RF gain sweet spot
Locked
12
12
 
|
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 this side by side to see if it was better.. and keep the best one.......as I am very happy now......
Ed K7WIA |
|
|
In reply to this post by Don Wilhelm-4
FWIW: K3 #642 does it too. I never mess with the RF gain so I never
noticed it before. Full gain on mine is at 5 o'clock. S-meter drops until 4 o'clock, then starts climbing. What I do NOT notice is an improved S/N on a very weak signal from my service monitor at the S-meter minimum. Signal goes down too. Not sure, but my "thinker" thinks I expected that. Fred K6DGW Auburn CA On 7/21/2011 3:40 PM, Don Wilhelm wrote: > Ed, > Ed, I no longer doubt your report - but I do find it a bit strange. > > 73, > Don W3FPR ______________________________________________________________ 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 |
|
|
In reply to this post by KD7PY
Don.....<<<<<<<<<< LEAVE IT ALONE I LIKE IT THIS WAY>>>>>>>>>>
Ed K7WIA |
|
|
In reply to this post by KD7PY
* 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 have to compare another K3 that did not do > this side by side to see if it was better.. and keep the best one.......as I > am very happy now...... It would be a nice effect, but I don't see this on the low bands although I just tried it on 15m. What I see is the S meter level remaining constant until the RF Gain is reduced to the point that the bars begin to rise above the band noise. What I am going to try is setting the RF gain just at the point before the bar advance pas the band noise. As I have my S meter set for absolute, I am seeing about an S9 level on the meter from the noise. I can reduce the RF gain until the next bar is displayed and then back down just to where it goes out and the noise level from the speaker is greatly reduced. I will see how things work on a net in a few minutes. I don't see a visible dip, though. I am at MCU 4.36, FPF 1.14, and DSP1 3.73, on K3 S/N 4762. 73, de Nate N0NB -- "The optimist proclaims that we live in the best of all possible worlds. The pessimist fears this is true." Ham radio, Linux, bikes, and more: http://www.n0nb.us ______________________________________________________________ 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 |
|
|
In reply to this post by KD7PY
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 ______________________________________________________________ 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 |
|
|
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 my problem. Have done a diagram showing the before/after behaviour (SCN ADC value versus RF gain knob angle) but since this reflector does not allow attachments I can't publish it here. 73, Markus |
Re: RF gain sweet spot
|
|
In reply to this post by KD7PY
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 switching from a wide bandwidth roofer to a narrow bandwidth roofer? On another reflector there has been some discussion about "pileup mush" which has been reported by only a small number of K3 owners, which problem IMHO could well be caused by some roofers and the termination presented to their output. Your observations of a "sweet spot" *might* be related. 73, Geoff GM4ESD (who must leave the List tomorrow!) On July 21, 2011 at 22:52 Z, Ed K7WIA wrote: >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 it to 2 bars on the > meter. > could be I got a special K3.. > > Ed K7WIA ______________________________________________________________ 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 |
|
|
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 |
|
|
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 over one of the various digitally multiplexed communication busses. It could be a non-linearity in the potentiometer, where on a normal K3, the "sweet" spot would be a point in the gain setting where the absolute unchanging difference between signal and noise is interpreted most favorably by the ear/brain which has its own way of hearing. That trick has been around for a long time. 73, Guy. On Fri, Jul 22, 2011 at 11:17 AM, K7WIA <[hidden email]> wrote: > 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 > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/RF-gain-sweet-spot-tp6604787p6610829.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > 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 |
|
|
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 I reduce the gain to where the ant. noise gets close to -136 dbm ( the noise floor of the K3) that is where I can detect the weak ones the best. It is just that my ears and brain seam to be more sensitive when the audio is soft than when it is loud, as when there is a lot of noise with the signal. it is just that I reduce the ant. noise close to the noise floor of the K3, the signals are still there and they stand out better for me... it's just that I started to use the old trick that been around for years, and noticed the S meter did not follow the gain control. Ed K7WIA |
|
|
In reply to this post by Guy, K2AV
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 fast you will never see it. I also find thats about where I run my RF gain almost 99 percent of the time, Its not the dip that means anything at all, its where you run the RF gain that is what works. With this many K3 exhibiting the same thing its not the gain pot, its something in firmware, which as far as I can tell does nothing at all other than its the same place approx where its a good spot to run the RF gain. Merv K9FD/KH6 > 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 over one of the various digitally multiplexed > communication busses. > > It could be a non-linearity in the potentiometer, where on a normal > K3, the "sweet" spot would be a point in the gain setting where the > absolute unchanging difference between signal and noise is interpreted > most favorably by the ear/brain which has its own way of hearing. That > trick has been around for a long time. > > 73, Guy. > > On Fri, Jul 22, 2011 at 11:17 AM, K7WIA<[hidden email]> wrote: > >> 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 >> >> -- >> View this message in context: http://elecraft.365791.n2.nabble.com/RF-gain-sweet-spot-tp6604787p6610829.html >> Sent from the Elecraft mailing list archive at Nabble.com. >> ______________________________________________________________ >> 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 > > ______________________________________________________________ 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 |
|
|
In reply to this post by KD7PY
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 |
«
Return to [K3]
|
1 view|%1 views
| Free forum by Nabble | Edit this page |