Gary's Gear!

Computer Aided Scanning

Imagine being able to hear every transmission, day or night, from the FBI, on your ham repeater, and by your business competitors; all without having to carry around a receiver and interrupting your daily activities when a signal comes in. This is what computer aided scanning is all about. The entire day's activity on any number of fleets goes into your sound card, is stored on the hard drive, and is played back at your convenience. A note on the screen indicates which fleet you are listening to, and the time of the call. (A tape recorder could never do that!)

There are two programs I consider essential, Scan*Star Deluxe, and Trunker. There is also a program called Probe which is very popular, though I've never had much interest in it because it has no digital audio logging or trunking capabilities. Each software company's webpage will tell you which receivers are compatible with their product.

My Equipment

I do not have a wall full of scanners, all tied to one antenna thru a multicoupler. For operations such as a newsroom, where they need to monitor all agencies in the area, and cannot miss anything, that type of setup is the way to go.

But for my interests, having a few carefully selected receivers, usually under computer control, works best.

At Home

Optoelectronics Optocom Love it!
Realistic PRO-2006, Optoelectronics OS456 (full) equipped
Uniden BCD996XT
AOR AR5000
Icom IC-R8500
AOR ARD25 Multimode Data Receiver
Avcom SDM-42A Spectrum Display Love it!
Kenwood TK-931, with RX preselector filters changed for 902 MHz ham/ISM band operation
Yaesu FT-847 HF/VHF/UHF/Satellite Base Station
Icom IC-706 Junk!
Heathkit SA-2060 HF Antenna Tuner
Uniden ARU251K UHF desktop repeater (echolink)
WB2REM & G4CDY Ultimate Linking Interface

On The Go

Uniden BC246T
Pro-92 with discriminator tap
Alinco DJ-596T
Alinco DJ-296T
Trident TRX-100XLT (UK/Canada version of the radio sold in Japan as Alinco DJ-X5)
Optoelectronics Techtoyz Micro RF Detector
Optoelectronics Techtoyz Micro DTMF Decoder
OptoElectronics Techtoyz Micro Counter
Magellan Triton 2000 GPS Receiver Love it!

Test Bench

IFR1100s service monitor
Bird 43 wattmeter
CT Systems (Wavetek) Model 300 Multi Format signaling Encoder Love it!

Special Applications

Optoelectronics Optotrakker
Uniden SMS 825TS
Uniden SMS 925TS
Alinco DJ-580T
Standard HX482UT UHF LTR Trunked Portable
Standard HX582T 800 MHz Motorola Type I/LTR Trunked Portable
Standard HX585T 900 MHz LTR Trunked Portable
Maxon TP-4800 800 MHz LTR Trunked Portable
Maxon TP-4901 900 MHz LTR Trunked Portable (transmits 902.0-908.7875 MHz in the 900 MHz Ham/ISM band)
Kenwood TK340 (GMRS and 440 MHz Ham)
Texas 2-Way DDM-4P 4-layer data slicer

Wish List

RFspace SDR-ONE Vaporware?
FlexRadio FLEX-3000
Vertex Standard VX-P929 VHF P-25 portable
Icom IC-92AD 2m/70cm D-STAR HT
Alinco DJ-G29T 222/900 MHz HT
Gap Antenna Voyager DX Way too big for my small suburban lot, but I can dream
Wellbrook Communications ALA1530 Active Loop Antenna RX only, outdoor, 50kHz to 30MHz
"X-Wing" UHF Milsat antenna
L-Band helical antenna, as broadband as possible
Optoelectronics Video Sweeper or AOR AR-STV
440 MHz duplexer


Uniden BC796D Junk!
AOR SDU5000 Spectrum Display
AOR SDU5600 Spectrum Display
Grundig YB40PE
Yaesu FT727R
Kenwood TH31BT
Optoelectronics Xplorer

Equipment Reviews

Optoelectronics Optocom

This receiver was only in production for a short time, and it is now very difficult to find a used one. As far as I'm concerned, it's the best scanning receiver for home use ever made. Without a computer, it's functionality is very limited. Under computer control, your only limitations are those of the program you are running.

For RF performance, it is sensitive enough to do well on an indoor antenna, and selective enough (though not completely immune to overloading and images) for good results with a rooftop antenna. For most scanners, the 455 KHz ceramic filter needs to be replaced with one taken out of an old junked analog cell phone before they will do well for data decoding. With the Optocom, this modification is not necessary. I've found that the discrimintor has a wide enough response range to do well with data, yet still does a good job with narrowband (12.5 KHz) voice. Performing a discriminator tap mod, and building a two-level data slicer, are also not necessary. These are already built in. (Optoelectronics uses the term "bit banger" to refer to the data slicer, and keep in mind when looking to purchase that the first production run did not have this essential feature).

The built in signaling decoder is capable of CTCSS, DPL, DTMF, LTR trunking, and Motorola Trunking subaudiable data. With the capabilities of this unit, you can follow any system using AM or FM analog voice transmissions from 25-1300 MHz.

Optoelectronics also provides a great control program. It will not record information, and really is not suitable for scanning, but it is very useful for testing the Optocom and observing activity on a single channel. It is a quick and effective real time means for determining the type of signaling used on a transmission you are hearing live. In the package they also included TrakkStar, a stripped down, but usable, version of Signal Intelligence's Scanstar program, with full trunking capabilities. If you're lucky enough to find a used Optocom, make sure the seller includes these disks.

Realistic PRO-2006 and Optoelectronics OS456

Like the Optocom, the RF performance of the Pro-2006 is vastly superior to anything in the current product line of Uniden or GRE. A bit more sensitive than the Optocom, though somewhat more susceptable to interference.

The lite version of the Optoelectronics OS456 will just do computer control, no signaling decoding at all. The full version decodes PL, DPL, and DTMF while under computer control. Unlike the Optocom, it will not decode LTR or Motorola Low Speed Handshake (subaudible data on the voice channel), and it does not have a built-in data slicer.

The Pro-2006 makes an excellent companion to the Optocom. For use with the Trunker program, feed the discriminator tap from the 2006 into audio in port of the Optocom, enter the frequency of the control channel on the 2006's keypad, and setup and run the program. Equipped with the OS456, it makes a good back up in case your Optocom fails, that does most of what the Optocom can do, and it is useful even without a computer, unlike the Optocom.

Icom IC-706

My reasons for dissatisfaction with this radio primarily have to do transmit audio performance. With the internal pot at max, and with the software setting at max, I have to chew plastic and really talk loud. With a normal voice, SSB only swings to about 30-40 watts.

As I understand it, this is characteristic with the entire model line, not an indication that I have a defective unit.

Trying to transmit on digital modes using either my MFJ-1278 or my WB2REM & G4CDY Ultimate Linking Interface has been impossible, due to RFI.

Uniden BC796D

Most people buy it this model for it's trunking capabilities, and they usually report that it works well. I was more interested in a radio that would demodulate the conventional P-25 I was finding in the federal government bands. Along with it, I bought the Trunkstar785D and ARC250PRO software to program it and to control it.

I hooked everything up, programmed in all the frequencies where I had heard P-25 in the 162-174 federal band, connected it to my Cushcraft AR270 on the roof, and ran trunkstar.

The result?

Even with the squelch at max, the recorded audio files were filled with so many false squelch openings, across all the channels programmed, that the setup was useless.

Itís RF performance is vastly inferior to my older receivers. Apparently the designers of the 796 are of the belief that todays scanner listener will use pl's or trunking, so we don't need to have a strong a front end. The only way to receive conventional P-25 on the 796 is in carrier squelch. There is no way to set it for P-25 only, like you would set a pl. This makes it completely worthless for what I was trying to accomplish.

I even tried putting an Optoelectronics APS104 active preselector in line between the 796 and antenna, tuned to 162-166 MHz. All I got from this was an expensive lesson: you cannot make a weak receiver into a strong receiver by adding filtering.

Uniden BCD996XT

Significant improvements over the BCD996T (no "X"), and miles ahead of the BC796D. Most important, it now does NAC decoding on P-25 channels.

At home, the Optoelectronics Optocom is still my receiver of choice for digital audio logging of analog conventional channels (using Scanstar Deluxe), for live monitoring of Motorola and EDACS (with Trunker), as well as for doing range searches to find new PL, DPL, LTR, P-25, MOTOTRBO, and NXDN operations. The BCD996XT picks up where the Optocom's abilities leaves off: digital audio logging of trunked systems, and analyzing P-25 operations that the Optocom has initially found.

I also use it in the car. When I bought the radio I also got the BC-RH96 remote control head, because there is no good place to mount a full sized scanner in the current Dodge Charger. For an antenna I use a glass mount 800 MHz, originally intended for cellular use.


I picked up an AR3000A receiver, service manual, and SDU5000 spectrum display in separate ebay auctions in the fall of 2002. The orignal owner of the AR3000A had the 455 KHz tap mod done, and it had been sitting unused for a long time.

AOR sent me the app note for the 10.7 MHz tap (needed for use with the SDM-42A and SDU5000 spectrum display units) and discriminator tap mods. I performed them, reassembled the radio, and found it completely non-functional. The display was usually blank, but sometimes a few segments would appear. The microprocessor reset switch did no good.

I figured I had blown up the radio, so I sent it in to the AOR depot in Torrence. They pulled the lithium battery for 30 minutes, verified it powered up ok, charged me $40, and sent it back.

In using the unit I discovered the internal oscilators were off frequency. At 450 MHz, performance was noticibly degraded, and by 800 MHz, it was practically unusable. Though it was my practice when I was a two-way tech to check out every radio with a service monitor before I returned it to the customer, aparently a quick checkout is not part of what I paid AOR for.

Fortunately I am still on good terms with a former employer, and they let me use a service monitor. Once the unit was propery tuned, I checked out the receive sensitivity, and was impressed. It's not as good as my Optocom, but it's still pretty good. Better than I was expecting.

Then it was time for the real world. At 50 MHz and below, for some reason unknown to me, it has a very high noise floor. On a good HF antenna, it's performance is mediocre. On antennas suitable to apartment living, specifically the LF Engineering H-800 and the telescopic whip that comes with the radio, the AR3000A is practically useless for HF. At 108 MHz and above, the noise floor is where it should be, and the unit perfoms well with both indoor and outdoor antennas.

AOR AR5000


AOR released pictures of a prototype called the ARD5000, an accessory to be used with it's existing line of high quality receivers, which would add the ability to demodulate P-25. Then, for several years, we heard nothing. The silence was broken with the ARD25 suddenly hitting the market.

Billed as a Multimode Data Receiver the ARD25 currently will only work with one mode: P-25. I understand that it has plenty of CPU power that is currently unused, so I am hoping to see great things in subsequent firmware updates.

After my abysmal failure with the BC796D, I bought an ARD25 to use with my AR5000 and AR3000A. Out of the box, the unit would not decode. After a trip back to the factory it performed well, as long as the signal was reasonably strong.

Once it determines that a received signal is encrypted, it mutes, reducing the time I have to listen to garbled noise on a channel with both coded and clear traffic to a minimum. This was a very pleasant surprise. The serial port on the back spits out a lot of data on the received signal, but for some reason, the most useful piece of information (the NAC) is not displayed. Hopefully this oversite will soon be rectified.

AOR and their resellers warn it will not work for P-25 on trunked systems. I have found that it works just fine on System 6227. The entire setup for trunking consists of multiple components: two receivers, a data slicer, an old DOS computer running Trunker, and the ARD25. Once again, Trunker shines as the best thing to ever happen to the monitoring hobby. Trunker may not be the most recent software released, but the day in which it is to be considered obsolete or outdated is still a long ways off.

Spectrum Display Units

With spectrum analysis, instead of just listening with your ears, you're listening with both your eyes and ears. In searching a range, many receivers will pass by a weak signal, a signal with a wide bandwidth, and some types of data or digitized audio (ie. Nextel's iDEN format). When you're watching, you can see the signal, stop the scan, and go back to figure out what is was. If you're listening to a signal, and it suddenly drops out, you can tell why. If you're getting lousy performance throughout an entire range, you can see if it is due to interference. In 800 MHz, it is a very useful tool for picking out analog signals among all the digital. It also tells which antenna works best for a particular application, and if an amplifier is helping or hurting.

I have owned an AOR SDU5000, an AOR SDU5600, and an Avcom SDM-42A. The SDU5000 was too slow to catch LTR idle packets and other data bursts, but worked well for voice and data streams. The SDU5600 was plenty fast enough, though the fact that it only displays down to -90 dBm (the noise floor is aprox. -120 dBm) made it unacceptable for my needs. It is also very cumbersome to operate. The SDM-42A does not have all the fancy features of the AOR units, but it has what I need.

Rat Shack Pro-92

My observation is that the signaling decoding capabilities of the Pro-92 are excellent, and it's RF performance is lousy. Bad receive sensitivity in general, and particularly bad in 800 MHz.

The US government continues to add to it's rules on analog cellular reception. Manufacturers are now required to supress cellular "images" on ajacent frequencies, in addition to blocking the cellular range. This filtering significantly degrades performance on the rest of the 800 MHz range, so really none of the recent scanner models (legal to sell in the US) perform very well in 800 MHz.

It was very difficult to figure out how I would perform the discriminator tap. I wound up having to cut a rectangular chunk out of the case. It looks cheesy, but it is electrically sound and mechanically reasonable. Now, if I find that I'm going to a location with a trunked system I have not yet analyzed, I can run trunker on it without needing 120 VAC. It also works with my Optoelectronics micro DTMF decoder.

Rat Shack Pro-2026

I found this receiver at a local pawn shop. The price tag said $70, and the pawnbroker accepted my offer of $60 cash.

I used it mostly at home, on an indoor antenna. It served as a data receiver for the trunker program, and to listen to a few local conventional (not trunked) frequencies. The discriminator tap mod was easy to perform.

To my knowledge, the main board is the same used in the BC760XLT (not to be confused with the BC780XLT). The difference between the processors, as far as I've heard, is that the 760 will accept an optional CTCSS board, and will not switch to 30 KHz channel steps above 869 MHz.

I once took the 2026 on a trip to California. Within a few minutes of turning it on and pushing the "Police" service scan button, I realized my mistake. Even driving through Podunk Nowhere, Nevada, I found it locking onto useless signals on frequencies I know the police aren't going to be using (constant data streams on 800 MHz input frequencies). I believe this is typical of scanners with a service search feature. I don't know who decides the frequencies to program into these preprogrammed banks, but they obviously don't have a clue as to how the frequencies are actually used.

Alinco DJ-580T

As for the receiver portion of this dual band ham handheld, I can't say much good about it. I've never owned a receiver with such a weak front end. Even on a mobile antenna (Larsen 2/70), it gets clobbered with intermod. In 800 MHz, it will not function below aprox. 860 MHz (the vco goes out of lock). I called Alinco about this, and they claimed that it is normal and no adjustment can be made.

It's construction I'm a little more positive about. I carried it on my belt in a hard leather case for many years while I was a two-way field tech, including on Winter helicopter trips to mountaintop sites, and it only once took damage requiring repair.

Optoelectronics Xplorer

When I obtained my new BC-246T, I compared it's close-call features to the Xplorer that I had owned for several years. After head-to-head tests with ham HT's, FRS radios, and cordless phones, the trusty 'ol Xplorer went up on Ebay.

Data Slicers

Many data decoding programs, including trunker, require a data slicer. The input is connected to the receiver, at a point called the discriminator tap (usually a mod is required to add this tap point), and the output is connected to the computer's RS-232 serial port.

I have experimented with several circuits designed for this purpose.

The most common schematic involves a 741 op amp. I've never gotten this to perform well. The level of audio at the discriminator of most receivers is not sufficient to make this circuit work.

A better circuit uses a TL-082 chip. Brett Miller, who lives in Utah County, has some good instructions, and sells assembled units on ebay. If you decide to build your own, spend the extra 10 cents on an IC socket. It makes it a lot easier to repair if you damage the chip.

The Optocom receiver, as well as several other products from Optoelectronics, have a two level slicer built in. This gives you everything you need, without so much as having to pick up a screwdriver. The data in port allows you to input discriminator audio from other receivers, the main advantage being the ability to make full use of the Trunker program with a minimum of fabrication and a single serial port.

A four-layer data slicer is more than I'd care to build myself, so I bought (wasted my money on) the Texas Two-Way DDM-4P. Theoretically, a four layer data slicer could be used for the RD-LAP data protocol, and to convert APCO 25 into intelligable voice. Anyone who has started to write code for these applications has been leaned on by Motorola lawyers and the federal government, so no usable code has ever been released. The only application which currently makes use of a four layer slicer is the Flex paging protocol, though the afforementioned bad guys will go after websites which make it available, even if the webmaster and server are outside the US. The claim is that the four layer slicer can be used for either two or four level applications. In practical operation, trunker locks up when I used it. I isolated it so trunker only say one of the lines and ground. It takes longer, but it still locks up.

This page last revised on Friday, 13 December 2013