Elecraft › [K3]

P3 level accuracy

Classic

List

Threaded

9 messages Options

Stephen Prior

P3 level accuracy

I have just run the RF gain calibration on the K3 via the utility (and
calibrated the S meter too) using my XG-2 on 40m. Default values of the S
meter give S9 as it should with 50uV from the XG-2. However, the P3 shows a
level of -78dBm which seems to be outside the P3's published spec of +/-
3dB. A calibration routine for the P3 utility has been mooted for the
future, but I am wondering whether it's normal for the level to be so far
out.

I'd be interested in what other XG-2 and P3 owners find. The XG-2 is
running on a new lithium button cell.

73 Stephen G4SJP

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Brett Howard

Re: P3 level accuracy

My XG-2 is within 1dB when tested on a recently calibrated spectrum
analyzer with MUCH less than .1dB error. More error was introduced with
the N to BNC adapter than by the analyzer in this test.

My P3 however is quite a bit off (similar to yours) but I don't remember
the exact values. I'm looking forward to a calibration routine. It is
something that has been planned but other more important features such
as fixed span tuning are ahead of it.

For what the P3 is intended for it does its job very well. Once the
amplitude calibration is in place it will do beyond its intention very
well.

~Brett (N7MG)

On Sat, 2010-09-25 at 16:50 +0100, Stephen Prior wrote:

> I have just run the RF gain calibration on the K3 via the utility (and
> calibrated the S meter too) using my XG-2 on 40m. Default values of the S
> meter give S9 as it should with 50uV from the XG-2. However, the P3 shows a
> level of -78dBm which seems to be outside the P3's published spec of +/-
> 3dB. A calibration routine for the P3 utility has been mooted for the
> future, but I am wondering whether it's normal for the level to be so far
> out.
>
> I'd be interested in what other XG-2 and P3 owners find. The XG-2 is
> running on a new lithium button cell.
>
> 73 Stephen G4SJP
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> 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:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Geoffrey Downs-3

Re: P3 level accuracy

In reply to this post by Stephen Prior

Dear Stephen,

My XG2 at 50 microvolts output nominal also shows near enough -78dbm on the
P3. At 1 microvolt output it's about -112 dbm. The battery isn't new but
doesn't get a lot of use. All after due recalibration procedures.

73 to all

Geoff
G3UCK

----- Original Message -----
From: "Stephen Prior" <[hidden email]>
To: "elecraft" <[hidden email]>
Sent: Saturday, September 25, 2010 4:50 PM
Subject: [Elecraft] P3 level accuracy

Stephen Prior

Re: P3 level accuracy

Hi Geoff

I've had several replies, all report the XG-2's -73dBm level to be between
about -78dBm and -80dBm on the P3, so it's at least consistent, and will, no
doubt receive Elecraft's attention in due course!

73 Stephen

On 27/09/2010 19:18, "Geoffrey Downs" <[hidden email]> wrote:

>
> Dear Stephen,
>
> My XG2 at 50 microvolts output nominal also shows near enough -78dbm on the
> P3. At 1 microvolt output it's about -112 dbm. The battery isn't new but
> doesn't get a lot of use. All after due recalibration procedures.
>
> 73 to all
>
> Geoff
> G3UCK
>
> ----- Original Message -----
> From: "Stephen Prior" <[hidden email]>
> To: "elecraft" <[hidden email]>
> Sent: Saturday, September 25, 2010 4:50 PM
> Subject: [Elecraft] P3 level accuracy
>
>
>> I have just run the RF gain calibration on the K3 via the utility (and
>> calibrated the S meter too) using my XG-2 on 40m. Default values of the S
>> meter give S9 as it should with 50uV from the XG-2. However, the P3 shows
>> a
>> level of -78dBm which seems to be outside the P3's published spec of +/-
>> 3dB. A calibration routine for the P3 utility has been mooted for the
>> future, but I am wondering whether it's normal for the level to be so far
>> out.
>>
>> I'd be interested in what other XG-2 and P3 owners find. The XG-2 is
>> running on a new lithium button cell.
>>
>> 73 Stephen G4SJP
>
>

Joe Planisky

Re: P3 level accuracy

Which do you suppose is inaccurate: the XG-2 or the P3?

73
--
Joe KB8AP

On Sep 27, 2010, at 11:22 AM, Stephen Prior wrote:

> Hi Geoff
>
> I've had several replies, all report the XG-2's -73dBm level to be
> between
> about -78dBm and -80dBm on the P3, so it's at least consistent, and
> will, no
> doubt receive Elecraft's attention in due course!
>
> 73 Stephen
>

Stephen Prior

Re: P3 level accuracy

Well, I'm kind of assuming it's the P3! That the figures quoted have been
consistent, suggests not only that the XG-2's have pretty much the same
output but also that there is a common scaling (gain) or perhaps a
systematic error in the P3.

It will, no doubt be sorted in time. Meanwhile, it's no big deal and I've
found that I don't know how I've survived so long without a panadaptor, it
introduces a whole new way of working.

73 Stephen G4SJP

On 27/09/2010 20:33, "Joe Planisky" <[hidden email]> wrote:

>
> Which do you suppose is inaccurate: the XG-2 or the P3?
>
> 73
> --
> Joe KB8AP
>
>
> On Sep 27, 2010, at 11:22 AM, Stephen Prior wrote:
>
>> Hi Geoff
>>
>> I've had several replies, all report the XG-2's -73dBm level to be
>> between
>> about -78dBm and -80dBm on the P3, so it's at least consistent, and
>> will, no
>> doubt receive Elecraft's attention in due course!
>>
>> 73 Stephen
>>
>
>

Joe Subich, W4TV-4

Re: P3 level accuracy

In reply to this post by Stephen Prior

> I've had several replies, all report the XG-2's -73dBm level to be
> between about -78dBm and -80dBm on the P3, so it's at least
> consistent, and will, no doubt receive Elecraft's attention in
> due course!

Well, my XG-2 shows up at -68 to -70 dBm on my P3. The P3 shows
a no signal noise floor of -150dBm (RX Ant) in a 2 KHz span. The
K3 has been calibrated to this same XG-2 using the K3 Utility and
reads S9. The 1 uV output shows up at -105dBm with the same test
conditions.

The K3 has the IF output modification fitted.

73,

... Joe, W4TV

On 9/27/2010 2:22 PM, Stephen Prior wrote:

> Hi Geoff
>
> I've had several replies, all report the XG-2's -73dBm level to be between
> about -78dBm and -80dBm on the P3, so it's at least consistent, and will, no
> doubt receive Elecraft's attention in due course!
>
> 73 Stephen
>
>
> On 27/09/2010 19:18, "Geoffrey Downs"<[hidden email]> wrote:
>
>>
>> Dear Stephen,
>>
>> My XG2 at 50 microvolts output nominal also shows near enough -78dbm on the
>> P3. At 1 microvolt output it's about -112 dbm. The battery isn't new but
>> doesn't get a lot of use. All after due recalibration procedures.
>>
>> 73 to all
>>
>> Geoff
>> G3UCK
>>
>> ----- Original Message -----
>> From: "Stephen Prior"<[hidden email]>
>> To: "elecraft"<[hidden email]>
>> Sent: Saturday, September 25, 2010 4:50 PM
>> Subject: [Elecraft] P3 level accuracy
>>
>>
>>> I have just run the RF gain calibration on the K3 via the utility (and
>>> calibrated the S meter too) using my XG-2 on 40m. Default values of the S
>>> meter give S9 as it should with 50uV from the XG-2. However, the P3 shows
>>> a
>>> level of -78dBm which seems to be outside the P3's published spec of +/-
>>> 3dB. A calibration routine for the P3 utility has been mooted for the
>>> future, but I am wondering whether it's normal for the level to be so far
>>> out.
>>>
>>> I'd be interested in what other XG-2 and P3 owners find. The XG-2 is
>>> running on a new lithium button cell.
>>>
>>> 73 Stephen G4SJP
>>
>>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Don Wilhelm-4

Re: P3 level accuracy

Joe,

Comparing the K3 S-meter with the P3 amplitude indication has some
limitations.

You stated that your K3 has been calibrated with the XG2 and I have no
reason to doubt that, but do realize the granularity in that calibration.
If you calibrate the K3 S-9 indicator bar to just barely come on at -73
dBm, and it will be the only bar illuminated until the signal goes up to
-67 dBm (assuming 6 dB per S-unit). So your indication is well within
that granular step. OTOH, if you calibrated the K3 S-meter so the S-9
indication is on full at -73 dBm, then your K3's S-9 could be as low as
-79 dBm.
When comparing the K3 S-meter reading to the P3, one must consider this
granularity in the K3 S-meter - in other words, it is not an "exact
science" - allow for a +/- 6 dB range when making comparisons unless you
have calibrated the K3 S-meter with this granularity in mind and can
define the S-9 range more closely with accuracy.

I believe Alan is working on additional calibration processes for the
P3, so if we could give this subject a bit of a rest until he completes
that work, we will keep the reflector more quiet for now - after the P3
calibrations are in place, then I am certain comments on accuracies and
inaccuracies of the response will be well received and appreciated.

What we have currently is a digital display with its digital granularity
being compared to an analog display with greater resolution than the
digital display - to me, that is like comparing apples and oranges
unless the granularity (and its consequences) is understood. Those of
us old-timers who grew up in the analog meter world do have a difficult
time with this fact - it just does not seem "natural" unless we have
gone through the "digital indoctrination" and learned its consequences.

73,
Don W3FPR

On 9/27/2010 5:26 PM, Joe Subich, W4TV wrote:

>
> > I've had several replies, all report the XG-2's -73dBm level to be
> > between about -78dBm and -80dBm on the P3, so it's at least
> > consistent, and will, no doubt receive Elecraft's attention in
> > due course!
>
> Well, my XG-2 shows up at -68 to -70 dBm on my P3. The P3 shows
> a no signal noise floor of -150dBm (RX Ant) in a 2 KHz span. The
> K3 has been calibrated to this same XG-2 using the K3 Utility and
> reads S9. The 1 uV output shows up at -105dBm with the same test
> conditions.
>
> The K3 has the IF output modification fitted.
>
> 73,
>
> ... Joe, W4TV
>

Joe Subich, W4TV-4

Re: P3 level accuracy

Don,

> You stated that your K3 has been calibrated with the XG2 and I have
> no reason to doubt that, but do realize the granularity in that
> calibration. If you calibrate the K3 S-9 indicator bar to just
> barely come on at -73 dBm, and it will be the only bar illuminated
> until the signal goes up to -67 dBm (assuming 6 dB per S-unit).

The primary point was not the K3 calibration (other than the IF gain
had been calibrated using the XG-2 and K3 Utility) but rather that
my particular XG-2 shows -70 dBm on the P3 vs. the -78 to -80 dBm
being claimed as "normal." In addition, since the 1 uV signal shows
-105 dBm (vs. a calculated -107 dBm) it would tend to indicate the
gain slope is accurate and the overall gain within 3 dB (reasonable
accuracy considering that the XG-2 is not a calibrated standard).

I did calibrate the S meter on my K3 so the S9 reference was
"centered" (that is, I adjusted SMTR OF to the center of the
range - between the point the S9 bar just comes on and where
the S9+5 dB just comes on). That should make my S9 bar indicate
-73 dBm +/-2.5 dB (-75.5 dBm to -70.5 dBm).

73,

... Joe, W4TV

On 9/27/2010 6:10 PM, Don Wilhelm wrote:

> Joe,
>
> Comparing the K3 S-meter with the P3 amplitude indication has some
> limitations.
>
> You stated that your K3 has been calibrated with the XG2 and I have no
> reason to doubt that, but do realize the granularity in that calibration.
> If you calibrate the K3 S-9 indicator bar to just barely come on at -73
> dBm, and it will be the only bar illuminated until the signal goes up to
> -67 dBm (assuming 6 dB per S-unit). So your indication is well within
> that granular step. OTOH, if you calibrated the K3 S-meter so the S-9
> indication is on full at -73 dBm, then your K3's S-9 could be as low as
> -79 dBm.
> When comparing the K3 S-meter reading to the P3, one must consider this
> granularity in the K3 S-meter - in other words, it is not an "exact
> science" - allow for a +/- 6 dB range when making comparisons unless you
> have calibrated the K3 S-meter with this granularity in mind and can
> define the S-9 range more closely with accuracy.
>
> I believe Alan is working on additional calibration processes for the
> P3, so if we could give this subject a bit of a rest until he completes
> that work, we will keep the reflector more quiet for now - after the P3
> calibrations are in place, then I am certain comments on accuracies and
> inaccuracies of the response will be well received and appreciated.
>
> What we have currently is a digital display with its digital granularity
> being compared to an analog display with greater resolution than the
> digital display - to me, that is like comparing apples and oranges
> unless the granularity (and its consequences) is understood. Those of us
> old-timers who grew up in the analog meter world do have a difficult
> time with this fact - it just does not seem "natural" unless we have
> gone through the "digital indoctrination" and learned its consequences.
>
> 73,
> Don W3FPR
>
> On 9/27/2010 5:26 PM, Joe Subich, W4TV wrote:
>>
>> > I've had several replies, all report the XG-2's -73dBm level to be
>> > between about -78dBm and -80dBm on the P3, so it's at least
>> > consistent, and will, no doubt receive Elecraft's attention in
>> > due course!
>>
>> Well, my XG-2 shows up at -68 to -70 dBm on my P3. The P3 shows
>> a no signal noise floor of -150dBm (RX Ant) in a 2 KHz span. The
>> K3 has been calibrated to this same XG-2 using the K3 Utility and
>> reads S9. The 1 uV output shows up at -105dBm with the same test
>> conditions.
>>
>> The K3 has the IF output modification fitted.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>