Re: [Elecraft] K2 BFO Test fails
Today I ordered a new L33 and X3/X4, will write as soon as they arrived ... At this point: thank you Don for your indefatigable help! Benny -- View this message in context: http://elecraft.365791.n2.nabble.com/BFO-Test-fails-tp584p5807300.html Sent from the [K2] mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
Benny, R116 is supposed to be a very high value resistor - in fact, it would be best if it were actually an insulator, but 5.1 megohms is sufficiently high to serve that purpose. The only reason the resistor is provided is that it produces both a mounting anchor for L33 and its leads provide a place to solder the fine wires. It sounds like you have a bad L33 or one end that is not actually soldered. Make certain the tinned part of the very fine wire is actually soldered to the lead of R116. If it is well soldered, request a replacement L33 from parts(at)elecraft(dot)com. 73, Don W3FPR On 12/4/2010 8:03 PM, kruegerbenny wrote: Hi, grounding of L33 doesn't bring the expected signal (7.xMHz). D37 seems to be mounted the right way (round caps in direction to front panel). If I put a resistor parallel to R116(it should be the right one: grn-brw-grn-(gold)), i get the 4.9MHz oscillation, but still no signal at TP2 (in this case, i get the following frequencies by contacting the int. probe to U11-P7: 4918.75 and 4916.12). __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
So, hello again. First of all i want to excuse but I give you some false informations. The 8.x MHz signal I measured was/is at Pin 7, not Pin 6 of U11. I did the test with grounding L33/X3/X4 and there's some interesting behaviour (at Pin 7): When I ground L33/X3/X4, the measured signal is about 7.7MHz. By removing the jumper(to ground), the frequency changes to 4.9MHz. After that, I changed the order of instructions: Now I connect the probe at P7(U11) and then ground L33/X3/X4. The result: Before grounding 8.02MHz, after grounding 4.9MHz (also when I remove the jumper) Benny -- View this message in context: http://elecraft.365791.n2.nabble.com/BFO-Test-fails-tp584p5803602.html Sent from the [K2] mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
Benny, Actually you should have a better signal at U11 pin 6 than you do at pin 7, but let that go for right now (we may get back to it if necessary). So you do get the proper BFO frequency when grounding the crystals, and as I recall you measured a low resistance across L33, so it should have continuity - all that should be good. Now, monitor the oscillation at U11 pin 6 (or pin 7) while you ground the side of L33 that is NOT connected to X4 and X5. Ignore any oscillation other than the 4.9 kHz because that is what you are looking for. If you get a 4.9 kHz oscillation with the low end of L33 connected to ground, then check the value of C172 - it should be 0.01 uF (marked 103). Also verify again that D37 is mounted the right way 'round. If you cannot get a 4.9 kHz oscillation with the lower end of L33 grounded, inspect the soldering of those fine wires to the leads of the 1/8 watt resistor very carefully - and make sure what you used for that high value 1/8 watt resistor was the correct item. It is a very high value resistor, and is actually used as an effective insulator across L33 to both solder the fine wire leads and secure L33. If you used anything else, that could cause your problems. 73, Don W3FPR On 12/4/2010 1:47 PM, kruegerbenny wrote: So, hello again. First of all i want to excuse but I give you some false informations. The 8.x MHz signal I measured was/is at Pin 7, not Pin 6 of U11. I did the test with grounding L33/X3/X4 and there's some interesting behaviour (at Pin 7): When I ground L33/X3/X4, the measured signal is about 7.7MHz. By removing the jumper(to ground), the frequency changes to 4.9MHz. After that, I changed the order of instructions: Now I connect the probe at P7(U11) and then ground L33/X3/X4. The result: Before grounding 8.02MHz, after grounding 4.9MHz (also when I remove the jumper) Benny __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
Hi, grounding of L33 doesn't bring the expected signal (7.xMHz). D37 seems to be mounted the right way (round caps in direction to front panel). If I put a resistor parallel to R116(it should be the right one: grn-brw-grn-(gold)), i get the 4.9MHz oscillation, but still no signal at TP2 (in this case, i get the following frequencies by contacting the int. probe to U11-P7: 4918.75 and 4916.12). -- View this message in context: http://elecraft.365791.n2.nabble.com/BFO-Test-fails-tp584p5804260.html Sent from the [K2] mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
Benny, Thanks for providing your name, and very good luck on acquiring your amateur license. I am also adding K2 to the subject - some here like to filter by rig type. OK, first the frequency is wrong, are you certain you have the time scale on your 'scope calibrated? The K2 BFO crystals should be marked for 4915 kHz (or something near that) - check those markings first. Then check continuity through L33 with your ohmmeter - it is best checked from the top of the board which will check for improperly soldered connections too. If the resistance is quite high, you may have an open L33 or an improper solder connection. Also check D37 to be certain it is not installed backwards - that could kill the BFO signal. Check for a solder bridge at pins 3, 4, 5 and 6 of RP6 - that also will kill the signal. 73, Don W3FPR On 12/3/2010 4:50 PM, kruegerbenny wrote: Q24: 5,76V L33(left): 8,33MHz(240mV peak-to-peak) L33(right): no signal (i think here is the lost) I have to admit that I don't have a call sign yet, but I'm already learning for the exam (I'm a student a had a lot to do the the last months..) Thanks for your help Benny __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
crystal values checked - ok continuity of L33 checked - ok D37 is correctly installed and I resoldered all pins of RP6 any other ideas? (how can I check if the crystals are ok?) -- View this message in context: http://elecraft.365791.n2.nabble.com/BFO-Test-fails-tp584p5801952.html Sent from the [K2] mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
Benny,
Well, if all that is OK, then it should work unless there is a problem
with Q24. Check the value of C169 as well as C173 and C174.
It is particularly worrysome that you are seeing something around 8 MHz
at pin 6 of U11. Please tell us how you are measuring that frequency
('scope or frequency counter).
If indeed you are getting an 8 MHz signal, you may have bad crystals at
X3 and X4, but that would be quite unusual.
There is not an easy method of checking the crystals.
You may want to beg parts(at) elecraft(dot)com for replacement BFO
crystals and a replacement L33.
Please include your name on all posts to this reflector.
73,
Don W3FPR
On 12/3/2010 7:03 PM, kruegerbenny wrote:
crystal values checked - ok
continuity of L33 checked - ok
D37 is correctly installed
and I resoldered all pins of RP6
any other ideas?
(how can I check if the crystals are ok?)
__
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Re: [Elecraft] K2 BFO Test fails
Benny, Additional thoughts - check D38 for correct orientation. Try putting a jumper from the junction on L33, X3 and X4 to see if you get oscillation at 4915 kHz or something close to that frequency - if you do, the crystals are OK and your problem is with L33, D37, C169 or Q24. 73, Don W3FPR On 12/3/2010 7:03 PM, kruegerbenny wrote: crystal values checked - ok continuity of L33 checked - ok D37 is correctly installed and I resoldered all pins of RP6 any other ideas? (how can I check if the crystals are ok?) __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
I will do the tests tomorrow, but one question: A jumper from junction of l33,x3 and x4 to where? Benny -- View this message in context: http://elecraft.365791.n2.nabble.com/BFO-Test-fails-tp584p5802044.html Sent from the [K2] mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K2 BFO Test fails
Benny, To ground. 73, Don W3FPR On 12/3/2010 8:15 PM, kruegerbenny wrote: I will do the tests tomorrow, but one question: A jumper from junction of l33,x3 and x4 to where? Benny __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
