GMRS WEB
Magazine

03/10/01

GMRS Web Magazine Reviews the Motorola JT1000 UHF Portable

by Greg Forrest, PE
KAF1291
intermod@gmrsweb.com

Overall Review

This is Motorola's first front-panel programmable portable radio that we are aware of. Its appearance is identical to the Motorola MT1000 (and possibly the MT2000) radio, with the exception of the 11-character display, keypad and front-panel programmability. The JT appears to be targeted at communications technicians, or possibly OES, SAR or Fire personnel who require programming flexibility. MT/MTS series batteries, antennas, speaker/mics and programming cables are compatible with this radio.

The JT has the highest sound pressure level (volume) of any radio I have ever used. Minimal distortion is detected even at the highest setting. New frequencies and codes can be programmed on the fly when the (obnoxious) programming appendage is attached to the speaker/microphone connector (sold with the radio). Programmable button flexibility is limited, and at least one firmware design flaw exists. However, the firmware is highly reliable (it has never failed in over three years of operation).

Its construction and durability is second to none, and the unit is splash proof. Using a hex code editor on the code plug file, we were able to get our 450-520 MHz version to front-panel program from 403-512 MHz (thanks to www.batlabs.com).

The radio is limited to 16-channels. Also, a firmware flaw associated with the talkaround switch restricts its use to channels with matching codes, or those using carrier squelch (it does not handle cross-coding correctly when in talkaround mode). If your radio network uses cross-coding, you must assign talkaround to one of the 16 channel positions, using up valuable channel space. The advertised "alphanumeric display" is NOT user-definable.

The JT's squelch circuit is - well, just horrible. Tightening the firmware squelch to reduce the squelch "crash" only resulted in too tight a setting - sometimes. We could never get it just right. Strong 12.5 kHz adjacent channel signals (such as FRS when using GMRS channels in wideband mode) caused the radio to spew a loud (and embarrassing) motorboat-like sound. Setting the particular channel to narrowband reduced but would not eliminate this problem.

All in all, this radio is a workhorse. Having just purchased a smaller Vertex (Yaesu) VX800 portable, I just wished I could get the JT in a smaller and lighter package, with longer battery life and more channels.

The JT1000 model may still be available new as of December 2000.

Display/Control

The alphanumeric display is not user definable, and the Manufacturer's glossy brochure indicates. Only two choices exist - a display reading "Channel 1, Channel 2, etc., or frequency and code (462.625 151.4). However, the display will change to the specific frequency and code in use when transmitting and receiving in the latter mode. The display sports Motorola's standard scan and talkaround indicators, and the display is backlit along with the 15 front-panel keys. In programming mode, the display provides soft-key labels above the top three buttons.

Front Panel Programmability

The following functions are available without using the physical programming appendage (which is just a modified speaker/microphone plug with an internal diode):

• Squelch (8 levels, settable on a per-channel basis)
• TX power (High/Low, per channel)

In addition to these, the following other functions are available when using the programming key and RSS-settable password:

• TX and RX Frequency (down to 5 kHz resolution)
• TX and RX code (permits cross-code and mixed code, e.g., CTCSS & DCS on same channel)
• TX and RX bandwidth (Narrow/Medium/Wide; sets both at once, per channel)

The deviation and IF selectivity for narrow and wide are for 12.5 kHz and 25 kHz channels, respectively. The 12.5 kHz setting is useful when communicating with FRS radios. The Medium setting is for 20 kHz channels.

Controls

Although there are eight possible switch and button positions (3-position toggle, a concentric switch around the channel knob, and four momentary types in various spots), their assignment choices are limited and poorly implemented.

For example, the concentric switch can only be used as a keypad lock; no other choices are available. Also, assignable functions for the A-B-C toggle switch are limited to a pre-established set of poor choices. For example, I desired to program the toggle switch for talkaround, such that positions A was normal repeater operation and position C (and possibly B) would be talkaround (so I could ram the button to its end-stops since the B position is difficult to land on). Although positions A and C can be programmed for this, selecting this also forced the radio into carrier squelch (or monitor) mode when in positions B and C. We cannot understand why a user would want to monitor in talkaround mode since as this is normally required for shared repeater operations (position A). Other, less useful options exist for this switch as well.

Scan programming and activation is difficult. Due to the limited programmable button choices, accessing the scan programming or scan mode is difficult. Since I had programmed the toggle switch for talkaround, scanning was limited to the recessed side buttons. There are three of these, and I always forgot which button did what. Using a momentary switch also lead to the scan function becoming deactivated when the radio's power was cycled. I guess I like keep my radio in a briefcase or pocket, and I cannot reach the side switches to reactivate scanning each time. Also, to place a channel in the scan list, you must firm have entered the "Scan Program Mode" using one button, and select each channel using another button. We are not sure why a scan program mode is even necessary. I miss my Bendix/King MPU portable now BK Radio). This BK allowed the scan list to be edited by a single button press (at any time) and showed the channel's status on the display at all times. The JT only allows you to view the scan list when in scan-programming mode (using the LED on top of the radio).

Frequency Spread and Bandwidth

The radio's large frequency spread is the main reason I purchased the radio (I don't like to carry multiple radios). The radio is available in 403-470 MHz or 450-520 MHz (frequency spread of 67 and 70 MHz). Front panel programming is limited to these band ranges unless the code plug file is modified. Reading the radio, saving the code plug file, and editing this file with a standard hex editor program modifies the code plug. This file can then be opened by the RSS and used to reprogram the radio (see www.batlabs.com). This mod appears to fool the radio into believing it's the other model and effectively modifies the firmware band stops. Of course, the radio's specifications remain unchanged. Interestingly, after the modification, my 450-520 MHz version can be front-panel programmed with frequencies between 403-512 MHz.

After the modification, the radio service software (RSS) band stops became one or the other factory ranges. Thus, my radio could only be programmed between 403 and 470 MHz. Some Motorola RSS packages will permit entry of out-of-band frequencies by holding down the shift key while entering the frequency. However, the HT1000/JT1000/VISAR software I had (R3.02.01, run 4098G) would not.

The performance of my 450-520 MHz version below 450 MHz was as follows:

Frequency (MHz)	12 dB SINAD (dBm)	12 dB SINAD (microvolts)	TX Power (W)
512.0000	-121	0.20	3.3
480.0000	-122	0.18	4.0
450.0000	-119	0.25	4.0
447.5000	-118	0.28	4.0
445.0000	-118	0.28	4.0
442.5000	-117	0.32	4.0
440.0000	-115	0.40	4.0
437.5000	-112	0.56	4.0
430.0000	-104	1.41	4.0
425.0000	-99	2.51	None
421.0000	-94	4.46	None
420.0000	-95	3.98	None

The radio's VCO locks consistently down to 420 MHz, although the VCO could be heard fluttering on the edge of acceptance. It was more stable at 421 MHz. Intermodulation performance is excellent, and the radio rarely became overloaded even at congested radio sites or in downtown San Francisco where RF levels are quite high. CTCSS and DCS sensitivity are excellent and fade-resistant as well. The only problem with radio performance was processor noise on the transmitted audio (minor), and the adjacent channel problem noted earlier.

User Features

The following is a partial list of the radio's more useful features.

• DCS and CTCSS-capable (direct entry of CTCSS to tenth of hertz)
• Cross-code and mixed-code (CTCSS/DCS) capable on the same channel
• Talkaround button (with cross-code limitations)
• Knobs for both channel and volume
• Low battery alert
• Keypad light
• · Scan features:
  • User-selectable or fixed-list scanning (RSS programmable)
  • Nuisance-channel lockout (one channel deep)
  • RSS programmable priority look-back repetition rate (dwell time fixed, however)
  • Selected channel or fixed priority scan
  • Channel-slaved scan activation

Operational features

We use the radio with Zetron community tone panels, MSR2000 and Ericsson MASTR III repeaters and found that squelch-tail elimination and reverse-burst work consistently.

If the toggle is programmed to activate scan, scanning will also resume after radio is powered down. Scanning speed (channel/second) is considered slow-to-medium; it is much better than all amateur products, and the priority scan muting is extremely short in duration.

The radio is capable of any one of three signaling & decoding formats (MDC1200, QCII pr GeSTAR).

Although I did not use them, many power saver features exist (I lost faith in this following my bad experience with cheesy amateur products). I did not like the battery life of the radio, although I had so many batteries I could never get a good handle on the run time.

The radio is not problem-free. The most notable are as follows:

1. The RX CTCSS/DCS code not used as the TX code when radio placed in talkaround mode using a programmable switch or button. This causes a problem only if the specific channel uses a repeater with different input and output codes (cross or mixed coding).
2. The radio is limited to 16 channels. If you operate several GMRS repeaters, each with separate codes, and a few public safety receive-only channels, you will likely run out of channels. Its saving grace is its programmability. I leave the last few channels open for on-the-fly changes.
3. Physical "key" (originally) required for programming. To be able to enter programming mode, a clamp-on "dongle" was required (a speaker/microphone cable connector with internal diode).
4. Squelch is extremely poor. Squelch hysteresis is limited (it opens with the same signal strength required to close it), and a seemingly random length squelch tail occurs independent of the squelch setting when operating in carrier squelch (even when level 8 is selected). However, there are eight levels available, with each channel having its own level.
5. Strong adjacent-channel (12.5 kHz) signals, such as FRS, can cause the receiver to emit a loud buzzing sound (similar to an oscillation). However, the transceiver has three selectable IF bandwidths available (narrow, mid and wide) on a per-channel basis; placing an affected channel in narrow will normally reduce the problem. Although this will impact compatibility with other radios on the channel.
6. DTMF mode is extremely inconvenient. To send a DTMF command, you must depress the top orange button (normally an emergency button) which places the keypad in DTMF mode. Radio keys automatically when the buttons are pressed. However, radio drops out of this mode when the channel selector switch is changed. To properly exit the DTMF mode you must depress the orange button again.
7. The RSS is horrible. The screen designs, navigation and overall operation of the DOS RSS are frustrating and clunky. As usual, each channel has its own screen (instead of a "spreadsheet-like" table format), and everything uses the F1-F12 function keys. I programmed my radio ONCE using the RSS to setup the features not available on the front panel, and used the front panel the remainder of the time.

RSS Screens

We have shown several screens below to demonstrate the options provided in the RSS. The first is the channel configuration screen - there are sixteen of these. The others show various other important screens.

Click to view RSS Screens

Conclusion

With the exception of the talkaround problem, physical size and its 16-channel limitation, the JT1000 radio is one of the best portable radios I have ever owned. Its design and operation is "classic Motorola", e.g., rugged, dependable performance with horrible programming software and limited button control assignability. With the exception of the classic (but unreliable) Bendix/King MPU/LPU models, I have not found another radio with such a wide frequency spread. I not longer have to carry two to three separate radios.

FCC

PRSG

Last updated March 10, 2001