What's New?
March 24, 2008
A new home page completely focused towards guitar experiments and equipment has been added to the site.
December 27, 2007
A new design TRF receiver for 5 MHz WWV is presented. This will be the last web addition for 2007.
December 22, 2007
A web page on a peaked low pass audio filter experiment was added. This project features the 5532 op amp.
Click here to see this web page or just use the regular menu later.
December 3, 2007
Another web page devoted to NDB listening was added. This page will be updated in the future. A new idea called 3 questions was initiated. I ask 3 questions to an expert on a topic and present their responses. I hope to make this a semi-regular feature on the web site. Updated Dec 23, 2007.
December 1, 2007
A web page concerning building a junk box low pass filter for non-directional beacons was added.
November 9, 2007
A web page entitled Medium Frequency TRF Receiver was added. On November 11, this web article was expanded to include methods to varactor tune the front-end band pass filter and the supplemental page was completed.
Oct 21, 2007
I have been unable to add to the site because of a pinched nerve in my neck. I have improved greatly and hopefully can add some new content in November. W7ZOI has really raised the bar on zero power receivers (crystal sets and such). Please check out Wes' new web site. His work with Hi- Q ferrite inductors illustrates the importance of measurement; we really do not have to resort to large, air core Litz wire coils to built high-performance inductors at MF and this is great news. I have eight FT114-61 ferrite cores on the way from Amidon Associates.
Giovanni, IW7EHC posted a follow-on to the astable multivibrator keyer project from 1998. Big thanks to him!
July 21, 2007
A MF plus HF receive antenna splitter web page and added at http://www.qrp.pops.net/swl-ant-split.asp.
July 14, 2007
A web page describing some experiments with an MF and HF receive antenna was completed and added. http://www.qrp.pops.net/swl-ant.asp. We continue to tweak and update the entire web site to our new "modern" format. Thanks for all your feedback. The next projects will be oriented towards SWL Homebuilders. A 49 meter receiver is being designed and will be presented in the future. 73, VE7BPO
June 18, 2007
The QRP/SWL HomeBuilder web site gets a whole new upgrade! The new code is CSS-based, error free and views on IE or Firefox. The new home page was designed by Daryle Zacharias. Much of the code and CSS was written also by Daryle - big thanks for his great work. Work is in progress to update the rest of the website - enjoy the new look!
May 15, 2007
The poor weather in the Pacific Northwest has caused the servers to lose power many times this spring. If the site is down, try again later. I have a new email address.
May 11, 2007
A new tube guitar amp page is up at http://www.qrp.pops.net/tube_amp.htm.
Dec 26, 2006
Very unusual weather has plagued the west coast this fall and winter. The web servers have been without power or Internet services for several days as a result.
Expect more of the same until spring. I have had very little time for any web updating, experimenting or operating because of my work. All email is being answered in a timely manner. I hope you have a safe and healthy 2007! 73, VE7BPO
Oct 7, 2006
A new SWL experiment is added. http://www.qrp.pops.net/wwv_receiver.htm . I have not had much time to add to the site this year, however appreciate the feedback and ability to connect with other experimenters through email.
Feb 18, 2006
A web visitor spotted errors in a JFET biasing experiment performed in 2002. This led to emails with Wes, W7ZOI and ultimately to this wonderful new JFET experimentation web page. http://www.qrp.pops.net/jfet-bias-2006.htm. In addition to providing information on JFET biasing, the article well describes some of the qualitative aspects of the experiments Wes performed. I feel we can learn a lot by reading the descriptive work of others and applying that knowledge to our own context.
On another matter:
When working on this web site, (which for me is a hobby intended to help the cause of radio experimentation) it is often difficult to spot errors in experimentation or hand-drawn schematics. Another set of eyes is occasionally needed to detect problems as after a point, "one cannot see the forest for the trees". However, I do not have this luxury, as very few of my friends know about electronics and those who do, lack the time because of work and family obligations. I therefore rely on the web audience for feedback to improve the quality of this site. I apologize in advance for any errors that occur and hope people consider that experiments and updates to this web site are performed after-hours and requires considerable time and effort. Although these are likely poor excuses, please also note I am a lay-person, receive no financial compensation and really just try to do my best. For those people who choose to send angry and personally critical emails upon discovering mistakes or because you feel this site is non-21st century, I offer you my sincere apologies and suggest to you to consider not visiting this web site. Thank you, Todd, VE7BPO.
Jan 28, 2006
4 Foot (1.22 meter) Electronic Lab
I am every interested in constructing amateur radio stations and electronics labs that have minimal internal environment impact and take as little space as possible. To that end, Don, K3PRN, wrote an article describing the electronics lab that he put together for ~ $500.00. He was able to find older, but functional equipment to develop a compact, yet functional work bench for his electronic experimentation. Don did a phenomenal job!
Dec 27, 2005
Experimental base bias tuned VFO main and supplemental web pages are added. Most of my winter 2005 experiments were audio and op-amp related, however, these RF experiments were performed and are presented. This was a fun project and more related experiments are needed , however, are not planned. I have a fun new 40M receiver to listen with over the holidays. Happy 2006!
New feature on this and future web pages: Click on a schematic to load it into a separate browser page for printing.
November 5, 2005
This SWL web page was added to the site. It may be of interest to HAMs as well. A couple of new experiments are planned/progressing. A 40M band HAM radio transceiver is also in the design stages. I have little time to build and even less for the web site at present, so progress will be slow. I have been very inspired by EMRFD lately. The upcoming transceiver will be built from circuits found in EMRFD. This book might be a Christmas wish item to tell your family about. A parts order from Digi-Key arrived this week. On the Upcoming? web page at the bottom you can see the big collection of op amps I recently purchased for future experiments and projects.
Sept 24, 2005
Greetings! The latest web page has been moved to final version. It has schematics to possibly appeal to both the SWL and Radio Amateur experimenter. These were a few of the experiments performed during the spring-summer months of 2005. You may have to push the refresh button on your Web Browser to see them (depending on your Web Browser settings). 2 new experimental projects are slowly evolving.
Sept 11, 2005
A drill press is added to the workshop. This was a gift and is greatly appreciated.
Sept 4, 2005
I hope your summer was pleasant. I have added a new draft 2005 Miscellaneous page with various circuits for experimentation purposes. I recently ordered the PICkit1 from Microchip www.microchip.com and will learn to program and use the PIC microcontroller in some of my my home experiments and projects. My latest projects have nothing to do with radio I am afraid.
May 10, 2005
A new web page is added entitled Cascode RF Amp Bias Experiments. It contains some of the better experiments with a 2N3904 cascode stage that I worked with in March-April. I hesitated to present this material, but decided it might be useful for reference and ideas. I will be re-doing experiment 3 in the near future for reasons to be explained.
Mar 24, 2005
A short wave radio page has been added to the top level menu. Please send any good links for SWL-related projects so they might be included. Thanks.
Mar 21, 2005
A web page entitled More Active Antenna Experiments was added. A little more will be added to it in the weeks to come.
Mar 20, 2005
After a long hiatus, the soldering iron has again been hot. A number of experiments have been completed including a few more VPA designs. Some new material will be added in the next few days. Thank you for the emails. I noticed some fabulous homebrew radio electronics web sites have sprung up since 2003. I found 3-4 new receiver projects on the web that use the W7ZOI cascode JFET stage as a mixer or product detector recently. This is a great popcorn mixer/product detector.
New projects will be targeted towards SWL needs. I am hoping to build some AM shortwave receivers that do not use exotic parts. I am working on a 10.0 MHz WWV receiver currently and depending how it turns out, may post it on the QRPHB/SWLHB site. If you have not already purchased it, please consider ordering Experimental Methods in RF Design. This book continues to amaze and inspire me. The included software is also very useful.
Dec 6, 2003
No updates or changes will be made to the QRPHB website for the next 6 months to a year.
Sept 15, 2003
Time is short, but experiments continue. Some feedback from a builder in Israel was added to the Cascode 7 MHz page. Please keep experimenting and bread boarding circuits.
August 25, 2003
We have been working hard to help our town cope with a severe local forest fire. We are very fortunate that we have escaped evacuation notice, or worse, property damage. Parts are arriving for the next round of experiments which will include more VPA's, cascode JFETS and VFOs and some 6 meter stuff. Shown below is the parts order which arrived today:
August 6, 2003
A new cascode nJFET receiver experiment is added to the site. I hope you find it interesting.
July 1, 2003
An old page was improved into a new version. This is the Misc. Pics-Circuits link which is found at the very top of the main page. Some outcast schematics, some experiments and a few personal pics were added to give a human interest element to the QRPHB website.
June 30, 2003 and updated July 16, 2003
A new page is added. This is the result of a generous experimenter who has allowed his recent work to be published on the QRPHB website. Presented is a cool SSB transceiver for 75M, a QRP SWR meter, some DOS software and many other schematics. My sincere thanks to the Dave Forsman, WA7JHZ.
May 09, 2003
A new topic written for the site by Wes Hayward, W7ZOI entitled "Regarding Tapped Capacitor Impedance Transformation in LC Bandpass Filters" is added. This is a fabulous explanation of, for some (me included), a tough topic. Inspired by a question to me from radio amateur Ed Miller, Wes developed the web page as shown. There is no doubt that this web page will be copied and placed on other web sites in different countries and languages. I am aware of over 25 different web sites which have material from the QRPHB site. Please respect the copyrights of the original authors of any material you find on the web. Here is the latest version found of Wes' JFET biasing tutorial. German web site
I am pleased that this site is contributing to the amateur radio knowledge base and am especially greatful to Wes for the support he has given me and the rest of the HAM world. Also, thanks to David White, WN5Y, for his web authoring assistance.
April 21, 2003
A small review and recommendation for EMRFD is added.
Jan 31, 2003
QRP HomeBuilder, had a total of 1196 visitors last week.
Unique visitors for last week divided per weekday:
2003-01-24: 195
2003-01-25: 200
2003-01-26: 200
2003-01-27: 177
2003-01-28: 133
2003-01-29: 136
2003-01-30: 155
Jan 26, 2003
A kind HAM mailed me a letter that my email was not working. The problem was the level of security/SPAM filtering on the QRPHB site is now extremely high and it is apparently set too high to allow normal email from other domains to get through. I apologize as, when we first tested it, it worked for us. It is now working as of 3 pm (Pacific Time) Jan 26, 2003.
Also the Thrifty Thrifty Receiver VFO was stabilized somewhat today. The new adjustments are described in red in the text and on the schematic. This project is at http://www.qrp.pops.net/Pnj_sup.htm
This is my favorite junk-box 30 meter band receiver. It currently has a ~frequency stable VFO. I use it as shown without any extra bandpass filter attached. BCI interference is not a huge problem at my QTH. This simple receiver has a very musical beat note with lots of bottom end which sounds great.
Best regards and thanks, Todd
December 26, 2002
The first new topic in ~ 2 years; Active or Voltage Probe Antenna Experiments was added. This addition exemplifies the totally experimental focus of the QRPHB web site from now onward. The experiments were a lot of fun and a provided many great learning opportunities.
Happy New Year!
VE7BPO
December 8, 2002
It has been nearly 2 years since anything was added to the site and many people have written me to ask why. Disinterest probably was the main reason. Sometimes leaving a hobby for awhile allows you to return later with renewed focus and vigor. In addition, there was some harsh negative feedback by electronic engineers who felt the 70's style schematics were "dumbing down" HAM radio. I welcome all criticism, however, many misinterpreted the purpose of this web site, which is fun, not complex math and using the latest products from the electronics industry. Also a lot of SPAM and viruses have been emailed. In spring 2002, two seperate hackers made attempts to sabatoge our family server and as a result I took the site down for a few months while I decided whether or not to delete it forever. Some nice letters in the mail changed my mind and eventually the site was returned to the web.
Some experiments are underway and new stuff will be posted in the next 2-3 weeks. My email qrp@qrp.pops.net is now working again. I am trying to improve the site look a little and a new logo design is forthcoming.
Thank you and happy holidays! Todd
Previous Updates
The old site history and bug-fixes updates have been moved to the QRPHB Site History Page as they were taking up to much room on this web page. Only the latest updates will be posted on this web page, so please visit the QRPHB Site History Page for more information.
