They've been doing it for years, but somehow I didn't participate in "SKN" until Jan. 1, 2006. Straight key night is a kind of ham New Year's celebration sponsored by the ARRL. For 24 hours, beginning at midnight GMT (7 pm EST in the US), this event encourages everyone to work many stations using CW (Morse code) sent by "straight key".
A straight key traditionally is the simple up-and-down telegraph key, well known from the movies. Lately, the definition has been expanded to include mechanical, semiautomatic "bug" type keys like the Vibroplex. Both these keys have largely been replaced by electronic keyers controlled by a key "paddle". An electronic keyer is much easier to use, especially at higher speeds.
Anyway! Straight key night encourages old-fashioned Morse conversations, and it's a lot of fun in a low-key and noncompetitive way.
I had contacts with 12 hams in the course of SKN: KB5IEU, WA7SPY, W6IO, KD5CB, PS8HF, ZS6SIG, AB5VA, WA5ZNU, XE1ELA, W3TMZ, N5KEV, and K8AQM, with time out to host a small New Year's Eve party at our house -- and some sleep.
SKN is old-fashioned, but as I was filling out QSL cards, I came across Leigh WA5ZNU's blog of our contact -- that he had already posted. You can't escape the Web!
Monday, January 02, 2006
Wednesday, December 14, 2005
Updated aa6e.net site
The ham and family web site at www.aa6e.net is now updated and reformatted with CSS styles. Unfortunately, upgrading the content will take a while longer...
Tuesday, November 15, 2005
Optimal Callsign Lookup Page
If you want a quick and minimal callsign lookup, you could do worse than www.aa6e.net/lookup.html.
Monday, November 14, 2005
Orion, recalibrated
Previously, I blogged about the Orion's Frequency Calibration. I was able to tweak the Orion's TCXO to within a couple of Hz at 15 or 20 MHz, after warmup. The ambient room temperature was 80 F.
So now, after about 3 months, I recheck and find the oscillator has drifted about 14 Hz low (dial readings 14 Hz high) at 15 MHz. The room ambient is 73 F. This is still within +/- 1 ppm, and the oscillator is spec'd at +/- 3 ppm over 0 - 50 C.
The upshot: just because you can adjust the oscillator to +/- 0.1 ppm with care doesn't mean it will hold up for too long, as the oscillator ages and ambient conditions change.
Note: I'm getting ready for the ARRL Frequency Measurement Test tomorrow. The Orion's slow drift doesn't really matter. I will have to measure the the apparent WWV frequency anyway and apply the correction to the measurement. It doesn't matter how closely I can set the TCXO, I still have to do the correction.
So now, after about 3 months, I recheck and find the oscillator has drifted about 14 Hz low (dial readings 14 Hz high) at 15 MHz. The room ambient is 73 F. This is still within +/- 1 ppm, and the oscillator is spec'd at +/- 3 ppm over 0 - 50 C.
The upshot: just because you can adjust the oscillator to +/- 0.1 ppm with care doesn't mean it will hold up for too long, as the oscillator ages and ambient conditions change.
Note: I'm getting ready for the ARRL Frequency Measurement Test tomorrow. The Orion's slow drift doesn't really matter. I will have to measure the the apparent WWV frequency anyway and apply the correction to the measurement. It doesn't matter how closely I can set the TCXO, I still have to do the correction.
Thursday, October 27, 2005
Linux & Blackfin for ham radio?
I have discovered the Analog Devices "Blackfin" DSP/controller lately. Using uClinux, you can run "real" software in this chip, with many options for I/O, including Ethernet and audio codecs. Cheap development boards and free software are pretty attractive. I am looking for anyone who is using this technology (or anything similar) in an amateur radio application.
The chip is powerful enough for a full SDR implementation, but I'm thinking more about building an intelligent controller & digital audio interface for conventional rigs.
The chip is powerful enough for a full SDR implementation, but I'm thinking more about building an intelligent controller & digital audio interface for conventional rigs.
Tuesday, September 27, 2005
DSL Wars, 2005
It's not ham radio, but it's communications.
I recently upgraded my QSB-laden 384 kbs DSL line to a shiny new fiber-fed 1.5 Mbs version, but it was not very easy, unless you like to chat with India.
The story is at my static website .
I recently upgraded my QSB-laden 384 kbs DSL line to a shiny new fiber-fed 1.5 Mbs version, but it was not very easy, unless you like to chat with India.
The story is at my static website .
Wednesday, August 03, 2005
Orion Frequency Calibration
The Ten-Tec Orion Transceiver is specified for frequency accuracy of + or - 3 ppm over the temperature range 0 - 50 C. That amounts to +/- 30 Hz at 10 MHz, or nearly +/- 90 Hz in the 10 meter band. In an SSB QSO, an error of 50 Hz is pretty noticeable. In a PSK31 QSO, a whole QSO fits into a 30 Hz band, so such an error could be quite serious. Fortunately, we rarely need to set our VFOs with such accuracy. We need precision, but we can just tune for best reception. It does matter near a band edge, but it would be unusual to have to work within 50 Hz of an edge.
The most likely case where good accuracy can help in the HF bands is when we operate in roundtable mode on SSB. Frequently, a group sets up on a specific frequency, like 3813.000 kHz. If we don't have good accuracy, and if we don't all tune up carefully on one station, we may have to use the RIT every time a different person is speaking. The better our absolute setting accuracy, the less trouble we will have in net operations.
So, how well can we do with a little effort on the Orion? I developed a technique for measuring my frequency error against WWV. (See note below.) My zero beat setting before adjustment was typically about 9.999987 MHz after warmup, 13 Hz low, corresponding to the master oscillator running high by about 1.3 ppm, well within Ten-Tec's spec.
The master oscillator in the Orion is a temperature-compensated crystal oscillator (TCXO) running at 44.55 MHz. It is a Siward series TXO32, apparently, with a mechanical fine adjustment. The following is my record of how I adjusted my oscillator.
First, remove the bottom cover of the Orion. There are 4 screws on the sides and many little Torx head screws around the rear lip. The top cover can stay in place. After the cover comes off, you are treated to the spacious glory of the Orion underchassis. The TCXO (circled) is on the A10 synthesizer board at the top.
This is the temperature compensated crystal oscillator (TCXO)
Here we do the actual adjustment. Note the pickup loop for the Icom R-8500 receiver to monitor 44.55 MHz. Fortunately, the TCXO does not require a non-metallic adjustment tool. An ordinary jeweler's screwdriver works fine. The adjustment feels a little coarse if you are trying for exact zerobeat with WWV -- i.e., sub-1 Hz beat. Keep in mind that 1 Hz at 15 MHz is .07 ppm, much finer than the specified oscillator accuracy. Because the oscillator temperature will be substantially less than normal with the case open, you do not want to zerobeat WWV. (See text below.)
The Icom R-8500 communications receiver was useful to monitor changes to the TCXO. It has its own internal TCXO reference. Such a receiver is not required for the Orion adjustment, but it is a help if available.
At the end, we put it all back together and give ourselves a professional-looking (?) calibration sticker.
Procedure
Before attempting the adjustment, it is useful to study the warmup characteristic of the Orion TCXO by zero-beating WWV over several hours, as the operating temperature stabilizes. Room ambient temperature was about 78-80 F. Naturally, you need to do this with the transceiver in its operating position with the covers on. Here is a typical warmup run monitoring WWV on 15 MHz.
It would have been interesting to measure temperature along with time, but I did not have a temperature probe. (The A10 board runs pretty hot to the touch, and it is in a poorly ventilated area under the chassis. I would estimate the operating temperature is around 50 C.)
After running the warm-up curve, we note that the TCXO ends up 1.3 ppm high. The dial reading is 1.3 ppm or 20 Hz low. Therefore, we want to trim the TCXO so the dial reading increases by 20 Hz. That should bring the TCXO very close after warmup.
Another issue is which WWV frequency to use: 2.5, 5, 10, 15, or 20 MHz. Other things being equal, the highest frequency gives the best setting precision. One Hz at 20 MHz is .05 ppm. Propagation is a concern, however. We need a strong and steady signal. If the signal has much QSB (fading), it is likely to have a lot of frequency dispersion. You won't be able to find a steady zerobeat. You may want to avoid periods of significant solar or geomagnetic activity for the same reason. (Check http://www.n3kl.org/sun/noaa.html for current data.) For the most part, for my path the 15 MHz transmission worked best. I compared my results at 15 MHz with 10 MHz as a check. They were in good agreement.
Conclusions
The Orion's TCXO can be adjusted to within a few times 0.1 ppm, and it will stay put if the transceiver's operating temperature is stable. Crystal aging is a factor, however, so the calibration may have to be repeated periodically.
---------------
How to Zero Beat the Orion with WWV.
I have tried two methods of finding a precise zerobeat between the Orion's effective local oscillator frequency and a reference frequency transmission.
Note added (1/8/2006): An alternative procedure is given by K6SE at http://www.n5na.net/download/Orion_Freq_Calibration.pdf .
The most likely case where good accuracy can help in the HF bands is when we operate in roundtable mode on SSB. Frequently, a group sets up on a specific frequency, like 3813.000 kHz. If we don't have good accuracy, and if we don't all tune up carefully on one station, we may have to use the RIT every time a different person is speaking. The better our absolute setting accuracy, the less trouble we will have in net operations.
So, how well can we do with a little effort on the Orion? I developed a technique for measuring my frequency error against WWV. (See note below.) My zero beat setting before adjustment was typically about 9.999987 MHz after warmup, 13 Hz low, corresponding to the master oscillator running high by about 1.3 ppm, well within Ten-Tec's spec.
The master oscillator in the Orion is a temperature-compensated crystal oscillator (TCXO) running at 44.55 MHz. It is a Siward series TXO32, apparently, with a mechanical fine adjustment. The following is my record of how I adjusted my oscillator.
First, remove the bottom cover of the Orion. There are 4 screws on the sides and many little Torx head screws around the rear lip. The top cover can stay in place. After the cover comes off, you are treated to the spacious glory of the Orion underchassis. The TCXO (circled) is on the A10 synthesizer board at the top.
This is the temperature compensated crystal oscillator (TCXO)
Here we do the actual adjustment. Note the pickup loop for the Icom R-8500 receiver to monitor 44.55 MHz. Fortunately, the TCXO does not require a non-metallic adjustment tool. An ordinary jeweler's screwdriver works fine. The adjustment feels a little coarse if you are trying for exact zerobeat with WWV -- i.e., sub-1 Hz beat. Keep in mind that 1 Hz at 15 MHz is .07 ppm, much finer than the specified oscillator accuracy. Because the oscillator temperature will be substantially less than normal with the case open, you do not want to zerobeat WWV. (See text below.)
The Icom R-8500 communications receiver was useful to monitor changes to the TCXO. It has its own internal TCXO reference. Such a receiver is not required for the Orion adjustment, but it is a help if available.
At the end, we put it all back together and give ourselves a professional-looking (?) calibration sticker.
Procedure
Before attempting the adjustment, it is useful to study the warmup characteristic of the Orion TCXO by zero-beating WWV over several hours, as the operating temperature stabilizes. Room ambient temperature was about 78-80 F. Naturally, you need to do this with the transceiver in its operating position with the covers on. Here is a typical warmup run monitoring WWV on 15 MHz.
| Time (min) | Frequency | Error (ppm) |
| 0 | 14.999 980 | 1.3 |
| 11 | 15.000 000 | 0.0 |
| 38 | 14.999 995 | 0.3 |
| 73 | 14.999 989 | 0.7 |
| 85 | 14.999 986 | 0.9 |
| 101 | 14.999 984 | 1.0 |
| 137 | 14.999 983 | 1.1 |
| 177 | 14.999 980 | 1.3 |
It would have been interesting to measure temperature along with time, but I did not have a temperature probe. (The A10 board runs pretty hot to the touch, and it is in a poorly ventilated area under the chassis. I would estimate the operating temperature is around 50 C.)
After running the warm-up curve, we note that the TCXO ends up 1.3 ppm high. The dial reading is 1.3 ppm or 20 Hz low. Therefore, we want to trim the TCXO so the dial reading increases by 20 Hz. That should bring the TCXO very close after warmup.
Another issue is which WWV frequency to use: 2.5, 5, 10, 15, or 20 MHz. Other things being equal, the highest frequency gives the best setting precision. One Hz at 20 MHz is .05 ppm. Propagation is a concern, however. We need a strong and steady signal. If the signal has much QSB (fading), it is likely to have a lot of frequency dispersion. You won't be able to find a steady zerobeat. You may want to avoid periods of significant solar or geomagnetic activity for the same reason. (Check http://www.n3kl.org/sun/noaa.html for current data.) For the most part, for my path the 15 MHz transmission worked best. I compared my results at 15 MHz with 10 MHz as a check. They were in good agreement.
Conclusions
The Orion's TCXO can be adjusted to within a few times 0.1 ppm, and it will stay put if the transceiver's operating temperature is stable. Crystal aging is a factor, however, so the calibration may have to be repeated periodically.
---------------
How to Zero Beat the Orion with WWV.
I have tried two methods of finding a precise zerobeat between the Orion's effective local oscillator frequency and a reference frequency transmission.
- Zerobeat using CW Spot tone. (easiest for me) Set up for normal CW reception with say 300 Hz bandwidth. Hold down the Spot button and tune until you hear the beat note when the signal frequency equals the spot tone. Again, you should find the zerobeat within +/- 1 Hz.
- Zerobeat on noise. If the IF passband offset (PBT) is set for say -100 Hz and the bandwidth is 200-300 Hz, set the AGC to "fast" and the mode to USB or LSB. The Rx audio deemphasis should be zero or positive. The tuning step needs to be 1 Hz. Find the beat note and adjust slowly for lower and lower audio tones. After the tone becomes sub audible (about 60 Hz depending on your speaker), carefully tune to zero. When you are within one or two Hz of zero beat, you should hear the receiver noise fluctuate up and down with the beat. (This is the effect of AGC.) It should be possible to locate the zerobeat to +/- 1 Hz. This method requires a fairly strong reference level.
Note added (1/8/2006): An alternative procedure is given by K6SE at http://www.n5na.net/download/Orion_Freq_Calibration.pdf .
Saturday, July 23, 2005
Morse Code, we hardly knew ye.
The handwriting has been on the wall for some time. First, the International Telecommunications Union (ITU) lifted the Morse Code requirement for ham licenses capable of international communications (mainly in the HF "shortwave" bands). Then many national communications agencies began removing the Morse component of radio amateur license requirements. Now, after some delay, the U.S. Federal Communications Commission (FCC) is proposing the same for the U.S.
Morse still has an avid following among ham operators. (I just joined the FISTS organization myself.) The Morse requirement is entwined with the long history of amateur radio. Recent changes to "water down" the license qualifications have been controversial. Often the arguments are of the type "When I was a boy..., men were men...".
Meanwhile the world has moved on. Demographically, the young experimenters who once sustained the hobby have moved on to video gaming and the Internet. The number of licensees seems to have peaked around 600,000 and has started a slow decline. (Removing the Morse barrier may give the numbers a boost.)
Technically, the operating modes available to hams have exploded. Beside traditional Morse and voice, there are now many computer-assisted options: keyboard-to-keyboard (many flavors), file transfers, digital voice and video, special modes for weak and bursty channels (moonbounce, meteor scatter), and more. Fortunately, we do not have to prove competence in each of these to qualify for a license.
Morse code is an anachronism, but we like our anachronisms. Listen to the low end of most HF amateur bands and you will find hams "pounding brass". Join in!
Morse still has an avid following among ham operators. (I just joined the FISTS organization myself.) The Morse requirement is entwined with the long history of amateur radio. Recent changes to "water down" the license qualifications have been controversial. Often the arguments are of the type "When I was a boy..., men were men...".
Meanwhile the world has moved on. Demographically, the young experimenters who once sustained the hobby have moved on to video gaming and the Internet. The number of licensees seems to have peaked around 600,000 and has started a slow decline. (Removing the Morse barrier may give the numbers a boost.)
Technically, the operating modes available to hams have exploded. Beside traditional Morse and voice, there are now many computer-assisted options: keyboard-to-keyboard (many flavors), file transfers, digital voice and video, special modes for weak and bursty channels (moonbounce, meteor scatter), and more. Fortunately, we do not have to prove competence in each of these to qualify for a license.
Morse code is an anachronism, but we like our anachronisms. Listen to the low end of most HF amateur bands and you will find hams "pounding brass". Join in!
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