Main Radio Interests
High levels of local radio interference from neighbours' switching-mode power supplies, LED lights, and solar panel installations have kept me off the air during recent years. In the past, major activities at VE3OAT have included the following :
- Precision radio frequency measurements.
- DXing (the excitement that got me first involved in radio so many years ago!).
- Observing HF radio propagation, especially to help find DX (distant) stations.
- Taking part in a radio experiment during the 2017 solar eclipse.
I will add more details about these activities as I find time.
Radio Frequency Interference (RFI)
Currently, most of these activities have been severely curtailed by heavy radio frequency interference (RFI) on almost all HF bands from two solar panel installation less than one kilometre from my home. Curiously, radio interference from these installations seem to be suppressed (filtered at source) on frequencies below 2 MHz but not above 2 MHz. The interference is very strong on the 80 through 30 metre bands.
In spite of the interfering noise (or, perhaps because of it), I have begun activity on the 160 m band using the new digital mode FT8 (part of the WSJT-X software package) and getting reasonable results. It helps that I have installed a small, active, receive-only magnetic loop antenna which is oriented to null-out at least some of the noise from the direction of its source. Transmitting is accomplished by shunt-feeding my 15-m tall tower which now has 20 ground radials, each a quarter-wavelength at 160 m. Unfortunately, my property is longer than it is wide so the radials don't go very far in the north-south directions. I might never make DXCC or even WAC with this set-up on the 160 m band but it is fun trying.
Spilsbury & Tindall SBX-11 Portable Radio Transceiver
At a hamfest many years ago I had picked up a very used Spilsbury & Tindall SBX-11 portable HF transceiver. These radios are famous in Canada for having been used extensively in the Canadian Arctic and other remote areas by Canadian government scientific survey groups and numerous commercial resource exploration teams, as between field survey crews and their temporary base camps. They operated on HF frequencies allocated internationally to the Land Mobile Service. Well, I brought it home, looked it over and put it on a shelf for a "rainy day" project. Last year we had a rainy day (and several more) and I can report now that this little radio works OK.
- Number of channels : 4, crystal-controlled (2 crystals for each channel, one for receive, one for transmit, allowing simplex and half-duplex operation);
- Frequency rage : 1.6–8 MHz, depending on tuning modules installed for each channel;
- Power output : rated 5–10 watts PEP, depending on battery voltage;
- Emission : USB or LSB, not selectable (determined by crystal installed);
- DC Power : 9 size "D" cells (seems OK over 10–13.5 VDC by my measurements).
I have done two mods to the radio : added a phone jack, and changed the hard-to-find "Charge" connector and removed the associated charging circuitry.
The phone jack was easy to do and, while the speaker behind the front panel is quite adequate, I am hard of hearing and prefer to wear headphones.
Since I did not plan to use rechargeable batteries in the radio, there was no need for a "charge" connector, so I changed it to a type of connector that I could actually connect something to, removed the wiring for the internal charge current limiter, and now use the connector to attach an external DC power source of 12–13 volts using Anderson Powerpole connectors, like the rest of my radios. The radio can still be powered with internal batteries (nine "D" cells in the bottom compartment), but I normally use it with an external power supply.
And of course I changed the original crystals for ones that will operate in our Amateur bands, using a couple from my junk box for 80 m and the rest (for 60 m) from the folks at Quartslab, unfortunately no longer in business. After getting some necessary tuning modules (and a few extra spare parts) purchased from John, VE7JBX, the radio now operates on all four channels, one at the top of the 80 m band and the other three in the 60 m band.
The radio works fine, although power output seems a little low (4 watts in the tune position and about 4W peak in voice), as if the transistors in the power amplifier are a little "tired". The receiver is sensitive, although a bit broad in selectivity, as expected for a "foolproof" radio. I have not yet tried it in the field with a portable antenna but it works fine at home with my 80/40m parallel dipoles and antenna tuner, and running on "shore power" (as the navy would say).
The somewhat newer model of the radio (SBX-11A) was usually painted orange. You can occasionally find the 11 and 11A models for sale on the Internet, often for ridiculously high prices. There is a very helpful discussion group about these radios, with downloadable documentation, at the "SpilsburySBX11" special interest group at Groups.io. See also the websites of John VE7JBX and Matthew Kendall for more information. And, for a little general history of communications in the Canada's North ...
Project with a Chinese 102E Radio Set
Several years ago I acquired the transmitter from an old Chinese (PRC) Type 102E army radio set. I don't have the matching receiver that was part of this set. My project involved designing and building a suitable P.S. in the re-purposed cabinet of an old Swan 117XC P.S. unit. (A big thanks to Frank, VE2KOI, for providing the Swan unit.) There is nothing remarkable about the design or construction of my power supply except that, according to markings on the dial, the voltmeter I chose from my junk box was originally used in the famous British Wireless Set No. 19 (which I have never owned). Besides a suitable B+ voltage for the transmitter, the power supply provides 6 VDC for the transmitter's tube filaments. I have ensured that this voltage is actually slightly on the low side of the rated 6 V in order to prolong the life of the tubes.
The Chinese transmitter provides CW, MCW and AM voice transmission capability over the 2 to 10 MHz range with about 10 watts output. In Canada the MCW mode of emission is not legal but the transmitter works fine for CW (I have not tested it for AM). Here is a link to a nice article about the radio set (receiver and transmitter) by Mark, NF6X. The Chinese transmitter and my "new" power supply are shown above.
RT-654A/TRC77 Receiver-Transmitter
I have another "green" radio, bought many years ago on the surplus market, a TRC-77 (RT-654A) HF man-pack radio used by U.S. forces during the Vietnam War. It was designed to receive AM and CW on six channels and to transmit CW on six channels (not necessarily the same channels) in the 3-8 MHz band with at least 10 W of output power. Since the transmit and receive channels are not necessarily the same, it is possible to work half-duplex, a requirement for many tactical operations. It came with the original headset (and multipin connector) and a J37-type Morse key mounted on a leg-clamp.
I have 'crystalled' it for CW frequencies in the 80 and 40 m Amateur bands. Other than changing crystals, the only "mod" I have done is to install two LED lights, a green one for when the radio is in Receive mode and a red one for Transmit. I should change the headset connector to the standard quarter-inch phone plug. Please ignore the obviously reversed antenna connections in the photo above — the setup was hastily done just to take a picture.
Here is a nice article by N6CC about the TRC-77.
Do You Belong to a Radio Club?
I support the following organizations with my membership :
Each of the national organizations (and many others around the world) is a member of the International Amateur Radio Union (IARU), an umbrella organization that, among other things, represents the Amateur Radio Service at international telecommunications conferences, especially those organized by the International Telecommunication Union (ITU), a world-wide organization of the United Nations.
If you are an Amateur Radio operator, are you a member of your national Amateur Radio organization?
If you would like to become an Amateur radio operator, you can find excellent tutorial material at the Websites of the two national societies mentioned above, as well as at many others. In addition, the Amateur radio clubs in many large cities organize classes to help students prepare for the licensing examinations, so check with your local Amateur radio club.