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Ten-Tec's Model 1254 is a general coverage AM and SSB superheterodyne receiver that comes in kit form. Controls are simple, and the display is numeric only, using six seven segment, and three fixed LEDs. While it is relatively easy to assemble, looks great, and performs well for its price, its design is strictly based on the technology and available parts from many years ago. As a kit everything on its two circuit boards are hand solderable through hole parts, not a single part is surface mount. Some upgraded parts have been incorporated into the circuitry over the years.
The radio has a few limitations in its design that are important to address. One major problem is it only tunes in coarse 2.5 KHz steps when in SSB mode, and in 5 KHz steps in AM mode. These are not fine enough steps for practical usage when trying to receive transmissions on single side band. In an effort to get around the large tuning steps the radio is equipped with a "clarifier" control. Its function is to slightly pull the second IF frequency mixer's oscillator off its 455 KHz center in an effort to shift the tuning frequency. Still its range of off tuning isn't broad enough to receive far off step frequency stations clearly.
The radio has the ability to store frequencies and recall them by a channel number, but the total amount of storage space available in the radio is limited. There is no computer interface available to control the radio externally, to program its memorized frequency channels, or to read digitized sound data through. Neither is there is an analog line level output. There is no signal processing available for the radio's baseband analog signals. The processor used in the radio, a PIC, uses one time programmable memory for its firmware, and once it has been programmed at the factory there is no way to update it.
To solve these problems an upgrade kit has been developed which resolves many of these shortcomings and adds new features with minimal physical impact and no design changes to the existing radio.
Totally new firmware has been developed to control the display, control an optional newly added LED on the radio's existing display board, read from the existing keys and tuning encoder, and to implement a new control algorithm for the radio's existing PLL used in the tuner's VCOs. The new firmware allows the radio to be to tuned from the main tuning knob in 100 KHz, 10 KHz, 9 KHz, 5 KHz, 2.5 KHz, 1 KHz, 100 Hz, or 10 Hz steps.
There are larger amounts of storage available for frequency channel memories, and the storage is maintained when the radio is powered down. The radio's backup power 9 Volt battery is no longer used.
A new feature for the radio with this upgrade is the ability for an external computer to control the radio using either a serial interface or USB connection. The control protocol is programmed to be compatible with software that is available for other Ten-Tec radios. Using the external computer control the radio can be tuned to precise frequecies. A Windows control program specifically designed for this upgrade is available free for download from this website. A new rear aluminum panel with either a DB-9 RS-232, or a mini-B USB connector, and a line output jack is included in a full upgrade.
Two extra features are available with the addition of two wires between the upgrade and Ten-Tec's main radio board. One is the ability to read the received signal strength information over the computer control interface. The other is ability to bring out an independent analog line level and digital audio output to the rear panel.
The Ten-Tec seven segment LED display has been known to be a source of audio noise and distortion. Three major new changes to the firmware now address this problem. To greatly reduce display switching noise the latest firmware now enables existing hardware on the Cypress processor to drive the display LEDs using spread spectrum techniques. The display brightness is now also adjustable, and set in the radio setup mode. Reducing the display brightness reduces the power requirements and generated noise. Lastly the display can be programmed to fade to off after a set number of seconds of operation.
A refined algorithm has been developed to tune frequencies with the PLL. The processing time to tune frequencies on sub 2.5 KHz steps has been significantly reduced, PLL tracking has been improved, and sidebands eliminated.
Signal strength readings have been calibrated and can be read over the CAT interface in S units using the Orion protocol. The CAT interface can be also be ordered supporting a superset of the Ten-Tec Eagle protocol where signal strength is reported in dBm.
To ease use of the digital audio stream output over the USB port audio data is now transmitted using straight Microsoft ADPCM coding (not currently supported in ComCAT).
The lowest decimal point used to signify that you are in either memory mode or VCO mode has been reversed to match the existing Ten-Tec PIC firmware, not Ten-Tec's documentation.
The firmware on the upgraded processor can be updated with the latest revision by processor (on older through hole versions) or daughter board exchange. European customers can upgrade through an E.U. location.
New firmware is compatible with all previous upgrade kit versions, apart from shipping costs, at no charge. Please contact the information address below for instructions.
The upgrade is primarily the result of replacing the radio's PIC16C5x processor with another processor of newer design from Cypress Semiconductor. Since the PIC variant that is currently used in the radio advances have been made in processor speed, program and data RAM size, reprogramablity, and on chip peripherals.
The upgrade processor is mounted on a printed circuit board that plugs in the socket formally for the PIC processor. The board has a 6 pin flex cable connector to an auxiliary interface board mounted on the new aluminum rear panel, and a small coax connector to tie into the radio's audio signal. The rear panel board holds circuitry and the connectors for the computer control interface, audio output, and AGC input.
ComCAT is a Microsoft Windows program that allows simultaneous control of the upgraded Ten-Tec 1254 shortwave receiver from either the radio's front panel or a remote computer connected via either a RS-232 serial link or USB connection. (See note 2)
Tuning frequencies, tuning speed, and memory channels can be adjusted up or down using mouse spin controls or by direct number entry from either the computer screen or keyboard. Instant jumps to any of the amateur radio bands are provided by clicking an appropriate radio button. Receiver mode is selected using another set of radio buttons. The receiver can be locked from radio front panel inputs by checking the Lock checkbox.
The control program is completely standalone and needs no installation. Just place the unzipped ComCAT.exe and it's DLL file in the directory of your choice. The COM port used for communications is selected using a windows system environment variable: COMCAT=COMx, where x is the number of the COM port assignment. A virtual COM port is used on the PC when communication to the radio is over USB. (See the setup documentation within the download zip file.)
ComCAT is downloadable free from this website.
The Ten-Tec 1254 was already a worthwhile investment, but with this low cost upgrade its features are greatly enhanced, making it the equivalent of more expensive receivers.
Updated 8/25/2013 : The basic, RS-232, and USB kits are available for order.
The basic version is simple to install. The radio's PIC processor is removed from its socket and the new upgrade board plugged in its place. The following extra features will then be available.
The full version builds on the basic version, it also includes a replacement rear aluminum panel with an addition circuit board and connectors. With these new components these additional features are available:
Price for the basic version upgrade is $58
Price for the full version upgrade with USB interface is $88
Shipping is via USPS is $7.15 within the U.S., $24.95 to Canada and Mexico, and $33.95 internationally.
Price does not include Connecticut sales tax if applicable.
To order or request information send an email to:
tt1254v4-information@yahoo.com
For orders a return e-mail with be sent with a PayPal payment link.
Installation Instructions Basic Kit
Installation Instructions USB Kit
Operation Manual
ComCAT Windows Control Program
ComCAT Documentation