++++++++++++++++++++++++++++ Date: Thu, 05 Jul 2001 17:15:00 -0700 From: Wayne Burdick Subject: [Elecraft] K2 firmware topics: "Fast-Play" CW messages This is the first in a series of postings about the new K2 firmware (revision 2). We thought this would be useful since so much has been added. Each posting will contain a bit of background on a particular new feature, as well as examples of how you might use it. The entire series will at some point also be posted on our web site. Note: the revision 2 firmware is supplied at no charge with the KIO2 option. But it can also be ordered separately. * * * Fast-Play CW Messages The buttons on the right side of the K2's front panel each have a primary and secondary function (activated by tap or hold). They also have a third function: representing the digits 0-9 for use in selecting frequency memories or CW message buffers. About 10 milliseconds after we delivered the first version of K2 firmware, we had a number of operators ask for, in effect, a *fourth* function. They wanted to be able to put the K2 into a mode where each message button played back its buffer immediately, so that the MSG button wouldn't have to be pressed first. This makes a lot of sense, especially during high-speed contest operation. We resisted this for a long time. Anyone who writes user interface software will appreciate the fact that such overloading of buttons, in particular the creation of "modal" operation, can lead to confusion. But when we switched to the new microcontroller--and had a lot more ROM to work with--we started testing more unobtrusive ways to accomplish the goal. What we realized is that careful selection of a *subset* of buttons to be made "hot" (i.e., Fast-Play) was a reasonable compromise. When you first power-up the K2 with the new firmware, Fast-Play is turned off. (We wouldn't want anyone to have to use new features without their consent!) To turn it on, you need to do two things: (1) assign PF1 or PF2 to "FPON" (Fast-Play on/off) using the menu; (2) enable Fast-Play by holding the assigned PF button until you see "FPLY ON" on the display. Once Fast-Play is turned on, anytime you select CW mode you'll see the letter "F" occasionally replace the normal mode letter ("C"). This serves as a subtle reminder. Next, you'll need to select which group of switches to use, and this is done with the "FPLY" menu entry in the secondary menu. (This is a completely new menu--the original or primary menu is still there, unchanged from older versions.) By default, you'll get "FPLY 45", which means that the "4" and "5" buttons are configured for Fast-Play when the rig is in CW mode. The other choices are 4/5/8, 2/3, and 2/3/4/5. Where did we come up with these groups? Simple: we tried to choose switches whose primary and secondary functions were rarely used (at least by many ops) when in CW mode. 4/5 is a good choice if you only need two buttons, since the preamp/attenuator and AGC settings aren't changed too often. If you do have to change these settings, you can temporarily exit Fast-Play mode with the assigned PF button. Using Fast Play Eric and I had our first serious shake-down of this new mode during Field Day. Since we had the KIO2 installed, we also used laptop-based logging and radio control for the first time at FD. We used the "CT" program, which works well for this contest. We might try TR Log next year. Using Fast-Play buttons for exchange/CQ messages turned out to work very well. We each made the classic "modal" interface mistake a couple of times--forgetting we were in Fast-Play mode, and hitting AGC, etc.--but after that, we were off to the races. We found that the time saved in not having to tap MSG first really did make things easier. To do message repeats, you still have to tap MSG first, then HOLD the numbered message button, but this is done much less often than the single-tap message transmissions. * * * The next posting in this series will be all about the new one-pass, more accurate CAL PLL algorithm. 73, Wayne, N6KR ++++++++++++++++++++++++++++ Date: Tue, 10 Jul 2001 19:13:23 -0700 From: Wayne Burdick Subject: [Elecraft] K2 firmware topics: improved VFO calibration This is another in a series of postings about the new K2 firmware (revision 2). * * * More accurate CAL PLL function (VFO linearization) The K2 VFO dial accuracy is affected by two things: how accurately you set the 4-MHz crystal oscillator on the Control board, and nonlinearities in the firmware calibration algorithm (CAL PLL) Due to limitations on code and variable space in the 16C77 microcontroller, the original CAL PLL function produced small nonlinearities at the high end of each ham band, as well as below a ham band. One K2 owner referred to these small nonlinearities as "scalloping," because if you tuned very slowly and plotted frequency vs. VFO knob movement, you'd find a curved error function that repeats every 5 kHz. The old calibration algorithm was implemented in such a way that you would rarely *hear* these anomalies as you tune across the band. But you could find them when measuring with a frequency counter, or if you were trying to tune to an exact frequency (say, for a net or sked) at the top end of a particular band. The old CAL PLL step also had to be done on *each* band, and was thus time-consuming. When we switched to the new microcontroller (18C452), all this old CAL PLL code got tossed out. With much more code space and RAM available, we were able to use an entirely new approach. [Optional technical details] In a nutshell, here's the difference: the old algorithm stored a 5-kHz DAC-to-VCO lookup table on each band, and was subject to round-off error as you moved away from the band edge; the new algorithm uses a single, 12-kHz DAC-to-PLL reference oscillator lookup table (big enough to cover the PLL reference range used on all bands), and mathematically scales the table entries using 24-bit math. There wasn't room for the 24-bit routines or the large RAM table in the old micro. There are two benefits to this new approach: (1) the CAL PLL function only has to be run ONE time, on 40 meters, rather than on each band (2) +/- 10 Hz accuracy is theoretically possible, across the *entire* tuning range, with no nonlinearities associated with where in the band you are (it's equally accurate inside or outside ham bands) So, basically, we've eliminated the CAL PLL algorithm itself as a source of error. If you align your 4 MHz oscillator (Control board, C22) as described in the manual, you'll have very good tuning accuracy, typically to within +/- 10 to +/- 20 Hz, with best accuracy on the lowest bands. (It may be hard to get the 4 MHz oscillator calibrated to better than 1 or 2 Hz. A 2-Hz error, e.g. 4.000002 MHz, translates to an error of about 12 Hz at 28 MHz because the ratio between the VCO and the 4 MHz oscillator is about 6:1 on this band.) Note: you'll still need to "tweak" each of your BFO settings using CAL FIL if you change the 4 MHz oscillator calibration. This forces each BFO setting to be re-measured and stored. Better calibration is especially useful in SSB mode, when you're waiting for a sked or net to come on at a specific frequency, or when you've clicked on a DX spot. It also helps when scanning or tuning for SSB signals when using large VFO steps. You'd be amazed at the percentage of SSB stations that can be found on exact 100 Hz or 1 kHz boundaries--the SSB sub-bands are nearly "channelized" thanks to all the synthesized transceivers! * * * The next posting in this series will discuss the programmable transverter band displays. 73, Wayne, N6KR ++++++++++++++++++++++++++++ Date: Mon, 16 Jul 2001 14:06:38 -0700 From: Wayne Burdick Subject: [Elecraft] K2 firmware topics: Transverter Bands This is another in a series of postings about the new K2 firmware (revision 2). * * * Transverter Bands A number of our customers who operate on VHF/UHF/Microwave bands have told us they were using the K2 as an I.F. for weak-signal work, including moonbounce. The K2 is has very "quiet" (low-noise) receiver and an effective noise blanker, both of which are desirable for this purpose. We decided to make high-band operation more convenient by providing a means to directly display these frequencies on the K2. With the new firmware, the K2 now provides three transverter bands (TRN1, TRN2, TRN3), each of which is fully programmable. You can leave these bands turned off, in which case you'd never know the feature was present. Or you can go into the secondary menu and turn one or more of the bands on. They then appear in the band rotation as you tap BAND+ and BAND-. When you set up any of the three transverter bands, you'll have five parameters to select: 1. Transverter band on/off Any band that is ON appears in the band list. 2. R.F. band edge This can be any frequency from 0-999 MHz. This provides some flexibility; you can use the display with LF or HF transverters as well as higher bands. For bands above 99 MHz, the K2 LCD contents is shifted to the right to accomodate the 100's of MHz digit, unless you have the 10 Hz tuning rate selected. You can even do direct frequency entry on transverter bands. 3. I.F. band edge (7, 14, 21, or 28 MHz) Most transverters require an I.F. of 14 or 28 MHz, but we included 7 and 21 MHz as well. An I.F. of 7 MHz might be useful with an LF or VLF transverter. 4. Offset (+/- 9.99 kHz) This parameter is used to compensate for errors in transverter oscillator/multiplier chains. This allows the K2 to accurately display the true transverter operating frequency to within 10 Hz (+/- K2 VFO linearization error, typically only 10-20 Hz with the new firmware). 5. Power output level (fixed 1.0-15W, or adjustable) You can set this parameter to "POT", in which case the POWER pot will control the K2's power output level even during use with transverters. But more commonly you'll set it to some fixed power level that matches either the transverter's requirements or is compatible with an attenuator between the K2 and the transverter. If you're thinking about trying the K2 with transverters, be sure to read the upcoming application note on this topic to be posted on our website. It should available by July 27th, probably sooner. * * * The next posting in this series will discuss RTTY Mode and Fine RIT. 73, Wayne, N6KR ++++++++++++++++++++++++ Date: Sun, 29 Jul 2001 19:09:51 -0700 From: Wayne Burdick Subject: [Elecraft] K2 firmware topics: RTTY mode and FINE RIT This is another in a series of postings about the new K2 firmware (revision 2). * * * RTTY Mode The revision 2 K2 firmware has some new features that should be of interest to anyone using data modes. The most noticeable change is that there's now an optional fourth basic mode: "r" (for "RTTY"). (We considered calling it "d", for DATA. But there's a purely aesthetic reason for using "r": this lower-case letter occupies only the bottom portion of a 7-segment display character, allowing us to put a "bar" over the "r" to indicate RTTY-reverse mode. The lower-case "d" has an ascender, meaning a bar can't be added.) RTTY mode really is optional--you have to go into the new secondary menu and turn it on. Once it is turned on, the MODE switch will cycle through four modes: CW, LSB, USB, and RTTY. When you're in RTTY and RTTY-reverse modes, the transceiver operates essentially the same as it does in LSB and USB, respectively. However, you'll now have four new filters that can be independently configured for data/RTTY use. CAL FIL is used for this, as usual. Pressing CW RV switches between RTTY normal and RTTY reverse. One subtle benefit of this is that you can now re-claim all four SSB filter settings for SSB voice. You could, for example, use OP1 for all four SSB settings, altering the BFO slightly on FL2, FL3, and FL4 to simulate a "discrete" version of passband tuning (or I.F. shift). But back to data/RTTY: having four filters means you can set them up optimally for any type of data operation you do. The SSB filter (OP1) as well as the variable-bandwidth CW filter can be used for RTTY-mode filters, and of course the BFO offset can be set according to your desired pitch. Speech Compression Settings In addition to the four filters, RTTY mode provides a separate speech compression setting for data use. When you have RTTY mode selected, the SSBC menu entry changes to "SSBCr". You can then set a reduced compression level (typically 1-1), which may appropriate depending on what modulation mode you're using. Fine RIT In some modes, such as PSK31, even a small shift in receive frequency when you switch from a wide to a narrow filter can cause loss of signal lock. The Fine RIT feature allows you to reduce this shift to typically just a few Hz. To use Fine RIT, you first tune in a signal using the wide filter (FL1 = OP1), then switch to a narrow filter (FL2-4) and turn on Fine RIT by holding XFIL and RIT together. The RIT control will then adjust the pitch of the signal only when the *narrow* filter is selected. Both the OP1 received signal pitch and your transmit frequency remain unchanged. New LCD messages and annunciator behavior are provided to help you keep track of the Fine RIT setting. Additional details on using Fine RIT will be posted on our web site shortly as an application note. * * * The final topic in this series will be odds and ends--a few miscellaneous new features available in the rev 2 firmware. 73, Wayne, N6KR +++++++++++++++++++++++ Date: Thu, 02 Aug 2001 16:38:16 -0700 From: Wayne Burdick Subject: [Elecraft] K2 firmware topics: various new features This is the last in our series of postings about the new K2 firmware (revision 2). * * * In addition to the major features new features (computer control, transverter bands, RTTY/data mode, and one-touch CW messages), the K2 rev 2 firmware includes a number of other useful enhancements. I'll touch briefly on each of these. Squelch Squelch ("SLCH" in the secondary menu) can be turned OFF (default) or set to a level between 1 and 10, corresponding to bargraph S-meter levels. While not as commonly used on HF as it is on higher bands, squelch can be very useful if you're waiting for someone on frequency. Examples include a sked, contest activity (like a QRP contest on 7040 or 14060), or maybe a broadcast station that comes on the air at a certain time. Or you might just sit on, say, 24936.00 MHz and announce to the world that it's your personal calling frequency ;) A signal over the squelch threshold will hold the receiver open for a minimum of 4 seconds. Transmitting holds squelch open for about 10 seconds. Extended RIT/XIT ranges Using the "RIT" secondary menu entry, you can now select one of four RIT/XIT offset ranges: +/- 0.6, 1.2, 2.4, or 4.8 kHz. The default is +/- 1.2 kHz, which is about right for normal operation. The wider ranges are especially useful for moonbounce or satellite operation where range is more important than frequency resolution. Those who prefer a slower RIT/XIT tuning rate can select +/- 0.6 kHz, as in the original K2 code. (Historical note: the smallest range was originally added out of self-defense when Bob, N6WG, decided the tuning rate was too fast, and mounted an aesthetically-challenged larger offset knob on his K2.) New VFO tuning rates The original K2 VFO tuning rates are 10, 50, and 1000 Hz per step, increasing as you tap the RATE switch. With the new firmware, you have three new options: (1) the original rates but in reverse order; (2) three rates optimized for CW contest operation (20 Hz middle rate rather than 50 Hz); and (3) two rates only (10 and 50 Hz). 8R HOLD mode This mode is intended for CW mode use with external amplifiers or transverters. In the original firmware, the "8R" (8-volt receive) line dropped after every code element. But when 8R HOLD mode is selected, the 8R line stays high approximately for the duration of your specified QSK delay. This can greatly decrease the frequency of relay switching in your amp or transverter. Some builders have extended the 8R line externally using delay circuitry, so this feature could simplify your installation and make it easier to change the delay. Per-band SPLIT/RIT/XIT For certain types of contest operation, it's an advantage to have the K2 remember the SPLIT, RIT, and XIT setup on a per-band basis. You might also prefer this if you do a lot of cross-band operation. This mode can be turned on by setting menu entry "SPLT" to "PER" rather than "NOR". "NOR" is the default, where split, RIT, and XIT are all turned off at power-up and have the same setting on all bands. PF1/PF2 assignments All of the new secondary menu entries can be assigned to PF1 or PF2, as well as the original primary menu entries. * * * The full series of postings on the new K2 firmware will be posted to our web site soon. In addition, you can download the K2 Rev 2 Firmware Manual, which has full details. 73, Wayne, N6KR ++++++++++++++++++++++++++++