Fw: K3/K144XV/P3 Signal Strength Readings

[Geoffrey Downs-3]

No comments from Elecraft or elsewhere on my posting below, so perhaps my
conclusions are wrong or maybe I'm just expecting results too quickly. Any
views anyone?

By the way, as with most postings that raise specific issues, it's not
intended to convey general negative vibrations about the K3/K144XV/P3. I
would not part with mine :-)

73 to all

Geoff
G3UCK

----- Original Message -----
From: "Geoffrey Downs" <[hidden email]>
To: <[hidden email]>
Sent: Monday, January 17, 2011 8:11 PM
Subject: [Elecraft] K3/K144XV/P3 Signal Strength Readings

> Having calibrated the K3 S meter and the P3 display with my XG2, I have 50
> microvolts equal to S9 and -73dbm (whether or not the preamp is on).
> However, on 2m (K144XV) there is a discrepancy between the K3 S
> meter and the P3. I believe Alan has told us on the reflector that on 2m
> S9 on the P3 is -93dbm in accordance with the IARU standard, but I also
> believe that when using the K144XV the K3 S meter still regards S9
> as -73dbm
> which is different by a factor of 10.
>
> Consequently K3 S meter readings are lower on 2m than they should be.
> Today,
> for example, I had a 2m qso where the two stations I was working were
> about
> S7 on the P3 but S3/4 on the K3 S meter. Is anything going on in the
> Elecraft f/w academy to address this?
>
> 73 to all
>
> Geoff
> G3UCK

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[VR2BrettGraham]

A lonely G3UCK said, seemingly talking to himself:

> No comments from Elecraft or elsewhere on my posting below, so perhaps my
> conclusions are wrong or maybe I'm just expecting results too quickly.
> Any
> views anyone?

I have wondered about this IARU R1 Recommendation about S-meters.  In
order to comply, it means transverters have to be 20 dB hotter on the
output for the same input signal level, as the transverter is usually
used with a radio where S9 is -73 dBm & not -93 dBm.

Or all radios have some means to make the S-meter seem 20 dB "hotter"
when used with a transverter. I am not aware of any that do.  None that
I have do this, so I guess transverters are that way.

For radios that straddle R1's -73/-93 dBm S9 boundary, we should also
see signs of compliance with the Recommendation.  A quick check of one
such reasonably current product from one of The Big Three I own that I
do not recall acting like it complies with the Recommendation shows that
indeed, it does not.  It is has one of these new-fangled "light bulb"
S-meters, where S1 is set to light up at different levels on 70cm, 2m,
6m, 10/20m & 80m (total spread between them: 9 dB).  S9 is set to 31,
31, 28, 25 & 22 dB above S1 on those bands, respectively.  From S9 to
S9+60 is 60 dB.

The narrative for this Recommendation, found at
http://iaru-r1.org/index.php?option=com_remository&Itemid=173&func=download&id=178&chk=b8ce4681621e009741d6eabdce8eef20&no_html=1

"At the IARU Region 1 Conference in Hungary 1978 the need for a
harmonised standard for the "S-meter
scale" was expressed and a proposal was accepted for publication in
society journals. The essential
recommendation was 1 S-point is 6 dB . At the Brighton Conference in
1981 the recommendation was
formally adopted as a standard for amateur radio equipment manufacturers.

At the 1990 Torremolinos conference an amendment was adopted which
reconfirmed the -93 dBm
reference level for frequencies above 144 MHz, but no statement was
issued for the bands between 30
and 144 MHz.

Although not explicitly stated the implication of the recommendation is
that on VHF and higher frequencies
the S-meter will deviate on the thermal noise only ( S2 in 3 kHz
bandwidth, S3 in 12 kHz bandwidth).
Although the recommendation is not too complex it seems to be rather
difficult to implement by
commercial manufacturers."

A good Recommendation would make sense on its own - not need a narrative
& perhaps not one that says what this one does.  A good Recommendation
would be followed & might also be something that we could look back at &
see why it was we are told things should be done that way.  This was
just a quick look, but my impression is that if S-meters are to work
this way, it should be like an IARU bandplan & apply to just R1.

73, ex-VR2BG/p.

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[Geoffrey Downs-3]

Very interesting, Brett, and thank you for your comments and the research
you have done. I *was* beginning to feel a little isolated by lack of
comment from anyone hihi! Although I did receive one reply offlist reporting
experience similiar to mine.

I was not aware of the 1990 Torremolinos recommendation as such but a recent
thread here on the reflector
http://mailman.qth.net/pipermail/elecraft/2011-January/143651.html noted the
ambiguity about 6m and Alan Bloom of Elecraft concluded that it was
generally accepted that it should be treated as in the -93dbm category like
2m. However, you are correct to point out that it is a Region 1 (ie EU)
recommendation and I have not been able find out whether or not there are
similar or different recommendations for Regions 2 and 3.

Compared with my FT847 (another rig that straddles the -73/-93dbm boundary)
the S meter on the K144XV/K3 reads low on 2m and there have been a number of
postings on the reflector from at least two of the IARU regions, if not all
three, by people who feel that at present it reads low compared with what
they are used to on other rigs. This suggests to me that other commercial
rigs for 2m do use the -93dbm standard - as the P3 now does. Unfortunately I
do not have any test gear that will produce a known 50 microvolts or 5
microvolts on 2m to do some checking. I accept that this doesn't seem to
accord with your findings on your rig, Brett, if I properly understand them.
As general comment, though, the rig doesn't seem to show enough difference
in db between S1 and S9 on the bands you mention.

Things were not always how they are now. When the K144XV first came out the
S meter registered too high and a firmware change reduced it, but perhaps
the correction was overdone? I would certainly like the P3 and the K144XV/K3
to agree on signal strength indication on 2m.

Elecraft or anyone care to comment?

73 to all

Geoff
G3UCK


----- Original Message -----
From: "VR2BrettGraham" <[hidden email]>


>A lonely G3UCK said, seemingly talking to himself:
>
>
> I have wondered about this IARU R1 Recommendation about S-meters.  In
> order to comply, it means transverters have to be 20 dB hotter on the
> output for the same input signal level, as the transverter is usually
> used with a radio where S9 is -73 dBm & not -93 dBm.
> ...........
 A quick check of one
> such reasonably current product from one of The Big Three I own that I
> do not recall acting like it complies with the Recommendation shows that
> indeed, it does not.  It is has one of these new-fangled "light bulb"
> S-meters, where S1 is set to light up at different levels on 70cm, 2m,
> 6m, 10/20m & 80m (total spread between them: 9 dB).  S9 is set to 31,
> 31, 28, 25 & 22 dB above S1 on those bands, respectively.  From S9 to
> S9+60 is 60 dB.
>
..............
> > A good Recommendation would make sense on its own - not need a narrative
> & perhaps not one that says what this one does.  A good Recommendation
> would be followed & might also be something that we could look back at &
> see why it was we are told things should be done that way.  This was
> just a quick look, but my impression is that if S-meters are to work
> this way, it should be like an IARU bandplan & apply to just R1.
>
> 73, ex-VR2BG/p.


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[N5GE]

Agreed Geoff.

I think it could be more accurate.  I do think it was lowered too much.  At
times when on 2m my k3 smelter S-Meter nothing at all when using the K144XV.



On Sat, 22 Jan 2011 18:04:28 -0000, "Geoffrey Downs" <[hidden email]>
wrote:

[snip]

>Things were not always how they are now. When the K144XV first came out the
>S meter registered too high and a firmware change reduced it, but perhaps
>the correction was overdone? I would certainly like the P3 and the K144XV/K3
>to agree on signal strength indication on 2m.
>
>Elecraft or anyone care to comment?
>
>73 to all
>
>Geoff
>G3UCK

[snip]
73,

Tom Childers
Radio Amateur N5GE
Licensed since 1976
QCWA Life Member 35102
ARRL Life Member
Retired Professional
C# Software developer
http://www.n5ge.net

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[VR2BrettGraham]

G3UCK now at least has ex-VR2BG to talk to:

> Very interesting, Brett, and thank you for your comments and the
> research you have done. I *was* beginning to feel a little isolated by
> lack of comment from anyone hihi! Although I did receive one reply
> offlist reporting experience similiar to mine.

The Brand-E community is rather USA-centric, in case you have not
noticed ;^).  You bring up something that falls in the
something-is-other-than-fantastic category & that is not conducive to
cheerleading or provides an opportunity to express economic patriotism,
hence you were ignored.  Hence your posts, my post & nothing else but
somebody saying "Yeah, I noticed the same thing" to you directly.  Is a
bit of a shame, because it gets in the way of sorting out a product that
has things that need sorting out.

> I was not aware of the 1990 Torremolinos recommendation as such but a
> recent thread here on the reflector
> http://mailman.qth.net/pipermail/elecraft/2011-January/143651.html 
> noted the ambiguity about 6m and Alan Bloom of Elecraft concluded that
> it was generally accepted that it should be treated as in the -93dbm
> category like 2m. However, you are correct to point out that it is a
> Region 1 (ie EU) recommendation and I have not been able find out
> whether or not there are similar or different recommendations for
> Regions 2 and 3.
>
> Compared with my FT847 (another rig that straddles the -73/-93dbm
> boundary) the S meter on the K144XV/K3 reads low on 2m and there have
> been a number of postings on the reflector from at least two of the
> IARU regions, if not all three, by people who feel that at present it
> reads low compared with what they are used to on other rigs. This
> suggests to me that other commercial rigs for 2m do use the -93dbm
> standard - as the P3 now does. Unfortunately I do not have any test
> gear that will produce a known 50 microvolts or 5 microvolts on 2m to
> do some checking. I accept that this doesn't seem to accord with your
> findings on your rig, Brett, if I properly understand them. As general
> comment, though, the rig doesn't seem to show enough difference in db
> between S1 and S9 on the bands you mention.

It was the FT-847 that I was describing - one product from one
manufacturer with Brand-Y's rather peculiar approach to R&D is obviously
not the best way to judge overall state-of-play of the industry, but it
is a start & I believe a more thorough look at how products are set up &
how they actually perform will find not many following this
Recommendation (do the likes of the really good, long established &
respected transverter manufacturers really add 20 dB gain to the output
of their products in order to comply?).

S-meters are of course S-meters, we both I suspect are long enough in
the tooth to understand their limitations, but a 20 dB delta is not
insignificant & I really do wonder about this Recommendation that is so
old, may not be followed & we cannot now see for ourselves why it is we
were told things should be this way.

It merits looking at further, especially if as I suspect (though my
experience is only from IARU R3 & what they get up to in their
conferences), there was zero involvement of anyone other than national
societies in drafting it.   To anyone with a relevant professional
background, this point alone is a bit of a show-stopper.

73, ex-VR2BG/p.

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[Alan Bloom-2]

I realize that IARU Region 1 recommendations officially apply only to
Region 1 (Europe, Africa, Middle East, N. Asia) but since I don't know
of any other official recommendation that's the one I used for the P3.

I was not privy to the IARU committee's deliberations, so I don't know
why they recommended S9 = -73 dBm on HF and S9 = -93 dBm on VHF and
above, but I can speculate. One reason may be the fact that antenna
noise levels (and signal levels for that matter) are generally much
lover above 144 MHz than below 30 MHz so it makes sense to adjust the
S-unit scale downward.

Another reason may be that most VHF/UHF transverters have gain and 20 dB
is probably a representative value. So the S meter on the HF transceiver
typically will read about 20 dB higher when the transverter is being
used.

My understanding is that is exactly how the K3 works now.  However,
since the gain of the K144XV is actually around 25 dB, that results in
S9 = -98 dBm rather than -93 dBm.  I believe it is on Wayne's list to
correct that in K3 firmware.

Alan N1AL




On Sun, 2011-01-23 at 02:51 +0000, VR2BrettGraham wrote:

> G3UCK now at least has ex-VR2BG to talk to:
>
> > Very interesting, Brett, and thank you for your comments and the
> > research you have done. I *was* beginning to feel a little isolated by
> > lack of comment from anyone hihi! Although I did receive one reply
> > offlist reporting experience similiar to mine.
>
> The Brand-E community is rather USA-centric, in case you have not
> noticed ;^).  You bring up something that falls in the
> something-is-other-than-fantastic category & that is not conducive to
> cheerleading or provides an opportunity to express economic patriotism,
> hence you were ignored.  Hence your posts, my post & nothing else but
> somebody saying "Yeah, I noticed the same thing" to you directly.  Is a
> bit of a shame, because it gets in the way of sorting out a product that
> has things that need sorting out.
>
> > I was not aware of the 1990 Torremolinos recommendation as such but a
> > recent thread here on the reflector
> > http://mailman.qth.net/pipermail/elecraft/2011-January/143651.html 
> > noted the ambiguity about 6m and Alan Bloom of Elecraft concluded that
> > it was generally accepted that it should be treated as in the -93dbm
> > category like 2m. However, you are correct to point out that it is a
> > Region 1 (ie EU) recommendation and I have not been able find out
> > whether or not there are similar or different recommendations for
> > Regions 2 and 3.
> >
> > Compared with my FT847 (another rig that straddles the -73/-93dbm
> > boundary) the S meter on the K144XV/K3 reads low on 2m and there have
> > been a number of postings on the reflector from at least two of the
> > IARU regions, if not all three, by people who feel that at present it
> > reads low compared with what they are used to on other rigs. This
> > suggests to me that other commercial rigs for 2m do use the -93dbm
> > standard - as the P3 now does. Unfortunately I do not have any test
> > gear that will produce a known 50 microvolts or 5 microvolts on 2m to
> > do some checking. I accept that this doesn't seem to accord with your
> > findings on your rig, Brett, if I properly understand them. As general
> > comment, though, the rig doesn't seem to show enough difference in db
> > between S1 and S9 on the bands you mention.
>
> It was the FT-847 that I was describing - one product from one
> manufacturer with Brand-Y's rather peculiar approach to R&D is obviously
> not the best way to judge overall state-of-play of the industry, but it
> is a start & I believe a more thorough look at how products are set up &
> how they actually perform will find not many following this
> Recommendation (do the likes of the really good, long established &
> respected transverter manufacturers really add 20 dB gain to the output
> of their products in order to comply?).
>
> S-meters are of course S-meters, we both I suspect are long enough in
> the tooth to understand their limitations, but a 20 dB delta is not
> insignificant & I really do wonder about this Recommendation that is so
> old, may not be followed & we cannot now see for ourselves why it is we
> were told things should be this way.
>
> It merits looking at further, especially if as I suspect (though my
> experience is only from IARU R3 & what they get up to in their
> conferences), there was zero involvement of anyone other than national
> societies in drafting it.   To anyone with a relevant professional
> background, this point alone is a bit of a show-stopper.
>
> 73, ex-VR2BG/p.
>
> ______________________________________________________________
> Elecraft mailing list
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[VR2BrettGraham]

N1AL said:

> I realize that IARU Region 1 recommendations officially apply only to
> Region 1 (Europe, Africa, Middle East, N. Asia) but since I don't know
> of any other official recommendation that's the one I used for the P3.

Not sure who has adopted the Recommendation.  As GM4ESD mentioned, what
IARU models itself on has another step to the overall process - though
this has more to do with regulatory matters.  The bits of that
organization that do standardization stuff like this involves
stakeholders & the process is one where they all agree on something,
rather than just some of them & then the rest of the world endorses
that.  Also note that since 1978, this is not one of the things that has
made the rounds of the IARU Regions.

Since the Recommendation is more like an endorsement of an existing
industry "standard", the industry association might be a better reference.

To be honest, it seems with transverter conversion gains ranging from
under 15 to over 25 dB & since they also can be cascaded, maybe with
products like the K3 & P3 where the signal strength indication now means
something, the best solution is something the user can set.  This seems
necessary just for the XVs/K144XV alone.

Or maybe just put a sticker below the meter: Signals in the meter
may/may not be as strong as they appear.  ;^)

73, ex-VR2BG/p.

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