Sunday, December 13, 2009
Saturday, December 5, 2009
One thing I forgot to do is swap out the AC line fuses when I re-wired the amp to run on 120 volts. It *will* draw more than 10 amps when run full tilt, and the manual specs a 20 amp fuse when running off 120.
Having said that, I don't have sufficient power in the shack to run the amp right now. I had a talk with an electrician about running 220 out to the shack, and it doesn't look too hard - run some SO cable, which is rated to be out in the elements, bring it to a junction box, and install a wall outlet.
Sunday, November 29, 2009
Band QSOs Pts Cty ZN
1.8 1 2 1 1
3.5 16 41 7 9
7 81 209 31 19
14 13 35 5 6
21 20 53 11 10
28 2 6 1 1
Total 133 346 56 46
Most of my operating was overnight, when the kids were in bed, but I did get to spend some time on 20, 15, and 10 during the day. I got six new countries, which brings my DXCC worked count to 114:
Barbados: 8P5A and 8P9SS
East Malaysia: 9M8YY
Costa Rica: TI5N
And, although this wasn't a new country for me, as I have it confirmed from 1977, I worked Senegal, 6W1RW on 40m.
I'm just amazed at how many of the stations along the east coast of Europe and Africa were able to copy my 100 watts and a dipole (Madeira Island, Canary Islands, Senegal, Galapagos Islands, Portugal)
Here's the complete list of all the different countries (34 total):
Bonaire, Curacao (Neth. Antilles)
British Virgin Is.
Turks & Caicos Is.
United States of America
Monday, November 23, 2009
As it turned out, I made exactly 200 QSOs, and got 57 sections, almost all on 40 and 80, plus a few when 20 opened in the AM:
Class: SO Unlimited LP
QTH: Mountain View, CA
Operating Time (hrs): 9
Total: 200 Sections = 57 Total Score = 22,800
Club: Northern California Contest Club
K3 barefoot, G5RV inverted vee at 60 feet.
Family obligations kept this to an overnight effort.
I actually had a nice 20-minute run on 80, working mostly other NCCC members. And, for the first time, I had someone deliberately QRM me. How flattering! I thought I wasn't loud enough to be a target!
But listening to the recording, I have some opportunities to crispen up my phone contesting. I tend to say "QSL," "you are," and "number" when they aren't really necessary, and the pace of my recorded exchange seems positively glacial compared to some of the better operators. On the bright side, I read numbers correctly, giving each number individually, and can more or less type and talk at the same time.
So between the CW and Phone weekends, I contributed 122,640 points to the NCCC club score. This was an improvement of 96,994 points over my scores from last year (4.75 times as many points).
Thursday, November 19, 2009
Friday, November 13, 2009
Wednesday, November 11, 2009
Listening to this, what strikes me is:
- How little traction I got calling CQ.
- How often I got an answer on my first S&P call.
- How lazy I was moving between S&P opportunities, or moving on after I didn't make it on the first call.
For SS SSB, which will probably be an all S&P effort on 40/80, I'd better keep moving faster.
Monday, November 9, 2009
Callsign Used : KM6I
Operator(s) : KM6I
Class: SO Unlimited LP
Name : Gordon Good
City/State/Zip : Mountain View CA 94040
ARRL Section : SCV
Club/Team : Northern California Contest Club
Software : N1MM Logger V9.10.3
Band QSOs Pts Sec
3.5 133 266 26
7 189 378 49
14 250 500 3
21 52 104 2
Total 624 1248 80
Score : 99,840 (yes, I missed 100k by one lousy Q)
Rig : K3 barefoot, WinKeyer
Tïme: 22 hours
Antennas : G5RV inverted vee at 60 feet, 2-el triband wire yagi at 35 feet
My goal for the two SS weekends this year is to beat my CW score from my first SS in 1978 (303 Qs, 57 Mults, 34,428 points), and make KB-500 between the two weekends. I actually reached both goals this weekend
My wife gave me the whole day off Sunday, so my plan was to get the kids to bed on Saturday, then operate from 0500Z until the end of the contest for a total of 22 hours of BIC. I wasn't sure how motivated I'd stay, as I recall getting pretty tired at some of the W8UM multi-op SS efforts in the 1980s, but it turned out to not be a problem. After 300, I got motivated to hit 400, 500, and then 600.
I was also surprised to find that by the time I came off the low bands and went to 20m for the first time at 1400Z, I already had 75 mults. I guess 40 and 80 were pretty good! I hadn't given any thought to trying for a sweep, but once I was that close, I started paying more attention to the red in the bandmap.
The "secret weapon" for me this year was a homebrew 2-element triband wire yagi, fixed at 70 degrees. I found the design in a back issue of QST (link: http://www.arrl.org/tis/info/pdf/0111035.pdf). The thing worked great - east coast stations were 1 or 2 S-units louder on receive, and I felt loud - often I'd come out on top when several stations were calling. I was able to work MAR with just a few calls (I did wait for the pileups to calm down a bit before I tried, though).
Here's a better picture of the wire yagi:
And this was my first contest with my new K3. It held up well. It got a good workout too, as my neighbor W6XX (5,000 feet east of me) was on and was 60 dB over S9. I was able to work stations a few kHz away from his run frequency - it wasn't easy, and I knew he was there, but I could do it. I also just love the K3's QSK, and the single knob for controlling both the DSP filter width and roofing filter selection. Get the station dialed in and twist the knob to the left until the QRM goes away.
I found that I was able to find a run frequency on the upper edge of the band and run for a while, but after 10 or 20 QSOs, things would dry up. I never got spotted on the cluster, but that's probably because I was up so high in the band and didn't hang around long enough.
Another strategy I used was to "bandmap surf" a few spots I hadn't yet worked. By that I mean I'd click on unworked spots up and down the map until I found one just about to finish a contact. It was more time-efficient than clicking on one and waiting for the current exchange to finish. I did tune and spot stations as well, however.
And my plans to use the K3's subreceiver to do SO2V S&P didn't come to fruition. I'd practiced the mechanics of switching from the run to the S&P frequency and logging the contacts, but I wasn't prepared for the aural onslaught that is a contest. I just lost all confidence in being able to pull it off, so I turned off the KRX3 and only used it when a rare mult went split. Maybe next time...
It was also nice to finally work Scot, KA3DRR in a contest, and to run into my W8UM acquaintance Steve, K8QKY, running stations on 20. I was looking forward to, but missed working Tim, KT8K.
Saturday, November 7, 2009
http://www.arrl.org/tis/info/pdf/0111035.pdf (ARRL members only)
I need to pull it up a little higher, but when I'm done, it'll be in a sloping configuration, with the feedpoint at about 35 feet. Just listening around 20m now, it's a really significant improvement to the east coast - a W2 calling CQ was down in the noise on my G5RV, but was much better copy on the beam.
If the antenna performs as expected, this should give me about one S-unit improvement at a heading of about 70 degrees.
Friday, November 6, 2009
SSCW Practice, 11-6-2009 (10mb mp3)
Thursday, November 5, 2009
- I'm pretty comfortable with basic operation of my new Elecraft K3. I can do all the things I *think* I'll need to do to the radio during the contest: tune either VFO, adjust the filter bandwidth, adjust receiver audio, use RIT. Other stuff I need to do via the computer: turn on/off subrx, log, etc. I think I'm good to go. The manual is handy if needed, though.
- N1MM logger is set up reasonably well.
- I've practiced with the SO2V support in N1MM enough to believe I can tune around for S&P QSOs while CQing. The KRX3 has some restrictions about which bands it can be on relative to the main RX that may make it hard to do multi-band SO2V in the heat of battle, but I'll see how I do. If all else fails, I can abandon SO2V (so I'm not "Single Operator Distracted").
- The Secret Weapon (2-el triband wire yagi) has been built and tuned. I just need to hang it from the tree Fri or Sat, and I should hopefully be one S-unit louder at 70 degrees.
- And last but not least: the shack is CLEAN (it was a real pig-sty last week):
The overall goal is to make 500 contacts between the CW and SSB weekends, although now that I've secured 22 hours for CW, I think I should raise the bar a bit.
Still to do:
- Get all the Butt-In-Chair support ready, which I think will be: energy bars, water, ham sandwiches (no pun intended - I often crave them*, a pot of coffee, and some leftover Hallloween candy for late in the contest.
- Look over W0YK's packet spot filters and figure out how to use them.
- That's a Yaesu FT-857D next to the K3 (in case a meteor lands on the K3 during the contest).
- The WinKeyer and paddle are to the right and behind the wire inbox tray.
- No, I don't have an amplifier (yet).
- Yes, the shack is narrow: the room is 5 ft by 10ft. It's a little room at the back of a detached garage on our property. I like to think of it as "cozy."
Wednesday, October 28, 2009
Thursday, October 15, 2009
I isolated just the high-speed part: listen
and slowed it down 4 times: listen
It sounds to me like he said "SD5AE". Huh?
And on 17m today: listen
Just the high-speed part: listen
Slowed down 4 times: listen
That one sounds like "RL-R"
Tuesday, October 6, 2009
- My first 300+ QSO contest (in 9 hours, for an average rate of almost 35/hr)
- A new one-hour rate record - 65 contacts
I was able to get a few nice runs going, and even managed a run of 7 contacts on 80 meter phone, which I would have never thought possible with 100 watts to a dipole at 60 feet.
- It was really instructive to listen to the real pros like K6XX and N6TV. I'd love to be a fly on the wall of their shack while they're operating.
- I couldn't believe it when I was running on 20 CW and was called by DL5YM.
- My best hour wasn't solely running - there was a lot of S&P as well, so I'm apparently getting better at S&Ping quickly.
- I was only called by 2 dupes the whole contest. I was pretty impressed with the quality of the operators.
Wednesday, September 30, 2009
Tonight, I got N1MM set up for CW, and got my Heil BM-10 out of storage and hooked up (that tells you how much I operate phone...). I think I'm pretty good to go, and excited about the contest.
Hope to see you in the CQP. I doubt Santa Clara County will be that rare (you can hardly throw a stone without hitting a ham here), but I hope I can provide it on a unique band/mode for you.
Friday, August 28, 2009
Later, it's clear that 20m is nice tonight. I was working into Russia with no problem. If this is how things are with no sunspots, 100 watts, and a dipole at 60 feet, I can hardly wait...
Wednesday, August 12, 2009
The biggest challenge was taking down a Hy-Gain 18-HT Hy-Tower vertical antenna. It's 53 feet tall, with about 24-feet of triangular aluminum tower and the remainder aluminum tubing.
Here is Dan, W7DR, and Barry, K6RM, planning how to approach the problem. As it turned out, this older version of the antenna didn't have a hinged base. Originally, we'd planned to climb the tower and pull the sections off with a gin pole. However, we eventually decided to "hinge over" the tower at the base and allow the legs to deform a bit. This worked out quite well, and it meant that the only climbing we needed to do was to loosen the tubing portion and drop that down inside the triangular tower portion to reduce the height (and leverage required).
The Hy-Tower after tilting it down.
With the antenna tilted over, we were able to detach the last two bolts in the base and walk it away from the base. The triangular tower portions all disassembled easily. Getting the tubular portions apart required a bit of drilling, but eventually it all came apart and was on its way to a new home in the central valley!
W7DR and his new (old) vertical.
All snug in the truck bed.
Sunday, August 2, 2009
As it turned out, I was able to escape for about an hour and 20 minutes during the day, and was able to fiddle around on 15 and 20 (and even on 10 for 2 QSOs) while they were open. I think my S&P skills are improving, and I made 46 contacts on the high bands between errands in the house.
After my wife and I got the kids to bed, I headed out to the shack to focus for the last two hours. I was really happy with my antenna's performance on 40 m. I felt loud, as I was answered first a few times when there were multiple stations calling. I was even able to call CQ and keep up about the same rate that I'd been doing S&Ping across a band full of fresh meat.
The only badness happened near the end of the contest. I miscopied a callsign while S&Ping, and went to correct it after the QSO. I noticed that N1MM started to act strangely after that - the input window was colored light blue, and it didn't seem to be reporting dupes by changing the callsigns red. Well, I had managed to put things into "quick edit" mode, and didn't realize this until I'd made 10 contacts. The problem was that it logged everying with the same time and frequency, even though I'd changed bands. D'Oh! I emailed the contest organizer after I'd submitted my log, and exlpained the QLF. Hopefully, they can keep the stations I worked from getting penalized for my error.
On the plus side, the 153 raw QSOs in 3 hours 20 minutes was a personal best for me as far as rate goes, and I was really starting to feel a lot more confident in both S&P and run mode.
Thursday, July 30, 2009
Oh, and if I didn't mention it before, the G5RV apex is at 58 feet now (I say "60 ft" or "20 meters" on the air, but what's 2 feet between friends?). Having the antenna 38 feet higher than the old antenna, plus not having an S9+ buzzsaw in the neighbor's garage really helps with the DX!
Thursday, July 2, 2009
The ops were in an old abandoned trailer (phone station), a tent (GOTA station), a Van (VHF station), and a tent (CW station - my post for the night). The old abandoned trailer was really freaky - it had three well-rendered pictures of the Daili Lama, and also some really scary gang graffiti ("187" - CA penal code for homicide) in this very remote location. I found that juxtaposition... interesting. I climbed into the trailer and watched as the op (sorry, don't remember your call) was doing about 150 qso/hour on 20 meter SSB at midnight (!).
I went over to the CW tent, and found John Miller, K6MM, at the controls of the CW station. Since it was way before I was scheduled to start, and I didn't want to mess with John's fun, I said hello and continued wandering around. Next to the CW tent was another building. It had cement walls, one tiny window, and inside were a bunch of large concrete slabs, piled hapharzardly. I also some some very old telephone interconnects, and some old AC wiring. And more scary gang graffiti.
Talking with some of the club members later, I learned that the site had been some sort of a communications site for Moffett Airfield (down in the valley, near where I live) during WW2. It had been abandoned at some point, and was now used by CalFire for rescue practice, which explains the large slabs of concrete inside the buildings.
Finally, at midnight local time, I took the helm of the K6SA CW station. I started out on 40m CW. I did a few S&P QSOs to get a feel for the band, then worked on finding a run frequency. I'd never used the rig (Yaesu FT-1000MP) before, so I tried to find a relatively quiet spot using the wide filters (2.0k), then used the 500 Hz filter while actually running. I tried to only use the 250 Hz filter when doing S&P on a weak station.
Kelly, N6KJ, had the logging set up such that the CW and Phone stations were networked together, so I could see every time the phone station logged a QSO. It was fun, because I could see that I was running a bit less than half the 20m phone stations rate, but I was getting 2x points per QSO. It was sort of a rabbit to chase.
Once I'd found a run frequency, things were lumpy - I'd call CQ for 2 minutes with no takers, then I'd run 3-4 stations in a row. As someone who's run contests with low dipoles and 100w at sea level, it was a relatively big gun experience to do 100w into dipoles on a 2000' ridgeline. My one regret is that I didn't try running on 20 CW, since the phone station was doing so well there. I was concerned that 40 and 80 were full of fresh meat, so I focused on those.
Rate steadily dropped during the night, and I did my share of QLFing Writelog. I gather the cursor position and the number of completed fields affect how enter-sends-message mode works, but it also interacts with run mode, and there were a number of times where I wanted to send an exchange, but sent "TU K6SA FD" instead (well, I usually hit escape before all that got sent). As an N1MM user, I was a bit mystified.
We also had a lot of RF in the headphones, despite a big-ol 31-mix ferrite on the cable. At one point, the FT-1000MP and the Winkey simultaneously zizzed out, requiring a hard reset of both. That only happened once, however.
Around 4:30AM I saw some hints of sunrise, and persevered on 80 meters despite a very low run rate. I'm hoping I made 150 QSOs during my 5-hour shift. I drove back down the mountain and got home at 6:30 am, just in time for my kids to wake up, and I made some breakfast for them (my wife was asleep, but she took pity on me and let me sleep for an hour after they had breakfast).
Many thanks to the Saratoga Amateur Radio Association for this great opportunity to operate!
Addendum - May 2010
K6SA placed 65th out of 2603 overall entries (top 2.5%) and 15th out of 440 entries in the 2A class (top 4%).
Thursday, June 11, 2009
That same night I worked a DL - it brought back some memories of working Europe from our QTH in northern Ohio where I grew up.
In contrast, I would have been really excited to work the South Pacific from Ohio. From here in California, it's not that hard...
Thursday, June 4, 2009
Unless we've had a resurgence of ham activity lately, my only conclusion is that the noise level at my new QTH is way, way, WAY better than the old one. There, on a typical weeknight, I could only hear a couple of CW and maybe 1 digital QSOs above the S7-S9 noise.
By comparison, I'm hearing AC2K in Redmond, WA, and he's S8 on this underground antenna, while the background noise level is S0 or S1. I'm getting excited!
As it turns out, I climbed up 58 feet before I chickened out. That's not quite the 1/2 wavelenength on 40 meters I was hoping for, but it's close enough. And I think whatever is up there will work a lot better than the G5RVjr at 22 ft.
Friday, May 15, 2009
Sunday, April 12, 2009
Friday, March 6, 2009
It's a bummer, but on the bright side, if we close on the new house and sell our current house, I'll have a 13,000 sq ft lot to work with (about 75 ft wide by 175 feet deep), and there are a couple of 75-foot tall redwoods.
Thursday, February 12, 2009
When I went to model this using EZNEC, I tried to build a model with two inverted-Ls, one cut for 80, and one for 160, fed from a single feedline. Try as I might, I couldn't find a combination of lengths that resulted in resonance on both bands at once. So I decided against trying to feed all the antennas at once, and started planning a remote antenna switch.
Now, about a year ago, I did a bang-up job of making a trench across the yard, so I could run the feedline underground to the tree (otherwise the coax would need to lay on the ground and pose a tripping hazard). Unfortunately, I only ran a single feedline, and I am not digging that thing up!
So I started looking for a remote antenna switch where the power was fed to the switch via the coax. The hard part is finding one that can handle three antennas. With a DC circuit, you've got one "bit" of information - power on or off - to select an antenna, and that's only two. Every circuit I could imagine was fairly complicated - using voltage levels to select antennas, or some sort of pulse-counting system.
Finally, I happened upon a design in the ARRL Antenna Book that uses 12 VAC at the shack side. Imagine an AC-DC rectifier, with half in the shack, and half out at the antenna. The original design has two independent relays. One actuates when the positive-going AC is put on the wire, and the other actuates when the negative-going half is put on the wire. When a complete sine wave appears, both relays actuate. The design in the ARRL book is a little skimpy on details (e.g. the value of the RFC chokes aren't specified) but I found an article in the QST Archive that had a similar circuit for delivering DC voltage an a coaxial cable, and it gave recommended values (as well as instructions on how to modify a widely available Radio Shack choke to have the correct value).
I reworked the design a little so that with an SPDT switch with a center-off position, I can actuate no relays, one relay, or both relays, and then wired the relay contacts together so that I have:
- Power off (center) = both relays off, antenna 1 selected
- Switch in up position = relay 1 engaged, antenna 2 selected
- Switch in down position = relay 1 and 2 engaged, antenna 3 selected.
I built the relay box into a waterproof plastic electrical conduit box, and sealed all the SO-239 connector holes with coax-seal. This thing should last a long time, I hope.
Now I'll be able to switch between 160, 80, and 40 for this weekend's WPX RTTY contest without going out in the rain!
Sunday, February 1, 2009
Front view of house TGM MQ-34SR and G5RV
This is my planned antenna system, barring any major snafus. It's a TGM Communications MQ-34SR mini-beam for 20/15/10 meters, with a G5RV mounted just below the rotator.
I selected the mini-beam because it's about all I can fit at the rear of the house, where I've only got 11 feet of space to the fenceline. A tower on the side of the house would allow for something bigger, but we may be remodeling or moving, so there's not much point in building something permanent. At best, I would need to abandon it if we move, and at worst I might need to take it down, if we remodel.
Tuesday, January 27, 2009
I still have my grandpa's bug - a 1917 Vibroplex. I sure wish it was in this photo, but I just can't seem to see it.
I wonder how big a deal it was for grandpa to give me his bug? It would have been around 1976-1977. At first, I thought maybe telegraphy had been long gone by that time, but this post says "and I had just begun as a small boy to recognize Marshfield's call letters of "SF" when the Soo Line pulled out all the Telegraphs in the early 1970's. " I can't help but wonder how big a deal it was for him to give me his bug? It certainly meant a lot to me, and it got a lot of use in my novice/general shack in the late 1970s.
P.S. If any blog viewers can identify the equipment in this photo, I'd love to hear from you.
Interestingly, the same day that I stopped hearing the noise, I visited my neighbors and checked in with them about any RFI they'd been experiencing (their living room is about 40 feet from my G5RV). I'd operated in the NAQP SSB contest the day before, and they noted that they'd heard some RFI coming out of their subwoofer ("it sort of sounded like Vietnamese").
I explained that I'd been operating using a different transmission mode called single-sideband, and that the sound they'd heard was probably me. I also explained that there were some things they could do to eliminate the problem, especially reducing gthe length of cable going to the subwoofer, using some sort of twisted-pair cabling, and using some special devices (RF chokes) to eliminate the interference. I gave this speech a bit half-heartedly, since they're renting while their house is being renovated, so they'll be moving out in a few weeks anyway.
Now, these are really nice people, and have been great neighbors, so I decided to mention to RFI coming from(I think) their garage - who knows who's going to move in next? And if the noise-generating device is part of the rental, now would be a good time to figure out where it is so I can contact the property owner about fixing the problem.
The reaction was very positive; I was invited to look around, inside and out, and I looked for possible RFI sources. While walking around, I described the problem I was having, the hours I heard the problem (about 1600-2300 local time) and made a point of explaining that I could hardly hear anything on my radio while the noise was happening.
I didn't see anything obvious, so I explained that, if the subwoofer RFI was a problem, I'd solved a similar problem with my son's stereo, and I'd be happy to advise them on a solution, but more likely, it wouldn't be much of a problem before they moved back into their remodeled house.
Now, a week later, I've not heard any significant noise problems on 80 or 40 in the evening hours. Last week, I had a very pleasant experience operating in the CQWW 160 CW contest. And tonight, when I tuned around 160, 80, and 40M, the highest noise level I saw was S4-S5.
It could be a coincidence, but I suspect my talk caused my neighbors to turn off some piece of electronic equipment that was radiating noise. I need to check in again and see if this is the case (and thank them!).
After the kids went to bed, I was still mostly awake, so I played for about 2 hours, took a break, and finished with another 45 minute stint. All S&P, I made 80 contacts in 2 3/4 hours (79 after my duh! dupe - thanks AD7AF for being nice, just logging me, and moving on). That's about 29/hour, which is a personal best for me from this QTH. No DX other than a KL7, but it was pretty easy to work stateside, and I even picked up a few new states for WAS.
Monday, January 26, 2009
For the last few months, I've been lusting after an Elecraft K3 HF Transceiver. Besides its excellent receiver performance, one of the features that I'm intrigued with is the diversity receive capability. If you add the KRX3 subreceiver module, you get a complete, no-compromises second receiver in the box. The diversity receiver feature allows you link both receivers together so they track the same frequencies, and you can connect different antennas to each receiver; presumably, you'd do this with different antennas with different receive characteristics (you can also run both receivers independently if you want). When a signal fades in one antenna, it might be increasing in strength in the other antenna. For those of you who have 802.11 access points in your house, that's why there are two antennas on the back (I don't think there are two separate receivers in the AP - they probably do some trickery to automatically switch antennas as needed, but you get the point).
That's all very interesting, but what's very cool is that the Elecraft engineers opted to put a very capable DSP unit - the human brain - in this loop, by allowing the user to put the two receivers' outputs into opposite sides of a stereo mix. Although I've never experienced this myself, since I don't (yet) own a K3, I've heard that the signals seem to "float" in the stereo field as they become more or less audible in each antenna/receiver combo. If you want to hear it first hand, listen to the samples on N1EU's web site.
If you're just interested in being able to copy a weak signal, I suppose a mono mix would have been fine. But I'll bet there are some real advantages under crowded band conditions where the human brain is able to use that stereo field separation to "sort out" the desired signal from the undesired ones. Maybe the fact that the desired signal is floating between the operator's ears in a slightly different way than the interfering signal would allow copy with the dual receiver system when it would be impossible with a single receiver.
So that got me thinking (always a dangerous thing). Is there a way to use DSP technology to separate CW signals, without separate receivers, by frequency and spread them out across a stereo field, such that an operator can get better copy than s/he could listening to the signals in a mono mix? In other words, can someone "lock on" to a CW signal better if that signal is separated from interfering signals in the stereo field?
My first thought was "certainly someone else has thought of this." And part of my reason for posting this on my blog is to see if anyone else has. I didn't find anything with the obvious Google searches, but maybe someone can point me to something...
My other thought was "why bother - with modern rigs with good roofing filters and high-quality DSP, you can dial the bandwidth down to 50Hz with no filter ringing." That's a great answer if, say, you're chasing DX and you're interesting in listening to exactly one signal at a time. But in contests, you get called off-frequency. Or, if you're a DX station, and you've got a pileup of 100 stations calling you, you probably don't want them all exactly zero-beat on you (or on your advertised split frequency) - you'd never be able to sort them out. You might be using a filter of 500, 800, or maybe even 1800 KHz to widen the net.
I don't have any direct experience with digital signal processing, but in a previous life, I was an orchestral trombonist and also dabbled with computer music applications. One application I was familiar with that would do the job here, and wouldn't require me to learn all about DSP, was an app called PureData, or pd. pd allows you to graphically build sound processing structures, and it is free.
The basic idea is to take a monophonic input signal, and feed it into a parallel set of hi-Q bandpass filters. The output of each filter is then sent to a specific position in the stereo mix. So, for example, any CW signals of 400 Hz might end up all in the left channel, while signals of 500 Hz would end up in the center of the mix, and signals of 600 Hz would end up in the right channel.
I also recall reading that the Elecraft engineers incorporated a bit of delay into their diversity receive feature. Although I had no idea why that was important, I built the capability into my pd model, and as it turns out, it just doesn't work without it. Maybe a blog reader can explain that to me. In order to get things to "spread out" in the stereo mix sufficiently for my ears, I needed to add a delay of 0 to 10 milliseconds to the various bands.
300 Hz - Delay 0 ms - Pan hard left
350 Hz - Delay 1 ms
400 Hz - Delay 2 ms
450 Hz - Delay 3 ms
500 Hz - Delay 4 ms
550 Hz - Delay 5 ms
600 Hz - Delay 6 ms
650 Hz - Delay 7 ms
700 Hz - Delay 8 ms
750 Hz - Delay 9 ms - Pan hard right
So the interesting parameters here are likely:
- The number of bands
- The bandwidth of each band
- The assignment of each band to a position in the mix (do they smoothly transition from low to high = left to right, or does the spectrum "circle around" multiple times with increasing frequency?)
- The amount of delay
- The distribution of delay times (e.g. is each adjacent band close to the delay time of its neighbors, or is it far away from them?)
How's It Sound?
I know by now you're curious what this all sounds like. So here's an example. The audio was recorded on my rig during the recent CQWW 160m DX Contest. It's one minute long, and I had the 500 Hz crystal CW filter turned on. I chose this one minute of audio because there are a few stations fairly well spread out.
Audio Clip - no processing
Audio Clip - stereo separation processing enabled
To be perfectly honest, I'm not sure I can copy the weak stations any better with the processed audio better than the unprocessed audio. I'm curious if you have the same experience.
I do have to say that I think the processed audio is a bit easier to listen to, and I wonder if it might reduce operator fatigue over a long contest weekend.
The parameters of this experiment really ought to be played with more, either by me, or someone who has more experience than I do with DSP technology. I don't understand how the delay affects the stereo spread, nor do I know how to measure how well the bandpass filters in pd are actually working.
What do you think? Please share your ideas in the feedback link for this post.
Thanks and 73!
Tuesday, January 13, 2009
Noise floor, noise off, G5RV: S2
Noise floor, noise off, inverted-L: S9
Noise floor, noise on, G5RV: S5
Noise floor, noise on, inverted-L: S9+10dB
My guess is that the inverted-L is just a generally better antenna, so it's just doing a better job of picking up signals, including local noise.
The neighbor garage noise sounds like this. It's pretty regular, in that the time between bursts, the duration of the bursts, and the very loud noise at the end of each burst repeat consistently.
It's odd that the G5RV is much closer to the noise source, yet receives about 30-40 dB less signal. One significant difference between the antennas is their polarization. Could polarization account for that much difference? I doubt it... there must be something else at work here.
Update: 01/15/2009: my first QSO on this antenna was DS1REE in Seoul, South Korea, at about 5am local time.
Monday, January 5, 2009
40M: 103 QSOs, 29 states/provinces, 5 countries
20M: 16 QSOs, 7 states/provinces, 1 country
I spent a lot of time at the beginning trying to get my 500 Hz filter in the FT-857D working with RTTY. Although I did get things working during the previous Thursday night's NCCC practice, I just used the standard 2.1 KHz filter. That really, really, didn't work during the RU. Strong signals within the wide passband would cause the AGC to kick in and the signal I was trying to copy would go away. I suppose I could have played around with disabling the AGC and riding the RF gain, but it seemed to make more sense to just use the 500 Hz IF filter.
The problem I had was that the passband of the 500 hz filter seems to be centered around 800 hz (a typical CW sidetone/beat frequency), even if you're in LSB or DIG mode. However, MMTTY sends a default mark tone of 2125 Hz. So the filter wasn't passing the frequencies the demodulator was looking for. I was able to change the mark frequency in MMTTY to 915 hz which was within the narrow passband, and I was able to decode signals with no problem, even with W6YX hammering away a few KHz away.
However, once I made that change, I couldn't work anyone, not even local stations that really should be hearing me. I was definitely putting power to the antenna, and I could hear myself on a portable shortwave receiver, but no QSOs.
I finally reconfigured MMTTY to use the other sound card in my computer for output, so I could listen to it, and I discovered that, although I'd changed the receive mark tone to 915 Hz, MMTTY was still transmitting with a 2125 KHz mark tone (see - my music degree comes in handy from time to time!). No wonder I wasn't making any contacts. No matter what I set the frequency to in the MMTTY preferences, the transmit tone didn't change.
What I didn't realize is that I needed to also set the HAM default setting values (directly below the receive settings) - those set the transmit values. As it turns out, I tried clicking on the NET button during the contest, and that solved my problem, since it locks the transmit frequency to the receive frequency. The names of those functions (HAM, NET) don't make much sense to me, but I'm a RTTY noob.
On the RF side, I continue to be impressed with how well my tree-mounted wire vertical works. Of course, I am only able to compare it to my G5RVjr, but I made a lot of S&P contacts on my first call, and worked some JAs and China with no problem. In terms of performance/cost, I'm happy.
On another note, NCCC member Ed Muns, W0YK went to Aruba and operated P49X for the RTTY RU. Ed made - get this - 3,214 contacts in 24 hours. The mind boggles...
Thursday, January 1, 2009
A photo of the operator and his/her station:
Information about the area in which the station is located. Although I didn't know it at the time, Halle-Neustadt is a planned community built in East Germany in the 1960s:
Something interesting about the town/city: one of the QSLs I have from the 1970s is from a ham in the town where the Czech composer Bedrich Smetana was born (Smetana wrote "The Moldau" and "The Bartered Bride" among other works):
And then, there are the low-budget QSLs which have a sort of endearing quality:
This one is kind of interesting - it's a Hollerith card! I haven't checked if the punched data has anything to do with my QSO - I suspect it does, since the printed labels appear to have been computer-generated. This is pretty impressive, as the QSO was made in June 1977!
Given that, it seems like I would benefit from a set of antennas that offer both reasonable low-angle radiation and NVIS performance (for close-in stations). If I can somehow fit a 40/80 meter vertical, along with a low dipole for those same bands, that seems like an effective set of antennas for contesting in the hours of interest.