Amplifier progress

I realized that I haven't written an update about the amplifier project in a couple of months. Some good progress has been made.

To recap, I've decided to home-brew an HF amplifier by taking two other kits (the Communication Concepts AN-762 amplifier and the HF Projects LPF kit) and combining them in my own enclosure, with a heatsink and a keying relay circuit. Once I have the basic amplifier working, I would like to home-brew some additional features, like a built in SWR meter, automatic bandswitching, etc.

Phase 1's goal has been to get the basic amplifier working with a manual band selector, etc. I harvested power transistors for the amp from a donor EB-63 kit that Nick's boss gave me, so that saved me some cash. Rob helped me get started populating the SMT parts on the board, and then I finished the through-hole stuff at home. I built the LPF in two evenings with no difficulty.

Choosing an enclosure was a real headache. I wanted something that would look nice and relatively modern, but finding the right thing in the right size (6"W x 5"D x 3"H or so) was next to impossible. I finally settled on a Ten Tec box with aluminum end panels and a steel top and bottom. I would have preferred all aluminum but that's life.

Finding a heatsink was another chore. Again I wanted something about 5" x 6", and it was just very difficult to find anything like that in quantity 1. I found lots of smaller stuff, and I found shops that would produce extrusions on demand (with minimum orders anywhere from 10 feet to 150 pounds). I also found surplus stuff, but with no thermal impedance information. Finally I found, who sell a handful of extrusion widths in custom lengths for a good price. I got a 5" piece for about $12 plus shipping.

Just as an aside, I have to say that Google really let me down on both of these searches. The heatsink company was about 3 pages in to the search results. I didn't even find Ten Tec enclosures on Google, I spotted their ad in the back of QST. I seriously must have looked at 20+ enclosure companies and 10+ heatsink companies before I found what I wanted.

I took the completed amplifier to Nick's house to perform some basic smoke tests on it, since he has an oscilloscope and a signal generator. On the whole, it definitely seems to amplify, so that's good! But the output signal was not very clean looking. Nick suspects this is either due to his ancient janky bench power supply and/or the insane amount of RF present at his apartment due to his proximity to Sutro Tower. It didn't catch fire, so that's a good start. He said we should get it mounted to the real heatsink I want to use before continuing to test, so that's up next.

I went to McMaster-Carr and ordered 4-40 screws, a 4-40 tap kit and wrench, spacers, and standoffs. Mouser supplied UHF panel mount jacks, a powerpole chassis mount plate, female header blocks (to attach to the LPF control headers), and RCA jacks for the keying interface to the K2. At Harbor Freight I got two step drill bits, a center punch, some small files, and a digital caliper. I think this should be everything I need to do the mechanical work (plus a drill press and a Dremel; I have access to the former and already own the latter).

The amp PCB is 5.25" x 3". Since the enclosure top is steel, which doesn't conduct heat as well as aluminum, I think I'm going to cut a hole in it big enough for the PCB, and mount the heatsink to the enclosure over that hole. Then the amp can mate directly with the heatsink. Nick is going to give me some SMA connectors and semi-rigid coax, so I should be able to connecterize everything inside the box and not have anything hard-wired. I'd rather do that for ease of modifications later.

I'll post some pictures of the various components soon.

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Gear lust got the better of me

Ever since I first got on the air with my K2, I've operated almost exclusively digital modes (except for a couple of early phone QSOs). Elecraft recommends that you limit yourself to 5w on digital modes with the K2, because their high duty cycles can be hard on the finals. So for the last year I've made almost every QSO using 5w, except for the occasional 10w for a rare DX station (if they couldn't hear me with 5).

And so it follows that most of the ham radio blogs I read are focused on either kit building or operating QRP, or both. That's how I learned about Steve Weber (KD1JV) and his wide array of cool ham radio kits. In early December his new ATS-4b kit was brought to my attention, and I began to drool. The ATS-4b is a 5 band, 4-5 watt, CW only rig that is about the size of two packs of playing cards (from what I can tell). It uses SMT parts, and costs just $240 – a steal compared to, for example, the Elecraft KX1 at $299 for only 2 bands.

Unfortunately, after hemming and hawwing for awhile, when I finally posted to the ATS mailing list to see about ordering one, Steve said he had just sold the last one that morning and probably would not be producing more. Doh! However, rescue came in the form of another member of the list, who had purchased two ATS-4bs and was willing to sell me one (brand new and unbuilt) for the price he paid. Yay! He even offered to put it on lay-away for me, since I had mentioned that Catherine might make me wait until my birthday in June to get one. In the end she said I should just get it now and build it when I can, so I did! Doug (K9DLP) put the kit in the mail today, so I should have it next week sometime.

I'm definitely going to need some help from Nick and Rob to get going on this kit, since it involves a lot of SMT parts, but it looks like they're mostly the larger sizes so hopefully it won't be too bad. When I showed the design to Nick he said something like, "Hey look at that – it's a modern rig!" Through-hole is for sissies I guess. Combined with my ZM-2 manual tuner and a 12v brick power supply, I should have a really nice portable QRP station to take camping or on other trips. My next visit to Australia will be in May, so hopefully I can bring it then. I just, uh, need to learn Morse code… (I practiced for awhile tonight!)

I'll close with a question for anyone (hello?) who may actually be reading. I get to choose the band configuration when I build the kit. My choices are: 80, 40, 30, 20, and 17 OR 15; OR 40, 30, 20, 17 AND 15. The ATS-4b build instructions mention that option 2 is probably a better choice if you're always going to operate portable, because putting up an 80m wire in those circumstances is a bit of a pain. But I've almost never used 80m at home due to local QRM; I hear it's actually a pretty good rag-chew band. And I'll have a tuner, which should give me a little extra flexibility. Which combination would you choose?

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2 years’ worth of ham radio

2 years, 10 watts or less (usually 5), 131 QSOs.

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More remote operating

Catherine and I went to Boston for Christmas to visit my family. Confined as I am to a very weak compromise antenna here in San Francisco, as well as being some 2,700 miles farther from Europe than I am in Boston, the temptation to bring a radio when I go there is strong. When I went in July I borrowed Rob's (AK6L) Pelican case and brought my K2, laptop, LDG autotuner, switching power supply, SignaLink USB, 25' of coax, a balun, a big spool of stranded wire, nylon line, and ceramic insulators. While essentially bringing my entire shack with me made for a versatile setup, it sure was a lot of crap to drag along. My wife was remarkably tolerant.

Since I've been working hard at Morse code practice lately, I decided this time to borrow Nick's (N1UBZ) Norcal 40a, along with a small brick-style DC transformer, and bring my manual tuner and White Rook travel key for a lightweight setup. Although I would be confined to the 40m band and CW only, the setup packed easily into my backpack and only weighed a pound or so. I measured out wire for a 40m dipole before I left, so I only had to bring that.

Once in Boston, I set up the antenna by simply attaching a ceramic insulator to the end of each wire and heaving it into a tree from the 2nd floor balcony off the living room. Then I ran the wires inside through a sliding double door and hooked them up directly to my Emtech ZM-2 manual tuner. Ladder line probably would have been better, but I needed a way to feed the antenna outside, and something I could close the sliding door on was preferable.

Signals on 40m were great with this setup, but I quickly discovered that my CW copying skills were nowhere near as good as I'd hoped they would be. I've been practicing on for several weeks, but I've been using the "Morse Machine" mode, where it plays you a character, you tap out the answer on the keyboard, and then it goes on to the next (or repeats if you get it wrong). Though I have the character speed set at 25 wpm, and I can respond almost immediately, when I tried to copy actual QSOs I was hearing I was barely able to get more than 2 letters in a row before getting lost, even at pretty slow speeds.

With this realization, I decided to just practice copying, rather than try to make any QSOs. The Norcal only puts out 1-2 watts, so it wouldn't be that easy for anyone to hear me anyway. For the next few days I spent an hour or two each night tuning around looking for slow morse, and then trying my best to copy it. It was a frustrating exercise, and I'm not sure I got much better at it over that time. My best attempt came on my last night there, when I heard a slow QSO that seemed to go on forever. I was able to get more of a rhythm going, and even copied a whole word or two. I started to wonder who could be sending such a long transmission at such slow speed. Finally at the end the call came: W1AW! I had stumbled on the ARRL's slow-speed code practice transmission. They send the same block of text at 5, 7.5, 10, 12wpm and so on. I'm guessing I was hearing 7.5wpm; I hope that's not wishful thinking.

In spite of the challenges, this was a fun exercise and I'm glad I did it. Phone mode doesn't interest me much, so that leaves me with CW and data modes, and data these days is almost all PSK31. I know there are loads of hams who only work CW, and as a weak signal mode it's arguably better than PSK31 too. Furthermore, if I learn it I'll be able to operate anywhere with my radio, sans laptop and digital interface. The idea of carrying a small QRP CW rig when I travel or go camping is appealing to me, so my resolve to add Morse to my arsenal of knowledge is still strong. I just need to keep practicing.

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It's been a fairly quiet 2 months in my shack, various chores have kept me busy, but I have made time for some operating. In particular, I made my first contacts on 10 meters about a month ago! When I first got on the air with my K2 the solar cycle was just starting to pick up. In retrospect I think it was a good time to become a ham, because I got some experience operating in conditions that were relatively poor, and have since watched them improve. I remember the first time 20 meters was open well after dark, it seemed impossible. Now that solar activity has increased it's a common occurrence.

When I was first testing out the K2 with my loop antenna, I found that I could tune it on 80 – 15 (it doesn't do 160 or 60). On 12m my tuner couldn't get a good match. On 10 it seemed to tune fine, but my old-ish RF wireless mouse would stop working whenever I keyed up. For the longest time I assumed I had some weird very high SWR/RF in the shack problem on 10, so I never used that band. Eventually for some reason it occurred to me to check what frequency the mouse uses – turns out it's 27.045, just 1MHz below the 10m band. I had been wanting to get a new mouse anyway, so I bought an Apple Magic Mouse, which uses bluetooth. Now I can operate on 10m with impunity!

On October 15th and 16th I made my first contacts on that band, including stations in Argentina, Japan, Hawaii, and eastern/Asiatic Russia, all on 5-10w! I guess that lends some credence to the understanding I have of loop antennas, which is that at greater multiples of antenna length to frequency their takeoff angle gets progressively lower. My loop is about 42m long, so on 40m it mostly radiates straight up. On 10 it's probably pretty good for DX. Of course, there's no telling what bizarre things are happening to it as a result of my mounting strategy.

Since getting licensed almost all my operating has been using data modes, especially PSK31. Often times I don't hear anything at the common data mode watering holes and think the bands aren't open, but then I tune around and hear Morse code coming in plenty loud. My attempts to learn CW have been pretty stop-start since the beginning, but lately I've been pressing forward with it and making good progress. I want to get to a point where I can copy all the letters at 25 wpm, and then start trying to make some contacts with forgiving hams who will send slowly. After I finish this post I'll practice some more.

I finally bought paper QSL cards for myself, with some birthday money. This may have been an ill-conceived move, because the minimum order was 1000 cards, and about a year of operating has only netted me 114 contacts. If I pass Extra, I would probably try to get a 2×1 call instead of my cumbersome 2×3. That would leave me with a lot of incorrect cards (though I could technically still send them out). Guess I'd better get cracking!

Last but not least, some slow progress is being made on my amp project. I'm not sure if I've blogged about this before, but I'm planning to build a home-brew amp, with help from Nick and Rob (AK6L). I'm going to use the HF Projects LPF kit and an the Communication Concepts AN-762 amplifier kit. I thought I had lucked out and scored the kit free from Nick's boss, who had one kicking around in his garage that he didn't want. Unfortunately it turned out that the one he had was the EB-63 kit, and the reviews of that one on are pretty negative; lack of sufficient bias on the output transistors leads to IMD and other issues.

The AN-762 is well-regarded by comparison, and has been the basis of many home-brew projects. Fortunately, it uses the same power transistors as the EB-63, so I still scored those for free. I now have both kits in hand, and I wound the inductors for the LPF Sunday night while watching the Abu Dhabi grand prix. Rob loaned me his L-C meter so I can verify those. Hopefully in the next week or so I can get both kits assembled and do some testing. I still need to decide on an enclosure. I had a great one picked out from Takachi, but then they wanted $50 to ship it from Japan, making the total price $130. Way too much for a box, but it sure looked nice. The options I've found domestically have been pretty weak by comparison. I haven't given up on finding something else that I like, but I'm getting close.

I'll take pictures and post more as the project progresses.

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All quiet, mostly

The last couple of months have been pretty quiet for me as far as radio goes. I've made 16 QSOs since I got back from Boston in early July. Notably, I finally worked Australia! On July 30 I saw Bob, VK2MBK, on 20m PSK31. After a few unsuccessful attempts at working him with my usual 5w, I decided to try 10w and managed to get through! We had a short QSO, but I'm pleased it worked out!

This weekend the solar index has been around 140-150, higher than I've ever seen it. 20m and even 15m have been open at night, and yesterday afternoon there was a MASSIVE 10m opening, from what I could see on the DX map. Unfortunately my antenna won't tune consistently on 12m, and on 10m it tunes but when I transmit the wireless mouse on my computer stops working. I take that as a sign that not much RF is getting out!

Tonight I finally managed to QSO with Rik, AB1KW, a fellow ham who hangs out on the #hamradio IRC channel with me. He's in NH, and we've tried to QSO once or twice before. He reported me coming in very weak, even with 10w, but we managed to complete the contact. Our respective descriptions of what 20m looks like at the moment are as different as night and day. He sees 10+ signals, I see 2 at best. During the day he says the band can be so packed that everyone is overlapping and it's hard to even make a contact. I never, ever see that here.

Part of the difference is that, being on the east coast, there's just a higher density of hams around, especially with Europe a lot closer than my nearest transpacific DX. But the real problem is my antenna. It's just not good enough, and being in the middle of a city doesn't help either. Rik's 80m sky loop is in the trees in his yard in a small New Hampshire town. 

Someday I'll own a house, and I'll be able to put up whatever antennas I want. A tower and a tri-band beam will be on the wish list! In the meantime, Rob and Nick and I are going to work on my amp project some more tomorrow. I've received the LPF kit I'm going to use, scored a free, already-built version of the amp module I wanted (unknown condition though), and have a candidate enclosure. Tomorrow we're going to try and work out the mounting details, as well as what components I will need for the manual band selection and a keying circuit. Once I have those I'll be looking to integrate everything and reach "phase 1" of the design; a working amp with manual band switching and nothing more. After that, I'd like to add auto band switching (via a frequency counter) and some form of SWR meter. The amp will be able to put out 140 watts, but I'm planning to use it at only 15-20 when at home on PSK31. Don't want to cause any RFI for my neighbors!

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This 4th of July weekend I am visiting my family near Boston. I decided it would be fun to bring my ham rig and see if I could work some new DX stations, since I pretty much never hear Europe with my setup in San Francisco. My friend Rob, AK6L, loaned me his Pelican 1510 hard-sided case, which he has used to carry his rig to various places. I packed my K2, switching power supply, tuner, SignaLink USB interface, a 1:1 balun, a spool of 18 AWG wire, and a spool of nylon string. I figured I would set up a 20m dipole and hang it from a balcony that faces my parents' back yard. 

If you're wondering, the TSA people were definitely curious about the case, but not hostile about it. They asked me to open it for them, and then they swabbed the inside for explosive residue. This involved disrupting all my careful packing, which was annoying but unavoidable. After getting the all-clear I re-packed everything and boarded my flight. I was surprised to see another guy with the same case getting on. His had a Bass Pro Shops sticker on it. Maybe he was carrying an expensive reel. Or a fish.

I set up the dipole on the first evening I was here, not being sure that it was high enough off the ground to get good propagation. I hung the balun from the balcony and ran two wires to trees in the yard. I was able to drape the ceramic insulators over tree branches to hold the elements in place, making an inverted V with the ends about 8' off the ground. When I turned the K2 on and tuned it to 14070 khz I immediately heard a cacophony of PSK31 signals. During the course of the evening I worked Hungary, Ukraine, and European Russia, all firsts for me. I also heard but couldn't work Azerbaijan, Spain, Italy, and Germany. Not bad for such a simple setup! Still 5 watts too!

Family activities have prevented me from using it since then, and tonight may be the same unfortunately. I go back to San Francisco tomorrow night, but with luck I'll be able to get in a little more time tomorrow before we leave. Either way, I'm definitely glad I brought it. Before I left Rob said, "If you use it once and make some good contacts, it'll be worth it." Definitely true.

I'd like to bring the rig to Australia next time we go, but apparently Qantas limits you to 7 kilos of carryon, and the Pelican case alone weighs 6.17 kilos. I don't know how I would feel about checking it. Maybe I could get a double allowance if Catherine doesn't bring a carryon? Hmmmm.

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Even more DX

Yesterday I got home from work around 6:30pm and flipped on the radio, as I usually do. The combination of later sunset relative to local time and (I assume) the improving solar cycle is keeping 20m open much later in the evening. It was hopping as usual, but I only heard US stations. Looking at the DX map I saw a couple of spots on 17 and 15 meters, so I switched upwards to see if I could hear anything. 17 seemed dead, but there were a few faint signals on 15, so I decided to stay and watch.

I've noticed that sometimes a band opening lasts only for a few minutes, so if you see a handful of spots on a band it can be worth it to "camp out" for awhile and see what you get. In this case, after a little while I saw Luis, CO6LE, from Cuba calling CQ and easily copyable. It took me a couple of tries but eventually he heard me and we had a short QSO. My first one with Cuba! I have heard other Cuban stations in the past but haven't been able to work them.

Just a couple of minutes later I heard a Brazillian station calling CQ. He called for several minutes, and I repeatedly tried to QSO with him, but he never heard me and as far as I could tell never QSO'd with anyone else either. There followed a longer period of quiet after this, and then I saw another faint trace and put my cursor on it. It took a couple of minutes before I could get a definite copy of his call, and when I did I almost fell out of my chair – it was Ernie, VK3FM, from Melbourne, Australia!

For those of you who don't know, my wife is Australian, from Melbourne, so one of my goals since getting licensed has been to work a VK station. Of course the odds of me working Ernie on 5 watts of PSK31 with my antenna were pretty slim. He was over 7,500 miles from my QTH, and my record distance is only 5,300 miles. As predicted, although he called CQ for about 10 minutes, he never heard me (or anyone else apparently). 

Even though I only got 1 out 3 attempted DX QSOs during this session, I was pleased to hear two new countries. I hear Mexico and Canada frequently of course, but any other DX has so far been a relative rarity for me. 

Although there's no hope of any improvement of my antenna setup while I'm living at my current QTH, I'm hoping to build an external amplifier for my K2 this summer. Elecraft recommends that you limit yourself to 5 watts on the K2 when running high duty-cycle modes like PSK31, so I've done that in order to ensure a clean signal and the long life of my finals. I could buy the Elecraft 100w integrated amp, but I would rather have something I can use with other rigs, or easily leave behind when operating mobile, etc. Also, I think it would be instructive for me to home brew something and try to learn some more about electronics design. Rob and Nick (AK6L and N1UBZ) are up for helping me, and there are some rough kits available already for the amp and BPF modules. The rest will be an exercise in integration and adding some other features (SWR meter? Auto band-switching?). I made a deal with my wife that if I get an A+ in the Java class I'm taking, which ends in 3 weeks, I can start working on the amp. Wish me luck!

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More DX

The bands have been treating me well lately, and I can say that in some ways I've definitely been bitten by the DX bug. These days, more often than not, if I see someone calling CQ in TX, AZ, or someplace else close by like that, I just pass. Part of that is that I've been busy with other things and don't have time for rag chewing, even though I enjoy that. But if I'm just sitting at the computer I'll keep the rig on and the DX map open, switch bands from time to time, and if I see a distant station on the waterfall I'll try and work them.

Since my last post I've worked:

UA0ZK – Kamchtaka/Russia – 3771 miles
UA0CAD – Khabarovsk/Russia – 4823 miles
TI2HAS – Escazu/Costa Rica – 3058 miles
JH3OWW – Japan – 5364 miles (!)
7L3LNF – Japan – 5160 miles
JH9FNB – Japan – 5215 miles 

And hey, presto! Just as I was writing this and monitoring a pretty dead 15m band, up popped French Polynesia (Tahiti to be precise)! Took me a couple of tries but I got a QSO with FO8RZ, 4212 miles away. A new country! All of these contacts have been on ~5 watts and PSK31 with my crappy loop antenna laying on the roof. As Nick said a couple of weeks ago, "I think you've actually managed to get your whole building to resonate."

Catherine gave me an ARRL membership and subscription to QST for Christmas, and I've been reading the "Life Above 50 MHz" column with interest. My K2 can only do down to 10m, but I started to think about the fact that it would be a lot easier to set up a beam for 10m, or 6m, than it is for the higher bands. Hell, I could even build a 6m stack if I wanted to get crazy. 

Someday when we own a house, a little tower and a big beam are going to be on the shopping list. Catherine can have whatever else she wants…

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A new record!

Since my last entry I've continued to listen and try to make QSOs on HF almost every day. The last 24 hours have given me a couple of great DX contacts, including a new personal record for distance!

Last night at around 11:30pm I suddenly heard a Hawaii station on 40m. Turns out it's the same station I worked once before, back in December. I answered his CQ and he responded right away. We just exchanged signal reports rather than having a long conversation – Hawaii is a rare contact for almost anyone so stations there are usually swamped with contacts.

I had the day off today, but Catherine had to work, so I was looking forward to some uninterrupted radio time (in between chores, of course…). At around 11am I saw a LOUD PSK31 signal on 20m. I was going to contact him and tell him to turn his power down, but then I saw that it was a Hawaiian club station. We had a brief QSO (and he did reduce power after his initial transmission), so that was Hawaii twice in 12 hours!

Then later this afternoon I saw that 15m looked open, so I switched down there to see what I could hear. There seemed to be a fair number of faint DX stations, and after awhile I heard someone in Russia, on the Kamchatka Peninsula. On a whim I decided to reply because my luck had been good so far in the past day. It held out, and RA0FLP, Leo, heard me! That smashes my previous distance record of 2537 miles – Leo was 4586 miles from me.

I chat with many hams on the #hamradio IRC channel (, and I've read many ham blogs as well. I think a lot of hams are afflicted with "perfect setup" syndrome. Rather than improvising or making do with what they have, they operate rarely or not at all while chasing the ideal antenna, rig, interface, morse speed, etc. Meanwhile I've been making great DX contacts with 5 watts, a pretty sub-par antenna, and living in the middle of a city! Of course, luck has a lot to do with it, and if I had a better setup I'd probably be making many MORE DX contacts… but for such a modest setup, I'm really pleased with what I've been able to accomplish.

Now, if you've read this far, I have a question: who are you? Tell me in the comments!

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