Radio Direction Finder
DF2020T (Kit)

DF2020T Radio Direction Finder kit requires minimum assembly for 10~15 Minutes

The Stealth DDF2020T/GPS is an economical but very sophisticated Doppler Direction Finder with GPS and can connect a PC or Laptop, to position and draw plots on GoogleEarthTM display window accompanied with “Navi 2020” plotting program.


** Required only minimum assembling for 10~15 minutes with the tested components in the case
The receiver and antennas are not included


  • Multi Display – Numeric & 36 LED pelorus display
  • Compatible with APRS software
  • Can use with “Navi2020” map plotting display program (with the optional GPS Receiver)
  • Uses GoogleEarthTM viewer for displaying map of ploiting.
  • Automatic or manual operation
  • Accepts standard $GPRMC NMEA GPS message
  • Archive Navi files are auto-saved



  • Microcomputer / DSP Doppler DF
  • DF Antenna Module with built-in magnetics on the bottoms for easy install
  • GPS input for "moving map" Windows display
  • RS232 output for PCs (can use with Serial to USB conveter)
  • Uses Any Type of  FM Receiver and Scanner, Wideband Antenna design
  • 12 - 28 VDC operation
  • Pre-assembled External Antenna  Unit for Plug and Play
  • 4 antenna elements and new circuit design for improving the sensitivity and accuracy
  • Suitable from 100 to 1000 Mhz and beyond
  • Useful from 88 to 100 MHz with reduced sensitivity  



  •  VHF/UHF Doppler type DF, (4 antennas) primarily for mobile DF operation, 100 to 1000 MHz
  •  The user must provide additional equipment (PC or laptop) to use the DDF2020T DF System:
  •  A VHF/UHF FM receiver is required. (For receiving a signal for DF)
  • Pre-assembled antena unit for Plug and Play 


  1. Comes With DDF2020T, Antenna Unit, GPS Receiver, Navi2020 Program, 3.5mm Audio Cable Set, Antenna Control Cable(4.5 m), RG174 Cable(4.5 m), Bracket, Cigar Cord. - Not Include Receiver and antennas
  2. The appearance of product may be different from the picture  


Cotents in the Package

  1. Case with assembled parts - requires a minimum assembly
  2. The Antenna Module with magnetics on the bottoms
  3. Cigar Jack Power Cord
  4. Screw pack
  5. 3.5 mm Audio Cable Set
  6. RG-174 cable
  7. Antenna Control Cable
  8. Bracket



      ·    Receiver Frequency: Determined by user-provided FM

          receiver, range 100 to 1000 MHz
·    Antenna : Four elements,  wave vertical with ground plane (recommended)
·     Ant Scan : Scan rate 430 Hz, rotation clockwise (viewed from above antenna)
·      Ant Switch : Modified Joe Moell Wideband Doppler DF antenna design
·      Employs Agilent HSMP3893 SMT PIN diodes
·       SMT / stripline circuit design, BNC output connector
·       Audio Input : FM receiver speaker audio, 1.0 K ohm 
     load. 25 db dynamic range.
·       GPS Input : 4800 baud RS232 input, NMEA $GPRMC,
     $GPGGA and / or $GPVTG messages.
·       Output : RS232 Agrello DF message, 4800 baud, 8N2.
      (15 messages / second)
·        Ant Outputs : Four discrete active HIGH outputs for
      DDF2020T Antenna (one per antenna) and 1 auxiliary antenna for improving it sesitivity and accuracy.
·       Voice Filter: Switched-capacitor filter, (SCF) 4
      sections. Bandwidth 0.2 Hz

DDF2020T Connection Diagram


  • When you use RS232(Serial) To USB Convertor, please install the right driver comes with it.

  • Antenna N should be placed in frontward of vehicle to indicate 0 degree of DF.Display.

  • When DDF2020 tunes with the right RF signal, it outputs clear 430 Hz audio signal which will indicates stable LED.




Navi 2020
Positioning and Map plotting program on Google earthTM with GPS data
The Navi2020 "map plotting" program accepts DDF2020 DF + GPS messages and plots them on a Google Earth display window. Manual latitude / longitude and DF bearing inputs allow operation without a DDF2020 DF. Up to 100 plot points allowed, and hunt results are saved in archive files.
Google Earth normally works with an open internet link, but areas previously viewed are archived and available for offline viewing. This makes Navi2020 suitable for use in real time mobile hunts, when an internet link is not available.
DDF2020T Full Set (Antennas not included)

Option; 4 Whip Antennas

Reviews Summary for KN2C Radio Direction Finder DF2020T

Reviews Summary for KN2C Radio Direction Finder DF2020T
KN2C Radio Direction Finder DF2020T Reviews: 1 Average rating: 5.0/5 MSRP: $399
Description: DF2020T Radio Direction Finder kit requires minimum assembly for 10~15 Minutes
The Stealth DDF2020T/GPS is an economical but very sophisticated Doppler Direction Finder with GPS and can connect a PC or Laptop, to position and draw plots on GoogleEarthTM display window accompanied with “Navi 2020” plotting program.
Product is in production.
More info:


You can write your own review of the KN2C Radio Direction Finder DF2020T.

K6*** Rating: 5/5 Dec 14, 2012 11:30 Send this review to a friend
Very good product for serious T hunters.   Time owned: 0 to 3 months
I regularly participate in the local 2M T hunt which is becoming more competitive every month. The hides are more creative and many of the hunters have rotatable 4 ele quads on their vehicle roofs as well as sniffers etc. The boundaries are wide and there are no rules about where one can start – distance travelled doesn’t matter – just who finds the T first hides it next month.

Last year I hunted with a friend who had a DF2020T I knew at once I had to own one. I really liked its ability to plot the bearings on Google Earth.

I bought the DF2020T "kit" along with the GPS for a total of $399.
Calling it a kit is misleading. It comes fully assembled except that one has to stick a decal on the front of the control unit, push the power switch into place and put in 4 screws. 

The one thing missing are the whip antennas (it comes with bases and magnets). I got 4 with BNC connectors from High Sierra ( for $12 each.
This is version 2.0 of the DF2020T and it uses 4 antennas. The prior version (1.2) used 5 and my understanding is the change to 4 increased the sensitivity. In addition to the antennas, you will also need to supply an HT or scanner.

Setup is simple. Connect it to the cigarette lighter and an HT with the supplied cables. Then connect the antenna control cable, put the antennas on your vehicle roof and adjust the lengths so they are slightly less than 1/4 wave and space them just under 1/8 wave from the center antenna module. 

One thing to note, not all speaker connections to HTs are the same. The supplied cable works fine with Icom and Kenwood HTs but it caused my Yeasu FT60 to go into transmit mode. And that’s something else to remember... set the PTT lock on your HT before connecting it to the DF2020T to avoid the risk of frying the PIN diodes in the 4 antenna modules if you TX accidentally. 

To calibrate it you will need a small flat-head screw driver to adjust the trimmer through a hole on the top of the control unit and a friend with an HT on low power to walk around the vehicle and transmit on the T frequency. Turn up the volume on the HT until the DF2020T starts to display the bearing and then adjust the trimmer until the direction indicator points at your buddy holding the HT. 

Calibration took a few minutes and afterwards it gave consistent bearings within a few degrees.
To get the most out of the DF2020T, you can add the optional GPS unit, connect your laptop and, assuming you have mobile internet access (e.g. via tethering a phone), you can plot your tracks and bearing on Google Earth. I tried this setup with my friend’s system. While it worked, it obviously required a partner to operate the computer while mobile and it took some practice to become proficient with the software. So for my first hunt with my new DF2020T, I didn't bother with the GPS or the computer.

I can report that first real test of the DF2020T was a success. The T was low powered and quite well screened from out start point. Although we were able to get a good bearing with a 5 ele beam, we could not actually hear it through the DF2020T when we started. As soon as the Doppler heard the T, the display pointed directly at it and we were there within a few minutes - well ahead of all the other hunters. We then discovered that the antenna on the T was horizontally polarized – this explains the low signal strength on the DF2020T’s vertical antennas. 

The only negative I have to say about the DF2020T is lack of sensitivity but I think that true for similar Doppler systems. One suggestion someone made was to add a pre-amp - I plan to try that and will update this review with my findings. 

The manual claims that it will work from 100 MHz to 1000 MHz.

I tried it on 6M with the whips fully extended and spaced as far apart as the cables would allow and it seemed to work fine.



                                                Your price     $398