I'm guessing this effect is an artifact of the AGC parameters and
the level of ambient noise. I would love to see a chart of AGC
level, K3 gain, and RFG bias voltage.
I see a flat zone between RFG at maximum and at 3-o'clock position
when I either have no preamps activated and when I activate
Hi Ed..I just did a check using the XG3. tap the disp button to display
AFV
I do not see a drop in voltage untill I turn the RF knob to about the 3:00
o'clock position.
so it seams that untill the RF knob gets to there, there is no gain
reduction untill we get past that point.
and at
Had the same problem in October 2010: RF gain tracking error between main and
sub RX.
Lyle then sent me a beta K3 Utility which performs the RF gain calibration
at 2 different power levels (-73 dBm and -33 dBm). Of course you need an RF
source capable of providing these power levels. This solved
Ed,
If you switch between different roofing filters, does the sweet spot occur
at the same position of the RF Gain control knob or does it change? Also
does the noise / S meter dip by the same amount regardless of which filter
is in use, if not does the depth of dip increase or decrease when
Geoff... my K3 only has the one filter in it at the present time, so I can't
check that out for you.
Ed K7WIA
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It is possible that there is a problem in the RF gain pot. It IS a
potentiometer. It has a standard voltage across it, and the variable
voltage in the pot's wipe is sent to an analog to digital converter,
which converts the pot setting to numerical advice which can be more
easily sent to the CPU
No I don't believe there is a problem with the pot. because as I just start
to turn it the gain reduces smoothly all the way. I believe it could be in
the software, where as when the gain is reduced the ckt. that controls the
bars in the S meter does not kick in soon enough.
but it seams when
: Thu, 21 Jul 2011 13:00:27 -0700 (PDT)
From: K7WIA emoss98...@msn.com
Subject: Re: [Elecraft] RF gain sweet spot
To: elecraft@mailman.qth.net
Message-ID: 1311278427206-6608306.p...@n2.nabble.com
Content-Type: text/plain; charset=us-ascii
Yes I am using the K3
I was using the preamp that is in the K3
Was interested in this thread and find that my K3 does the same thing,
but takes a
vernier touch to see it, very slight movement of the pot at about
the 2:30 to 3 oclock
position causes the S meter to dip down about 1 bar. Never noticed
it because
of the very small area, one passes by so
This would be a nice feature to have put into the menu.
to set the manual gain to max. then go into the menu and be able to adjust
the maximum gain to the way you like it.
Ed K7WIA
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K7WIA's experience with his 6m receiver got me to try this with my
K3. I have an ARR P50VDG preamp installed and see typically S4
flickering up to S5 for noise connected either 6m yagi. Reducing
RFGain immediately increases s-meter reading with the ARR preamp so I
switched it off. Noise is
Ed,
I suspect he was not using a K3 because he said the S-meter did reduce
when the RF Gain was reduced.
You could turn off the K3 preamp and turn on the attenuator and see if
that drops the ambient noise level. With your external preamp, I
suspect you can reduce the K3 gain substantially.
. Cole kl...@acsalaska.net
Subject: Re: [Elecraft] RF gain sweet spot
To: Elecraft@mailman.qth.net
Date: Thursday, July 21, 2011, 11:13 AM
K7WIA's experience with his 6m receiver got me to try this with my
K3. I have an ARR P50VDG preamp installed and see typically S4
flickering up to S5
Yes I am using the K3
I was using the preamp that is in the K3,I also have the ARR P50VD
preamp on the back of the K3 but using it just raises the background noise
to S7.
Remember I live in the city. I can turn off the preamp that is in the K3,
disconnect the antenna listen to the hiss of the
Ed,
When one reduces the RF Gain on the K3, the S-meter indication increases.
So how are you accomplishing this S-meter dip?
I do not doubt your results, but perhaps your description of the S-meter
deflection has been misunderstood.
73,
Don W3FPR
On 7/21/2011 4:00 PM, K7WIA wrote:
Yes I am
Ok we did the RF calibration per the K3 utility program using the XG3 for the
signal source and I see no change with the way the S meter responds, being
I use the K3 for 6 meters only I set the S meter calibration for that band
using the XG3 this is how my S meter is set up in the Confg. menu.
Don, when the RF gain is fully cw ( max ) I have 3 bars on the S Meter,
when I slowly reduce the RF gain control I watch the S Meter and when I get
it just past the 9 o'clock position the S Meter will reduce to only 1 bar
showing. you can hear the background noise drop as you do this, then I
oops this should be reduce to the 3 o'clock posistion,,,sorry
Ed K7WIA
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Don, when the RF gain is fully cw ( max ) I have 3 bars
on the S Meter,
when I slowly reduce the RF gain control I watch the S Meter
and when I get
it just past the 9 o'clock position the S Meter will reduce
to only 1 bar
showing.
???
As I gradually reduce the RF gain on my K3,
Ed,
Something is strange. It may be your ambient noise level, so try it
with the K3 connected to a dummy load (or just no antenna).
Normally, as the RF gain is reduced, the S-meter indication will
increase. Apparently your K3 is doing something different.
At a 9 o'clock position, my K3
I don't know but I like it this way, as my noise floor changes through the
day I do have to readjust the sweet spot, but it is just a very small turn
of the RF knob
I checked this with the noise blanker on and off and I see the same effect,
it's just with the blanker off I can only reduce
Well when i disconect the antenna I have no bars on the S meter, a 2 inch
piece of wire at the ant port gave me 1 bar on the S meter and I can still
dip the meter,,
THIS ALL HAPPENS AT THE 3 O'CLOCK POSITIONNOT AT 9'CLOCK MY ERROR
Ed K7WIA
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OK I just did a test using the XG3 set at the 1uv 50uv level and I can dip
the S meter. it dips the signal level of the XG3 shown on the S meter...
Ed K7WIA
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...@msn.com
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] RF gain sweet spot
OK I just did a test using the XG3 set at the 1uv 50uv level and I can dip
the S meter. it dips the signal level of the XG3 shown on the S meter...
Ed K7WIA
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I seem to recall that somebody demonstrate a similar artifact in the RF
gain control to Elecraft at Dayton. Anybody recall just what that demo was?
73 de Brian/K3KO
On 7/21/2011 21:37, Don Wilhelm wrote:
Ed,
Something is strange. It may be your ambient noise level, so try it
with the K3
The RF pot in the K3 is a encoder, not a carbon pot found in old tube radios
used as a volume control.
Ed K7WIA
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Ed,
Ok, I have just confirmed your experience (but I cannot explain it). If
I tune to a band where the noise level is S-3 and I reduce the RF Gain a
bit (to the 2:30 or 3 o'clock position), the S-meter reading will
reduce, but if I reduce the RF Gain more CCW, the S-meter reading will
OH! Well, my non tube type K2 has a carbon pot.
Date: Thu, 21 Jul 2011 15:34:01 -0700
From: emoss98...@msn.com
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] RF gain sweet spot
The RF pot in the K3 is a encoder, not a carbon pot found in old tube radios
used as a volume control
I don't know if this is a software glitch or not. but if it's in the
software I would sure like to keep this feature as it has given me a edge on
weak sig, just being able to have a set point for the gain just right for
the band conditions. I would have to compare another K3 that did not do
Don. LEAVE IT ALONE I LIKE IT THIS WAY
Ed K7WIA
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__
Elecraft
* On 2011 21 Jul 17:48 -0500, K7WIA wrote:
I don't know if this is a software glitch or not. but if it's in the
software I would sure like to keep this feature as it has given me a edge on
weak sig, just being able to have a set point for the gain just right for
the band conditions. I would
No, the RF Gain control is one-half of a dual potentiometer, see the
K3 Front Panel schematic,
page 5 of 7 Front Panel - Miscellaneous.
Bob NW8L
The RF pot in the K3 is a encoder, not a carbon pot found in old tube radios
used as a volume control.
Ed K7WIA
I found something interesting when I was working the CQ VHF contest this last
weekend.
I live in the city in which my noise level stays around S3.
while searching for weak signals, I started to reduce the rf gain. as I
reduced the gain I watched the S meter go down and as I contuned to reduce
it
Dave,
By setting the RF Gain as you did, you have maximized the dynamic range
of your receiver.
The lowest level signals that you will be able to hear (and understand)
will be at your local noise level - there is no sense (to me at least)
to use more than the amount of gain that will give you
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