Roanoke Doppler DF
This is the world renowned Roanoke Doppler DF unit. Originally designed by Charles Tavares, N4FQ, and published in "Transmitter Hunting" by Moell, K0OV and Curlee, WB6UZZ, this unit features a sixteen L.E.D. circular display with a center reference L.E.D. to provide a quick and easy visual indication of the direction to the signal you are tracking. Advances in technology have enabled us to reduce the number of parts in the circuit to some degree, thus slightly improving power efficiency and reducing the cost of the unit over the original design. The low signal lockout and phase inverter features from the original design are included. Also, we have incorporated a parallel data output feature to facilitate easy interface to ASCII/RS-232 serial port adapters offered for use with A.P.R.S. (Automatic Packet Reporting System) Software.
We offer a professionally etched P.C. board, detailed schematic, parts list and a well written step-by-step instruction manual with illustrations and the full calibration prodedure.
Product Alert!
Some of the boards appear to have a minor error on them. This is characterized by a "stuck" low-level LED and non-functioning reverse switch. Please be aware, even the boards we are offering now may have this issue.
To repair, look at the trace from C29. Check to see if you have conductivity from the right side of C29 to pin 14 of U-12. If you have conductivity here you have a problem. This trace should run from C29 to U-12 pin 13.
The Repair: Cut the trace and add a jumper from the right side of C29 to U-12 pin 13.
Special thanks go out to Bill Rupp N0MKJ, and Joe Moell K0OV for identifying this problem and developing a solution.
Roanoke Doppler DF
Roanoke Doppler DF
This is the world renowned Roanoke Doppler DF unit. Originally designed by Charles Tavares, N4FQ, and published in "Transmitter Hunting" by Moell, K0OV and Curlee, WB6UZZ, this unit features a sixteen L.E.D. circular display with a center reference L.E.D. to provide a quick and easy visual indication of the direction to the signal you are tracking. Advances in technology have enabled us to reduce the number of parts in the circuit to some degree, thus slightly improving power efficiency and reducing the cost of the unit over the original design. The low signal lockout and phase inverter features from the original design are included. Also, we have incorporated a parallel data output feature to facilitate easy interface to ASCII/RS-232 serial port adapters offered for use with A.P.R.S. (Automatic Packet Reporting System) Software.
We offer a professionally etched P.C. board, detailed schematic, parts list and a well written step-by-step instruction manual with illustrations and the full calibration prodedure.Some of the boards appear to have a minor error on them. This is characterized by a "stuck" low-level LED and non-functioning reverse switch. Please be aware, even the boards we are offering now may have this issue.
Product Alert!
To repair, look at the trace from C29. Check to see if you have conductivity from the right side of C29 to pin 14 of U-12. If you have conductivity here you have a problem. This trace should run from C29 to U-12 pin 13.
The Repair: Cut the trace and add a jumper from the right side of C29 to U-12 pin 13.
Special thanks go out to Bill Rupp N0MKJ, and Joe Moell K0OV for identifying this problem and developing a solution.
Roanoke Doppler DF
No longer available!
It took 15 years to sell a run of 500 boards.
I'll release it to the public domain as time permits.
No longer available!
It took 15 years to sell a run of 500 boards.
I'll release it to the public domain as time permits.
Frequently Asked Questions
Frequently Asked Questions
About the Roanoke Doppler DF
Q: How much is shipping?
A: FREE! The $21.00 includes First Class shipping in the U.S.A.
Q: What does this unit use for a radio source?
A: The Doppler unit works with any receiver (you must provide your own).
frequency coverage of the unit is determined by your radio and the antenna array.
The most effective range is 50 - 1000 MHz. It works with ELTs too!
Q: Are there any hard to find parts?
A: This unit uses only two components which might be classified as "hard to find." First, the 74hc154 1 of 16 data switch. This is a common item, but this board uses the "narrow body" (.3") version. The other item is the MPN3401 PIN Diodes. Both of these items are available, just not from your local Radio Snack.
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