K2 RF Board TP3
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Hi All,
Is there any reason why I cannot mount TP3 (PLL Reference Oscillator Test Point) on the underside of the RF board instead of on top. This will give easier access for frequency checking after K2 completion. A suitable hole drilled in the bottom cover and plugged with a bung (like one from an inkjet cartridge refill set). This is my second K2 build - #5565. Many thanks. (on or off list) 73, Mark G3XYS _______________________________________________ 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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Mark G3XYS asked:
Is there any reason why I cannot mount TP3 (PLL Reference Oscillator Test Point) on the underside of the RF board instead of on top. This will give easier access for frequency checking after K2 completion. A suitable hole drilled in the bottom cover and plugged with a bung (like one from an inkjet cartridge refill set). ----------------- Why would that be easier? You still need to get inside the top of the K2 to plug the test cable into the control board connector, and you'd need a longer cable than specified in the kit. Besides, it's not something one needs to access very often... Ron AC7AC _______________________________________________ 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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Mark brought up an interesting point off-line that I'll repeat here for the
lurkers who may be following the thread. He reports that the DSP module gets in the way of TP3. I don't have DSP installed in my K2 so that didn't occur to me. He was looking for easier access to TP3 without removing the DSP module. One other important point that Mark is quite aware of, and why he suggested a small hole with a cover to access the TP3 in the "inverted" position, is that the bottom cover *must* be in place when doing the testing. The bottom cover has a small but significant effect on the PLL reference oscillator. Ron AC7AC -----Original Message----- Mark G3XYS asked: Is there any reason why I cannot mount TP3 (PLL Reference Oscillator Test Point) on the underside of the RF board instead of on top. This will give easier access for frequency checking after K2 completion. A suitable hole drilled in the bottom cover and plugged with a bung (like one from an inkjet cartridge refill set). ----------------- Why would that be easier? You still need to get inside the top of the K2 to plug the test cable into the control board connector, and you'd need a longer cable than specified in the kit. Besides, it's not something one needs to access very often... Ron AC7AC _______________________________________________ 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 _______________________________________________ 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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Ron, Mark, and other interested folks,
TP3 need to be used only once in the K2 construction (unless something is changed in the PLL Reference Oscillator). It must be used to verify that the PLL range is within bounds, but all other calibration steps required may be done with TP1 and TP2. Yes, the manual tells you to attach the probe to TP3 when calibrating the 4 MHz reference oscillator by comparing the CAL FCTR frequency with an external frequency counter - but TP1 can be used just as well for that same purpose. Note that by setting the K2 to 40 meters, the frequency at TP1 will be in the same range as that at TP3. When C22 is adjusted, the frequency that is being measured does not change - only the result of the frequency calculation done by the microprocessor changes, any internal frequency source (except the reference oscillator) in the K2 can be used when setting the reference oscillator. Bottom line - TP3 is almost expendable, so it matters little that the KAF2 or KDSP2 blocks access to it. In the rare occasions when one needs to check the PLL range, the KAF2 or KDSP2 likely has already been removed. Given that, I am not certain what would be gained by installing TP3 in an inverted position. 73, Don W3FPR > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]]On Behalf Of Ron D'Eau Claire > Sent: Saturday, June 24, 2006 10:54 AM > To: [hidden email] > Subject: RE: [Elecraft] K2 RF Board TP3 > > > Mark brought up an interesting point off-line that I'll repeat > here for the > lurkers who may be following the thread. He reports that the DSP > module gets > in the way of TP3. I don't have DSP installed in my K2 so that > didn't occur > to me. He was looking for easier access to TP3 without removing the DSP > module. > > One other important point that Mark is quite aware of, and why he > suggested > a small hole with a cover to access the TP3 in the "inverted" position, is > that the bottom cover *must* be in place when doing the testing. > The bottom > cover has a small but significant effect on the PLL reference oscillator. > > Ron AC7AC > > -----Original Message----- > Mark G3XYS asked: > Is there any reason why I cannot mount TP3 (PLL Reference Oscillator > Test Point) on the underside of the RF board instead of on top. This > will give easier access for frequency checking after K2 completion. A > suitable hole drilled in the bottom cover and plugged with a bung (like > one from an inkjet cartridge refill set). > > ----------------- > > Why would that be easier? You still need to get inside the top of > the K2 to > plug the test cable into the control board connector, and you'd need a > longer cable than specified in the kit. > > Besides, it's not something one needs to access very often... > > Ron AC7AC > > > _______________________________________________ > 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 > > _______________________________________________ > 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 > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.394 / Virus Database: 268.9.3/374 - Release Date: 6/23/2006 > > _______________________________________________ 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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