD = ABS, that the calibration
>>> procedure indicated in the manual may (or may not) be the "proper"  
>>> thing
>>> to do.
>>> The manual suggests that you calibrate the S-meter with the preamp ON.
>>> If you do that, and set the S-meter to ABS, you will find that the
>>> S-meter response is about 2 S-units lower than what you may expect.  I
>>> prefer to do the calibration with the S-meter off, and then the  
>>> response
>>> in SMTR ABS is more what I would expect.
>>>
>>> Since everyone's expectations do not necessarily match mine (obviously,
>>> I disagree with Wayne on this item), you can take your pick - do it the
>>> way the manual says, or do it like I have.  The choice is entirely
>>> yours.  Like all things S-meter reading related, there is a great
>>> variation between receivers,  The K3 has re-vitalized the old Collins  
>>> 50
>>> uV equal S-9 "standard".  That standard is not a standard at all, and
>>> many transceivers do it differently, but with the K3, you do have a
>>> choice depending on how you want to set it up.  If you cannot decide  
>>> how
>>> you want it, go with the manual instructions - they work and work quite
>>> well.  If you deviate, know why you are doing that deviation and know  
>>> it
>>> is for your own situation, others may or may not make the same choices.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 1/16/2011 12:20 AM, Alan Bloom wrote:
>>>> There are a couple reasons why the K3's S meter and the P3 display may
>>>> show a different level.
>>>>
>>>> As Don mentioned, the P3 will generally show a much lower level than  
>>>> the
>>>> K3 on noise.  It's because the effective bandwidth of the P3 is
>>>> generally only one display pixel, about 1/450 of the span.  Less
>>>> bandwidth means less noise power in each display point.  The same  
>>>> thing
>>>> happens to some extent with an SSB signal.
>>>>
>>>> Another issue is that the S meter reading on the K3 may change when  
>>>> you
>>>> turn the preamp or attenuator on or off.  To prevent that happening,  
>>>> set
>>>> CONFIG:SMTR MD to "ABS".
>>>>
>>>> If you do that and calibrate both the K3 S meter and the P3 amplitude,
>>>> then the two should closely agree when measuring a steady CW carrier.
>>>>
>>>> Alan N1AL
>>>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html


-- 
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/