KPA100 R12 Voltage query
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Hi there,
I have just got around to building the KPA100 (to Appendix G - Rev. C-5) for my K2 (53 * * ), and I have got to the voltage test on R12, on page 47 of the manual, where it asks to verify that the voltage is within the 100 -110VDC range. Upon performing this check, mine can only manage 91V, Is this OK or do I have a problem?. 73, Les M0BSI _______________________________________________ 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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Les,
It may or may not be a problem. You should turn to the DC voltage chart and measure the DC voltage on each of diodes D1 thru D8. If all of the voltages are roughly 10% low, it is not a problem, but if you have a bad diode, or one of them oriented the wrong way, the variation will be much more than 10%. 73, Don W3FPR > -----Original Message----- > > I have just got around to building the KPA100 (to Appendix G - > Rev. C-5) for > my K2 (53 * * ), and I have got to the voltage test on R12, on page 47 of > the manual, where it asks to verify that the voltage is within the > 100 -110VDC range. Upon performing this check, mine can only > manage 91V, Is > this OK or do I have a problem?. > > 73, > Les M0BSI > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 268.18.3/700 - Release Date: 2/24/2007 8:14 PM _______________________________________________ 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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In reply to this post by Les Preston
Don
Just re-checked the voltage in-between R11, R12 and the cathode of D1 - all OK (same readings). RFC5 side of R12 with Power set at 5 watts gives:- RX TX 144.1V 143.9V At >11 watts:- RX TX 123.7V 92.1V One thing that I did come across during the build was, the value of R4 had been changed to 39K, to reduce the stress on certain components, and I now remember that when carrying out the voltage checks on page 43 of the manual, my D13 cathode to ground was a little excessive at 170.8 volts. I searched through the archives and found several posts which were of the same problem and the answer was to put the 100K resistor back in at R4 to reduce the voltage at D13. Is this correct? it certainly reduced the D13 cathode voltage down to 138.1V, with the rest of the checks being within spec. 73, Les M0BSI ----- Original Message ----- From: "Don Wilhelm" <[hidden email]> To: "Les Preston" <[hidden email]> Sent: Monday, February 26, 2007 6:09 PM Subject: RE: [Elecraft] KPA100 R12 Voltage query > Les, > > OK, the diodes are not the problem - you have 144.6 volts on the cathode > of > D1. That voltage goes direct to the junction of R11 and R12 where you > should measure the same thing - if not, there is a bad connection. > > Is there a chance that you were measuring at the wrong end of R12 and > thought you had a problem when in fact none existed? > > 73, > Don W3FPR > >> -----Original Message----- >> From: Les Preston [mailto:[hidden email]] >> Sent: Monday, February 26, 2007 12:56 PM >> To: [hidden email] >> Subject: Re: [Elecraft] KPA100 R12 Voltage query >> >> >> Hi Don, >> >> The voltage checks on D1-D8 were (not good) as follows:- >> Anode Cathode >> D1 12.05 144.6 >> D2 92.80 12.03 >> D3 12.61 92.70 >> D4 39.50 12.60 >> D5 14.43 39.50 >> D6 13.49 14.48 >> D7 -25.33 -0.477 >> D8 -0.555 0.1mV >> >> I've replaced the diodes, but it made no difference! >> >> 73, >> >> Les M0BSI >> >> ----- Original Message ----- >> From: "Don Wilhelm" <[hidden email]> >> To: "Les Preston" <[hidden email]>; >> <[hidden email]> >> Sent: Monday, February 26, 2007 1:08 AM >> Subject: RE: [Elecraft] KPA100 R12 Voltage query >> >> >> > Les, >> > >> > It may or may not be a problem. You should turn to the DC >> voltage chart >> > and >> > measure the DC voltage on each of diodes D1 thru D8. If all of the >> > voltages >> > are roughly 10% low, it is not a problem, but if you have a bad >> diode, or >> > one of them oriented the wrong way, the variation will be much more >> > than >> > 10%. >> > >> > 73, >> > Don W3FPR >> >> -- >> No virus found in this incoming message. >> Checked by AVG Free Edition. >> Version: 7.5.446 / Virus Database: 268.18.4/702 - Release Date: >> 2/25/2007 3:16 PM >> > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.5.446 / Virus Database: 268.18.4/702 - Release Date: 2/25/2007 > 3:16 PM > > _______________________________________________ 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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