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files area is open for uploading and downloading - please follow these conventions
I've set up several folders, titled by broad topic, in the files area. Feel free to share interesting stuff with other members by storing it here. Please follow these conventions: * Use the existing folders first. If you can't find a topic area that fits, create a new top level folder. The management reserves the right to rename top level folders according to whatever mysterious scheme they envision makes sense. * Create a folder with your callsign underneath the topic folder and store your offering in your callsign-labeled folder. Please don't store files directly in the topic folders; it makes it too hard to find stuff when there are a lot of files. * Give your file a good descriptive name. Trust me, you won't remember the title antennaibuilt.doc in six months. * In the description area, please include a pointer to the source , whether it is a magazine, book, website, or your lab notebook. It is not only important to credit sources, it is helpful to the reader. I've created folders with my callsign and put stuff in them according to these guidelines which you can use as an example. Please don't upload entire books, magazines, or commercial software to the files area. It rightly pisses off the owners and authors of that material and could get us shut down. *EDIT* (09.02.20) - Please downsize photos and PDFs before uploading them to the website to help us conserve our limited storage. In general, if a file is larger than 250KB, consider posting a link to it rather than uploading the original.
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for new members: please introduce yourself and add your call sign to your profile
Welcome to *qrpdx*. If you've just signed up here, please introduce yourself. Since we are focused on QRP operating, along with building/homebrewing, *please add your call sign* *to your profile name* so it shows on all your posts. Here is how you do that: click on *subscription* (left menu) click on *group profile* button (top center) click on *edit group profile* button fill in the *display name box* with your *first name and callsign* scroll to the bottom and click on *update group profile* This will change your display name for this group only. Members are moderated until this change is made. If you don't have a call sign, please send an email to the list owner (check the home page for the address link). 73 - the mods
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Hi, I have designed and built a GPS-time-base frequency counter. It's a simple design. The GPS generates a PPS (pulse per second) signal which is used to gate a 32-bit counter (74lv8154). The GPS module is a ATGM336H which is available from Amazon. The microcontroller is an Atmega328pb and the OLED module has a 128x32 resolution and is also available from Amazon. I soldered all the parts by hand which was a bit of a challenge with a few of the smaller (.5mm pitch) SMT parts. I use it mainly to calibrate Si5351 clock generator modules (3.3V voltage levels) For this application I use a standard 10x scope probe to measure the Si5351 clock outputs. The software still needs some work, but it is functional. It also has a mode where it just acts like a GPS and shows your current Maidenhead locator and GMT. 73, Scott KJ7NLA
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The soldersmoke podcast crew spun up a homebrew challenge, building the the direct conversion receiver they designed for a high school class project. Quite a few people have taken up the challenge, resulting in a bunch of 40M DC receivers being built, a soldersmoke discord channel being set up, and many youtube videos being produced. I haven't built anything from scratch for a while and this seemed like a good way to dive back in. The receiver is built in four sections: bandpass filter and diplexer, variable frequency oscillator, double balanced mixer, and audio amplifier. The idea is to build using manhattan construction techniques and through-hole parts, and test each section before moving on to the next. An oscilloscope or nanovna-like testing tools are handy but it can be, more or less, built without them. I finished the filter/diplexer, VFO, mixer, and one stage of the three stage audio amp before the rain stopped, and all work as intended. I need to finish the audio amp, which I will try to do over the next couple of days between hikes and outdoor spring chores. I will post a photo of the assembled project but here are a couple of photos of each section. This is the BPF and mixer, with SMA connectors added for testing. This is the last stage of the three stage audio amplifier. You build this from back to front because it is easier to detect problems as you go that way. What is interesting about the project for first timers especially, I think, is the opportunity to actually learn firsthand how mixers work or what "overcoupling" means in a tuned filter or how to test an audio amplifier stage by stage. The discord channel is very active, too, so there is a place to ask or answer questions in real time. If you've never built anything from scratch, this is a good first project... check out their blog (https://soldersmoke.blogspot.com) or hop on to the discord channel (https://discord.gg/Fu6B7yGxx2). 73 Bill K7WXW
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Hi, I made another Pi tuner. It's similar to one that I made previously, but I used an idea from Barb's Pocket tuner where the tuning capacitance is selected using a hex encoded rotary switch. https://www.lcsc.com/product-detail/Rotary-Encoders_SM-Switch-SKBR-16_C2909098.html?s_z=n_C2909098 73, Scott KJ7NLA
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MEMS microphone experiment
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Hi, I recently designed a circuit board (and a 3D-printed case) for a MEMS mic for my Xiegu X6100. Overall I am happy with the mic and I think it sounds better than the original X6100 mic. One downside of using a MEMS mic is that the tiny (1.9mm x 2.8mm) SMT package (they are designed for use in cell phones). To attach the mic to the circuit board, I first put small solder dots on the four SMT pads on the circuit board. I then placed the mic onto these solder dots and used used a hot plate to heat the board to 200 degrees C for a few seconds to melt the solder and attach the mic. ** The main problem with this method is that the burning/scorching point of the circuit board is only slightly higher than the melting point of the solder. You need to reduce/remove the the heat as soon as the solder melts to avoid damaging the circuit board. Has anyone else experimented with MEMS microphones? 73, Scott KJ7NLA PS: I used this MEMS microphone element: https://www.lcsc.com/product-detail/MEMS-Microphones_WILLSEMI-Will-Semicon-WMM7027ATSN1-4-TR_C2931973.html?s_z=n_C2931973 This is an analog MEMS mic with a built in amplifier, and the analog signal output level is higher than the original Xiegu electret mic. The X61200 has a programmable gain pre-Amp that can be adjusted to compensate for this. In practice, I found that I did not have to adjust this much. ** A alternate SMT solder reflow method would be to use an SMT rework hot air gun. ** A third method would be to use an SMT reflow oven (some hobbyists have used modified toaster ovens).
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Thanks
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To all the members of this group: Thanks for letting join in on your discussions, etc. I'm an old timer who is still addicted to the mystery of electromagnetic waves. Low power, digital and CW are my current interests. Hands on education has given some skill in compiling Arduino scripts and I've breadboarded gear using most of the common displays. There are some really good souls out there who were patient with me and helped me move beyond my mental blocks. I've learned more about computers here than I did when I was in the computer industry. My bio is on QRZ. 73s to all. Jack W6VMJ in Fort Collins, CO
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Hi, I've designed a new QRP HF transceiver. It is heavily inspired by the open source uSDX project but it will not run the exact same code base because of some design choices/changes that were made. Like my previous MI3 digital radio design, it is a multi-band with pluggable band filters. The band filter modules are interchangeable with those of the MI3. I received some prototype boards this week. The board dimensions are ~100mmx~85mm (3.9"x3.3") Here are a couple of YouTube videos demoing this radio. https://youtu.be/UFrwQQpohvQ https://youtu.be/uQLGzWsYZqU This is an ongoing project and there is still lots of code writing and testing to do. 73, Scott KJ7NLA
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So... I've only ever done SOTA QRP and, most of the time at home, I have my FT-857 turned down to five watts. Given the noise levels at home, I can't hear signals buried in the S6-S7 noise, no matter how strong, so QRP is sort of a ground leveler. A few months ago, I got a Hermes Lite 2 SDR transceiver, which has been a game changer. Running a variant of Thetis, a SDR software built for the HL2, I have more tools for dealing with noise, along with a spectrum display, two receivers, and other goodies. So now, running higher power at home makes a little more sense... I can hear more so I want more ops to hear me, but the HL2 is a five watt rig. The solution: build a power amplifier, in my case the Hardrock 50, with an ATU. It was a fairly easy build, though the build instructions are for an earlier version of the PCBs, which I did an hour or so at a time over a few nights. After fixing a couple of missed solder connections, it booted right up. The ATU mounts on to the bottom of the amp, the amplifier to the top (and to the big heat sink). I tested it with my KX2 and it puts out over fifty watts on 80M through 6M, usually on a bit less than five watts. In practice, I turn the output power of the rig driving the amplifier to average between forty and forty-five watts, which is plenty of power and lets the amp run a little cooler. Here's the test setup: A couple of things I like about the amp: it has a QRP mode that allows you to use the ATU and wattmeter while bypassing the power amp and will trigger transmit on the presence of RF, which means interfacing it with simple rigs like the NORCAL40 is easy. With fairly simple cabling, it will get band data from a KX2, Yaesu, or my HL2 SDR. Here it is on my radio bench, with the HL2: So I still have my QRP-only setup -- the BLT ATU and heckits watt meter on the right -- but it is pretty easy to swap one of my QRP rigs for the HL2 when I want to do that. I am still learning how to use Thetis and the HL2 signal processing to my advantage and will post more on that. But if you are looking for a good fifty watt power amp with lots of useful features, I can recommend the Hardrock-50. 73 BIll K7WXW
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Hi Scott This is one of the best alternatives I have seen in a while to the typical QRP tuners that use the plastic dielectric "polyvaracon" caps that W7ZOI in his article "The Two Faces of Q" found to be the lossiest and worst capacitors in his junkbox! Though at QRP power levels one may "get away with" using very lossy matching networks due to the fact they don't tend to catch fire as they certainly would at QRO power levels, the fact is, loss is the same at any power level and even though a surprising number of contacts can be made even when actual radiated power is QRPp (when the transmitter is a QRP output), but I've always been of the opinion that when one chooses to work at low power, one should be at least as, or even more concerned about loss as the QRO operator. Nice design. Best regards...Joe ve7vxo On 2025-01-05 19:34, Scott Baker KJ7NLA via groups.io wrote:
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Hi, I designed a receive-only HF radio. If there is enough interest, I could have some boards made at JLCPCB. For a small quantity (JLCPCB) order, I suspect it will be about $30 per board. 73, Scott KJ7NLA
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Hi, I designed an x6100 replacement microphone. I tested it out this weekend on a SOTA outing and it works great. The circuit board files are here: https://github.com/scottlbaker/x6100-microphone And the 3D-printed case can be found here: https://www.thingiverse.com/thing:6703337 73, Scott KJ7NLA
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[CalQRP] Pacificon 2025
Well worth the trip-definitely returning next year. Someone has to challenge me for the ‘HOTA’ (hotels on the air) event. I tied for first place… Dan Presley 503-701-3871 danpresley@me. com N7CQR@... Begin forwarded message: From: "Doug Hendricks via groups.io" <ki6ds1@...> Date: November 13, 2024 at 09:55:38 PST To: [email protected] Subject: [CalQRP] Pacificon 2025 Reply-To: [email protected] ? Save the date. Pacificon 2025 is October 10th, 11th and 12th in 2025. You definitely want to come. We are working hard to return Pacificon Qrp to one of the 3 biggest QRP events of the year. We have several announcements coming, the first of which we are doing a modern version of the Norcal 40 transceiver. But this one will have lots of up to date features. It will be called the Pacificon 40. Anyone who pre-orders one must pick it up at Pacificon in person. This kit is open to anyone who attends Pacificon. You don't have to be on the builder list. More details later. Save the date. Make plans now. Pacificon 25 is going to be a not miss qrp event. We have new activities planned, and you want to be there. Stay tuned for more exciting announcements to follow..
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As the weather turns wet, workbench projects get more of my attention. Last night I built a set of attenuators from calqrp club, designed by N9YS, for my VNA. These are the first SMD builds I've done with solder paste and a hot air gun (the SMA connectors I soldered into place with an iron then reflowed with the hot air gun). I also used a digital microscope but mostly to check my work; I still haven't gotten the knack of coordinating my hands with what I see looking at a screen. You can guess where I stopped last night... right afer I reversed the connectors on the 6dB attenuator, which makes me crazy, but isn't a functional issue. I did a DVM check of the set this morning and all looks good. I will check them on a VNA later today. bill K7WXW
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CW practice net
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Hi Folks-I’m finally looking to start up a CW practice net/session . It’s been a very busy summer and fall but things are starting to calm down a bit, so I thought I’d see what we could put together. My schedule has changed so that Tuesdays are not available for the foreseeable future. What I would really like to do is share the NCS with another station or two as sometimes I can’t do every week predictably, or do it on a bi weekly basis. Also I think I need to keep the net to one band to manage my time commitments. Right now Wednesdays and mostly Thursdays in the evening on 80M would work but I’m open also to a possible daytime slot-maybe Wednesday morning? We’d help to look at what band is most practical for everyone for a daytime slot- not everyone has antennas or radios for all bands. I’ve tried 6 and 2 M but again not every has the right setup for these bands ( as far as I know). Let me know your thoughts and preferences and let’s see what we can do. Thanks! Dan Presley 503-701-3871 danpresley@me. com N7CQR@ARRL .NET
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K2 dust cover
Doing some cleaning and discovered that I have an extra dust cover for a K2. If anyone wants it (locally-PDX) let me know and I’ll pass it along. Dan Presley 503-701-3871 danpresley@me. com N7CQR@...
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SOTA and soldering
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my summer has been mostly outside... i was down in bend this past weekend to hike and activate mount bachelor, ball butte, and a couple of easier hills. i finished hiking the indian heaven SOTA summits a couple of weeks ago and hiked and activated mount saint helens a couple of weeks before that. lots of CW contacts, especially on the high bands, over the course of the summer, all QRP using the end fed random wire i built a couple of years ago and a KX2. i've posted trip reports on the pnwsota.org website for your reading pleasure. as the rains arrive, i will be spending more times indoors and at my workbench. lots of projects and kits are stacked up around here and i am part of group of calqrp club members building a kit from doug hendricks each month. our current kit, a new PCB layout of the W7ZOI direct conversion receiver from the EMRDF book, is mostly SMT components and i am trying a new method of SMT soldering: a hot plate. theoretically, it should be perfect for a small board like this. practically, figuring out how the hot plate works - it doesn't have a user manual to speak of - has definitely steepened the SMT soldering learning curve. i will post more info on this as i go along and, hopefully, get a working DC receiver in the bargain. between now and december: continuing the SOTA hiking, albeit at a slower rate, and putting more time in at the bench, doing a little building and learning some new skills like SMT soldering. what's on your workbench? 73 bill K7WXW
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Not Exactly QRP but....
Please pardon my off topic post. I'm having issues with an Amp Supply LK-500ZC. I've been advised that a good first step would be to test the integrity of my 3-500zs. I wonder if there is anyone within a 100 miles of Portland (or between Portland and Bellingham) who would be willing to test my 3-500z tubes by swapping them into their amp? I'd also like to pick the brain of anyone who is familiar with my amp or anyone who might be willing to take a look at it. TIA /John W7SWB
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PACIFIC NORTHWEST NOT-QUITE-FOURTEENER - AUGUST 3-4
The fourth annual Pacific Northwest Not-Quite-Fourteener is on for August 3rd and 4th. The PNW NQF runs at the same time as the Socal SOTAFest and the Colorado Ham 14er. Since most of us are too lazy to lug heavy radios and batteries uphill, it is generally a QRP event. SOTA activators will be on 146.58MHz, along with CW, SSB, and digital operations across the HF bands. The Socal SOTAFest and Ham 14er are running the same weekend, which translates to plenty of S2S opportunities throughout the western United States. If you are an activator Washington, Idaho, Montana, or Oregon and want to join the fun: post an alert to SOTAWatch for August 3rd, 4th or both. Please include “PNW NQF” in the comment field of your alert. send an email to K7WXW at qrpdx dot org to be added to the PNW NQF op list. That’s it! Most of the S2S activity will happen between 1600 and 2200 UTC but ops will be on the air all day. I will send an email with the full list of ops/summits to everyone a few days before the event. If you are a chaser, watch the alerts on SOTAWatch and make some contacts! Contact me directly if you need more information or if you'd like to join the Socal, Colorado, and PNW groups and organize a regional event. 73 Bill K7WXW
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