Re: [Elecraft] K2 AGC Off Problem
Thanks for the message. A 10 pf at C8 did the trick. The receiver is now working properly in AGC off mode. Think that's at least 5 or 6 of us on the reflector have had this issue, and this easy fix, so far. Does it deserve a builder alert on the website yet? For anyone else: If you are seeing AGC problems (hold PRE/ATT and AGC, see if your K2 goes deaf), check your junk box for a 10pF cap and change control board C8. Wayne says 680 pF at C7 may be another option. I DO NOT recommend this mod UNLESS you're seeing AGC OFF issues though. -- Nosey Nick Waterman, G7RZQ, K2 #5209. use Std::Disclaimer;[EMAIL PROTECTED] Know what I hate most? Rhetorical questions. -- Henry N. Camp ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K2 AGC Off Problem
If in some cases the value of C8 has to be reduced OR the value of C7 has to be increased ( as Wayne suggests ) for proper operation of the 5.068 MHz oscillator, it would seem that the original capacitor values result in too much feedback in the oscillator. This could be a batch problem where some crystals have a higher Q than the norm OR the oscillator part of the NE602 (U1) has higher gain than the norm, or both. IMHO changing the value of either C8 or C7 sounds like a good fix, and any small change in frequency that results does not matter. If it is a batch problem I would think that it would affect a small group of K2s (by serial number) if Elecraft use the crystals / NE602s soon after delivery. Whether or not the problem deserves a Builder Alert should be suggested by a more experienced Elecrafter than I. 73, Geoff GM4ESD - Original Message - From: Nick Waterman [EMAIL PROTECTED] To: elecraft@mailman.qth.net; [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Sent: Sunday, May 21, 2006 9:36 AM Subject: Re: [Elecraft] K2 AGC Off Problem Thanks for the message. A 10 pf at C8 did the trick. The receiver is now working properly in AGC off mode. Think that's at least 5 or 6 of us on the reflector have had this issue, and this easy fix, so far. Does it deserve a builder alert on the website yet? For anyone else: If you are seeing AGC problems (hold PRE/ATT and AGC, see if your K2 goes deaf), check your junk box for a 10pF cap and change control board C8. Wayne says 680 pF at C7 may be another option. I DO NOT recommend this mod UNLESS you're seeing AGC OFF issues though. -- Nosey Nick Waterman, G7RZQ, K2 #5209. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K2 AGC Off Problem
Hi Darrell: Your report is very similar to what I experienced. From an earlier email 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 I installed a 10pf cap at C8 and it worked. I'm sure someone else did the same thing with success. Good luck. 73, Ken K3IU -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Darrell Bellerive Sent: Saturday, May 20, 2006 5:37 PM To: elecraft@mailman.qth.net Subject: [Elecraft] K2 AGC Off Problem Just finished alignment and test, part II of K2 #5093. All seems to be working as it should, except for the AGC off function. This problems appears to be the same as a few others have had, the cause of which was a bad 5.068 MHz crystal (X1). Perhaps I have the same problem. When the AGC is turned off the S-meter pegs at 40 over and the receiver is muted. The AGC threshold at pin 5 of U2 measures 3.8 volts whether AGC is on or off. The voltage at pin 1 of U2 goes from 3.8 volts with the AGC on to 5.4 volts with the AGC off. All components in the AGC circuit have been inspected again for correct values and placement. All solder joints have been reheated. I cannot measure the 5.068 MHz oscillator with my frequency counter (MFJ-259) at pin 6 or 7 of U1. Perhaps this counter loads down the circuit too much for it to oscillate? Listening with a portable shortwave receiver (5 kHz steps) finds a weak carrier at 5.070 that goes on and off with the power on the K2. Before I email Elecraft support, what else should I check? Darrell VA7TO ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K2 AGC Off Problem
Ken, Thanks for the message. A 10 pf at C8 did the trick. The receiver is now working properly in AGC off mode. What are the implications of this substitution? Does changing C8 from 39 pf to 10 pf cause any other problems? Since I robbed the 10 pf from it's future spot in the 10 meter low pass filter, a replacement part is needed in any case. Is it better to replace X1, and go back to the original 39 pf capacitor, or should I just get another 10 pf for the low pass filter and leave the 10 pf at C8? Darrell On May 20, 2006 04:16 pm, Ken K3IU wrote: Hi Darrell: Your report is very similar to what I experienced. From an earlier email 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 I installed a 10pf cap at C8 and it worked. I'm sure someone else did the same thing with success. Good luck. 73, Ken K3IU -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Darrell Bellerive Sent: Saturday, May 20, 2006 5:37 PM To: elecraft@mailman.qth.net Subject: [Elecraft] K2 AGC Off Problem Just finished alignment and test, part II of K2 #5093. All seems to be working as it should, except for the AGC off function. This problems appears to be the same as a few others have had, the cause of which was a bad 5.068 MHz crystal (X1). Perhaps I have the same problem. When the AGC is turned off the S-meter pegs at 40 over and the receiver is muted. The AGC threshold at pin 5 of U2 measures 3.8 volts whether AGC is on or off. The voltage at pin 1 of U2 goes from 3.8 volts with the AGC on to 5.4 volts with the AGC off. All components in the AGC circuit have been inspected again for correct values and placement. All solder joints have been reheated. I cannot measure the 5.068 MHz oscillator with my frequency counter (MFJ-259) at pin 6 or 7 of U1. Perhaps this counter loads down the circuit too much for it to oscillate? Listening with a portable shortwave receiver (5 kHz steps) finds a weak carrier at 5.070 that goes on and off with the power on the K2. Before I email Elecraft support, what else should I check? Darrell VA7TO ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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 -- Darrell Bellerive Amateur Radio Stations VA7TO and VE7CLA Grand Forks, British Columbia, Canada ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K2 AGC Off Problem
No. Changing that cap only affects the heterodyne oscillator for the AGC and nothing else. As long as the oscillator comes on and off on command (AGC On and Off work properly) you're FB. Ron AC7AC -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Darrell Bellerive Sent: Saturday, May 20, 2006 5:50 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K2 AGC Off Problem Ken, Thanks for the message. A 10 pf at C8 did the trick. The receiver is now working properly in AGC off mode. What are the implications of this substitution? Does changing C8 from 39 pf to 10 pf cause any other problems? Since I robbed the 10 pf from it's future spot in the 10 meter low pass filter, a replacement part is needed in any case. Is it better to replace X1, and go back to the original 39 pf capacitor, or should I just get another 10 pf for the low pass filter and leave the 10 pf at C8? Darrell ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K2 AGC off problem
Dr. Werner Furlan wrote: I should have posted this before... I found a related message when searching the archive. The reply was: -- Sounds exactly like the problem I had with 5196. The problem was fixed by replacing X1 on the Control Board. You will probably find that CtrlBd-U2-1 goes to about 6 volts when you turn the AGC OFF virtually shitting down the IF amplifier. I encourage you to communicate with Gary ([EMAIL PROTECTED]) regarding this problem. Yesterday, someone reported a similar problem with a close serial number(s/n5219). -- My serial # is 5203, so maybe I am also affected by this failure? Damn, mine too. #5209. Hold PRE/ATT and AGC, it says OFF, all bars light and the K2 goes deaf. Hold them again, it says On, the bars come down, and stuff can be heard again. I've not had a chance to measure Ctrl-U2-1. Doing WHAT to the IF amp? Nice typo! :-) -- Nosey Nick Waterman, G7RZQ, K2 #5209. use Std::Disclaimer;[EMAIL PROTECTED] Having control over myself is almost as good as having control over others. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K2 AGC off problem
hi Nick, Nick Waterman schrieb am 23 Mar 2006 um 9:19: Doing WHAT to the IF amp? Nice typo! :-) well, I should have read the quote before pasting it - anyway, we are probably having the same problem and it shouldn't be a great deal to exchange a Quartz. I wrote a message to support and am awaiting their advice. 73! de Werner OE9FWV -- Das Problem mit den alten Leuten wird nicht weniger obwohl so viele sterben. Aber es wachsen immer neue nach. 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: Elecraft@mailman.qth.net 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
RE: [Elecraft] K2 AGC off problem
I corrected the typo in an email to the reflector shortly after re-reading what I had sent. u is right next to I on my keyboard g 73, Ken K3IU -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Nick Waterman Sent: Thursday, March 23, 2006 4:20 AM To: [EMAIL PROTECTED]; Elecraft support Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] K2 AGC off problem Dr. Werner Furlan wrote: I should have posted this before... I found a related message when searching the archive. The reply was: -- Sounds exactly like the problem I had with 5196. The problem was fixed by replacing X1 on the Control Board. You will probably find that CtrlBd-U2-1 goes to about 6 volts when you turn the AGC OFF virtually shitting down the IF amplifier. I encourage you to communicate with Gary ([EMAIL PROTECTED]) regarding this problem. Yesterday, someone reported a similar problem with a close serial number(s/n5219). -- My serial # is 5203, so maybe I am also affected by this failure? Damn, mine too. #5209. Hold PRE/ATT and AGC, it says OFF, all bars light and the K2 goes deaf. Hold them again, it says On, the bars come down, and stuff can be heard again. I've not had a chance to measure Ctrl-U2-1. Doing WHAT to the IF amp? Nice typo! :-) -- Nosey Nick Waterman, G7RZQ, K2 #5209. use Std::Disclaimer;[EMAIL PROTECTED] Having control over myself is almost as good as having control over others. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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
Re: [Elecraft] K2 AGC off problem
Joe, I have the same problem with my AGC and when I replaced the 5.068MHz X1 the problem remained. I wonder if both crystals are bad or if there is some other cause? In my case, when I turn off the AGC, the s-meter gets pegged at +40 and the audio is muted. Did you change any other components or did just replacing X1 the first time fix the problem? Also, what value of RP6 is installed on your control board? My RP6 is a 4.7K network. Thanks. Jeff (K2#5210) -Original Message- From: jo benoit Sent: 3/8/2006 8:27:20 AM To: Elecraft@mailman.qth.net Subject: Re: [Elecraft] K2 AGC off problem hi elecrafters, I received a new 5.068 Mhz Xtal and replaced the X1 on the control board. The Audio is not muted any more when I turn the AGC off. Thank you Ken K3IU, Bill WU0R, and Gary, Scott and Brian at Elecraft service/parts. 73 de ON5AO K2#5237 joe __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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
RE: [Elecraft] K2 AGC off problem
Hi Joe: Sounds exactly like the problem I had with 5196. The problem was fixed by replacing X1 on the Control Board. You will probably find that CtrlBd-U2-1 goes to about 6 volts when you turn the AGC OFF virtually shitting down the IF amplifier. I encourage you to communicate with Gary ([EMAIL PROTECTED]) regarding this problem. Yesterday, someone reported a similar problem with a close serial number(s/n5219). 73, Ken K3IU -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of jo benoit Sent: Monday, February 27, 2006 12:00 PM To: elecraft mailman qth Subject: [Elecraft] K2 AGC off problem Hi Elecrafters, When I turn the AGC to off pushing pre/att and agc together, the display reads off, but the audio mutes and s-meter goes to maximum . I reheated the solderings on U1 C10 and D2. Voltage on U1 pin 2 is 1.44V when agc slow or fast and 0.52V when agc is off The other side of D2 , the /AGC OFF signal is 5.0V when agc slow or fast and 0.004V when agc is off. Anyone an idea ? joe on5ao K2#5237 __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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
RE: [Elecraft] K2 AGC off problem
Obviously, I meant shutting down :-(. Also, Joe, I should mention that you should check and double check component placement and value as well as check all solder joints. 73, Ken K3IU -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ken K3IU Sent: Monday, February 27, 2006 1:40 PM To: 'jo benoit'; 'elecraft mailman qth' Subject: RE: [Elecraft] K2 AGC off problem Hi Joe: Sounds exactly like the problem I had with 5196. The problem was fixed by replacing X1 on the Control Board. You will probably find that CtrlBd-U2-1 goes to about 6 volts when you turn the AGC OFF virtually shitting down the IF amplifier. I encourage you to communicate with Gary ([EMAIL PROTECTED]) regarding this problem. Yesterday, someone reported a similar problem with a close serial number(s/n5219). 73, Ken K3IU -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of jo benoit Sent: Monday, February 27, 2006 12:00 PM To: elecraft mailman qth Subject: [Elecraft] K2 AGC off problem Hi Elecrafters, When I turn the AGC to off pushing pre/att and agc together, the display reads off, but the audio mutes and s-meter goes to maximum . I reheated the solderings on U1 C10 and D2. Voltage on U1 pin 2 is 1.44V when agc slow or fast and 0.52V when agc is off The other side of D2 , the /AGC OFF signal is 5.0V when agc slow or fast and 0.004V when agc is off. Anyone an idea ? joe on5ao K2#5237 __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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
