The shipping costs are no longer built in to our prices — instead we have reduced the price of many items and now have various shipping options. You can choose lower-cost flat-rate shipping (typically USPS Ground Advantage, delivery time 2-5 business days within the USA), or Expedited shipping (more expensive and we hope faster delivery, probably FedEx).
For international orders the same flat-rate and expedited options are available, and the charge is more, reflecting our costs.
Here is my Time of Flight presentation, where I describe the addition of the time domain to the suite of precision measurements delivered by the wsprdaemon system. The following two videos are of the same presentation (because I like redundancy for fault-tolerance):
Discussing the TAPRX-888 SDR design — This is a TAPR project that I am working on, creating the schematic and layout package for a true open-source SDR:
Upcoming: Hamvention 2026 — I will be presenting an update on the Time of Flight systems, including details on the implementation of a time-stamped transmit beacon. If you miss the presentation, please stop the TAPR and HamSCI tables and say hello!
Just a note: Most of my circuit boards are fabbed and assembled in China. My semi-custom aluminum enclosures are also made in China. Recent orders are being charged a 175% import tariff and this will definitely affect the prices I need to charge in order to not lose money.
I am not increasing the prices for currently in-stock items.
I have added the Turn Island Systems “Product Satisfaction Policy” to our “About” page. This has always been our intent, so here it is in writing:
If you purchase a Turn Island Systems product and you are not happy with it for any reason (excluding obvious damage or abuse), return it to us and we will refund the purchase price less our shipping and sales tax costs. Even if the product works as specified, if it does not meet your needs you are welcome to return it for the refund.
“Any reason” means just that. For example, if it turns out that a preamplifier or filter doesn’t actually help your system performance (which can sometimes be tricky to determine), or you for any reason decide you don’t want it, feel free to return it.
I’ve been trying to avoid this one because winding and adjusting all those toroids is tedious and time-consuming, but this thing just makes so much sense that I had to do it. The Nine-Band Filter-Combiner (9BFC) is yet another filter-combiner for use with the WSPRSONDE and other QRP transmitters, and it allows a single multi-band antenna to be driven by multiple transmitters. It combines inputs on 80, 40, 30, 20, 17, 15, 12, 10, and 6 meter ham bands. You don’t have to use all the inputs; leaving any unused ones unconnected is just fine.
The 9BFC design is quite a bit more critical than the previous 6-band combiner, as the added 17 and 12 meter bands are extremely close to the 20, 15, and 10 meter bands. This tight spacing requires rather narrow filter passbands, and there is always a tradeoff between filter bandwidth, inductor “Q”, and filter loss. In order to keep the 9BFC loss to a reasonable level, commercially-available surface-mount inductors as used in the 6BFC are not adequate for these five closely-spaced bands. Instead, I am using iron-powder toroids (T50-6 variety) for those frequencies. The 80, 40, 30, and 6 meter filters do use surface-mount inductors.
Not only are these toroids tedious to wind, but the inductance of each of the ten toroids must be carefully adjusted to provide the proper filter shape and impedance match. Adjustment is done by spreading or compressing the windings while observing the filter response with a Vector Network Analyzer — this process requires some iteration since each channel has two toroids and they do interact. Once adjustments are complete the windings are secured with fingernail polish.
Of course, your antenna has to support the bands in use. When using the eight-output WSPRSONDE and the EFHW-8010 (end-fed half wave, 80-10 meters, from myantennas.com) I am using all the 9BFC inputs but the 6 meter port. It works quite well (my two WSPRSONDE locations are shown here, Friday Harbor WA, and Occidental CA). I have a separate 6-meter antenna for the Occidental site.
This has been in use for a while, combining the multiple outputs of the Beacon Blaster and WSPRSONDE onto one SMA jack, allowing the use of a single antenna. The results have been excellent, so this box is now on the Turn Island Systems website, available for purchase:
Applications for the Filter-Combiner are not limited to the WSPRSONDE. Some have used this to combine the outputs of other QRP (1W or less) transmitters. One person is using the Filter-Combiner in reverse as a general preselector, sending the output of a single multiband antenna to several narrow-band SDR receivers (reducing overload from out-of-band signals).
What about eight bands? I glad you asked that question! Fitting additional bands into the combiner has proven to be a major challenge. A 160 meter port can’t be implemented using available (inexpensive) components — too much inductor loss. Squeezing the 17 and 12 meter bands into the gaps between 20, 15, and 10 meters also requires inductor tolerance and loss well beyond that of readily-available parts. However, if there is demand for it a future combiner could include a 6-meter port.
But single-channel filters can be provided for those “oddball” frequencies.
Rob Robinett and I will be co-presenting at the upcoming HamSci Workshop (https://hamsci.org/hamsci2024), our topic being High Resolution WSPR Transmissions for Ionospheric Research.
We will also have a hands-on demonstration of the hardware and software used, including the new WSPRSONDE-8.
