Dave, Yes, I agree. Several folks have sent me their K2 just for such a checkout and calibration and alignment. I have the advantage of being familiar with the K2 and its normal behavior. BUT with a little bit of ingenuity, each builder can determine if his K2 is performing up to par without sending it away (see below).
I do have an good array of test equipment for testing the receiver path, but I do not (yet) have a spectrum analyzer here which limits my ability to check the purity of the transmitter output. I can however do narrow band spectrum analysis with a block converter to bring a portion of the spectrum down to baseband where it can be analyzed with Spectrogram or other FFT analyzer. That technique is good for analyzing near-in transmission products and works well for driving with a two-tone test signal (the Elecraft 2T-gen), but would take forever to check the entire spectrum in that manner (Spectrogram limits the span to about 11kHz). The time to do a full lab evaluation of any transceiver similar to the ARRL product evaluation tests would be too costly to consider IMHO. If I were to do that type of evaluation, I figure I would have to charge something on the order of $500 to $1000 per test because of the calibration costs and equipment maintenance that I would have to assume and amortize it over the number of jobs that I anticipate - I don't believe many hams would like to spend that kind of money for such a detailed analyis of their K2 - you are really asking for certification similar to that which would be obtained from a calibration lab - check their prices for comparison. Even 'off the assembly line' transceivers do not receive that level of testing you are suggesting. They would be tested with a few simplified tests after assembly, but for assembly level testing, the K2 already has the instructions for the builder in the manual. If one wants a quick additional check on performance, one can purchase the Elecraft XG1 or XG2 mini-module and do an MDS test to see if their K2 is performing within the normal range - cost for that is either $39 or $59, and you have a tool for other purposes too. Add a CP1 to your toolkit as well and you can drive the input of a fellow ham's spectrum analyzer if you want to check out the transmit spectrum. Those mini-modules can offer a lot of test capability, and if one wishes to learn other methods of using such tools, buy a copy of Experimental Methods In RF Design and read the chapter on Measurements. It is amazing how much can be done with only a few pieces of precision test equipment - one oscilliscope whose vertical deflection has been verified (see my website for a Voltage 'standard') can go a long way to calibrating other measurement devices - it may not be to calibration lab standards, but it is usually acceptable for ham use. 73, Don W3FPR > -----Original Message----- > > Seems to me that a few might be missing the main point here. While > assembling a K2 there are a few hundred parts to be stuffed into holes. > It is not all that difficult to stuff the wrong part into a pair of > holes. Seems that I remember a firm (Sherwood Engineering I believe was > the name, but not positive) who loudly and longly claimed that the K2 > did not meet its published specs nor those of the ARRL tests. Seems > that the fellow was testing just such a K2 as I'm describing. The > testing firm was not the builder and the builder had made errors. That > sample did indeed not meet spec. When he later tested a good sample the > results fell in line with expectations. > > Knowing the propensity of folks to make errors, I'd say that at least > 10% of the K2's out there, and maybe as high as 25%, do not meet the > published specs. Although I'm a very careful worker I'm well aware that > the one I built might not meet spec. I don't have the test equip to > fully test it so don't know for sure. > > So it does not seem to me to be all that bad of an idea to have someone > who would run assembled K2's through a rigorous series of tests - > similar to those the ARRL does - to assure that a unit is in proper > working order. These would be more than the simple alignment tests > proposed so far in this thread, and would include IMD3 (at 1 or 2 kHz > spacing as well as wider spacings), IMD2, actual sensitivity, and > whatever else was needed to assure that the unit is up to speed. > > I would think that anyone buying a used K2 would be interested in such a > service. > > I am aware that one cannot make single errors in the assembly process - > if the wrong part is stuffed into a pair of holes then the correct part > must then be stuffed into the wrong pair, making for two errors rather > than one. This means the builder has two chances to catch their error. > But most of us have, at one time or another, bought a used kit, looked > it over carefully and found assembly errors. One small transceiver I > bought - nowhere near as complex as a K2 - had 8 such errors. (And, > yes, the builder claimed to be an expert builder.) Others have had the > far-more-common poor solder joints. This kind of stuff happens every > day. Be good to have a way of testing for it. > > 73 de dave > ab9ca > > > > > > David A. Belsley wrote: > > Boy, I don't get this one at all. The whole essence of Elecraft, > > IMHO, is doing it yourself and getting something really great for the > > effort. That's a conjunction: doing it oneself AND getting a great > > product. If all you want is the latter, there are plenty of other > > sources. And if you want the former, then do the former. It's good > > to have self doubts, but they work best when they lead you to do > > what's necessary to remove them -- yourself. Don, > > _______________________________________________ > > _______________________________________________ > 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: 7.5.432 / Virus Database: 268.16.0/610 - Release Date: > 12/30/2006 2:59 PM > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.16.0/610 - Release Date: 12/30/2006 2:59 PM _______________________________________________ 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
