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Commtel COM216 notes

Also a brief User manual for the radio

The Commtel COM216 is a scanner radio very much similar to the Realistic PRO-26 and the Uniden UBC-3000XLT, but not quite exactly the same as either one. The keypad layout is a bit different in all three, some functions work a little differently, and also there are some technical differences outlined in the table below. (I made a short user manual for the scanner based on the PRO-26 and UBC-3000XLT manuals I found online.) The most important difference to me is that the UBC-3000XLT does not have continuous coverage, whereas the COM216 does (as does the PRO-26 also, according to sources on the net, though other sources suggest it does have cell phone gaps that can be enabled with a simple hardware modification). All have the same search speed of 100 steps per second, plus they have the 300 steps per second high-speed search mode (i.e. "Hyper mode", "Turbo search" or "Jet turbo mode", depending on brand). The scan speed is 100 channels per second, except in the PRO-26 only 50 channels per second. (These are all probably best-case speeds, as my scanner is somewhat slower in all three modes.)

The similarities between the radios are no coincidence, as all three are actually made by Uniden, as is evident from the circuit boards. The boards inside my COM216 are marked "(c)1996 Uniden" and contain one custom Uniden IC as well (it may be just a re-labeled one-time-programmable microcontroller). The COM216 can be equipped with a discriminator output the same way as a PRO-26. I have not (yet) done this to my radio.

Of course, with its continuous coverage from 0.1 to 2039 MHz with step sizes down to 50 Hz, its selection of FM, WFM, AM, NAM, LSB, USB and CW modes at all frequencies, and a way better display, the MVT-9000 runs rings around the COM216 and friends in everything but scanning speed.

  Realistic
PRO-26
Uniden
UBC-3000XLT
Commtel
COM216
Yupiteru
MVT-9000 Mk-II
Frequency
coverage
25 MHz – 1300 MHz
continuous (cell gaps?)
25 MHz – 550 MHz
760 MHz – 1300 MHz
25 MHz – 1300 MHz
continuous, no gaps
0.1 MHz – 2039 MHz
continuous, no gaps
ModesFM, WFM, AMFM, WFM, AM FM, WFM, AMFM, WFM, AM,
NAM, LSB, USB, CW
Memories200 in 10 banks 400 in 20 banks400 in 10 banks 1000 in 20 banks
Priority channels1 (of 200 channels) 10 (1 per bank
in 10 first banks)
1 (of 400 channels)10 (fully independent)
Scan speed50 channels/sec 100 channels/sec100 channels/sec 30 channels/sec
Search speed 100 steps/sec
300 steps/sec at 5 kHz/step
100 steps/sec
300 steps/sec at 5 kHz/step
100 steps/sec
300 steps/sec at 5 kHz/step
30 steps/sec
BatteriesFour AA cells Special NiCd battery packFour AA cells Four AA cells
External power9 V input, separate jacks
for power and charging
12 V input for both
power and charging
12 V input, NiCd/Alkaline
switch enables/disables
in-radio charging
12 V input for both
power and charging
Audio outputSingle 3.5 mm jack Separate 3.5 mm jacks for
headphone and speaker
Single 3.5 mm jackSingle 3.5 mm jack

Operating manual for the Commtel COM216

I never could find the manual for the COM216 (I bought mine second hand, and no manual was included), so here's a summary of what I've managed to scrape together from the manuals of the other two (which are found online), as well as from other sources on the net. I have tested these on my scanner, so this should be reasonably correct. Please let me know if there are any errors.

Setting frequencies, modulation and step, and programming channels
  • To manually tune a frequency and program a channel:   First press "MANUAL" to go into manual mode. Then type a channel number ("1" to "400") and press "MANUAL" to go to that channel (Note: it will be overwritten!). Now type the frequency and press "E" (Enter) to tune to that frequency and store it. If it is already programmed into another channel, e.g. channel 21, the scanner will inform you by saying "CH 21". If that happens, you can press "E" again to store another copy of that frequency anyway, or any other key (for example ".") to cancel. Any time you decide not to overwrite a channel after all (e.g. if you pressed some number keys by accident), press "." twice to cancel.

  • To manually tune to a previously programmed channel:   Press "MANUAL" to switch to manual mode. Then type the channel number and press "MANUAL" to tune to that channel. To tune to another channel, type its number and press "MANUAL" again, or press "MANUAL" repeatedly to step forward through the channels in numerical order.

  • To delete a programmed channel:   Go to that channel in manual mode (see above), then press "0" and "E" to store a frequency of 0.000 MHz to that channel. The channel is now "empty" and is also excluded from scans until programmed again.

  • There are no gaps in frequency coverage:   The radio may at first seem to refuse to program some frequencies, but that's only due to some crazy 8 MHz frequency steps it defaults to in some frequency ranges, and rounds all frequencies downwards to the nearest 8 MHz step. But if you first manually set the frequency step (see below), then it will accept any frequency in the 25 MHz – 1300 MHz range. It took me a while to find this out, and at first I thought the "Full coverage" claim was an outright lie...

  • To change the frequency step:   Press "SHIFT"–"5 kHz" or "SHIFT"–"12.5 kHz" or "SHIFT"–"50 kHz". Any search you now perform will use this frequency step, and also any manually programmed frequencies will be rounded downward to the nearest step.

  • To change the modulation:   First select or program the channel, then press "SHIFT"–"AM" or "SHIFT"–"NFM" or "SHIFT"–"WFM". The new modulation is immediately taken into use and also stored into the channel. To go back to the default modulation, press "SHIFT"–"CLEAR".

  • To turn on the priority channel:   Press "PRI" so that the "PRI" indicator on the display becomes visible. Now the radio will tune to the selected priority channel (see below) whenever it becomes active. This works in the MANUAL and SCAN modes, but not while searching (also the "PRI" indicator turns off while searching). The priority channel is checked for activity every two seconds, which causes a momentary but annoying break while listening to broadcast radio... Press "PRI" again to turn the feature off (the "PRI" indicator disappears).

  • To select the priority channel:   Press "MANUAL" to switch to manual mode. Then type the number of the channel, but instead of pressing "MANUAL" to go to that channel, press "PRI" instead. A letter "P" will be displayed on the left-hand side of the display when the priority channel is selected. There can only be one priority channel at a time.

Searching
  • Direct search:   This will start searching continusouly in the current modulation mode with the current frequency step either upward or downward from the current frequency, with no other limits. First press "MANUAL" to switch to manual mode, enter a channel number and press "MANUAL" to go to that channel. Then press the SEARCH up-arrow or down-arrow key to start searching up or down from that frequency. Searching will stop when an active frequency is found, and will continue when activity ceases or when you press up-arrow or down-arrow again. You can also press "LIMIT" to halt the search at the current frequency ("HOLD" appears on the display). While halted, up-arrow and down-arrow will move one step at a time up or down. Press "LIMIT" again to continue searching. "–d–" blinks on the display during direct search.

  • Limit search:   Like direct search, this will search continuously in the current modulation mode with the current frequency step, but repetetively between two frequency limits. To set the limits, press "MANUAL" to go into manual mode. Type one frequency limit (frequency, not channel number) and press "LIMIT". Then type the other frequency limit and press "LIMIT" again. Now press the SEARCH up-arrow or down-arrow key to start searching upwards or downwards between those two limits. There are no separately defined upper and lower limits, the search will always commence between the last two limits entered. When the latter limit is reached, search will restart from the first limit. In all other respects, limit search works like direct search (see above). "–L–" blinks on the display during limit search.

  • High-speed search:   When searching, you can press "SHIFT"–"SPEED" to switch to high-speed search (300 steps/sec). This automatically sets the step to 5 kHz.

  • To lock out (skip) frequencies from a search:   When search stops at an uninteresting frequency (noise or interference), you can press "L/O" to lock out that frequency from the search. On the next search round, that frequency will be skipped and ignored. A total of 50 individual frequencies can be locked out. Press "SHIFT"–"RVW" (review) to see the list of locked-out frequencies. Scroll the list with the up-arrow and down-arrow keys, and press SHIFT to exit from review mode and continue searching. While in review mode, press and hold "L/O" for three seconds to remove all skip frequencies. Removing individual skip frequencies is quite a bit more involved: You must be in search mode, then halt the search by pressing "LIMIT", and go to that frequency with the up-arrow and down-arrow keys. The "L/O" indicator is shown to indicate the frequency is locked out. Press "L/O" to remove the indicator and include the frequency in future searches.

  • To automatically store frequencies in search mode:  Set up a direct search or a limit search as above, but do not start the search with up-arrow or down-arrow. Instead, press "SHIFT"–"AUTO". The bank numbers on the display's top row begin flashing. Select one or more banks to store the results into by pressing their corresponding number keys. Non-flashing bank numbers have been selected. Completely full banks cannot be selected (the display will say "FULL"). When ready, press up-arrow or down-arrow to begin the search. Any new active frequencies that are not yet stored in some memory will be stored into the selected bank(s). The search will continue without stopping until all the selected banks have been filled, at which point the display will read "End". Or you can stop the search yourself e.g. by pressing "MANUAL".

Scanning
  • To start scanning:   Press the "SCAN" key. All channels (except locked-out ones) from all active banks are scanned. The active banks are shown on the top row of the display. The number of the bank currently being scanned blinks. Press the number keys to activate or disable individual banks. Scanning will stop at any active channel, and resume when the activity ceases. You may also press "SCAN" again to immediately resume scanning.

  • Locking out channels:   When scanning stops on an active channel, you can press "L/O  to lock it out. Scanning will immediately resume, and that channel will be ignored on the following scan rounds. (Note: This is different from locking out frequencies from a search. This is stored on a per-channel basis for each of the 400 channels, whereas for search lock-out up to 50 individual lock-out frequencies can be defined without affecting any stored channels.) You can also select a channel in manual mode and press "L/O" to lock it out from future scans (the "L/O" indicator appears on the display). To re-enable a locked-out channel, select that channel in manual mode (the "L/O" indicator will be displayed) and press "L/O" (the "L/O" indicator disappears). To review which channels have been locked out, in manual mode press "SHIFT"–"RVW". Scroll the list with up-arrow and down-arrow and press "L/O" to re-enable individual channels. Press "SHIFT" to exit review mode. To re-enable all channels from selected banks, first go into scan mode and select all the banks you want to remove lock-outs from. Then go into manual mode, and press and hold "L/O" about three seconds.

  • To turn on the delay:   This causes the radio to wait either 2 or 4 seconds (see below) before it continues scanning (or returns from the priority channel) after transmission stops on that channel. Manually select the channel and then press "DLY". The "DLY" indicator appears on the display. This setting is specific to that channel only, and can be set separately for all stored channels (including the priority channel, of course).

  • To set the delay:   Hold down the "DLY" key while turning on the scanner. The display will momentarily read "2 SEC" or "4 SEC", indicating which delay is now in use. The setting is the same for all channels using delay, and is remembered over a power cycle.

Other functions
  • The display light, attenuator and key lock:   The "LIGHT", "SHIFT"–"ATT" and "LOCK" functions work exactly as expected. The light stays on for 15 seconds, or longer if you keep using the keypad. The switchable attenuator seems to have an attenuation of about 12 dB at 25 MHz, about 17 dB at 100 MHz, and it seems to do nothing at all at 1000 MHz! An external coaxial attenuator might be a bit more reliable... The attenuator remains in effect until turned off, even when changing channels, scanning or searching. The key lock is enabled and disabled just by pressing the recessed "LOCK" key with no further tricks.

  • The data skip function:   If an unmodulated signal (i.e. silence) is encountered during search or scan, the data skip function will cause the search or scan to continue after a few seconds. This does not seem to work very reliably, i.e. it has a tendency to continue scanning even if the signal is modulated. This works only in the FM and NFM modes, and is enabled with "SHIFT"–"DATA".

  • The keypad beep:   Oh boy the beep is LOUD! But you can disable it by holding down the "L/O" key while switching on the scanner. It can be re-enabled the same way. The display will confirm the setting by momentarily reading "Off beep" or "On beep". The setting is remembered even over a power cycle. I just wish there was several beep volume settings to choose from...

  • To reset the scanner to factory settings:   Press and hold the "MANUAL", "2" and "9" keys while switching on the scanner. This will immediately clear all memories and reset all settings.

  • NiMH batteries:   Modern NiMH batteries work just fine in this radio, but they do not like trickle charging with no delta-V cutoff. Therefore I would not charge NiMH batteries in the scanner, which was likely designed for NiCd batteries. They probably won't explode or anything, but they may lose capacity due to overcharging if left connected for prolonged periods of time (say, weeks). Anyway getting a full charge will take quite a long time. When the battery switch (inside the battery compartment) is set to "REG. ALK. BATT" instead of "Ni-Cd BATT", I think the scanner won't try to charge the batteries when on external power.

  • Data retention:   The microcontroller circuit board inside the scanner has a hefty memory backup capacitor. This will probably maintain the programmed channels and other settings for a few days, but not indefinitely. Don't let the batteries die if you don't want to lose the memory contents.

What's missing?  (Please correct me if I'm wrong!)
  • Completely manual VFO mode:   If you want to tune to some random frequency, you have to do that by programming it to some channel. Oh well, big deal, just use channel 1 for that purpose. You can afford to lose one channel of 400. But of course that frequency will be included whenever you scan bank 1. Well, just lock out that channel, ok? Fine, but whenever you re-use channel 1 to tune to some other random frequency as a one-off test, the lock-out is automatically removed, so the random frequency still gets included in your next scan!

  • Monitor memories:   The PRO-26 and UBC-3000XLT manuals mention something called "monitor memories". It seems like these are not available on the COM216.

  • Index mode:   There doesn't seem to be an "index mode" i.e. a setting that would make a search or scan continue after a few seconds of listening to an active frequency. The radio will just continue listening until the transmission ends, or until the user commands it to move on.


Antti J. Niskanen <uuki@iki.fi>