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RF gain calibration and S meter

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Gary, W7TEA

RF gain calibration and S meter

Just ran the RF gain calibration with the new Mac K3 Utility and an XG2. I did it
a few times because I would get an ERR DSE error message when
calibrating the SUB rx on occasion. I then went back and re-calibrated the
S meter. I've noticed three things.

1) The rx seems considerably "quieter." The PRE is needed now where I seldom
used it before.

2) Turning RF gain to minimum quiets the rx but the S meter only advances to
S-5

3) I calibrated the S meter with PRE on and SMTR MD set to normal as Wayne
recommended. When I change the MD setting to ABS, the 50uv signal drops to
S-6 and cannot be adjusted up to S-9 with SMTR OF.

I would appreciate any help here. I'm tempted to go back redo
the RF gain calibration using the factory defaults option.

73,

Gary W7TEA K3 #1001, #5763

ab2tc

Re: RF gain calibration and S meter

Hi,

Go back and redo the calibration! Make sure to follow the instructions exactly and pay special attention to ensure you have test signal centered in the passband. This is critical since the instructions call for a 100Hz bandwidth. I had similar symptoms as you until I did this the 3rd time. 3 times makes perfect and my S-meter is not dead on at 1uV, S9 and S9+40, the three easy cal points I have. Backing off the RF gain, S-meter rises smoothly to S9+60 and the radio gets deadly quiet.

AB2TC - Knut

W7TEA wrote

Just ran the RF gain calibration with the new Mac K3 Utility and an XG2. I did it
a few times because I would get an ERR DSE error message when
calibrating the SUB rx on occasion. I then went back and re-calibrated the
S meter. I've noticed three things.

1) The rx seems considerably "quieter." The PRE is needed now where I seldom
used it before.

2) Turning RF gain to minimum quiets the rx but the S meter only advances to
S-5

3) I calibrated the S meter with PRE on and SMTR MD set to normal as Wayne
recommended. When I change the MD setting to ABS, the 50uv signal drops to
S-6 and cannot be adjusted up to S-9 with SMTR OF.

I would appreciate any help here. I'm tempted to go back redo
the RF gain calibration using the factory defaults option.

ab2tc

Re: RF gain calibration and S meter

Uh typo: Make it read "my S-meter is *now* dead on...."
<quote author="ab2tc">
Hi,

Go back and redo the calibration! Make sure to follow the instructions exactly and pay special attention to ensure you have test signal centered in the passband. This is critical since the instructions call for a 100Hz bandwidth. I had similar symptoms as you until I did this the 3rd time. 3 times makes perfect and my S-meter is not dead on at 1uV, S9 and S9+40,<snip
</quote>

Joe Planisky

Re: RF gain calibration and S meter

In reply to this post by Gary, W7TEA

I agree. Something is not right here.

I just tried the RF gain calibration (3 times) with the Mac K3
Utility. I followed the instructions presented by the program to the
letter. I then proceeded to do the S-meter calibration as specified
in the manual. Immediately after RF gain and S-meter calibration,
everything seemed fine. Sensitivity seemed normal, s-meter responded
to signals as expected, turning RF gain full CCW resulted in an s-
meter reading of S9+50.

After turning the rig off and back on, however, things are about like
W7TEA reports: sensitivity seems reduced, turning the RF gain fully
CCW gives an S-meter reading of S3, and a 50uV signal now gives an S5
reading (with preamp on.)

I borrowed a Windows computer and repeated the exercise. This time,
all was well even after a power cycle. It seems like the problem is
with the Mac version of the K3 Utility.

73
--
Joe KB8AP

On Oct 31, 2009, at 9:48 AM, W7TEA wrote:

>
> Just ran the RF gain calibration with the new Mac K3 Utility and an
> XG2. I
> did it
> a few times because I would get an ERR DSE error message when
> calibrating the SUB rx on occasion. I then went back and re-
> calibrated the
> S meter. I've noticed three things.
>
> 1) The rx seems considerably "quieter." The PRE is needed now where I
> seldom
> used it before.
>
> 2) Turning RF gain to minimum quiets the rx but the S meter only
> advances to
> S-5
>

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David Fleming-2

RF gain calibration (K3 Utility for Mac)

I believe I've discovered a subtle bug in the RF Gain calibration code that could possibly cause the problem you're describing. Please try this version and let me know if it solves the problem.

http://sight.net/K3/K3Util/10-27-2009/K3UtilityOSX.zip
(7.5MB)

tnx,

David, W4SMT

> I agree. Something is not right
> here.

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Gary, W7TEA

Re: RF gain calibration (K3 Utility for Mac)

Re-calibrated a couple more times with this version and all seems to
be working here as advertised!
No ERR returns with the SUB either.

Really appreciate the quick work, David!

73, Gary--W7TEA

On Nov 1, 2009, at 11:47 AM, David Fleming wrote:

> I believe I've discovered a subtle bug in the RF Gain calibration
> code that could possibly cause the problem you're describing. Please
> try this version and let me know if it solves the problem.
>
> http://sight.net/K3/K3Util/10-27-2009/K3UtilityOSX.zip
> (7.5MB)
>
> tnx,
>
> David, W4SMT
>
>> I agree. Something is not right
>> here.
>

73,

Gary W7TEA K3 #1001, #5763

rlindzen

Re: RF gain calibration (K3 Utility for Mac)

I've been having trouble calibrating with the Windows version, but
probably I'm doing something wrong. I have an XG-2 connected to the
receive antenna input. Does it really have to be connected to Antenna 1?

Dick, KA1SA

At 04:24 PM 11/1/2009, Gary Tuck wrote:

>Re-calibrated a couple more times with this version and all seems to
>be working here as advertised!
>No ERR returns with the SUB either.
>
>Really appreciate the quick work, David!
>
>73, Gary--W7TEA
>
>On Nov 1, 2009, at 11:47 AM, David Fleming wrote:
>
> > I believe I've discovered a subtle bug in the RF Gain calibration
> > code that could possibly cause the problem you're describing. Please
> > try this version and let me know if it solves the problem.
> >
> > http://sight.net/K3/K3Util/10-27-2009/K3UtilityOSX.zip
> > (7.5MB)
> >
> > tnx,
> >
> > David, W4SMT
> >
> >> I agree. Something is not right
> >> here.
> >
>
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>Elecraft mailing list
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==================================================
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Alfred P. Sloan Professor of Atmospheric
Sciences

Office: 54-1720, MIT
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1 (617) 253-2432 (voice)
1 (617) 253-6208 (fax)

Temporary Home: 100 Memorial Drive
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==================================================

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KK7P

Re: RF gain calibration (K3 Utility for Mac)

> I've been having trouble calibrating with the Windows version, but
> probably I'm doing something wrong. I have an XG-2 connected to the
> receive antenna input. Does it really have to be connected to Antenna 1?

Yes. The software was written that way because it is the only antenna
connection that is available on every variant of the radio. You must
use Antenna 1.

73,

Lyle KK7P

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rlindzen

Re: RF gain calibration (K3 Utility for Mac)

In reply to this post by David Fleming-2

Dear Lyle,

I've connected the XG-2 to Ant 1, and gone through the calibration
routine. I've turned off the preamp (and the attenuator), and used
the utility to calibrate. The s-meter still reads S7 for the XG-2,
though it rises to s8+ when I turn on the preamp. This also puzzles
me. When I first used the K3, I was under the impression that the
s-meter reading was independent of whether the preamp was on or
not. Have recent firmware changes alterred this? More likely, I'm
doing something wrong. Incidentally, how close to the stated
frequencies are the crystals in the XG-2?

73,

Dick
KA1SA

At 06:03 PM 11/1/2009, you wrote:

>>I've been having trouble calibrating with the Windows version, but
>>probably I'm doing something wrong. I have an XG-2 connected to
>>the receive antenna input. Does it really have to be connected to Antenna 1?
>
>Yes. The software was written that way because it is the only
>antenna connection that is available on every variant of the
>radio. You must use Antenna 1.
>
>73,
>
>Lyle KK7P

Don Wilhelm-4

Re: RF gain calibration (K3 Utility for Mac)

Dick,

The RF Gain calibration provided by K3 Utility is entirely different
than the S-meter calibration.
Do the S-meter calibration (see the manual) after running the RF Gain
calibration. The only commonality is that the XG2 (or other source of a
50 uV signal) is used for both.

If you want S-meter readings independent of the preamp and attenuator
settings, you must set CONFIG: SMTR MD to AbS - if set to 'nor', the
attenuator and preamp will change the S-meter response.

73,
Don W3FPR

Richard S. Lindzen wrote:

> Dear Lyle,
>
> I've connected the XG-2 to Ant 1, and gone through the calibration
> routine. I've turned off the preamp (and the attenuator), and used
> the utility to calibrate. The s-meter still reads S7 for the XG-2,
> though it rises to s8+ when I turn on the preamp. This also puzzles
> me. When I first used the K3, I was under the impression that the
> s-meter reading was independent of whether the preamp was on or
> not. Have recent firmware changes alterred this? More likely, I'm
> doing something wrong. Incidentally, how close to the stated
> frequencies are the crystals in the XG-2?
>
> 73,
>
> Dick
> KA1SA
>
> At 06:03 PM 11/1/2009, you wrote:
>
>>> I've been having trouble calibrating with the Windows version, but
>>> probably I'm doing something wrong. I have an XG-2 connected to
>>> the receive antenna input. Does it really have to be connected to Antenna 1?
>>>
>> Yes. The software was written that way because it is the only
>> antenna connection that is available on every variant of the
>> radio. You must use Antenna 1.
>>
>> 73,
>>
>> Lyle KK7P
>>
>
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