| KB6MMS QRP and Simple Wire Antennas K1 Measured Performance on the 30 Meter Band |
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30 Meter Band The 30m band is not my favorite. I have a few contacts on this band, but I just don't use it too often. The performance of the K1 on 15m is good. I am happy with results in every way. |
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| Output Power I have included my test data for the maximum output power as a function of frequency from 10.100 MHz to 10.1500 MHz. The results show a fairly flat output power verses frequency characteristic. I am sure that I could get the response to be perfectly flat if I tuned on it for the effect. When I do use this band I am on the first 10-12 KHz and the output power is pretty flat in the range. This result is above the manufacture's advertised spec of 5.0W. Actually, Elecraft says "Adjustable CW power output, nominally 0-5 watts or higher." I am happy with this result and believe that I can improve upon this with just a little more careful tuning.
Configuration for this test
I conducted this test using my SWR meter/power meter manufactured by Diesel to monitor the power. I used my homebrew 50 ohm load. I know that the 50 ohm load is good because I measured the return loss to be better than 20dB to 60MHz. Just a quick note on measuring output power. I have seen some reports of output power and there is sometimes a comparison between output power into a 50ohm load and output power into an antenna. The two measured output powers are usually different and often the result into the antenna is higher. Now, I will give my two cents on this. The measurement into the antenna is really the wrong way to do it, unless your antenna has extremely good SWR. This is due to the fact that poor, or even pretty good SWR, will cause a larger voltage (voltage standing wave, hence VSWR) to be present at various points on the transmission line up to the antenna. This includes the coax between the rig and swr meter and everything up to the antenna. Since most, if not all, swr meters measure a voltage, any increase due to SWR issues will cause a false reading. Therefore, it is always best to measure output power into a know good 50 ohm load. OK that is my two cents on this issue.
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Maximum Tuning Range The K1 is advertised to cover "up to 150Kz". Since this band is only from 10.1 to 10.15MHz, I am only interested in that range. The K1 will cover the entire 30m band with extra bandwidth to spare. Tuning Range > 50 KHz
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| RIT tuning Range I measured the RIT tuning range. I know this is not a real big issue for some. However, I do know that some DX stations like to work offset TX/RX. This is when a wide RIT can be helpful. Also, sometimes you get a contact where the other guy is off frequency by 1-2 KHz or more. This is very rare in my experience, but still happens. Anyway the results are below. The RIT range is about +/-3.5KHz. I am surprised by this result a little. Though the RIT range is way more than I will use, I am a little puzzled by it since the other bands had repeatable ranges which are a tad bit higher. I think it is due to the fact that the RIT for this band is measured at a different VFO frequency. This is really not big deal. It is just a little puzzle I want to work out if I have the time one day. Minimum Frequency = 10.1166MHz RIT Lower Range = 3.4 KHz
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| Spectral Purity The spectral purity of the transmitted signal was measured. Though it may come as a surprise to some, when your transmitter is tuned to, let's say, 7.040 MHz and you transmit, you will generate a signal at 7.040MHz plus other spurious and harmonic signals at other frequencies. Those spurious signals are not desired and in fact the level (or power level) of those undesired signals is controlled by FCC regulations. This spectral purity test directly measures the output from the transmitter over a very broad frequency range so that one can immediately see what is actually being transmitted. For instance, if you set your transmitter to 7.040MHz again and key it, it is likely that you will radiate some level of power at the harmonics. Those harmonics are at 14.080, 21.120, 28.160 MHz and so on. In addition, you may also be transmitting at other frequencies which are generated in the mixer stages, amplifiers and other non-linear elements in the transmitter. The frequency of those components is determined by several factors one of them is the IF frequency. These undesired signals are often called spurs which is short for spurious. The tests on the K1 were conducted using an Advantest R3273 Spectrum Analyzer with a bandwidth of 100Hz to 26.5 GHz. I know that that is way over the top as far as bandwidth overkill, but it was what I had available. I had 48.2dB of attenuation between the K1 and the Advantest.
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