K3 / RF gain - S meter issue - Similar issue

[Elecraft mailing list]

More info.

Thanks to Brian, K3KO, some hints were given to check my particular
issue.  Thanks also to Bob, K4TAX.

Since I have no intention of opening my radio (as the radio does work
fine), I have discovered something of interest and a potential cause for
the symptom I'm seeing.

As I apply a high signal level into the radio, I reach a point where the
S-Meter behaves exactly like rotating the RF Gain control
counter-clockwise (the reading drops).  This is easily duplicated.

Brian noted that perhaps what I am seeing is being caused by the K3
Automatic Front-End Protection modification which my radio had its
modification years ago.  The mod protection works as designed while
injecting a high signal level into the K3, and I do see where the preamp
(if engaged) is disabled.  Furthermore, I see HI SIG displayed in the K3
VFO-B area.

Interestingly, my symptom happens at the same "signal level" the S-Meter
reacts to with preamp disengagement, but without an injected signal just
by rotating counter-clockwise the RF Gain control.  I do not, however,
see the HI SIG level notification during this test and it matters not if
the preamp is engaged or disengaged.  That said, the resultant S-Meter
reading that had been "dropped" does follow both attenuation and preamp
values.

Brian might be on to something!

Again, no intention of pursuing further unless Elecraft can duplicate
and create a mod.

73 and thanks for the BW,
Dan



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  [Elecraft] K3 / RF gain - S meter issue - Similar issue

*Bob McGraw K4TAX* rmcgraw at blomand.net
<mailto:elecraft%40mailman.qth.net?Subject=Re%3A%20%5BElecraft%5D%20K3%20/%20RF%20gain%20-%20S%20meter%20issue%20-%20Similar%20issue&In-Reply-To=%3Cf76213ce-61de-69fb-f4c5-3b0dc10f7db8%40blomand.net%3E>

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My concern would be "does the S meter indicate correctly?"

Thus with 50 uV applied to the antenna input it should read S-9, and
with 0.78 uV applied it should read S-3, and with 5000 uV applied it
should read S-9 +40 dB.    I've checked my K3S at these and other values
and I'm confident that the S meter is accurate. Hence, I'm confident I
can give accurate signal reports.  Thus unlike many radios and their S
meters, they are only good for a rather unscientific and largely
inaccurate signal report, somewhat like a SWAG.

73

Bob, K4TAX


On 12/14/2017 10:16 AM, Dan Atchison via Elecraft wrote:
>/I have a similar - but different! - issue on one of my Elecraft's. />//>/I own both a K3 and a K3s.  Both are configured equally with the K3 />/having been upgraded to the highest level to achieve near K3s />/equivalency. />//>/My K3s RF Gain control works exactly as expected, i.e. as the control />/is rotated counter-clockwise the "S-Meter" increases to a point at />/almost full scale. />//>/On the K3, however, as the RF Gain control is rotated />/counter-clockwise and the "S-Meter" increases to about the "40-over" />/point at the control's 10 o'clock position the "S-Meter" then />/inexplicably drops to the "S9" position where it remains for the />/remainder of the RF gain control counter-clockwise rotation. This />/shouldn't be but like N1LN's issue, the radio does otherwise perform />/correctly.  I have done everything that N1LN has done including the RF />/Gain calibration using a signal generator. />//>/Very strange, indeed. />//>/Dan -- N3ND />//>/************************************* />//>/Date: Wed, 13 Dec 2017 16:25:20 -0500 />/From: "Bruce Meier"<bemeier at bellsouth.net
<http://mailman.qth.net/mailman/listinfo/elecraft>> />/To:<elecraft at mailman.qth.net
<http://mailman.qth.net/mailman/listinfo/elecraft>> />/Subject: [Elecraft] K3 / RF gain - S meter issue />//>//>/Looking for suggestions here from someone that might have experienced />/this />/same issue - - />//>//>//>/I have (2) K3 units (not the S model) that are acting different when />/the RF />/gain adjustments are turned fully counter clockwise. />//>/?  Unit one ? s/n 1062: When the RF gain is decreased to full counter />/clockwise position the S-Meter registers full scale (60db over S9) as />/expected. />//>/?  Unit two ? s/n 1193:  When the RF gain is decreased to full counter />/clockwise position the S-Meter registers only S8. />//>/  Facts: />//>/?  With the exception of the S-Meter readings with RF gain settings, both />/units are working fine />//>/?  Both units have ?almost? all mods installed.  If not all, they are at />/least both the same. />//>/?  Both units are running the same version of microcode (5.54) (2.88) />/(2.88) />/(1.26) />//>/?  Both units seem to register very close actual RF gain of stations when />/connected when tested on the same antenna />//>/?  Both units have the new synthesizers. />//>/?  Both units have second RX />//>/?  In both cases (both units) I can hear the audio level decreasing />/linearly />/as expected as the RF gain is turned counter clockwise />//>/I have tried to initialize the K3 and reload the firmware resulting in no />/change to the RF gain / S-Meter readings. />//>//>//>/Elecraft Tech Support suggested: />//>/?  Calibrating the s-meter ? did nothing />//>/?  Next suggestion ? send the rig to California. />//>//>//>/Anyone have this issue and fixed it?? />//>//>//>/73, />//>/Bruce N1LN /

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