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GMRS Equipment Reviews

GMRS Equipment Reviews

by Gregory J. Forrest

Cost (new/used): $800/$300

Overall review:

This is Kenwood's top-of-the-line model mobile radio targeted for public-safety and heavy industrial users. The most significant difference between it and the lower cost TK805 (D) is its construction, operation and receiver performance. The radio and control head is much more durable and splash-proof. Its operational features (firmware) are much more "developed" and therefore easier to use. Some models have an alphanumeric channel display. It also is not as susceptible to intermodulation as the lower-line models when used as a mobile.

More "developed" is a relative term. The full-featured alphanumeric control head and radio have great potential, but there are some significant firmware and hardware "nuisances" that exist; these will be especially noticeable if you have used other public-safety grade radios, such as the Motorola Syntor X or Syntor X9000's. However, given the radios' options and flexibility, and its ease of programming, it has become my primary radio

For those who also need 150 MHz or 40 MHz capability, the control head can be equipped with a second radio making it a dual-band radio. I use a secondary 150 MHz radio. I understand that two UHF radios could also be added, but this would only be useful to extend the effective frequency spread of the system. You may have problems with the IF's beating together however.

This model may still be still available new as of January 1999, but will likely be replaced by a very similar TK890 model. The TK890 has more front-panel buttons and appears to overcome some of the earlier firmware limitations. Its transmitter frequency spread is much wider, but it appears that the receiver frequency spread remained unchanged.

Display:

This unit has a myriad of control head options that can be very confusing; here are the most common:

The alphanumeric display is key if you desire to use more than a few channels. As it relates to GMRS, many repeater systems have multiple CTCSS ("PL") capability, so I tend to have the same frequency programmed into many different channel positions, with each having a different CTCSS code and channel name.

Frequency Spread and Bandwidth:

Manufacturer spread of 450-470 MHz, but the Service Software (SS) has a "Special Tune" option which when selected disabled the frequency spread limits. The VCO locks from 443-483 MHz without any modification. However, without re-tuning the receiver, there will be significant sensitivity degradation below 443 MHz and above 470. However, the transmitter operates with specified power over the entire 443-483 MHz range. It was easy to re-tune the receiver for acceptable sensitivity between 438 and 470 MHz (maybe a 1-2 dB degradation over entire range). Unless you use the 470-476 MHz band in your area, the radio is not a good choice for wide frequency spread use (i.e., 438-512 MHz). VCO was also easily adjusted.

The (G) series radios (model TK830(G) instead of TK830) can operate on 12.5 kHz narrowband channels on a per-channel basis, per 1996 FCC narrowband or "Refarming" rules. Although this primarily applies to those using other Part 90 business or public safety frequencies, it can be useful when trying to communicate with FRS units on the offset channels (FRS units operate in narrowband mode). It appears that no voice companding is employed in narrowband mode, so it is likely that narrowband use will reduce received (demodulated) volume levels. I am not sure how the transmit bandwidth is changed other than a reduction of the deviation from +/- 5 kHz to +/- 2.5 kHz. However, the receiver is equipped with dual IF stages that are selected via a steering line from the microprocessor.

User Features:

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

• · Low-power model is 40 watts (high is 100 watts). (Remember 50 max in GMRS), ed.
• 160 channel model has 10, 16-channel groups
• Talkaround key (not a worthless "reverse" switch like amateur products!)
• Channels are selected by knob; groups by ramp switches
• 16 auxiliary SS-programmable CTCSS/DCS codes (display reads CODE 1 , CODE 2, etc.)
• AUX button for alternate global decode/encode selection (overrides SS programmed codes(s))
• Any combination of CTCSS/DCS on a per-channel basis
• Home key
• Squelch key (selectable 1-16; 7 is threshold)
• Gaskets around most seams and connectors
• Scan features:

• Service Software (SS) programmable group or global (all group) scan
• User-selectable or fixed-list scanning (SS programmable)
• Entire group or individual channel lockout with "second function + key" combination
• Nuisance-channel lockout, eight-plus deep
• SS programmable priority lookback repetition rate (dwell time fixed, however)
• Two-level priority scan (P1 and P2)
• Selected channel or fixed priority scan
• On-hook or off-hook scanning

• Operational features:

• Remains on last selected channel if powered down (if power is always applied to radio). Can transmit on selected channel when in scan mode and will resume scanning after un-keying. Squelch-tail elimination, and reverse-burst capable.
• Allows channels to be changed when in scan mode. Scanning will also resume after radio is powered down and up again Scanning speed (channel/second) is considered medium; it is much better than the TK805 series radios, but possibly only one-third as fast as high-end Motorola public safety radios (Syntor X, Syntor X9000, etc.). However, enabling scan on even half of its 160 channels will result in intolerable scan performance.
• Speaker level is very good but less than the high-end Motorola or Ericsson models (even when both are rated for the same 10-watt output power). Separate power switch so that volume level is maintained.
• Priority scan muting is medium-to-short in duration.
• Also has "group-memory". The radio remembers the last channel selected in each group so that the radio "lands" on the same channel you were previously on in a given group (as opposed to resetting to the first channel in each group).

Drawbacks:

Display reads SCAN while scanning: Display reads "SCAN" while scanning, so unless you know what channel you were on originally, it is tough to tell which one you will transmit on (you can however quickly key it temporarily stop the scan and display the selected channel).

Talkaround mode resets: The talkaround function resets (turns off) when the unit is placed in scan, if the channel is changed, or if the ignition power sense lead is cycled (car is turned on and off). I finally programmed every other channel in the radio for talkaround to get around this problem (which reduces the radios "effective" channel capacity to 80).

Display/Scan list reset problem: My unit had an intermittent problem where when powered on, the display would occasionally read (GR1 CH1), which is the default label for unnamed channels. The user-selectable scan list would also be reset to the SS-programmed list (I would lose all of my recent manual scan list modifications). Maybe adding the lithium battery backup option (I did not have this option) could solve this.

No group labels: It would be helpful to have alphanumeric labels for each of the 10 groups. Currently, when you change groups, it shows the channel you had previously selected in the specific group (see "group memory" above.

2-second nuisance channel delete: User must hold down a DEL key for an entire 2 seconds to have an active channel temporarily deleted from the scan list. Sounds trivial, but its extremely annoying compared with an immediate delete functions on other model radios.

Minor intermodulation problem in a high-RF environment: Although much better than the TK805 series, the unit occasionally will reproduce a burst of paging or other radio traffic; but this was only in downtown San Francisco and not normally in the suburbs.

Priority scan muting is short-to-medium in duration.

Transmit power fixed: The transmit power is set at rated level and is not adjustable (except from inside radio). This can be in violation of FCC rules if used on the GMRS interstitial channels what are limited to lower power.

Service Programmability:

This unit cannot be front-panel programmed but instead uses a very simple and affordable cable ($25) and DOS software ($50?). Cable plugs into microphone jack; the radio is placed in programming mode by holding down two keys during power-up. Uses the same cable as the TK805 series radios. Cable can be made at home with a TTL-to-RS232 converter chip. Entire process rates high on ease-of-use since it employs a spreadsheet-like frequency, code and scan list entry screen. Separate screens are used for every group of 16 frequencies. This is in contrast to most all "rotten" Motorola RSS products, known for user-unfriendliness. A bit unreliable when used in Win3.1 because of COM port problems. Otherwise bulletproof software.

FCC

PRSG

Last updated August 8, 1999