RE: RE: [Elecraft] K2 BFO Test
Don B. Thanks for that information - it adds credibility to that method along with a good dose of common sense. Don W. W3FPR -Original Message- Hi Don and All I have used this method on 3 or 4 of the K2's I have built. I use a 1pF or 2pF NPO cap to lower the bottom end of the range to get it to meet the spec. I agree with you on pulling the crystal much with this method. I would not recommend cap values above maybe 3 or 4 pF. I have never needed more than 1 pf. Padding C173 and C174 is a better method if the radio needs more than 1 or 2 pf. I believe this method was suggested by Gary at Elecraft some time back. At any rate it is a little easier to do than the padding or change out of C174 and C173 The other Don Don Brown KD5NDB - Original Message - From: Don Wilhelm [EMAIL PROTECTED] To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; elecraft@mailman.qth.net Sent: Thursday, December 08, 2005 5:03 PM Subject: RE: RE: [Elecraft] K2 BFO Test Sverre, I have not tried that small capacitor from the junction of the crystals and L33 so I cannot comment on it from that standpoint. What I would like to state is that when one pulls a crystal by any method, the stability becomes worse as the amount of pulling becomes greater. One should be aware of this and related facts when modifying any circuit in a way that is not 'approved and tested'. Also due to the nature of crystals, something that happens to work in one situation may not work the same for all cases. Remember that I am only bringing up cautions here, I am not makeing a firm statement about the operation one way or another. It certainly would be nice if someone (or better yet, several someones) with access to suitable instrumentation could try this or any other mod and report the results. The fact that it worked on a sample of one does not create a statement that it will work in other cases - that is simple statistical knowledge - I would like to see something that says it works in at least 5 or 10 trials before drawing any firm conclusions. So, yes I think it should be left on your website, but you may want to put a Use at your own peril disclaimer on all those that are not 'approved by Elecraft' or otherwise adequately tested (and I invite you to add any of my mods to that group as well, even though I have absolute confidence in my own work). 73, Don W3FPR -Original Message- The preferred method of padding the BFO capacitors is to maintain the ratio between C173 and C174 by paralleling them with capacitors. A single capacitor from the junction to ground will be in parallel with the series combination of C173 and the varactor D38 and could make the BFO less stable than it should be. Don, How about a single capacitor (1-4 pF) from the junction of the crystals and the L33 inductor as in http://www.ac6rm.net/mailarchive/html/elecraft-list/2005-08/msg00562.html? Does that create potential stability problems also? I've got this link on my K2 mods page and just wanted to make sure I can recommend it and keep it there. I have never had any problems with BFO range myself so I have no personal experience with this myself. 73 Sverre LA3ZA http://www.qslnet.de/la3za/ ___ 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 -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.13.13/197 - Release Date: 12/9/2005 ___ 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: RE: [Elecraft] K2 BFO Test
Hi Don and All I have used this method on 3 or 4 of the K2's I have built. I use a 1pF or 2pF NPO cap to lower the bottom end of the range to get it to meet the spec. I agree with you on pulling the crystal much with this method. I would not recommend cap values above maybe 3 or 4 pF. I have never needed more than 1 pf. Padding C173 and C174 is a better method if the radio needs more than 1 or 2 pf. I believe this method was suggested by Gary at Elecraft some time back. At any rate it is a little easier to do than the padding or change out of C174 and C173 The other Don Don Brown KD5NDB - Original Message - From: Don Wilhelm [EMAIL PROTECTED] To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; elecraft@mailman.qth.net Sent: Thursday, December 08, 2005 5:03 PM Subject: RE: RE: [Elecraft] K2 BFO Test Sverre, I have not tried that small capacitor from the junction of the crystals and L33 so I cannot comment on it from that standpoint. What I would like to state is that when one pulls a crystal by any method, the stability becomes worse as the amount of pulling becomes greater. One should be aware of this and related facts when modifying any circuit in a way that is not 'approved and tested'. Also due to the nature of crystals, something that happens to work in one situation may not work the same for all cases. Remember that I am only bringing up cautions here, I am not makeing a firm statement about the operation one way or another. It certainly would be nice if someone (or better yet, several someones) with access to suitable instrumentation could try this or any other mod and report the results. The fact that it worked on a sample of one does not create a statement that it will work in other cases - that is simple statistical knowledge - I would like to see something that says it works in at least 5 or 10 trials before drawing any firm conclusions. So, yes I think it should be left on your website, but you may want to put a Use at your own peril disclaimer on all those that are not 'approved by Elecraft' or otherwise adequately tested (and I invite you to add any of my mods to that group as well, even though I have absolute confidence in my own work). 73, Don W3FPR -Original Message- The preferred method of padding the BFO capacitors is to maintain the ratio between C173 and C174 by paralleling them with capacitors. A single capacitor from the junction to ground will be in parallel with the series combination of C173 and the varactor D38 and could make the BFO less stable than it should be. Don, How about a single capacitor (1-4 pF) from the junction of the crystals and the L33 inductor as in http://www.ac6rm.net/mailarchive/html/elecraft-list/2005-08/msg00562.html? Does that create potential stability problems also? I've got this link on my K2 mods page and just wanted to make sure I can recommend it and keep it there. I have never had any problems with BFO range myself so I have no personal experience with this myself. 73 Sverre LA3ZA http://www.qslnet.de/la3za/ ___ 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: RE: [Elecraft] K2 BFO Test
-Original Message- The preferred method of padding the BFO capacitors is to maintain the ratio between C173 and C174 by paralleling them with capacitors. A single capacitor from the junction to ground will be in parallel with the series combination of C173 and the varactor D38 and could make the BFO less stable than it should be. Don, How about a single capacitor (1-4 pF) from the junction of the crystals and the L33 inductor as in http://www.ac6rm.net/mailarchive/html/elecraft-list/2005-08/msg00562.html? Does that create potential stability problems also? I've got this link on my K2 mods page and just wanted to make sure I can recommend it and keep it there. I have never had any problems with BFO range myself so I have no personal experience with this myself. 73 Sverre LA3ZA http://www.qslnet.de/la3za/ ___ 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: RE: [Elecraft] K2 BFO Test
Sverre: This fix (that you describe) worked for me on a K2 that I built within the past year. The LOW BFO freq was just slightly high and putting a low value cap as you describe lowered the LOW freq to within specs, didn't change the high BFO freq, and did not cause any instability. I don't remember the exact value cap I used and the K2 is no longer here for me to look at. 73, Ken K3IU -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Sverre Holm Sent: Thursday, December 08, 2005 4:07 PM To: [EMAIL PROTECTED]; elecraft@mailman.qth.net Subject: RE: RE: [Elecraft] K2 BFO Test -Original Message- The preferred method of padding the BFO capacitors is to maintain the ratio between C173 and C174 by paralleling them with capacitors. A single capacitor from the junction to ground will be in parallel with the series combination of C173 and the varactor D38 and could make the BFO less stable than it should be. Don, How about a single capacitor (1-4 pF) from the junction of the crystals and the L33 inductor as in http://www.ac6rm.net/mailarchive/html/elecraft-list/2005-08/msg00562.html? Does that create potential stability problems also? I've got this link on my K2 mods page and just wanted to make sure I can recommend it and keep it there. I have never had any problems with BFO range myself so I have no personal experience with this myself. 73 Sverre LA3ZA http://www.qslnet.de/la3za/ ___ 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: RE: [Elecraft] K2 BFO Test
Sverre, I have not tried that small capacitor from the junction of the crystals and L33 so I cannot comment on it from that standpoint. What I would like to state is that when one pulls a crystal by any method, the stability becomes worse as the amount of pulling becomes greater. One should be aware of this and related facts when modifying any circuit in a way that is not 'approved and tested'. Also due to the nature of crystals, something that happens to work in one situation may not work the same for all cases. Remember that I am only bringing up cautions here, I am not makeing a firm statement about the operation one way or another. It certainly would be nice if someone (or better yet, several someones) with access to suitable instrumentation could try this or any other mod and report the results. The fact that it worked on a sample of one does not create a statement that it will work in other cases - that is simple statistical knowledge - I would like to see something that says it works in at least 5 or 10 trials before drawing any firm conclusions. So, yes I think it should be left on your website, but you may want to put a Use at your own peril disclaimer on all those that are not 'approved by Elecraft' or otherwise adequately tested (and I invite you to add any of my mods to that group as well, even though I have absolute confidence in my own work). 73, Don W3FPR -Original Message- The preferred method of padding the BFO capacitors is to maintain the ratio between C173 and C174 by paralleling them with capacitors. A single capacitor from the junction to ground will be in parallel with the series combination of C173 and the varactor D38 and could make the BFO less stable than it should be. Don, How about a single capacitor (1-4 pF) from the junction of the crystals and the L33 inductor as in http://www.ac6rm.net/mailarchive/html/elecraft-list/2005-08/msg00562.html? Does that create potential stability problems also? I've got this link on my K2 mods page and just wanted to make sure I can recommend it and keep it there. I have never had any problems with BFO range myself so I have no personal experience with this myself. 73 Sverre LA3ZA http://www.qslnet.de/la3za/ ___ 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: RE: [Elecraft] K2 BFO Test
All the components look right. I guess I've got the dreaded high Q crystals. I've noticed in the Elecraft archives that it is possible to put a capacitor at the junction of X3/X4 to ground. Which is the preferred method? Thanks. From: Don Wilhelm [EMAIL PROTECTED] Date: 2005/12/07 Wed AM 09:30:04 PST To: [EMAIL PROTECTED], elecraft@mailman.qth.net Subject: RE: [Elecraft] K2 BFO Test Ted, Yes, you should get the BFO range and frequency correct - you can continue with no extra effort, but it must be resolved eventually, and there is no time like the present to do it. Check the values of the capacitors C173 and C174, and while you are at it, check C169 too. Additionally, check the varactors D37 and D38 for the correct type (1SV149 - the smaller ones) qne proper orientation. Be certain the BFO crystals were the ones you soldered in - they are typically marked ECS D4.91 -S If you find all the above correct, you may have to pad Capacitors C173 and 174. Should that become necessary, use 47 pf in parallel with C174 and 120 pf in parallel with C173. The padder capacitors will lower the low frequency end more than the high frequency end of the range, so it should work for you - but do the padding only if there is nothing else wrong with the components. 73, Don W3FPR -Original Message- I am in the process of testing the BFO on page 62. Everything tested fine up to this point but now I can not get the proper BFO range. The BFO high frequency is 4917.56 and the BFO low frequency is 4914.26. This provides a BFO range of 3.2 kHz. It appears that I can not the the BFO low frequency below 4912.7 as specified in the manual. I checked L33 to make sure R116 is not shorting any turns. Should I troubleshoot this problem before proceding? If so where else should I look. Thanks. Ted K6OI ___ 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: RE: [Elecraft] K2 BFO Test
The preferred method of padding the BFO capacitors is to maintain the ratio between C173 and C174 by paralleling them with capacitors. A single capacitor from the junction to ground will be in parallel with the series combination of C173 and the varactor D38 and could make the BFO less stable than it should be. You are welcome to try the single capacitor solution, but do beware of the pitfalls. If you would like further documentation on padding the BFO, download the K2 AtoB instructions and look at the 2nd column of page 12. 73, Don W3FPR -Original Message- All the components look right. I guess I've got the dreaded high Q crystals. I've noticed in the Elecraft archives that it is possible to put a capacitor at the junction of X3/X4 to ground. Which is the preferred method? Thanks. From: Don Wilhelm [EMAIL PROTECTED] Date: 2005/12/07 Wed AM 09:30:04 PST To: [EMAIL PROTECTED], elecraft@mailman.qth.net Subject: RE: [Elecraft] K2 BFO Test Ted, Yes, you should get the BFO range and frequency correct - you can continue with no extra effort, but it must be resolved eventually, and there is no time like the present to do it. Check the values of the capacitors C173 and C174, and while you are at it, check C169 too. Additionally, check the varactors D37 and D38 for the correct type (1SV149 - the smaller ones) qne proper orientation. Be certain the BFO crystals were the ones you soldered in - they are typically marked ECS D4.91 -S If you find all the above correct, you may have to pad Capacitors C173 and 174. Should that become necessary, use 47 pf in parallel with C174 and 120 pf in parallel with C173. The padder capacitors will lower the low frequency end more than the high frequency end of the range, so it should work for you - but do the padding only if there is nothing else wrong with the components. 73, Don W3FPR ___ 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: RE: [Elecraft] K2 BFO Test
I just added the pad capacitors to c174 and c173. It helped but not enough. The high freq. is now 4917.37 and low is 4913.92 for a range of 3.45 kHz. Is it possible to get new crystals from Elecraft if indeed I do have the ones with the higher Q? Thanks From: Don Wilhelm [EMAIL PROTECTED] Date: 2005/12/07 Wed PM 01:31:31 PST To: [EMAIL PROTECTED], elecraft@mailman.qth.net Subject: RE: RE: [Elecraft] K2 BFO Test The preferred method of padding the BFO capacitors is to maintain the ratio between C173 and C174 by paralleling them with capacitors. A single capacitor from the junction to ground will be in parallel with the series combination of C173 and the varactor D38 and could make the BFO less stable than it should be. You are welcome to try the single capacitor solution, but do beware of the pitfalls. If you would like further documentation on padding the BFO, download the K2 AtoB instructions and look at the 2nd column of page 12. 73, Don W3FPR -Original Message- All the components look right. I guess I've got the dreaded high Q crystals. I've noticed in the Elecraft archives that it is possible to put a capacitor at the junction of X3/X4 to ground. Which is the preferred method? Thanks. From: Don Wilhelm [EMAIL PROTECTED] Date: 2005/12/07 Wed AM 09:30:04 PST To: [EMAIL PROTECTED], elecraft@mailman.qth.net Subject: RE: [Elecraft] K2 BFO Test Ted, Yes, you should get the BFO range and frequency correct - you can continue with no extra effort, but it must be resolved eventually, and there is no time like the present to do it. Check the values of the capacitors C173 and C174, and while you are at it, check C169 too. Additionally, check the varactors D37 and D38 for the correct type (1SV149 - the smaller ones) qne proper orientation. Be certain the BFO crystals were the ones you soldered in - they are typically marked ECS D4.91 -S If you find all the above correct, you may have to pad Capacitors C173 and 174. Should that become necessary, use 47 pf in parallel with C174 and 120 pf in parallel with C173. The padder capacitors will lower the low frequency end more than the high frequency end of the range, so it should work for you - but do the padding only if there is nothing else wrong with the components. 73, Don W3FPR ___ 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
