Posts Tagged ‘going broke saving money’
Quick notes on converting the HP ES120 2950-watt blade server power supply to run “48-volt” amateur radio amplifiers. The power supply I have has a slightly different in configuration from the one described by W8ZN on the K8GP site.
I picked up the power supply on good terms at Dayton some years ago and finally managed to get around to hooking it up after I put two 240-volt, 20-amp circuits in my shack this spring/summer. I used a molded air conditioner extension cord with the female end cut off to attach it to the wall. Hot-ground-hot is the wiring on the AC input side. On the output, there is a jumper block and two pairs of blade connectors, with one pair being positive and the other negative, strapped together. In the middle of the output there is a jumper block.
Here is where the steps differ from the W8ZN steps: instead of shorting two pairs of pins together, this power supply requires three in a line to be shorted together. It’s visible in the photo below, I think. The center row.
I’m getting 51.4 volts unloaded. Load will be described in the future as it comes to be…
On Christmas Eve, I was sitting at my in-laws’ kitchen table with the Small Wonder Labs SW-40 I built as a high school kid in 1998 listening to beautiful music and I got the itch to come up with a radio smaller (and less expensive) than the K3 to drag around with me when I go places. My mind wandered to the NorCal Sierra, which was a featured project in ARRL Handbook’s of my youth. I was able to come up with a draft version of that Handbook article on the web—pause for a moment and think how revolutionary that is—my in-laws don’t have an ARRL Handbook, let alone the one that contained the Sierra article. I looked at the bill of materials and realized that I had some 70% of the parts in my junkbox. This seemed like a good idea until I went searching for a PCB.
Why PCB? Well, I’ve done the dead-bug thing and it works great but it’s a pain to troubleshoot and unless you have decades of experience doing it, it looks like a Mexico City suburb, sprawling unpredictably in every direction with only the most tenuous connections to the core. Since I was seeking a travel radio, I wanted it to be compact, easy-to-troubleshoot, and relatively rugged. Due in no small part to the wishes of the Sierra’s designers (not coincidentally founders of Elecraft), boards are no longer available. I looked into doing my own board, but if you don’t mix chemicals yourself, you’ve suddenly spent $150 on PCBs, plus the layout effort. I toyed with making the board smaller (a win in several ways) by using surface-mount parts but even that was a non-starter since my junkbox parts are through-hole, requiring me to buy everything.
Astute readers can extrapolate what occurred next. I went to the Elecraft web site to price the Sierra’s successor, the K1. I had all but made up my mind to sell off some junkbox items and raise the capital to buy a K1 kit when something occurred to me: fellow ham blogger Mike, VE3WDM, had recently moved to a smaller QTH and was offering a half-completed K2 kit for sale. His asking price was only a little more than the K1 kit with some of the options I wanted and it was all-band. The ad had been posted for some days by this point, so I fired off a sheepish e-mail to Mike asking if the radio was still available. It was. We sealed the deal and the radio made the somewhat tortuous ride (for us, not the radio—it sat in Chicago for two weeks) from his QTH to mine via the postal system.
I would not have bought a partially-finished kit from just anyone. However, since this was Mike’s second K2 build and he was documenting it carefully in a blog, I figured it was a pretty safe bet. So far, that is definitely true.
While I was eagerly awaiting the radio’s arrival, I redoubled my efforts to get a friend’s TS-930S off of my workbench, a task that involved replacing all 115 electrolytic capacitors on the cookie-sheet-sized “Signal Unit” board (similar to the K2 and K3 “RF unit”). That radio still has low drive (it has ALC again and sounds like a million bucks), something I traced to a hard-to-find semiconductor that’s now on-order. So, I gathered it up and started work on the K2 on Sunday afternoon.
Last night, I got it on 40 meters RX-only and peaked up the RX BPF. Former K2 owner KL9A mentioned to me that it has some blow-by on strong signals but that he thinks it’s a pretty good radio. I can confirm that based on my experience last night. It sounds really really good on CW.
More on the build to come…including a look back at some troubleshooting of the BFO circuit.
Some good planning on Sarah’s part yielded a bridal shower for her sister scheduled on the same weekend as the Hamvention. Huge win.
- Speaking of huge wins, there was no sewer back up this year.
- Like the last time I attended in 2011, I’m pleased to see more younger (than me) hams in attendance. A high-ranking ARRL official noted to me the “energy and enthusiasm” present in this generation of young hams that was not present 15 years ago (this year marks my 20th year as a ham, but I didn’t mention that). Attendance was still thin compared to my first visit in the mid 1990s.
- Deals. I stimulated the economy by purchasing a small CDE rotor for my VHF activities, an HP server power supply for a future solid state amplifier project (>55 amps at 50 volts), a couple of 900-MHz antennas, and some miscellaneous small parts. I sold some junk to partially cover that expense.
- People. Ran into a lot of old friends and made some new ones. This is really why I go to Dayton, well, that and the junk. K8MFO tells me there are Bureau cards coming. W8AV has 930s for me to work on. W2NAF had people for me to meet. AD8P was able to win himself a pizza from an unnamed W5 in the “SB-200 challenge” of correctly differentiating an SB-200 from an SB-220 at a distance of 20 feet—a tribute to the W5′s failure to distinguish the two until after the sale last year.
- W2NAF has written an article about our trip to Adak (NA-039) that was published in the June 2013 issue of CQ. It has a lot more background detail than what I wrote on the blog. Check it out. I picked up a copy of that and the May 2013 issue which has the 2012 CQ WW CW results in it.
- Products. I just don’t care that much about new products. The Ten-Tec Rebel that several people have already discussed is a cool idea. I know that Ten-Tec took some flak for not opening up the Orion SDR core when they produced it. But, let’s be realistic, people. Hams would have bricked those suckers in a heartbeat. A sandbox “open source” radio is a step in the right direction, but I question what a ham can really customize that matters without screwing it up. Maybe I’m just not visionary enough. Almost 10 years ago now, I interned in the R&D lab at a large consumer appliance manufacturer as an undergraduate my supervisor was always saying, “How can we make this attractive to the [hardware] hackers?”
- Guns. The Hamvention web site was very specific that the Trotwood Police Department would be actively enforcing Hara Arena as a non-gun zone. Seriously? It’s a ham radio convention. Bill Goodman is there at least once a month the rest of the year. Do hams bring their go-kits to gun shows? They must. Inquiring minds want to know…
- Suites. I did not do the contester suite thing. Was thinking of going on Friday night but fell asleep in my in-laws’ living room. This is a recurring problem when I visit so no one bothered to awaken me.
Was the trip worthwhile? I think so.
Air travel is hard on luggage. Just yesterday, I was sitting on the tarmac at Washington National (DCA) as we waited for our arrival gate to become available. The ground crew were loading baggage into the departing aircraft and did not elevate the loading elevator quite enough. Several suitcases and a Pack ‘n Play (the technical, brand-inspecific term for these things is a “playard”…who knew?!) toppled blissfully off the end of the elevator and landed in a pile beneath the aircraft. That’s just the stuff you see…
Until recently, I managed to travel carry-on only most of the time, something that preserved the life of my inexpensive soft suitcase far beyond expectation. However, the proliferation of checked bag fees has caused thrifty passengers to stuff as much stuff as possible into their carry-ons, making the overhead bins a nightmare. My employer is willing to pay for the first checked bag when I travel for work, which is 90% of cases or more, so thrift is slightly less motivating for me. I suspect that checked-bag fees have also increased the size of the average piece of luggage, making it perilous for my small soft-sided bag. So, like U.S. drivers of 10 years ago who preferred gas guzzling SUVs for their “safety,” I decided to fight back with a hard-sided suitcase.
After a trip to Europe in 2008 in which one of our soft-sided suitcases was essentially destroyed, Sarah was on board with this idea. I proposed a Pelican case at the time, but she thought it was ugly and “looks like a toolbox.” Since it’s a well-known fact that women drive household purchasing decisions, it should be no surprise that we ended up with a set of highly-rated, yet inexpensive hard sided suitcases. After one or two domestic trips, one of these developed a crack. The trip to Greenland in January of this year was impetus for me to take matters into my own hands: I bought a Pelican 1560 (empty with no foam) and the 1569 lid organizer.
The genius of the 1560 is that you can’t load it to more than 23 kg with “normal” contents. Although, Sarah—and airline, security, and customs employees the world over—would argue that very little that goes into my bags is indeed “normal.” It’s only a little more expensive than a department-store suitcase and definitely cheaper than most of the high-end brands. And, of course, it’s indestructible…and it floats. What’s not to like about that? There is one downside—it is almost always loaded to near 20 kg, so it’s heavy. But, until the airlines force us to pay by the kg, I have my suitcase for life.
Upon return from our latest trip yesterday, the two larger hard-sided suitcases had big cracks in them. “I think all of our suitcases should be Pelican cases,” Sarah remarked as we left the airport.
I do not spend a lot of time on VHF/UHF FM and have not for many years. My first radio in 1993 was an Alinco DJ-580T handheld and I’ve thought at various times that a new handheld might suit me well, especially for receiving. A few weeks ago, as I tend to, I came across a Yaesu VX-3R offered “for parts or repair” on attractive terms and so acquired it—my second handheld ever. The problem seemed straightforward enough: full TX power, but no RX on amateur bands. RX on FM broadcast OK. The seller assured me, after I had agreed to purchase based on his description, that “somebody” had told him that this problem occurs when “only one component is bad.”
Based on the seller’s description of the problem and a thorough reading of the Technical Supplement, I developed a short list of candidate failure modes, components, and sources. Fortunately, all of the components could be sourced easily from the usual sources.
When the radio arrived, I gave it a functional check and it indeed exhibited the problem that the seller had advertised. I quickly popped it open and noticed a small red sticker in the lower right-hand (when facing the device like you would operate it) corner of the Main Unit (Side A, per the Technical Supplement’s notation). A neatly hand-drawn arrow pointed to component Q1025, which upon closer inspection, was clearly damaged.
So, I quickly set about identifying the component and procuring a replacement. It was a NJU7007F3 operational amplifier. Huh…it did not contribute to any of the failure modes I had initially suspected. However, a careful reading of the Technical Supplement indicated that this op amp drives varactor diodes in a tracking preselector—so, if it does not work, the radio will exhibit varying degrees of deafness in the amateur bands. I found out later that the “somebody” was actually a Yaesu technician who had seen the radio for repair at the behest of a previous owner and left the sticker for me. At any rate, this component clearly would have to be replaced if I were to fix the radio, so I set about looking for a source.
Mouser listed it in their catalog but wanted me to buy a reel of 3000. No thanks. At least they had it listed. So, I did the next most logical thing—I made a list of other parts that I needed and called Yaesu. The part was back-ordered to Japan for 4-6 weeks, but only cost 0.42 USD. I bought three.
After however many weeks it has been, a package from Yaesu showed up on my doorstep tonight. After repairing a damaged PCB trace (non trivial on something this small), I was able to replace it. The little black speck in the middle of this photograph is the removed component. For my non-US readers, the US 0.01 USD coin (“Penny”) is about 19 mm in diameter.
The radio fired right up and received NOAA/NWS right away. The entire repair once I had the parts was about 30 minutes. There are still two unbuilt SoftRock kits, an IC-290A with an unlocking PLL, and W1GHZ transverters for 903 and 1296 to be worked on…maybe tomorrow…