AGC off problem solved
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I can report a success with my problem I reported yesterday.
I changed C8 to 10 pF and now AGC off works as expected. Thanks to Gary, Wayne and everybody on the list for their support. Its great how this group works together. > Wayne suggested this too: > > "The simplest cure for this may be a different capacitor in the > oscillator that makes it too inefficient at reduced bias to even start. > > You might try 10 pF at C8 or 680 pF at C7 73! de Werner OE9FWV -- f u cn rd ths, u cn gt a gd jb n cmptr prgmmng Email powered by Pegasus Mail free at <http://www.pmail.com> Homepage: <http://www.qsl.net/oe9fwv/> Fone +43 5522 75013 Fax +43 820 555 85 2621 Mobile +43 664 6340014 Elecraft K2 #5203 _______________________________________________ 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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Dr. Werner Furlan wrote:
> I can report a success with my problem I reported yesterday. > I changed C8 to 10 pF and now AGC off works as expected. Yay! Me too! Much easier than sending off to Elecraft for a new X1. When I tune the RWM pips with fast AGC, it properly goes "pip sssSSSHH pip sssSSSHH pip sssSSSHH", and more importantly, when I turn the AGC OFF, the rig doesn't go deaf. The S-Meter looks a whole lot more believable too, the rig feels a whole lot more sensitive, and now I can turn AGC off, I can confirm that my N-GEN really does work after all! That was a very worthwhile 3 minutes at the iron. :-) > Thanks to Gary, Wayne and everybody on the list for their support. > Its great how this group works together. Seconded, and thanks to Werner! Anyone else with a serial number in the high 5100s or low 5200s... If you are seeing AGC problems (hold PRE/ATT and AGC, see if you go deaf), check your junk box for a 10pF cap and change control board C8. Wayne says 680 pF at C7 may be another option. -- "Nosey" Nick Waterman, G7RZQ, K2 #5209. use Std::Disclaimer; [hidden email] Design: The activity of preparing for a design review. _______________________________________________ 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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I was perhaps the first one to encounter this "AGC Off" problem and
ultimately changed X1 to solve the problem. Nosey's comment below re the improved S-meter action caused me to try something. I am currently realigning and tweaking K2 5044 that I built last August and remembered that there had been (and still is) a lot of "weirdness" in the S meter action. Very difficult to get it set correctly; anyway, I decided to replace Ctrl-C8 with a 10 pf cap to see what difference it made. Well, it made all the difference in the world. Now very easy to set the AGC threshold level, S meter Low, and S meter High. I checked it with the 50 mV from XG-1 and it is about S9 + a wee bit with Pre and Att OFF. It reacts sanely and appropriately. Nice! 73, Ken K3IU -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Nick Waterman Sent: Sunday, March 26, 2006 11:54 AM To: [hidden email] Cc: [hidden email]; [hidden email]; [hidden email] Subject: Re: [Elecraft] AGC off problem solved Dr. Werner Furlan wrote: > I can report a success with my problem I reported yesterday. > I changed C8 to 10 pF and now AGC off works as expected. Yay! Me too! Much easier than sending off to Elecraft for a new X1. When I tune the RWM pips with fast AGC, it properly goes "pip sssSSSHH pip sssSSSHH pip sssSSSHH", and more importantly, when I turn the AGC OFF, the rig doesn't go deaf. The S-Meter looks a whole lot more believable too, the rig feels a whole lot more sensitive, and now I can turn AGC off, I can confirm that my N-GEN really does work after all! _______________________________________________ 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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No, no, Ken. That was just the subject line of the email thread. The
ORIGINAL problem occurred when turning the AGC OFF, the AGC voltage to the S meter and IF amp went high causing the IF amp to shut down. In the K2, the S meter is a visual representation of the level of the AGC voltage being sent back to the IF amplifier in the presence of strong signals. The stronger the signal, the higher the voltage sent back to control the gain of the IF amp. The S-meter gets set with the AGC turned ON. If you have set your AGC threshold level, S meter Lo, and S meter High settings per the instructions and are happy with the action you see, then you probably don't have a problem to solve. 73, Ken K3IU -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Ken K3IU Sent: Sunday, March 26, 2006 12:58 PM To: 'Nick Waterman' Cc: [hidden email] Subject: RE: [Elecraft] AGC off problem solved I was perhaps the first one to encounter this "AGC Off" problem and ultimately changed X1 to solve the problem. Nosey's comment below re the improved S-meter action caused me to try something. I am currently realigning and tweaking K2 5044 that I built last August and remembered that there had been (and still is) a lot of "weirdness" in the S meter action. Very difficult to get it set correctly; anyway, I decided to replace Ctrl-C8 with a 10 pf cap to see what difference it made. Well, it made all the difference in the world. Now very easy to set the AGC threshold level, S meter Low, and S meter High. I checked it with the 50 mV from XG-1 and it is about S9 + a wee bit with Pre and Att OFF. It reacts sanely and appropriately. Nice! 73, Ken K3IU -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Nick Waterman Sent: Sunday, March 26, 2006 11:54 AM To: [hidden email] Cc: [hidden email]; [hidden email]; [hidden email] Subject: Re: [Elecraft] AGC off problem solved Dr. Werner Furlan wrote: > I can report a success with my problem I reported yesterday. > I changed C8 to 10 pF and now AGC off works as expected. Yay! Me too! Much easier than sending off to Elecraft for a new X1. When I tune the RWM pips with fast AGC, it properly goes "pip sssSSSHH pip sssSSSHH pip sssSSSHH", and more importantly, when I turn the AGC OFF, the rig doesn't go deaf. The S-Meter looks a whole lot more believable too, the rig feels a whole lot more sensitive, and now I can turn AGC off, I can confirm that my N-GEN really does work after all! _______________________________________________ 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 _______________________________________________ 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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