K2 RF Gain control
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I have a K2 with almost all of the add-ons (everything but DSP - and the
100 watt amplifier has just been added) and all elecraft mods that has functioned well for over a year - but I recently noticed that the RF gain control doesn't change signal levels coming out of the speaker. The control has been left at max until I played with it recently, and I was surprised to notice that its only function seems to be changing the number of illuminated LEDs in the S-meter. I tried it with various AF gain control levels and with the AGC both active and turned off - no difference. Before I get into massive troubleshooting, is it possible over time and changing various internal settings several times I have misadjusted something? I get signals on the bands. Bob Greenwalt K6VZT _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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FYI,
Robert I just replace the RF control when I did the SMD Indicator mod. The RF control started to act like a squelch whenever I touched it or bumped it when turning the dial. Had to leave it in it's wide position. After replacing it, things are back to normal. take care -- 73 Fernando N2FQ/NNNØJYM San Jose, CA <http://pages.sbcglobal.net/n2fq> _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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http://webpages.charter.net/peanut/ Didn't have much time to work on the webpage...thus, I just added them to one that was sitting on my hard drive, hi. Anyway, this will give you the basic idea... A quarter inch hole in the middle of the back panel, down about an inch from the top edge... 73 John K7FD _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Robert Greenwalt
Bob,
If the RF gain control changes the number of LEDs on the S-meter reading, it is functioning properly. Now, with that said, yes you MAY have the AGC Threshold set incorrectly. As long as AGC action is present, the audio level should be more or less constant - that is its proper function. When the AGC threshold is set too low (higher voltage on U2 pin 5, the K2 will produce more AGC voltage it should and will de-sensitize the receiver even with no signal. The proper fine adjust setting for the AGC Threshold is just at the level where the K2 internal noise does not activate the AGC - you can test that condition by switching from AGC on to AGC off on a quiet band or with no antenna connected. If the noise rises with AGC off, the AGC Threshold is set too high. I commonly find the correct setting will yield a voltage at U2 pin 5 of 3.6 to 3.8 volts. If you have a high noise level at your QTH, the noise alone may be activating the AGC and cause the conditions you describe. 73, Don W3FPR ----- Original Message ----- >I have a K2 with almost all of the add-ons (everything but DSP - and the > 100 watt amplifier has just been added) and all elecraft mods that has > functioned well for over a year - but I recently noticed that the RF > gain control doesn't change signal levels coming out of the speaker. > The control has been left at max until I played with it recently, and I > was surprised to notice that its only function seems to be changing the > number of illuminated LEDs in the S-meter. I tried it with various AF > gain control levels and with the AGC both active and turned off - no > difference. Before I get into massive troubleshooting, is it possible > over time and changing various internal settings several times I have > misadjusted something? I get signals on the bands. > > Bob Greenwalt > K6VZT _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Robert Greenwalt
Hi Bob,
Sounds normal and very much like my K2. The RF gain in the K2 is really an IF gain with the front end RF gain set at a constant level and only affected by switching in the preamp or the attenuator. I have an old JRC receiver where the RF gain works the same as the K2 in that the effect as the RF gain is turned down is the lower level signals fall below the threshold as the S meter rises and are effectively suppressed. This is a useful effect to give arm chair copy of stronger signals and minimises the amount of noise between syllables. Bob, G3VVT _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Robert Greenwalt
Hello Bob,
I have noticed on my K2, that if I adjust the AGC threshold such that the background noise level *truly* doesn't change when turning the AGC on and off, then the RF gain control when turned completely ccw, does not sufficiently reduce the level of very strong stations. I have to adjust the AGC threshold such that there is at least some AGC action, and then the RF gain control does actually reduce volume level when turned ccw. When trying to copy weak signals, I prefer to operate with the AGC off, the AF Gain advanced, and I use the RF Gain control to control the signal level. This seems to give me the best signal-to-noise ratio. So, in order to have enough range of adjustment with the RF Gain control, I adjust the AGC threshold until the RF Gain, when adjusted fully ccw, sufficiently attenuates the largest signals. That seems to be the best compromise. I make no claim that this is the 'correct' way to adjust the AGC threshold. It's just a method that I've found works best for the way I prefer to operate. What's nice about the K2, is that we *can* perform these kinds of optimizations. 73, Dale WA8SRA Robert Greenwalt wrote: >... I recently noticed that the RF >gain control doesn't change signal levels coming out of the speaker. >The control has been left at max until I played with it recently, and I >was surprised to notice that its only function seems to be changing the >number of illuminated LEDs in the S-meter. I tried it with various AF >gain control levels and with the AGC both active and turned off - no >difference. ... >Bob Greenwalt >K6VZT > > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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On Thu, 20 Jan 2005 10:11:38 -0500, Dale Boresz wrote:
> Hello Bob, > > I have noticed on my K2, that if I adjust the AGC threshold such that > the background noise level *truly* doesn't change when turning the AGC > on and off, then the RF gain control when turned completely ccw, does > not sufficiently reduce the level of very strong stations. > > I have to adjust the AGC threshold such that there is at least some AGC > action, and then the RF gain control does actually reduce volume level > when turned ccw. > > When trying to copy weak signals, I prefer to operate with the AGC off, > the AF Gain advanced, and I use the RF Gain control to control the > signal level. This seems to give me the best signal-to-noise ratio. So, > in order to have enough range of adjustment with the RF Gain control, I > adjust the AGC threshold until the RF Gain, when adjusted fully ccw, > sufficiently attenuates the largest signals. That seems to be the best > compromise. > > I make no claim that this is the 'correct' way to adjust the AGC > threshold. It's just a method that I've found works best for the way I > prefer to operate. What's nice about the K2, is that we *can* perform > these kinds of optimizations. > > 73, Dale WA8SRA > or off. I tend to use the RF ATT - better from the point of overload, IMD's etc. The RF gain control on my FT1000MP can reduce S9+60 signals to zero. 73 Stewart G3RXQ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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