Ripples in the Ether

Disclaimer: For those who don’t know, I’m an employee of Buddipole, and I do speak quite a bit of my positive experiences with some Buddipole products in this post.

Yes hams, it’s that time of the year again. Field Day, the Super Bowl of the ham radio world. I haven’t had the best track record of participating in Field Day over the years, due to a few different factors. The largest stumbling block is the nasty allergies that I get during late spring, which usually end up peaking in intensity right around the end of June. The other problem is that I’ve never been a big fan of the big-time organized local clubs. I won’t go in to the reasons for that (you can dig back in the blog if you are really interested), other than to say that in my experience they are not the kind of places that I find interesting.

Now that I own a house with a proper backyard, I feel like I now have the option to participate in Field Day by setting up out back, so that I can duck inside if my allergies get too out of control. It also helped that I recently started taking some new meds, which have helped to control the allergies quite a bit better than anything else so far. So I was more than happy to give FD a go this year, even though it wasn’t going to be more than a backyard adventure.

Station Setup

Field Day 2009 - Backyard

Given the recent development of my employment with Buddipole, and the demise of my main station random wire antenna in a recent spring storm, it only made sense to deploy the Buddipole. I could have dragged out the IC-718 sitting idle in the shack and paired it with my very heavy 35 Ah gel cell, but I was feeling up for a bit of a challenge. I settled on using the FT-817, and considered pairing it with my recently constructed 20 watt linear amp, but I realized that running 20 watts would give me the same power multiplier as running 100 watts would. So I figured, why not take the dive and go QRP for the entire event? Not only that, but why not make SSB the main mode of operation? This was appealing to me not only because I am a QRPer at heart, but also because it would push my limits, and give me something new to try.

I’ve run into my share of hams who think that QRP is the devil’s handiwork, and that anyone running less than 100 watts is inflicting undue hardship on the poor receiving station. While I know that a QRP signal does have a more difficult time being heard (especially SSB), I also know that there have been plenty of times when the receiving station would have had no idea that I was running QRP unless I told them (and many times, I won’t tell them). The fact is, if you can hear me well enough, you’ll answer me. If not, you won’t. Yes, I get less contacts running QRP. But if the conditions are too painful for the other station, they will just not answer me or will politely cut it short. I especially feel absolved of any guilt running QRP SSB on Field Day because of the whole nature of the event. The concept is to test how well we do under less-than-ideal conditions. Quoth the rules (emphasis mine):

2. Object: To work as many stations as possible on any and all amateur bands (excluding the 60, 30, 17, and 12-meter bands) and in doing so to learn to operate in abnormal situations in less than optimal conditions. A premium is placed on developing skills to meet the challenges of emergency preparedness as well as to acquaint the general public with the capabilities of Amateur Radio.

Field Day 2009 - Buddipole

The great thing about using the Buddipole was the ability for me to use it in conjunction with the frequency agility of the FT-817 to hop around the bands. Yes, it does take a bit of time to change bands, which is not quite as fast as using a multiband doublet with a tuner. However, with just a bit of practice, you get to know what setting sare needed to resonate your antenna on any band and can reconfigure and tune it in a matter of a few minutes. Given that I decided to run QRP SSB, I needed every bit of power I could get, so I was glad to not have a lossy tuner in the way.

Given the somewhat last minute nature of my decision to play in Field Day, I didn’t have a way to power a notebook PC with a battery, so I settled on the old standby of paper logging. Since I decided to stay strictly search & pounce, it wasn’t a big deal to paper log. The biggest pain is in dealing with dupe avoidance, but I figured that I wouldn’t have to worry about that too much since I would be racking up huge QSO counts.

Field Day 2009 - A123 Battery Pack

The only thing left to nail down at this point was power. I knew that I wanted to try out our brand new A123 lithium nanophospate battery technology that we are ramping up at Buddipole. If you don’t know about this battery technology yet, prepare to be blown away when we officially roll these out. This technology has been used in the R/C hobby for a few years, and is just now making it’s way into amateur radio use. It also happens to be the same technology used in the upcoming(?) Chevy Volt plug-in hybrid vehicle. It would take too long to list all of the advantages of this technology here, but the amazing flat discharge curve, long life, very quick charge time, and incredible safety are all reasons why I’m confident that this will be the dominant battery technology in the portable/pedestrian mobile ham circles within the next few years. The particular pack that I was using is a 3S1P configuration, which means 3 cells in series, one parallel set (we also have 4S1P and 4S2P packs). Each cell is 3.3 V nominal, so this pack is rated at 9.9 volts, which is perfect for use with the FT-817. A **1P pack has a capacity of 2.3 Ah, which I figured would give me at least a few hours of operating time.

Field Day 2009 - Solar Power

Being at a bit of a disadvantage in the “contest”, I wanted to pick up some extra bonus points, so I remembered the 5 watt Harbor Freight solar panel that I had gathering dust in the closet. Using that in conjunction with my half-depleted 7 Ah gel-cell, my power strategy was fully formed in my mind. During the sunny part of the day (my backyard is on the north side of the house and is fairly narrow, so it doesn’t get a ton of sunlight) I would use the solar panel/gel cell combo, then switch to the A123 pack when there wasn’t anymore sunlight to be had at the station.

Given the set up that I described, it looked like I would fall into the 1E class for the event. Given a very strict reading of the rules, it seemed like I might have been able to claim 1B Battery, but in the spirit of the event, 1E was the appropriate choice.

Operating

I wasn’t able to start operating right at 1800 UTC due to some chores that needed to be completed first before play time. When I did get going, I started on 20 meters with the Buddipole in vertical dipole configuration and quickly started to get QSOs in the log. As I mentioned earlier, my strategy was strictly search & pounce, choosing only the loudest stations to try to work. For the most part, it was a successful strategy. I was able to work just about everyone that I heard at a S5 – S7 signal level or better.

Once the afternoon wore on and 20 meters started heating up, the pileups started to heat up as well. I found that it was getting harder and harder to be heard as I was the little fish in the big pileup. So by mid-afternoon, I started working my way up the bands. By jumping to 15 meters (then 10, and eventually 6) was the band was starting to open, I was able to stay ahead of the really competitive pileups. One of the coolest things about the operating was the feeling of riding the QSB like a wave up and down; waiting for a crest in the propagation to strike fast with my callsign. It could have all been in my mind, but it did seem to help to operate like this.

As the sun started to set behind the neighborhood houses, a good sporadic E opening hit the West Coast and I was able to get some nice 6 meter and 10 meter QSOs out to about 1000 miles or so. I had big plans for staying up late after dark to operate, but by the time that dusk fell on Beaverton, I was totally exhausted. So I laid down on the sofa and set the alarm on my iPhone to wake me in a few hours. Not surprisingly, I must have turned off the alarm in my sleep, because the next thing I remember is that it was 5 AM the next morning.

A bit disappointed, but feeling renewed, I put on a pot of coffee and decided on my strategy for the morning. It seemed obvious to give the lower bands a shot, since the propagation was bound to be best there and I hadn’t worked them the day before. So the Buddipole was reconfigured as a Versatee Vertical with the low band coil, and the power was supplied by the A123 pack. Once I got going again around 7 AM, I was shocked at how well I was doing on 75 meters. The puny 5 watt signal from the FT-817 into the Buddipole had some good mojo, as I got multiple unsolicited “great signal” reports from the stations that I contacted (many of them VE7s). In my QSOs on the previous day, it was obvious that I was a QRP station, often needing multiple calls to bust a small pileup and sometimes needing a repeat or two. But both 75 meters and 40 meters were working remarkably well for me. The call got through on the first try nearly every time, and almost no fills were necessary. It truly felt like I was running 100 watts.

After a morning of fun, I had to go QRT for the day in order to complete some other chores that I had put off for far too long. It was a bit tough to tear myself from the station, but responsibility trumps fun, even if you try to put it off for as long as you can.

Results

Before I started operating, I thought that 50 QSOs would probably be a reasonable goal to shoot for as a QRP SSB station. As it turns out, I got really close; with a final tally of 49 QSOs, all of them SSB. Twelve of those QSOs were on solar power, so I qualified for the 100 point alternate power bonus. Since I was on emergency power the entire time, I also got 100 points for that. Given my 5 watt power limit and 100% emergency power status, I qualified for a power multiplier of 5. I also managed to copy the special W1AW bulletin for 100 points, and plan to submit my log via the web for another 50 points. If I did the arithmetic correctly, that should give me a final score of 595 points.

I also want to make note of the performance of the A123 battery pack. I started the event by charging the pack to a full charge with my Cellpro Multi4 charger. Although I did the majority of my operation timewise on the solar panel, by far I had the most QSOs with the A123 pack. According to my rough log calculations, I used the A123 pack for over 3 hours of operating time and logged 37 QSOs with it. When I returned the pack to the charger after Field Day, the charger reported 19% of the charge was left (the voltage display of the FT-817 never dipped below 9.6 V the entire time I was operating with the A123 pack). The next charge only took 38 minutes to get me back to 100%, and ready to go again. The 3S1P pack only weighs about 8 oz. and gave me a ton of operation time, much more than I expected. It sure blows away the much heavier and bulkier 5 Ah gel cell that I usually use with the FT-817. Ask the Goathiker, he’ll tell you how great these things are.

I could wax poetic about the event, but I think you get my feelings about the thing by now. I’ll just end by saying that this was my best Field Day by far, and that I had more fun with QRP SSB than I thought possible. I have a great appreciation for the excellent ops that put up with my peanut whistle, and learned a lot more about how capable a QRP SSB station can be.

OK, I admit that I don’t care for a lot of these goofy Internet neologisms like “blogiversary”, but I needed something to get your attention for a boring post like this. I don’t normally pay attention to these things, but I happened to notice during my last post that my first posting to this blog was in June of 2008. This post will be number 90, and most of them have been fairly original content, not just a rehash of something else I found on the web. I hope that you’ve enjoyed the content that I’ve posted and I appreciate all of those who have taken the time to visit the site and subscribe to my RSS feed.

Here’s to another good year of blogging, I think that things are going to pick up in the ham radio world!

20 Watt Broadband Linear Amplifier

QRP is tons of fun on CW, but it gets a bit rough trying to work other stations on SSB with 5W, especially when you are using antennas that are low to the ground. I had been eyeballing the nice RF MOSFETs from Mitsubishi for a while, and since I got a hankering to get a bit more active on SSB, I took the plunge and ordered five of the RD15HVF1 devices. At a current price of $5.25 at RF Parts, they are a bit more expensive than the IRF510 that you see in a lot of 20-40 watt range linears, but these devices have a few advantages over the IRF5xx series. One of the biggest, in my opinion, is that these RF transistors are designed to run off of a 12 volt drain voltage, unlike the IRF510 amps which don’t really work well until they get around 24 volts on the drain. These things can also take quite a beating from poor mismatches, and have the convienice of having the source connected to the metal tab on the case, making for a nice solid ground connection.

20 Watt Broadband Linear Amp - Inside

Having the appropriate parts in hand and some designs on the internet to steal from, I set out to build my own linear. There isn’t a ton of creativity to be used when designing a linear of this class (Push-pull Class-AB). Every design that I’ve seen looks nearly the same. Not surprisingly, the real focus of the design is in optimising the input and output networks. Feeling lazy and anxious to just get on the air, I pretty much did “cut and paste” from some different circuits to find out what works best. I know, not the best method, but sometimes the desire to just put out some RF trumps proper procedure. I don’t have a scehematic to post at the moment, but if you click through on the photo to the right, you can see a close-up with descriptions of major circuit blocks. Below, I’ve posted links to the two circuit resources that I used the most for this design. I’ll have more details about the designs to comment on at a later date, when I can pull some proper notes together.

• HPSDR Pennywhistle
• TF3LJ SoftRock Amplifier

One of my weakest homebrewing areas is in the mechanical engineering, but now that I have a bit of a real “shop” in my garage, things have been getting better. A bit of scrounging at the surplus stores around town led me to some cheap heat sinks that looked like they might be suitable for this project. After attacking them with an angle grinder to get a lip off of the bottom side, I was able to bolt two of them to the lid of an aluminum Hammond enclosure. I nibbled a nice square area right out of the middle of the copper clad I used to build on, soldered the RD15HVF1 devices to some pads etched out with a Dremel, then bolted the MOSFETs and copper clad directly to the lid of the enclosure. Drilling the holes for the BNCs and the LED was a piece of cake with the aluminium box material.

Without getting into too many details at this point, I was able to get the amplifier working right off the bat. I didn’t get quite as much output power as I initially liked (only got about 10 watts), but the amp was working correctly. More troubling was the fact that output on 6 meters was only 2.8 watts. Not too great when you are putting in 2.5 watts. I figured it had to be something with the input or output network. The input return loss measured quite good; -15 to -20 dB across all the bands. So I figured that left the output network. My initial iteration of the amp used a transformer similar to the one in the Pennywhistle amp (this is a configuration that I’ve also successfully used before in a push-pull class-C CW amp). Without doing any actual measurements and calculations, I dropped in the broadband transformer pair used in the TF3LJ amp, and immediately improved my output power by a few watts. But I was still a bit low on 6 meters. A bit more searching showed that I might need another compensation cap on the output, so I experimented a bit more until I found that a 1200 pF silver mica in series with the drain transformer outputs worked wonders and boosted my power on 6 meters to nearly 15 watts CW. I haven’t done any analysis to see why this helped. I know, sloppy…but sometimes expedience wins.

Since there’s no output filtering built into the amplifier enclosure, I had to assemble some outboard filters in order to get this thing on the air. I was going to use 7-pole low-pass filters until I realized that everybody else uses 5-pole filters because push-pull amps already suppress the even-ordered harmonics by at least -30 dBc. A bit of work with the new LADPAC software in EMRFD enabled me to crank out a table of filters for all of the bands (160 m – 6 m) using the silver mica caps in my junkbox plus T68-6 toroids. If you click through the photo below, you can get a glimpse of the copper clad enclosure sticking off the output of the amp.

Backyard Linear Test

Last Monday, after a bit of checking of the signal purity with my dummy load and scope, I was satisfied that everything was working OK and took the amp out for a spin on the back porch. I set up the Buddipole in Versatee Vertical configuration with the Low Band Coil. It tuned right up on the upper end of 75 meters, and I had no problems at all checking into the Oregon Emergency Net. One watt out of the 817 gave me about 25 watts out of the linear on 75 meters. I was too busy to do much else with the amplifier until today (the following Sunday), but I was excited to give the amp a try on 6 meters, since that was one of my biggest motiviations for building the thing. The Buddipole was set up in a simple 6 meter dipole configuration about 10 feet above the ground and I parked the 817 on 50.125 MHz. It didn’t take long before I heard N6OR booming into Beaverton from Southern California (grid DM12). I snagged him on the first call, getting a 57 signal report in return and a report of good, clean audio when asked. He was running 100 watts into a quad, which you can see on his QRZ page. I was really thrilled since this was not only a victory for my mad homebrewing skillz, but was also my first 6 meter QSO!

I’ve been parked on 50.125 for most of the afternoon here at the NT7S shack and have picked up a few more QSOs. So far, all reports of the audio quality of the linear have been FB, so I’m satisfied that it (and the LPF) are working as they should be. I think I’ve about worn out my keys on this post, so I’ll wrap it up for today (I always start with modest ambitions on these posts, they they grow exponentially). I’m having way more fun than I should be, and I’m very pleased to be back out of my ham radio funk.

Whew, I just got back from a nice day at the SEA-PAC 2009 convention in Seaside, OR. Due to the *ahem*unstable*ahem* financial situation that I have recently found myself in due to the current economic conditions, I decided a few months ago that I would skip the show this year. However, things ended up changing, as they often do. Since I’m now working for Buddipole, I figured that it would be good to make an appearance, if for nothing more than getting in some time at the booth, soaking up the feeling of the chaos, and maybe trying to learn a thing or two. The deal was sealed when Chris, W6HFP called me last night to let me know that he had an extra exhibitor’s pass that I could use. Being a ham, thus cheap by nature, I jumped on the chance.

Found: SSDRA

The morning started a bit late for me since I was busy doing some much-needed hibernation the night before. I ended up rolling into Seaside around 1030. Surprisingly, I didn’t have much trouble finding a parking space within a few blocks of the convention center. After a quick check-in at the Buddipole booth, I started off with a first walkthrough of the convention floor. As usual, the sheer mass of stuff, along with the throngs of hams smashed together in narrow aisles kept me too distracted from finding much that I wanted to buy. However, when I was about ready to quit my first pass through the show floor, I found it: my reason for being there. The thing that I knew made the trip worth it, regardless of whether I found any other good purchases. Sitting on a lonely swap table in the middle of the main floor was two first edition copies of Solid State Design for the Radio Amateur (SSDRA). For those of you who aren’t homebrewers and don’t listen to SolderSmoke, just know that SSDRA is a long out-of-print book that can command quite high prices on eBay and other reseller sites. These two copies carried a cover price of $7.00, but the seller had marked them down to $5.00! Immediately, I snagged both of them. However, I’m not quite as greedy as it might seem. I had loaned out my 3rd printing copy to W8NF, who hadn’t had access to one for years. Since I knew he needed one, I had to save one copy for him (coincidentally enough, he had brought along my loaner copy to return to me). I know that still puts me in that club of hoarders who have more than one copy, but I don’t really care! I’ve got two copies of EMRFD (1st edition and Revised 1st edition), so it feels right to have the first and third printing copies sitting on my shelf. Don’t hate me.

After that small bit of excitement (yes, I’m a geek to the core), I went back to the Buddipole booth for a stint in helping out. What I thought would be a fairly small amount of time behind the booth turned out to be about three hours during some fairly busy periods. I was at a pretty big disadvantage because I couldn’t remember the prices on most items, and I had to bug poor Chris numerous times to ask. However, I started to get more comfortable fielding questions as the afternoon wore on, especially regarding the technical side of things. The best part was getting people pumped up about our new A123 nanophosphate battery packs and chargers. A lot of folks were interested in these things. I also ran into a few people of note while manning the booth. First off, I got to meet Randy K7AGE when he stopped by the booth. He was a really nice guy and I got to tell him how much I appreciate his YouTube videos, especially the 6 meter stuff he recently released. A bit later, Dan KK7DS and his wife (Mrs. D-RATS, according to her t-shirt, LOL) stopped by. You may remember him from our January Eggs & Coffee, where he was kind enough to stop by to demo D-RATS. Dave W8NF, came to the booth to give me my copy of SSDRA, and I had the pleasure of surprising him with a copy of his very own.

The Law

Across the way from the Buddipole booth was a vendor selling ham radio-related t-shirts. I had to do a double-take at one point because I saw someone well-known to the locals browsing the wares across the way. Paul Linnman, who used to report for KATU and now broadcasts on radio station KEX, was right there, along with who I assume was his wife. He was there to give the evening banquet speech regarding the famous Oregon Exploding Whale story, which he covered as a newbie reporter back in the day. I pretty much expect media types to kind of look down their nose at us nerds, but Paul seemed genuinely interested and amused at the hamfest. Speaking of the t-shirt vendor, I spotted a shirt that I just had to pick up. I don’t normally go for the extremely nerdy fare that you find at these things, but if you check out the photo to the left, you’ll probably appreciate why I had to have this one. Of course, I got a ton of eye-rolling from Jennifer when I brought it home, but it’s not like I plan on wearing it out everywhere we go in public. Or maybe I will, just so she’ll be embarrassed to be seen with me.

Even with all of the cool stuff that I saw, the best was still to come. After my stint at the Buddipole booth, I had a bit of time to kill before the seminar I wanted to see. When I was wandering near the front doors of the convention center, I spotted the ham homebrewer #1 rockstar, Wes W7ZOI. I’ve communicated with Wes a few times via e-mail but I’ve never met the guy in person. I almost walked up to introduce myself to him, but chickened out, figuring the poor guy didn’t want to be ambushed by some unknown geek at the front door. So I continued browsing the tables to see if I could find anything else I couldn’t live without. As fortune would have it, I ended up right next to Wes once again on the mezzanine level right by the table full of old Tek junk. Since it appeared that the universe was giving me a second chance, I got up the nerve to walk up and introduce myself. Surprisingly to me, he actually recognized my name and mentioned that he had been hoping to meet me at some point, since I’m one of the few locals who is out there homebrewing and publishing my work on the Internet. To say I was flattered is a huge understatement. He also invited me over to visit his shack some day; asking why I hadn’t come over sooner. My reply was something along the lines of “I didn’t want to be a crazy stalker”…or maybe it wasn’t quite that dramatic, but you get the gist of the message. Wes is a really nice guy, and it was truly an honor to finally meet him. When I do get over to his shack, you can bet I will get some photos and a write-up for you.

The end of the evening was a presentation on “Construction & Design Ideas” by Jeff WA7MLH. Jeff is a protege of Wes, and it showed in his really neat presentation. He brought along a PowerPoint deck showing off his shack and many of his homebrew rigs. He discussed strategies for acquiring parts cheaply at hamfests, techniques for repurposing used chassis,  design elements for receivers, transmitters, and transceivers, as well as a bunch of other random homebrewer wisdom. After an hour-and-a-half, he still wasn’t done with the first part of his presentation, but I had to go! Which was a bummer, because I really wanted to stick around for part two, which was about building crystal filters. Alas, real life had to intrude into my geek bliss, and I needed to return home.

This was the best time that I’ve had yet at any hamfest. Even though I’m a pretty shy guy, I got a lot of socializing in this time. I’ve come away really reinvigorated to get building more stuff, but unfortunately I don’t have much time for that right now. But that’s OK, because the fire is really burning once again. Thanks to everyone who I met at SEA-PAC this year, and a special thanks to Buddipole for giving me the opportunity to get reconnected with a lot of good ham radio stuff.