Anyone have the new RDF from Global TSCM Group?

[prcguy]

I picked up a newly released RDF at Dayton and it works really well so far except for the antenna heading pointing in the wrong direction. I had to reverse the antenna array on my truck to make it point correctly and the antenna headings are probably just mislabeled.

The antenna is comprised of five little mag mounts with female BNC connectors and you have to supply the whips or rubber duckies. You can move the mag mounts to optimize for VHF, UHF, 800, etc. You also need to supply a VHF/UHF FM receiver and once you get the volume at the right level it takes off and points like a bird dog.

Cost is only $300 for the non GPS enhanced version (which I got) and its display is a 36 LED circle that points toward the radio source and a three digit compass heading. The GPS version overlays headings on Google Maps and the more headings you add the more accurate it will point to the source on a map. That was $98 extra and I can add the GPS module later.

Check it out at: Radio Direction Finder DDF2020T - GLOBAL TSCM GROUP, INC.
prcguy

 

[N_ALSCAN]

I saw this at Dayton, and thought about buying one for a LONG time....

I have an older doppler that I rarely use, and made myself justify a need for a newer DF system

I did not get to see a demo of the software in "action" showing a location plot of the transmitter. Does it actually show an direction "cone" on screen or does it simply show the numerics of the direction of the transmitter.

Hope you enjoy, and you may push me over the edge to actually purchase one.

Rob

 

[kc8hnz]

I saw this and am sceptical that a unit at only $300 can be expected to give even satisfactory results. If i see some reviews for it and its positive I might be tempted...

 

[prcguy]

I called the Global TSCM about my RDF showing the wrong heading and it turns out there is a calibration adjustment on the top panel. This will allow you to use a hand held radio in front of the vehicle at some distance and dial in the heading in just right. I'll be tweaking it this weekend.
prcguy

 

[harrycs]

hi prcguy,

Yes, I have a DDF2020T. I just tried it for the first time today. I have the same issue as you had where it seems to need to be reversed. Do you think I should just use the calibration adjustment to reverse it or do you think it would be better to reverse the antennas and then use the calibration adjustment to fine tune it?

Thanks,

Harry
Rancho Cordova, CA

 

[harrycs]

I reversed the position of the antenna and used the calibration adjustment using an AM test beacon. The DDF2020T then gave the correct readings for whatever direction I drove past the test beacon.

My next test will be to find a good FM signal and test with that signal. Then I will connect the GPS and the laptop computer.

I have used the software that comes with the DDF2020T's GPS to manually plot bearings from a lat/long position on Google Earth. That would even be useful just by itself. I'm anxious to see it done by the GPS unit and the software while tracking a signal.

Harry
Rancho Cordova, CA

 

[prcguy]

Just saw your post, sorry for the late reply. I installed the antennas in the correct orientation and the cal adjustment was able to center up the display just fine. I get a lot of multi path when driving around So Cal but you can tell when the display is not going to be accurate by the phase shifted audio. I don't have the GPS module yet but can see it will really make this a rockin hot DF system.
prcguy

I reversed the position of the antenna and used the calibration adjustment using an AM test beacon. The DDF2020T then gave the correct readings for whatever direction I drove past the test beacon.

My next test will be to find a good FM signal and test with that signal. Then I will connect the GPS and the laptop computer.

I have used the software that comes with the DDF2020T's GPS to manually plot bearings from a lat/long position on Google Earth. That would even be useful just by itself. I'm anxious to see it done by the GPS unit and the software while tracking a signal.

Harry
Rancho Cordova, CA

 

[wd9cms]

How is this unit working out?

I was wondering how this is working for you that have had a chance to try them out for awhile???

Thanks,

Bill

 

[prcguy]

I used it for a couple of weeks and it works very predictably and very well. There is a residual buzz in the receive audio from the doppler switching and you get used to listening for distortion in the buzz and then can tell you have a lot of reflections or other problems that may give erroneous readings.

I really need to get the GPS module, then as I drive around and occasionally hit the computer space bar it will add a compass heading line on the computer screen with Google Earth so eventually you've driven far enough and have enough lines to point right to the transmitter.
prcguy

I was wondering how this is working for you that have had a chance to try them out for awhile???

Thanks,

Bill

 

[wd9cms]

Thanks for the reply prcguy.....

Bill

 

[Astro25]

I like it. I currently own the model with the GPS module (which then plots it's location data via Google Maps) and so far it's worked great. For the price and what it does, you really can not beat it.

 

[wd9cms]

Thanks for the reply ASTRO25....

Bill

 

[Skysho]

Stealth DF2020T

Just seeing if I can kick start this thread again since I just recently picked up one of these units. Just tested it a couple weeks ago and getting the rest of the gear fit up for my pickup. I was curious, since this is a old thread, if anyone has some tips or tricks for us recent owners or somebody sitting on the fence looking at making the jump.

So far for mine, I've made three thin rubber mat templates for the mag mounts on top of the cab. I can measure and set the center unit and lay the mat over the top and position the four antenna in the notches on the mat and toss the mats in the box. That way its easy to get them relatively close each time I use it. I made the templates in 2m, 1.25cm, and 70cm. I also purchased a Yaesu FT-90 micro mobile that is dedicated to the Stealth, velcro'd right to the top of the unit. I removed the mic and made up a fused cigarette plug to power both units. I eBay'd a small 6" audio jumper yesterday so when it arrives it'll cut down on extra wire on the backside. This week I hope to make up a rubber insert for the back window of the truck so the wire run has a waterproof (semi) access point into the cab.

I did a demo of the unit at a local club meeting. I set it in the middle of the large room and passed around a 1/4 watt micro bunny. I didn't set up the computer to it but showed some slides of what it looks like when running Google Earth and Navi DF-2020. Lots of interest. However, when I asked if the club wanted me to set up and hunt, several said they don't want to compete against me. I told them, I set out the bunnies for them, one pipe up that it would even be worse because then I knew where they were. No hunt yet.

Anyway, hope to hear some others chime in on how their unit is working and sage advice for us newbies.

Thanks in advance for any feedback

Bryant
W7BDB

 

[N8RDF]

Working great, made some mods

I've had this just over a year and have been very happy with it. I pulled the 2-DIN OEM Radio out of my dash and replaced it with the RDF unit and my BCD996XT using a Metra DIN mounting kit. It took a little mechanical tweaking and I made 2 mods.
1- Cal Pot: I wanted easy access to the cal pot when in the dash. It turned out by drilling a small hole in the face and rotating the cal pot from vertical to horizontal (along with some epoxy to hold it in place) I can cal the display from the front.
2- Volume: this RDF seems to need lots of volume for good bearings, but I like to sometimes hear the audio to get a feel for the quality of the tone. The BDC996XT has a record (fixed level) output, but needed more gain. I took a small RadShack battery powered amplified speaker and installed just the PCB in the RDF in place of the RDF speaker and powered by the RDF +5V. It has 1/8" audio jacks in & out so it's easy to integrate. Now there's plenty of audio for the RDF and I can use the scanner Volume control when I want to hear the tone.

I spent of lot of time taking readings of known transmitters and checking the RDF readings. It's pretty amazing how accurate you can be when you use the WinDopp software. I just moved from an XP netbook to a Winbook with Win 8. I was getting all "zero" readings until I added the VSPE Com port utility (doesn't make sense, but it worked). I use two wooden yardsticks bolted at the center with holes drilled for 2m, 220 and 440 spacing to adjust the antenna spacing quickly. I'm usually configured for 440, 2m works OK at 440 spacing but is180deg out of phase with the BCD996XT. For a real hunt I'd re-space for 2m.

 

[Skysho]

Thanks for the information on your setup. Mine still hasn't been out for an actual hunt, one is planned for next Saturday (Jan24th). Monday I plan to do a little testing. I haven't spent much time using the WinDopp software, have tried the DF2020 with some quirky results. My choice for the hunt will be Fox Hunt Pro on my iPhone. Once I calibrate to my truck and a small mobile compass that gives me some fairly decent degree readings, I'll point the phone and place a vector line. Move to another spot and add another vector line and I should get in quite close. I also have the Mk4 Sniffer for walking up to a transmitter if necessary. I tried using Google Earth and DF2020 on a laptop but they became a real pain in the front seat of the truck. Plus getting it to place vector lines never quite worked the way it should.
Thanks again and 73
Bryant

 

[N8RDF]

Windopp Mobile easy operation

I agree using Windopp (or any windows app) while mobile can be a challenge. One item I use to make it easier is a USB device similar in form factor to a mouse but smaller. It has six programmable push buttons to emulate keyboard keys. I assigned some of them to (A)cquire, (C)lear, (R)educe and (O)ptions. I can control the major Windopp functions without having to touch or even look at the keyboard.
example: http://www.dx.com/p/6-key-usb-handle-hid-keyboard-173cm-cable-70892#.VM0X42dOVE0

 

[Skysho]

I finally got on an actual hunt last weekend. The unit worked flawlessly, I learned I need to trust where its sending me. I didn't think the guy that hid the transmitter would hide it so close to our start. I use the Mk4 Sniffer along with the Doppler to give me range readings. I think Fox Hunt Pro on an iPad up close to the dash will work better than setting up my laptop anyway. Thanks for the information, I'll search of the info on that USB device.

Bryant
W7BDB

 

[poltergeisty]

I have a question about this unit. Even since I seen the Ramsey kit Doppler unit I thought of using two of them with the antennas wired on the roof of the house. Four antennas on the right side and four antennas on the left side. Then I would plot the direction and where the two lines intersect I would have the location of the transmitter. :lol: Is that even possible with this TSCM unit given my scenario? Or would you have to be mobile? My idea was to find CBers and FRS users.

 

[Skysho]

Interesting idea but my experience so far with the TSCM is the accuracy has a few degree variable. The use of the application in conjunction with the GPS does require you to be moving. So using your scenario you'd have to orient each set of units facing north and plot the readings on a mapping program. I've discussed with other hams the idea of a couple of us taking readings from our shacks and plotting it on a map to locate interference like stuck mics or jammers. I currently have a 2m quad in my attic connected to a TV rotator that I attach to a Mk4 Sniffer. If its a local signal I can get a pretty good bearing. Anyway, my guess is that you won't be able to get that fine of a reading. Still a cool idea. I'll be curious if anyone weighs in with additional input.

Bryant

 

[prcguy]

Just thinking about this and it would probably only work for pinpointing a signal very close, like within a few houses and perpendicular to the two sets of fixed pickup antennas. Using a target signal 1 mile away as an example, the circumference of a 1 mile circle around your house would be 33,175.2ft. Divide that by 360 and at 1 mile, a 1 degree swath is only 92.15ft wide.

Lets say you can get the pickup antennas maybe 60ft apart on an average large house. I don't see how any doppler DF is going to give enough resolution to pinpoint a signal a mile away with only 60ft or so of antenna separation. I think the only way you could triangulate something to 1 deg accuracy at 1 mile is with an optical instrument like a surveyors Theodolite.

If your only interested in triangulating signals in your immediate neighborhood with two sets of fixed antennas you would still have to buy a second set of antenna mounts with the electronics from the doppler company and figure out how to switch the RF and switch control signals between the sets.
prcguy

I have a question about this unit. Even since I seen the Ramsey kit Doppler unit I thought of using two of them with the antennas wired on the roof of the house. Four antennas on the right side and four antennas on the left side. Then I would plot the direction and where the two lines intersect I would have the location of the transmitter. :lol: Is that even possible with this TSCM unit given my scenario? Or would you have to be mobile? My idea was to find CBers and FRS users.