Re: [Elecraft] K2: Control Board Strangeness; Low AGC threshold
Tim, I had a similar problem with my K2. I was not able to get the full 3.8 volts with the pot cranked all the way over. Search 'Low AGC threshold" on the e-mail list archive for more info. I was getting full brightness on the LCD display. I'm certinally no expert, but sound like yuo may have a bad connection somewhere. When you bet the better DVM, check the input voltage to the 8v regulator. It should be same as the voltage at your power supply. Good luck, and 73, Mike, W8ENG - Original Message - From: "Tim Cailloux" <[EMAIL PROTECTED]> To: Sent: Monday, November 29, 2004 10:28 AM Subject: [Elecraft] K2: Control Board Strangeness > My Christmas project of the K2 build got started early (s/n 4539). > > Here are the two problems I have right now: > > * Display LCD (i.e. text readout) is very dim. It's almost impossible > to read with the backlight off. Everything displays as normal, but > just very dim text. (The LED backlight comes right on and is great.) > > * When adjusting the pot on the control board (R1) for 3.80V per the > alignment procedure during the checkout of the control board and > display board, the most I can get is 3.6V. > > The measured and reported supply voltage is 14.7-14.8V and the current > draw varies between 80 and 100 mA. > > Yes, I've checked the solder joints. First item I looked at. I was > using a pretty bad DMM (since I started the build much sooner than I > planned, I didn't have everything with me) but I *think* the > resistance checks were all normal (I'm stealing a better DMM from work > this weekend). > > Thanks in advance, > > tim > > -- > Tim Cailloux > [EMAIL PROTECTED] > W4EGT > ___ > 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] Re: K2 AGC Threshold.
Geoff, I think I'm all set for now, and the work is progressing nicely. I would be interested in hearing Elecrafts thoughts on the AGC circuit, and what you thought the problem was. Thanks again for the help. Mike, W8ENG - Original Message - From: "Geoffrey Mackenzie-Kennedy" <[EMAIL PROTECTED]> To: "Mike, W8ENG" <[EMAIL PROTECTED]> Cc: "Elecraft Discussion List" Sent: Thursday, November 18, 2004 4:51 PM Subject: K2 AGC Threshold. > Mike, > > Just to let you know that I have received a very positive response from > Elecraft about the K2's AGC Threshold setting problem.. > > Your DMM appears to be fine, and I hope that the info I sent you solves your > problem. Would appreciate hearing when you have time. > > 73, > > GeoffGM4ESD > > ___ 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] troubles with kits
Herb: Congratulations on getting you license. I'm in the middle of building a K2 and having a great time with it. If you watch the e-mail reflector, there are not really that many problems being posted. Most of the messages (excluding the net schedules, for sale and contest items) are responses to questions. I've posted one queston here, and received two responsed within 2 hours, and several more over ths next two days. So far I have no regets about the K2 decision. That siad you may want to consider starting with a simpler kit. There are a lot of others available. Small Wonders Labs http://www.smallwonderlabs.com/ makes several nice kits for under $100.00 I built one of thier kits as practice for the K2. TenTec http://www.tentec.com/ also has kits, including a 2-meter transcevier that you could use immediatly. When you are ready to upgrade to General and looking for a HF radio the K2 is one of the best available, and the support is excellent. Any way, good luck with what ever you decide, and welcome again to Ham radio. 73 Mike, W8ENG Original Message - From: <[EMAIL PROTECTED]> To: Sent: Thursday, November 18, 2004 11:48 AM Subject: [Elecraft] troubles with kits I am Herb Winn a new ham (kc8ylj). I was going to try to build a kit for my first rig but am not sure now. I found the elecraft web and have noticed that all that is posted is troubles with kits. Is this common ? if so i'm not going to try a kit. Thanks73 Herb ___ 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] Low voltage on AGC threshold
John, My DMM is a $30 Radio Shack unit. I do not have anything handy to calibrate or check the accuracy. It does report DC voiltage to 2 decimal points, but I doubt that it is that accurate. Any way, for now I'm proceeding with construction. Mike, W8ENG - Original Message - From: "John R. Lonigro" <[EMAIL PROTECTED]> To: "Mike, W8ENG" <[EMAIL PROTECTED]> Cc: Sent: Tuesday, November 16, 2004 10:29 PM Subject: Re: [Elecraft] Low voltage on AGC threshold > Mike: > > How accurate is your DMM? The 8v and 5v regulators should still produce > 8 and 5 volts even with a slightly low supply voltage. Also, if the > K2's internal voltmeter reads the same as your DMM, that tells me your > DMM is reading low because there is a diode in the K2 power line which > will make the K2 internal voltmeter read LESS than an accurate external > DMM. Only if the external DMM reads low would the two voltmeters agree. > > Try to check your voltages with a different DMM. My guess is your > problem is NOT low voltage all around. Good luck. > > 73's > > John AA0VE > > Mike, W8ENG wrote: > > >This is an update to my earlier post. I touched up a solder joint and > >reassembled the radio. The voltage on pin 5 of U2 was still 3.78 volts, > >with the RF gain set fully clockwise. The input voltage from my power > >supply was 12.4 volts, both on my DMM and on the K2's internal voltmeter. > >The voltage out on the 8v regulator was 7.8,a nd on the 5v regulator was > >4.9. > > > >I'm thinking that the problem may be low voltage all around. I don't have a > >better power supply to check with at a higher voltage. > > > >Any addational help or comments would be appreciated. > > > >73, Mike, W8ENG > > > > > ___ 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] Low voltage on AGC threshold
This is an update to my earlier post. I touched up a solder joint and reassembled the radio. The voltage on pin 5 of U2 was still 3.78 volts, with the RF gain set fully clockwise. The input voltage from my power supply was 12.4 volts, both on my DMM and on the K2's internal voltmeter. The voltage out on the 8v regulator was 7.8,a nd on the 5v regulator was 4.9. I'm thinking that the problem may be low voltage all around. I don't have a better power supply to check with at a higher voltage. Any addational help or comments would be appreciated. 73, Mike, W8ENG - Original Message ----- From: "Mike, W8ENG" <[EMAIL PROTECTED]> To: "W3FPR - Don Wilhelm" <[EMAIL PROTECTED]>; Sent: Monday, November 15, 2004 8:23 PM Subject: Re: [Elecraft] Low voltage on AGC threshold > Don, Thanks for the fast reply. > > I did have the FR gain fully CW during the test. Anyway, I just checked > (for the third time) the solder joints on the control board. Pin 4 on RP6 > may have had a cold joint. I touched it up, and will re-assemble and > recheck the votltage. > > 73 > > Mike, W8EMG > > ----- Original Message - > From: "W3FPR - Don Wilhelm" <[EMAIL PROTECTED]> > To: "Mike, W8ENG" <[EMAIL PROTECTED]>; > Sent: Monday, November 15, 2004 7:34 PM > Subject: Re: [Elecraft] Low voltage on AGC threshold > > > > Mike, > > > > Since your adjustment range is on the 'edge of the cliff', it would be a > > good idea to identify what is causing it before it bites you later on. > > Check all the components for proper values and check solder connections > very > > carefully to determine why you are running out of adjustment range. Look > at > > the schematic to determine which components are connected to the AGC > > threshold pot circuits and check them all with a careful eye, then check > > again and when you have finished, check it once more - these things are > > difficult to spot even with careful inspection (I know, I've been there, > > done that many many times). > > > > 3.78 volts may be fine for the AGC Threshold adjustment - I often > (usually) > > find that the proper AGC threshold is between 3.6 and 3.8 volts. > > > > Just as an afterthought - you do have the RF gain control full clockwise > do > > you not? It will alter the reading on the AGC threshold measurement > point. > > > > 73, > > Don W3FPR > > > > - Original Message - > > > > When setting the AGC threshold I was not able to get 3.8 volts on pin 5 of > > U2 as described in the manual. The voltage varied from 2.60 to 3.78 when > > adjusting R1 to the extreme settings. Is this close enough or should I > have > > more room for adjustment? > > > > I have a faily good DMM, and it compares very closely to the K2 internal > > meter, and when checking values on 1% tolerance resisters. All other > checks > > to date have been fine. > > > > > > > > > > ___ > 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] Low voltage on AGC threshold
Don, Thanks for the fast reply. I did have the FR gain fully CW during the test. Anyway, I just checked (for the third time) the solder joints on the control board. Pin 4 on RP6 may have had a cold joint. I touched it up, and will re-assemble and recheck the votltage. 73 Mike, W8EMG - Original Message - From: "W3FPR - Don Wilhelm" <[EMAIL PROTECTED]> To: "Mike, W8ENG" <[EMAIL PROTECTED]>; Sent: Monday, November 15, 2004 7:34 PM Subject: Re: [Elecraft] Low voltage on AGC threshold > Mike, > > Since your adjustment range is on the 'edge of the cliff', it would be a > good idea to identify what is causing it before it bites you later on. > Check all the components for proper values and check solder connections very > carefully to determine why you are running out of adjustment range. Look at > the schematic to determine which components are connected to the AGC > threshold pot circuits and check them all with a careful eye, then check > again and when you have finished, check it once more - these things are > difficult to spot even with careful inspection (I know, I've been there, > done that many many times). > > 3.78 volts may be fine for the AGC Threshold adjustment - I often (usually) > find that the proper AGC threshold is between 3.6 and 3.8 volts. > > Just as an afterthought - you do have the RF gain control full clockwise do > you not? It will alter the reading on the AGC threshold measurement point. > > 73, > Don W3FPR > > - Original Message - > > When setting the AGC threshold I was not able to get 3.8 volts on pin 5 of > U2 as described in the manual. The voltage varied from 2.60 to 3.78 when > adjusting R1 to the extreme settings. Is this close enough or should I have > more room for adjustment? > > I have a faily good DMM, and it compares very closely to the K2 internal > meter, and when checking values on 1% tolerance resisters. All other checks > to date have been fine. > > > > ___ 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] Low voltage on AGC threshold
Greetings All, I'm building K2 SN 4245. When setting the AGC threshold I was not able to get 3.8 volts on pin 5 of U2 as described in the manual. The voltage varied from 2.60 to 3.78 when adjusting R1 to the extreme settings. Is this close enough or should I have more room for adjustment? I have a faily good DMM, and it compares very closely to the K2 internal meter, and when checking values on 1% tolerance resisters. All other checks to date have been fine. Thanks and 73, Mike, W8ENG ___ 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
