Alignment/Test II assistance request
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Need a second opinion with some Align/Test II results.
Item 1: PLL Reference OSC Range. Fref-high = 12100.5 kHz, Fref-low = 12091.0 kHz. Fdiff - 9.5 kHz. The manual says the diff. _must_ be 9.5 - 15 kHz. I'm a little low. I followed the T/S steps and checked associated components C84, C85, D19, D17, L31 & X1--all are correct. Item 2: BFO, BFOhigh-freq = 4917.16 kHz, BFOlow=freq = 4912.88 kHz, Both a "smidge" higher than the manual spec. 4917 kHz and 4912 kHz respectively. Frequency measurements were made with the internal frequency meter, after calibrating it per the manual with a Radio Shack wide range frequency meter. Experience building K2s told me to call it good because they things were so close and press on. But I've been away from building for 2 years or so, and thought I better get a second opinion. FWIW PLL linearization worked just fine, as did Filter/BFO setup. Item 3: Adjusting L34 for best S/N ratio I could not really notice much change. L1 & L2 seamed to peak OK with a Noise Generator connected to the antenna jack. But with a few feet of wire connected to the ANT jack I could _NOT_ receive any signals on 40m. Is 40 that dead? It might be my QTH, river valley surrounded by low mountains. I'll have to get access to an XG1 or XG2 and do more trouble shooting. Anyone have either they would like to loan out or sell? Back in the day when I had a decent "bench" and more test equipment things were a lot easier. Now, after downsizing QTH and test equipment, doing this stuff on the kitchen table presents some "challenges". :-) -- Rod Ai7NN, --the ham formally known as N0RC-- _______________________________________________ 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 |
Re: Alignment/Test II assistance request
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Rod,
I believe you had a typo - the PLL range must be between 9.8 and 15 kHz, so your PLL range is on the low side by quite a bit, and should be corrected (it could possibly be the cause of your 'no signals on 40' situation). First do some more verification steps - carefully check the soldering of the varactors (D16 and D17) and RP2 and R19 (check the values too). After that, monitor the voltage out of U5 pin 7 when in CAL FCTR. When you tap BAND+ you should find 4 volts and when tapping BAND- you should see close to zero volts. Do the same thing but this time monitor the voltage at U6 pin 1 - the swing should be about twice the voltage swing you found at U5 pin 7 (if it is not, check the thermistor board). If you do have these voltage swings as expected, and the components and soldering are OK, you may have to replace the PLL crystal - some crystals have a higher Q than others and will not move as far in a VXO circuit (the PLL Reference is really just a VXO). For the BFO range, it may be OK for most of your filter settings, but if you have to change it, a small value capacitor (10 to 20 pf) connected between U11 pin 6 and ground (use U11 pin 3) should bring it into range - you may have to experiment a bit with the value. If you can connect a real antenna to the receiver, you stand a better chance of hearing signals on 40 meters. While there are usually some signals on 40, many evenings I have found them quite weak and barely able to move the S-meter - we can blame the sunspot cycle for that. If you have a 40 meter crystal and a few parts, you could build the oscillator shown in the manual appendix E page 9 - that has plenty of output to give you a signal for troubleshooting. Alternately, you can use most any other transmitter running into a dummy load along with your short wire antenna on the K2. 73, Don W3FPR [hidden email] wrote: > Need a second opinion with some Align/Test II results. > > Item 1: PLL Reference OSC Range. Fref-high = 12100.5 kHz, Fref-low = > 12091.0 kHz. Fdiff - 9.5 kHz. The manual says the diff. _must_ be 9.5 > - 15 kHz. I'm a little low. > > I followed the T/S steps and checked associated components C84, C85, > D19, D17, L31 & X1--all are correct. > > Item 2: BFO, BFOhigh-freq = 4917.16 kHz, BFOlow=freq = 4912.88 kHz, > Both a "smidge" higher than the manual spec. 4917 kHz and 4912 kHz > respectively. > > Frequency measurements were made with the internal frequency meter, > after calibrating it per the manual with a Radio Shack wide range > frequency meter. Experience building K2s told me to call it good > because they things were so close and press on. But I've been away > from building for 2 years or so, and thought I better get a second > opinion. > > FWIW PLL linearization worked just fine, as did Filter/BFO setup. > > Item 3: Adjusting L34 for best S/N ratio I could not really notice > much change. L1 & L2 seamed to peak OK with a Noise Generator > connected to the antenna jack. But with a few feet of wire connected > to the ANT jack I could _NOT_ receive any signals on 40m. Is 40 that > dead? It might be my QTH, river valley surrounded by low mountains. > I'll have to get access to an XG1 or XG2 and do more trouble shooting. > Anyone have either they would like to loan out or sell? > > 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 Rod Ai7NN
Whoops, a typo in my original post
On 10/29/07, [hidden email] <[hidden email]> wrote: ... > Item 1: PLL Reference OSC Range. Fref-high = 12100.5 kHz, Fref-low = > 12091.0 kHz. Fdiff - 9.5 kHz. The manual says the diff. _must_ be 9.5 ^^^ > - 15 kHz. I'm a little low. > Should read 9.8 - 15 kHz, I'm 300 Hz below. Thanks to Eagle Eye Don, W3FPR for catching the error, and suggesting some additional troubleshooting steps. -- 73, Rod Ai7NN _______________________________________________ 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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