Radio W4KAZ Thanks for stopping by the virtual KazShack. Feel free to comment - I often approve them.
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By w4kaz, created on 2009.05.18 at 05:16:06 | last changed on 2010.10.01 at 09:05:34 | So, a long hiatus between band pass filter musings. In Part 1, I laid out several reference sources for band pass filter projects. Part 2 details the decision process, plus some notes on what happened with initial attempts at reproducing the K4VX Filter and NVARC filter projects.
Here I have a bit more detail on each project. After obtaining a small supply of the capacitors specified by the NVARC design, I’ve completed the 40m and 80m filters.
Measurements on the 40m NVARC filter show about 0.8db loss through the filter, with the SWR pass band covering the entire band easily. Outside the band, the SWR rises rapidly above 7.370 Mc, and below about 6.775Mc. That would seem to indicate the filter is resonant lower in the band, but it actually shows about 2 watts more attenuation at the bottom of the CW segment than it does at top of the SSB area.
The 80m NVARC filter also shows about 0.8db of loss through the filter. The SWR is about 1.5:1 across the entire band, and the filter seens to have its sweet spot right near the SSB DX window at about 3.775 Mc. That should prove fortuitous, since it is also where my 80m folded dipole resonates, but it is completely by chance.
These last two filters probably have slightly higher losses than they should due to construction techniques. The cases I had available for their enclosures were not ideal. Their assembly did not allow easy construction by the NVARC guidelines, and the coils are probably mounted less than optimally inside their cases. Through experimentation I found that slight variations in coil positioning had an effect on their insertion losses.
Additionally, the 15m filter began acting up, showing terrible losses. It turns out that in slinging it around the shield had become dislodged and was either in contact with or too close to one of the coils. Re-securing the shield solved the problem, and put the filter back very close to the NVARC spec’d performance.
By comparison, the K4VX set I have show less attenuation. I have K4VX versions for 20m, 40m, and 80m. Both the 40m and 80m filters show very low losses through the filters, both at about 0.3db of loss, only a couple of watts. The 20m version shows losses similar toits NVARC counterpart, in the vicinity of 0.7db. I expect to rebuild the 20m filter from this series using the ceramic caps rather than silver mica caps. It will be interesting to see if the loss figures change.
I have not yet built the 10m and 15m versions of this design, and may not. The attenuation specified by K4VX on these bandsis not as good as the NVARC spec. It might be worth trying the NVARC filter designwith toroids rather than air wound coils. An excellent experiment idea, and the 10m and 15m NVARC design seems to work well as described and reproduced here.
Given the low losses through the K4VX design, I may use that set for the run station, and the NVARC design for the mult station in an SO2R setting. The K4VX design is also physically much smaller, another practical advantage. The NVARC design has a better set of attenuation figures specified, but it will be nice to get actual measurements on the filters before declaring them a better choice. Some actual on-air testing can’t hurt either.
The coax stub project has been placed on the shelf for the moment. It is worth noting that coaxial stubs are probably better described as notch filters rather than band pass filters, as they are designed to place a notch on the harmonic or sub-harmonic frequencies. The book by W2VJN, “Managing Interstation Interference – Coaxial Stubs and Filters”is a treasure trove of useful information. For anyone with an interest in the subject of coaxial stubs, the book is worth every red penny of its price. Add it to your library and you won’t be displeased.
Previous in series: Band Pass Filter Fever – Untangling The Web – Part 2
Next in Series:Band Pass Filter Fever – The Kludgy Switch Box – Part 4.
By w4kaz, created on 2009.05.12 at 06:43:37 | last changed on 2009.05.12 at 06:43:37 | PVRC club members received word from PVRC president Ken, K4ZW, that PVRC will be introducing a series of Webinars on various contest subjects. Jamie, NS3T has a news release posted with a bit more info. Most of the webinars will be available to all contesters, although I suspect there may be a few club internal “stategery” sessions held more tightly to the vest.
I sprung for the original PVRC 2005 “Contest College” DVD, which has a lot of great information on it. Not every subject was a priority interest to me personally(e.g., VHF contesting), but each was well conceived and delivered. Really wanted to make the original PVRC “Contest College” in VA, but could not.
PVRC Contest College evolved quickly beyond the club into Contest University at Dayton Hamvention, and has already been taken internationally by K3LR, drawing on local talent for lecture sessions. Given the hundreds of years experience held in the minds of so many great operators and technical folks, this is a great idea.
A repository of simlar webinars would be a great asset. It will be of greatest benefit to folks who are in rural areas, and not able to get the sort of elmering that can be obtained by joining a club, or who cannot make a long pilgrimage to CTU at Hamvention.
Built it, and they will come….
By w4kaz, created on 2009.05.01 at 06:28:31 | last changed on 2009.04.30 at 12:04:58 | The tree pollen is really flying now. It is thick enough that it looks like a light snowfall or a misty rain when seen with the sun at the right angle. (Ahhhh-CHOOO!)
Pollen must be good for antennas. Two new ones sprouted up over the past weekend on new lines I shot into the biological supports before the kids’ spring break from skool.
I somewhat reluctantly packed up the 15m/10m nested rectangular loops. The support was just too good a height(about 15m/50 ft.) and location to leave it being used on relatively unproductive bands. In its place there is now a 40m dipole that favors the NW/SE directions. A bit of tuning around the 40m band doing A/B comparisons between the new dipole and the old NE/SW dipole showed promising results. The new dipole is much better into 8-land and 9-land. The old is better into 2-land and Europe. For some reason most of FL seems about the same on both. Interesting.
The differences on rx signal strength is more than I expected in a lot of cases. It makes little difference for strong signals, but a lot of difference on weaker signals. Hopefully this will help add Q’s to the contest logs. It also is a bit of commentary on the non-linearity of S-meters.
The antennas are at an almost perfect 90 degree angle to one another. They do not actually cross one another. Looking down from above they form an L shape with the south end of the NE/SW antenna pointing towards the eastern most tip of the NW/SE antenna. Modeling showed ther was little interaction between two dipoles in that configuration, but it seems likely they are not completely invisible to one another. I’m happy with it so far.
40m turned out so well I decided to do the same thing for 20m. The new NW/SE 20m dipole may be somewhat less productive, but maybe it will help to bag AK and NT and BC in the domestic tests. Unlike the 40m pair, these two antennas definitely show a difference in coverage into FL. Over the weekend there was one FQP station that was in the noise on the NE antenna, and peaking at S-5 on the SE antenna. (More S-meter non-linearity?)
The lesson learned here is that a single fixed dipole is leaving gaps in the coverage. The solution is simple. If it is practical to do so, adding a second dipole at 90 degrees to the original will definitely help fill in the holes. It’s not as good as a yagi, but better than a single fixed dipole. A rotatable dipole would also do the job if you remember to turn it. Note: switching between dipoles is a lot faster than a rotator, but coverage is less continuous .
By w4kaz, created on 2009.04.28 at 08:40:54 | last changed on 2009.04.28 at 08:49:33 | Well known contester W4MYA announced the availability of a new radio repair service. Bob and George, KF7NN, have teamed up to form Vetex to provide radio repair services to licensed amateurs’ equipment.
That’s going to be a real convenience. Goochland is only about three hours up the road. UPS ground in one day from here.
By w4kaz, created on 2009.04.27 at 05:09:10 | last changed on 2009.05.25 at 16:05:02 | Spring Fever, Hay Fever, and on the positive side, Antenna Fever.
The antennas are still in somewhat dis-array. But chugging right along in its 9th year of service is the trusty 80m folded dipole. The dipole serving the KazShack is cut according to the cookbook dimensions for folded dipoles outlined in the ARRL Antenna Book. In the ?? edition, the most recent available here, it is the lead off in Chapter 15, Portable Antennas. For those without the Antenna Bible, it was also re-published WITH permission from the ARRL, in the March 2002 edition of the CARC “FEEDLINE” newsletter. See pages 5 and 6.
I didn’t realize it had been in service so long. Given its construction from 300 ohm TV twinlead, I expected the wires to fail. It has required a repair, but that was due to damage from falling limbs. That is a problem with all of the antennas here.
It has occupied two seperate locations. Its first install favored the northwest, and it was really a killer into the upper Midwest, even with just 100w. It currently is oriented favoring a compass heading just to the east of due north. This improved the signals from Europe and the New England states, but is really a compromise.
The wonderful thing about folded dipoles is the hugh SWR bandwidth. The local version favors the CW/80m end, but the 2:1 SWR bandwidth is from about 3580kc to 3800kc. It is still well below 3:1 SWR at the bottom of 80m. It goes above 3:1 at around 3970kc. The internal tuners of both the FT-920 and K2 can bring the match down to 1:1. Sweet.
This antenna is a keeper. The only problem I have with it is that the construction article does not delve deep enough into the theory. I would like to reproduce the antenna using 450 ladder line, but don’t understand the methodology of the matching section well enough to scale the antenna. Hmmm. A conundrum.
By w4kaz, created on 2009.04.24 at 07:44:49 | last changed on 2009.04.25 at 09:37:37 | Ed, N4EMG stirred the mental pot with his recent post about S&P contesting. Since I really have not met a lot of contesters that prefer S&P to running stations, it is difficult to address some of the questions Ed raises.
As luck would have it, contesting S&P with modest antennas is almost the only sort of contesting experience I have. Only in the last year have I begun to mix in runs with my more typical S&P operating. A quick glance at my scores by year page show only a couple of contests with 500+ QSO’s. 2006 Sweeps is a good sample of my best mostly S&P effort. It’s also one of the few contests I have kept my BIC for most of the duration.
Beyond that, there is not a lot of information you can use as a comparison. Unless you know the type of station someone uses, it is difficult to make comparisons. Even then, the differences in geographic location, amount of time operated in the contest, antenna height and quality, and operator skill level all come into play. Operator skill level is a tremendous factor. A good operator will run rings around a less experienced op. “Butt In Chair” factor is therefore not limited to the current contest, but is also a cumulative factor. There is no substitute for experience, and that is not unique to contesting.
Contesters seem to migrate away from all S&P fairly rapidly. Many begin that way when first discovering radiosport, although I suppose some jump in and start running right away. Folks come to the point where they realize(as Ed has) that running is the best way to increase rate. Some of the good operators will do all S&P when they are time limited, but even then most folks seem to prefer running. So the data on “all S&P” operating would be further limited if it were available at all.
Power level matters. Running with low power is a challenge. But if you want proof that good scores can be done successfully with low power and modest antennas, I’d refer anyone to look up some of the scores posted by N4YDU. Nate is a run operator, S&P’ing less often, but he is a great op and can rack up QSO’s. He has operated HP a few times, but most of his scores are in the LP category. There are also no tall towers at N4YDU. Nate has a tri-bander at about 30 feet, and a lot of various wire antennas. “Various wire antennas” because Nate likes to try out different things, including dipoles, doublets, loops, half squares, etc.
For low power, CW is the mode to concentrate on. A LP op will have more punch on CW, and better luck holding a run. But don’t expect to be able to hold a run forever with LP and modest wire antennas. There are a lot of HP stations that will see you spotted and squat only 100hz above you to poach your run fq. There are some who won’t even allow the dignity of the 100hz offset. (I have a name for those sort, but it is not suitable for refined company;) Sometimes it is worth dueling, sometimes it is just time to move along.
I personally enjoy S&P operating more than running stations. S&P is fun because it keeps me focused. My best single hour rates are just under 60 QSOS/hr on SSB, and 49 Qsos/hr on CW. The ten minute rate can and does often go higher, but I find it hard to tune, copy, and dupe check much faster than that. Better ops can S&P at higher rates, but their time is better spent running. This is probably why So2R has appeal. When runs slow down the second radio keeps one from dying of boredom in a rate productive manner. Reading a magazine seldom translates into QSOs.
I also find that rate is easier on SSB, when conditions are good. Better CW ops may find just the opposite. Probably everyone would agree that good conditions make S&P a real blast. Except for those that hate S&P.
S&P is really fun when three or four bands are open at the same time. 10m is also fun when it opens. On 10m SSB the bandwidth is so large that by the time you have finished the first S&P pass across the band and start a second pass, all of the run stations might be new ones. That is fun, and I sure hope it happens again. The sooner the better!
Other ways to improve S&P rate are by using packet spots and making use of the temporary memories, if your logging software supports them. I use the memories for those juicy mults/DX. Writelog has three. I generally load two stations needed in the first two memories, and the current frequency into the last. Then I can toggle back and forth between then using mouse clicks as if they were spots.
Even when not connected to packet, using the band map window to load Q’s is useful. By loading a station into the band map, I get to see a “preview” of who might be there when I scan through the second and third times.
A lot of the QRP and LP stations have good antenna systems. QRP is a challenge of a different sort for them. Great antennas are better than QRO, because they work on receive too.
Just some ideas, some of which you already have probably either used or seen elsewhere before. However you choose to do it, concentrate on the fun first. That’s the motivator for everything else.
By w4kaz, created on 2009.04.17 at 06:57:44 | last changed on 2019.04.19 at 17:13:28 | The current plan is to incorporate a SixPak into the antenna switching scheme here in the KazShack. The SixPak is to help enable an exploratory foray into SO2R operating.
It would also be useful to have the ability to use more than one resonant antenna on a given band. For example, the station is currently limited to a single dipole on 40 meters. It would possibly be helpful to have another dipole at right angles to the first. This would likely help bring up stations that are off the ends of the current dipole. It might be even more helpful on 20m where the antennas are higher relative to the percentage of the bands wavelength.
So a quickie two antenna remote switch is in order.
 Two Position Switch  W4KAZ Switch
The requirements are not critical for my low power application. It is simple enough. The relay is the P&B RTB14012F, a SPDT relay rated at 12A in its normal general purpose AC applications. This series of relays has been in use in my seven position switch for a couple of years now, and is in the same series of relays used in several high power switch project articles from NCJ. In this specific switch there are no losses that are measurable up through 6m. This was tested only with an ordinary watt meter into a dummy load, and applies to either output port of the switch. So far so good.
The only other components are a clamping diode, a 10nf bypass capacitor, a few bits of hook-up wire, and three coax connectors. The diode and the cap go across the coil on the relay to suppress nasty RF side-effects on the DC side of the circuit. The enclosure was easily the most expensive item. Total cost is about $12 USD. The 12v control cables are potted with hot glue. The enclosure is not water tight, but the switch will be mounted in or under a rain shield. The relay itself is sealed, so insects might be the only issue should they infiltrate the enclosure.
The switching controls are going to be in a yet to be determined integrated panel. That will add to the cost by the amount of the switch which will be mounted in the control panel. Cat5e will be used for all control cable runs.
I expect to place this puppy between the SixPak and the 40m antennas. Coax stubs for 40m will connect the SixPak to the two position switch. The default position(switch off) will be the primary antenna facing NE/SW. There will not be a grounded or unused position, as lightning protection will be added at the “radio A/radio B” positions of the SixPak. That arrangement will keep the radios isolated from one another via the SixPak, and unable to simultaneously select antennas resonant on the same band. (maybe….depends on the antennas used for the other bands, aina?)
With the addition of one relay and one extra control wire, it is easy to make a similar three or four position switch.
Sometimes simplicity is good, or as in this case, “good enough”.
By w4kaz, created on 2009.04.10 at 06:12:02 | last changed on 2009.04.10 at 09:28:50 | Scores for the 2008 CW Sweepstakes have been published on the Web. The Sweepstakes LCR report is always worth looking over, since my error rate is still far too high on CW. For 2008, it looks like 44% of my errors were on the check number. The errors on the exchange was about 45%, and I busted only four callsigns. The score suffered dramatically, but I showed some incremental improvement over the 2007 Sweepstakes. I didn’t match the improvement in error rates I managed in the 2007 IARU, but it was better than the error rate of the 2007 CWSweeps.
The callsign copy needs to be 100%, but I made progress in that area over 2007.
The big problem seems to be busts on 7&8 and 2&3. Not a surprise. That mistake is accounting for the bulk of the cross check number busts. It is also the biggest problem in the exchange busts, where the year license is busted because of 7&8 or 2&3 busts. By correcting this copy error I will clean up almost 80 percent of my over all bust rate.
The other remaining errors are a mixed bag. There are several transposed digits in year licensed(e.g., where I logged 67 instead of the correct 76). This is a typing dyslexia that I often can catch as it is happening. So more attention to detail is needed when typing.
The rest are just generic inexusable errors. The callsign busts are fixable. “agn? ?”
Overall, I’m disappointed in the lack of overall improvement in clean copy. The score suffered mightily. But it still holds up as my best ever CW score, despite the inadequate copy. Besides, it was a blast.
K8AC, AA4NC, and N4AF all won their categories here in the Roanoke Division. Cool.
By w4kaz, created on 2009.04.09 at 06:22:12 | last changed on 2015.03.17 at 09:48:32 | Engineer the possible. The “best” is too often the enemy of “good enough”. Â If you wait until you have “The Best”, you may miss out on a lot of operating. Â Â Better to aim for “the best POSSIBLE”, i.e., what can be accomplished within the constraints of resources and time frame available.
The recently completed W4KAZ SO2R box is going to be something “New” in the KazShack. But the choices made in building it are all “old” technology. It is a case of engineering the possible.
This has been a project that I have flipped and flopped on. The choice made was based on practicality rather than “the best” approach. The best approach would have been to utilize a new computer and the USB rather than the LPT port. That choice implies using some of the newer CW keying technologies(Winkeyer or Microham). O’course, that would also entail blowing a couple of thousand dollars on the new off-the-shelf hardware, none of which is currently on hand. This approach I characterize as “New Hotness”, per Agent K from MIB. So, where do I get a couple thousand dollars I can divert to this frivolity? (Answer: convince Number One Son to join the Navy rather than go to college? Didn’t work…)
The alternative is to see what can be accomplished using “Old and Busted”.
It turns out that practically speaking, “Old and Busted” is perfectly serviceable, even if it is not quite so much fun as “New Hotness”. New Hotness certainly has an advantage in the effectiveness of generating the CW in a seperate piece of dedicated hardware. Nice, but not essential. New Hotness also uses current technology. Also nice, and also not essential.
The fact is that Old and Busted can be designed to competently and reliably perform the essential basic tasks required:
- Key the CW
- Control the radio TX focus
- Provide the band data or pass it along
- Be easily home brewed [!!!!!the most important criteria!!!!!]
- Be easily modified as needed/wanted/for experimentation
Even better yet, “Old and Busted” can be cobbled together very inexpensively relative to New Hotness. For my own part, the cobbling together is tremendously more satisfying than waiting for the postman or UPS truck for delivery.
O’course, price is also a big factor. But I have not found any home brew solutions utilizing USB. A hybrid solution could be derived by using the PIEXX SO2RXLAT device to convert USB to LPT type data. That seems like a workable bridge between old SO2R hardware and new computer tech. Possibly not ideal, but very plausible, and very attractive for those with money already invested in LPT hardware.
So, “Old and Busted” wins. Since I don’t like N1MM logging software, I don’t NEED a better shack computer. I can get by with a clunky old Win 98 box running good ole Writelog. Relying on an old CPU could be a reliability issue, but old CPU’s are free for the taking, and I already have several backup boxes on hand. The old boxes all have LPT ports, which is the approach that seems simplest for home brew of an SO2R box. A single LPT port can be configured to carry the CW, PTT, radio A/B switching, and also carries the band data for one of the radios.
So, Old and Busted wins out, at least for now.
Besides, I just can’t get my head wrapped around “needing” the latest-n-greatest technology for CW contesting. Really? Because CW is so cutting edge? Really?
It may all be moot. I may get the whole kit assembled and decide I don’t want to operate SO2R after trying it out. By going the old an busted route I have at the very least learned a lot by cobbling together several design ideas into a custom solution. That hands on education has more value to me than the cost of the New Hotness hardware. So even if I put the new toys aside after light usage, I win.
Engineer the possible. If you wait until you have “The Best”, you may miss out on a lot of operating.
By w4kaz, created on 2009.02.24 at 05:51:15 | last changed on 2010.10.27 at 13:15:47 | Okay, it is pretty minor, but in listening to the K5D pileups last week, I figured out that the K2 is less user friendly for chasing splits than the FT-920. Even though the second VFO on the 920 is not a genuine second receiver, it is a lot simpler to use than the K2 for hunting down the guy the DX is working. So the 920 is definitely the first choice for hunting DX. The close in capability of the K2 is not as important when the DX is working split. But the ergonomics of using the 920 is so much easier for split DX hunting, it will take a lot of effort to adjust to the K2 ergonomics.
🙁
I guess the solution is to buy a second K2. 🙂
But that’s not going to happen with the first college tuition check for the eldest only months away. Until that is behind us, I’ll just need to use the 920 for SWL’ing and some DX’ing. And SO2R, if I ever get geared up to practice that.
And of course, the K2 can’t get WWL during LSU football season. We won’t count that as a demerit since it was not designed for that purpose.
– more – at the K2 Impressions page
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