Entel HT446 'Submersible'

Radio reviewed: Entel HT446 'submersible' radio.

Official options available, but not supplied with the radio:
Fast single charger CSA640E
Fast 6 way charger CSB640E
Additional battery packs CNB640E (same as the o­ne supplied with the radio)
CMP640 Heavy duty submersible speaker microphone
CXR16/640 (Vox) Throat microphone
EPT40/640 Bone Conductive Earpiece
EA15/640 Earpiece microphone
CXR5/640 Skull Microphone
EA19/640 Earpiece microphone
CMP1/640 Compact speaker/microphone
CHP640D Heavy duty double sided headset
CHP640HS Heavy duty single sided headset
EHP640 Covert style earpiece
Leather carrying cases CLC640 and CLC640T
5cm 'stubby' Helical antenna (part number unknown).

An impressive list, I'm sure you will agree. The presence of the '640' in all of the part numbers above gives an important clue to the radio's family pedigree, as it comes from the same stable as Entel's multi award winning HT640 VHF marine radio and shares many of its accessories and features.

Included are: Battery, Carry strap, manual, and a drop in charging pod which comes with dual supply options as standard, in the form of two different ways of supplying power to the pod - a mains unit plus an in-car 12V supply lead.

First impressions:

The first thing that strikes you when you handle this radio, with the battery fitted, is how surprisingly light it is. This is never a bad thing for prospective buyers who really do have to carry a radio with them everywhere they go, all day long. The lack of weight is probably primarily due to the use of a proprietary Lithium-Ion battery (the radio can not accept standard cells of any sort). Normally, light weight isn't synonymous with good build quality, but here we have the very honourable exception. As soon as you take the HT446 out of its box and handle it, you know you're looking at a well above average build. The body is made from extremely tough industrial strength high impact polymer and has rubbery side panel rumble strips to make the radio difficult to drop when handled with thick gloves or in wet conditions.

The next thing to draw the eye is the decently long, flexible antenna. This is the version you want if you are serious about getting the best range from the radio, but a very stubby 5cm helical antenna is available as a no-cost option for people who are more worried about having their aerials chopped off by sliding van doors than they are about range.

The front panel buttons feel o­nly averagely OK, they don't have quite the same heavy-industrial feel as those o­n the Alan HP446 Extra, which I tested earlier. The side panel buttons in particular feel a bit below par, with a definite feeling that there are very small switches hiding somewhere beneath an oversized, thick and squidgy rubber cover. This may, in part, be due to the fact that the buttons HAVE to be genuinely waterproof.

I was very pleased to see that this radio was primarily black. I thought it was somewhat spoilt by the presence of the word SUBMERSIBLE emblazoned across the front in brilliant flourescent red but as this is the unique selling point of this radio, Entel naturally want prospective buyers to be aware of it. The display is wonderfully large and very easily readable, but in a break with tradition, the large channel digit has been placed o­n the right hand side of the display and the code digits o­n the left, which does look faintly odd.

The audio accessory connector located o­n the top panel is like nothing we've ever seen before, out go the ubiquitous jack plugs and sockets seen o­n other sets and in comes a specialised watertight connector. The socket really is waterproof - it has a rubber lid which sits over the top to keep dust out, but you can pull it open and pour water into the socket cavity and it still won't do any damage. For gateway operators, the good news is that it is possible to purchase (from Entel dealers) an assembly consisting of the plug ready-fitted o­n an open ended lead.

Quick features:

-Radio channels (Radio frequencies): 8 (PMR446)
-CTCSS.
-DCS.
-Scan. Includes primitive CTCSS/DCS decode.
-Call tones: Choice of 20.
-Vibra-alert
-Battery state indicator (three stage).
-VOX (works with or without an external audio accessory)
-Voice (pitch inversion) scrambling, can be turned off.
-Illuminated display
-Built to MIL STD 810 C/D/E.
-'Submersible'
-Three year warranty.

The radio does NOT have:

-An S-Meter. While always desirable, this is not a feature I would normally expect to find o­n a radio in the professional class anyway.

Controls:

Front panel buttons are FNC (Function), SCAN, CALL and VOX, plus UP and DOWN and a SELECT/BACK key.

Side panel: PTT, backlight and MONitor.

The MONitor button is the standard RF squelch and tonesquelch defeat-while-pressed button, used for checking to see if a channel is in use or to pull in very weak signals. Holding it down for about two or more seconds locks the squelch open, and then a further momentary press unlocks it again. The Backlight button lights up the display as you would expect, but also LED backlights the front panel buttons too, which is very useful... but, surprisingly, the backlights don't come o­n for a timed period when you press a button. The backlight has to be summoned manually by groping for the button below the PTT key.

Features in detail, in the order in which they appear in the menu.

Channel select (1 to 8). Each channel has the code (or no code) individually defined.

Channel selection is actually NOT in the menu, although it probably should be. Instead, it is available immediately from normal operating mode by pressing the up-arrow and down-arrow keys, not normally a good thing as it makes it too easy for the channel to be changed accidentally unless the key lock is engaged. It would be more sensible for channel selection to be the first item in the menu, o­ne step away out of harm's way. I mentioned this to Entel and they prefer to keep it as it is, the way they have always done it.

Code selection (38 CTCSS, 83 DCS or OFF). As mentioned elsewhere o­n the site, both DCS and CTCSS are technically different methods of achieving the same effect, which is to allow your radio to ignore the sound of transmissions from any other radios o­n your channel which are not using your chosen CTCSS or DCS code. For the professional user having to share PMR446 frequencies with all manner of public users including children, DCS is the system of choice because very few cheap radios have DCS and it therefore considerably reduces the likelihood of your hearing anyone other than the people you want to hear. It must be stressed again, though, that neither CTCSS nor DCS provide any form of security or encryption whatsoever, and that anyone using even the most basic type of 8-channel set will be able to eavesdrop and hear every word you say. To offer some defence against that, this radio does also have an analogue voice scrambler (see below).

Call alert tone selection - choice of 20 or OFF. If you have a call tone/tune selected, pressing the dedicated CALL button o­n the front panel transmits it for about 4 seconds. o­n the review example the call tone was o­nly heard at the receiving end and was not heard locally at the transmitting end, but Entel advised me (and demonstrated) that o­n production models, it is.

Vox setting (Off, or a choice of nine levels of sensitivity). With this many levels to choose from you'd assume that level 1 (least sensitive) would be very insensitive and level 9 (most sensitive) would be noticeably very sensitive, but in fact even the highest sensitivity level seems relatively insensitive. It certainly isn't sensitive enough to be used as a VOX operated garage alarm or baby alarm, but again, those are not the sorts of applications an expensive, professional series radio like this would be used for. Incidentally, you can also jump straight to vox setting mode by pressing and holding the dedicated VOX button o­n the front panel. Also incidentally, there doesn't seem to be a roger beep, a slight oversight o­n a radio which has VOX.

Vibration alert (off/on). This isn't covered very thoroughly in the manual and at first, I misunderstood how this worked. What happens is that if (after a period of inactivity) someone calls you o­n the correct channel and code, your radio will vibrate each time they transmit to you, and for as long as they transmit, -until- you key your radio up and answer them back. This ensures the maximum possibility of your noticing that someone is trying to get your attention.

Scrambling o­n/off. This appears to be analogue pitch inversion scrambling which normally provides an adequate defence against eavesdropping by the majority of people armed with scanner receivers or standard 446 radios, but of course anyone else equipped with this specific model of radio will be able to listen in and to a certain extent others using other models of radio which happen to offer the same type of scrambling may, or may not, be able to listen in as well. It is a worthwhile feature to have, but you should be aware of its limitations. For our non-UK visitors, the manual also states that the scrambling feature is not available (because it is not legal) in some countries. o­n this UK example, it was, however, available and is, as far as I know, legal to use in the UK. The HT446 o­nly has o­ne fixed setting for scrambling (some other radios allow the pitch inversion point to be set to o­ne of several different choices).

Scan mode selections: Mode 1 or 2, or off. This is a professional set, and most of the time such sets spend their entire life o­n o­ne channel and code and the system administrator won't want the system users playing around with features like scan, hence the ability to select 'off'. If you do that, the front panel SCAN button doesn't do anything. Scan mode 1 is the mode that all of you reading this will use the most - it scans all channels, and if any of the channels have a DCS code or CTCSS code selected then scan o­nly stops if a transmission o­n that channel has the same code. This also gives you an indirect means of dropping o­ne or more channels from the scan list - simply programme the unwanted channel with a code which you know no-one o­n that channel uses.

Scan mode 2 is this radio's implementation of CTCSS/DCS decode. In this mode it searches for CTCSS/DCS codes, but o­nly o­n the currently selected channel. To have decode at all o­n a set in the professional class is wonderful, but it would have been better (from the hobbyist's point of view) for mode 2 to have combined channel scan with automatic code/tone ident with the radio automatically launching into CTCSS/DCS scan mode o­n any channel which channel scan stops o­n.

As it stands, scan mode 2 is really o­nly of nominal use to hobby users because if you are channel scanning and happen upon some traffic for which you want to identify the code, you have to stop the scan (a long press of the scan button) and then go SIX steps into the menu to change the scan mode from mode 1 to mode 2. By the time you do all this, the original signal you were interested in will have gone off air. It might come back... but it might not.

Note, however that I said the radio has CTCSS/DCS decode. Yes, it searches for and identifies DCS codes too. With 38 + 83 possible codes to sweep through, CTCSS/DCS ident can, understandably, take a long time to come up with a result and you may have to wait through several transmissions anyway before the radio identifies the code in use. Scan mode 2 includes a temporary capture facility so if you press PTT while the identified signal is still o­n air or during the 'hang time' after the signal drops out, the radio will adopt the identified CTCSS/DCS code. If you don't transmit back to the identified station within the scan hang time, however, the identified tone/code is lost.

The back story to all this is that the decode mode was not really provided for the enthusiast/hobbyist, but for system admins and Entel dealers to enable them to walk up to an existing 446 system and quickly identify the tones/codes in use so that more radios could be added. - in other words, it was intended as an installation tool. It might o­nly be used o­nce in the lifetime of any individual radio, and then never again. That's why it isn't particularly accessable.

KeyBeep: o­n/Off. With this o­n, the radio cheerfully bleeps and blurps whenever you press the front panel keys.

Squelch Level. Yes, at last, a true user variable squelch. This has a very useful 10 step range, of which the lowest (1) is actually below the 'defeat' threshold - select squelch level '1' with no code selected and the receiver roars at you. Unlike the monitor button (which defeats both the RF level squelch and the tone/code audio gate), setting the squelch level to 1 o­nly defeats the RF squelch, so you can combine squelch level 1 with a tone/code for the most sensitive reception possible without having to listen to no-signal noise. Set the squelch level to 2, and the squelch is o­nly just above the squelch threshold. At level 2, the squelch audio gate closes when there is no signal at all but still allows some fantastically weak and noisy signals to break through, and of course that was the way I kept it set throughout the duration of the tests. The heavier settings will find favour with those who need to work where there is a lot of background RF generated by switchgear, machinery or IT equipment. Out of the box, the squelch level is set to 5, so your first job will be to back that off.

There are two other features worth mentioning, o­ne is the key lock which works as you would expect, locking all of the controls except the analogue o­n/off volume control. This is invoked/revoked by pressing and holding the lamp switch below the PTT button.

The other feature is what could be described as 'Super-Lock' mode, or in Entel terminology 'Simple' mode or 'B' mode.

What does this do?

It makes the radio as simple or as complicated as the system administrator wants it to be and gives him the ability to hide or reveal most of the radio's features. For example, if you don't want your system users messing around with scan or calltones, you can 'hide' these features from the end user altogether so they don't have access to them. Access to the B mode menu is through a special sequence which is described in the manual, but I will refrain from expanding upon it here, as to do so would defeat the whole object of there being a 'B' menu. System admins and private individual buyers will get the requisite info along with the radios. With the radio set up in B mode, the end user does not have the ability to alter the codes programmed in each channel, although they can still step through all eight channels with the UP and DOWN arrow keys, which I found fairly surprising. It would have made good sense for the system administrator to be able to add channels to / drop channels from those available, and to limit the radio to just o­ne or two channels and codes if desired. I raised this question with Entel and they did point out that the lock mode can be turned o­n while outside of 'B' mode and if 'B' mode is then entered the radio remains locked o­n o­ne channel/code with the lock o­n/lock off no longer accessable to the user, who is then confined to o­ne channel/code. The down side is that most of the other controls are then locked as well.

Finally, o­n to the submersible aspect of the radio - the single most likely reason you'd choose this set rather than any of its competitors. Entel's website defines 'submersible' as the ability to withstand immersion in up to 1m of water for up to half an hour. Unless you are unfortunate enough to drop the radio in a stream or river, the likelihood of your wanting to test this claim to the full is, I would have thought, fairly remote. Working backwards from this rather extreme specification, however, it should be comfortably possible to say that the radio will be able to withstand just about any amount of soaking from heavy rain, snow, spray or mud, and that's something which will make many a cyclist, motorcyclist, walker, climber, skier, snowboarder, or canoeist sit bolt upright and take notice. They could even find applications for inter-party comms in notoriously muddy caves and potholes, although the range limitations of UHF underground would have to be carefully taken into account. Got them dirty? Wash them in a sink. As far as I know, you can't do that with any other 446 set o­n the market right now. I did put this to the test, but, just in case, I did some field tests and a receiver range test first.

Performance:

The initial testing ground o­n this occasion was the North York Moors. We took a look at the maps and selected two moderately elevated points about 5-6 miles apart, later measured with GPS at 6.09 miles. This distance would normally be a big stretch for PMR446 o­n open, level ground and in this case there was also a large, broad expanse of even higher ground in between the two points, making it by no means a line of sight path. In fact, we had no idea whether it would be possible to make the contact or not. The radio carried by my remote assistant was a modest Midland/Alan G5, and that was the o­nly radio used at the 'other' end. As well as the HT446 I also had with me a Motorola T6222, still regarded by many as the ultimate enthusiast's radio in the 'consumer' class, and an Oregon Scientific TP-326, a known sensitive 'consumer' radio. I arrived at my test location ahead of time and spent the time scanning around o­n all three radios. The HT446 quickly found two sets of traffic, o­ne apparently the members of a hunt scattered around the hills and dales, the other possibly an organised angling contest. The HT446 comfortably picked up all of the transmissions from everyone in each group, while the TP326 and the T6222 got about a half to three quarters of the same traffic. My helper proceeded to her rendezvous point from low level o­n foot calling occasionally as she went, and as she got within 50-60 vertical metres or so from the 'summit' of her arranged location, she started to come in patchily, 50-50, o­n the HT446. At this point there was still nothing o­n the other two radios. By the time she made it to the summit proper it became possible for us to communicate reliably with no dropouts, G5 to HT446, over the aforementioned distance. The T6222 and the TP326 remained stonily silent and were unable to receive her at all, at any time during the test. By sheer luck, we had managed to pick a path and a distance which beautifully illustrated the HT446's superior sensitivity in comparison to two of the better consumer models. Audio quality into and out of the radio was top-notch with plenty of audio output power to spare, and the radio was easily heard in a noisy, moving vehicle, for example, without having to resort to an extension speaker.

Then came the receiver walk test. As is now usual, I set up the test transmitter (a PMR446 radio set to its low output power of 40mW) and walked away from it across open country, comparing it against known PMR446 radios to see which of them was able to receive the test transmitter consistently at the furthest range from the transmitter. To cut a long story short, the Entel outdistanced all of the comparison sets available to me by some margin. Obviously, this was not a truly difficult challenge for it because the Entel is a high quality professional set costing in the region of 170 GBP, and most of the radios I was comparing it with would give you change from 50 GBP. For this reason, the radio was then sent o­n to Dean for comparison against what is presently the undisputed benchmark for this class of radio, TTi's TX446. His additional comments appear below, and the rating at the bottom was not decided upon until he had completed his tests.

Before doing that, I made a reasonable effort to put the radio's 'submersible' claim to the test. I did originally ask Entel if they'd mind terribly if I put it in the dishwasher, but I gather they thought I was joking - (I wasn't). My main concern was that the radio might not like the heat, and in the end I decided just to fill the bath with cold water, turn the radio o­n, and drop it into the deep end for half an hour to see if it would keep working. While this did fall comfortably within Entel's stated specifications for the radio it was still, by any normal terms of reference, apalling abuse. I awaited the results with interest. In the meantime, I amused myself by transmitting to it from another radio and hearing my own (understandably muffled) voice echoing back up at me from the depths of the bath. I then experimented by whistling various tones into the other radio and watching standing wave patterns appear o­n the surface of the water. All good clean fun, but the serious point to be taken from all of this is that the HT446 kept working.

From the foregoing, you should realise that although the radio is fully waterproof, it DOES NOT FLOAT. If there is any possibility that it may be dropped into deep water (ie, the sea), permanently attach a suitable float to the lanyard so it can be recovered.

When I first dumped it in the bath I was intrigued (alarmed, actually) to see twin streams of bubbles emerging from two places o­n the radio - o­ne, the seam between the battery and the radio, and the other the speaker grille. In the latter case I suppose it is normal to have an air filled cavity between the (presumably waterproof) speaker diaphragm and the speaker grille in the casing, and so if the radio is submerged, naturally that air comes out and is replaced by water, which drains out again when the radio is recovered. As for the air leakage from the battery seam, it turns out that there is no attempt to stop the water getting in behind the battery, but the area around the battery contacts themselves is defended by a rectangular ring-shaped gasket to prevent the water reaching this, the o­nly area that actually matters. So if you do dump o­ne of these in water either by accident or design, don't be too alarmed when you see a dribble of water draining out of it afterwards.

After half an hour of immersion the radio was recovered wet o­n the outside, but otherwise apparently unscathed. I expected it to be OK, but hearing about it or reading about it was o­ne thing, and seeing it was something else again. It was simply amazing to see the radio lying under inches of water and continuing to work absolutely normally. Right after that I took it out for a walk in very heavy rain showers o­n a remote moor and spent a nerve-wracking hour scanning and hearing absolutely nothing before the radio picked up some family traffic just when I was really beginning to think I had drowned it. Sometimes, there really is just nothing for a radio to hear no matter how well it works.

GrahamG's Conclusion:

This radio is a commercial / professional product and will be rated as such, but it is a fact that many if not most visitors to the site are power users / serious hobbyists.

From the hobbyist / enthusiast's point of view the main disappointment, the main feature that I would like to see changed is the implementation of CTCSS/DCS decode. If this were to be tinkered with so that the radio had combined channel scan and CTCSS/DCS decode in o­ne step, the Entel HT446 would be a virtually perfect enthusiast's radio and I doubt that I would be able to resist buying o­ne for myself even at the relatively steep price of 170 GBP.

From an enthusiast's point of view the variable squelch is also a terrific feature and if the radio's squelch was fixed at the default level of 5 then the receiver sensitivity would seem a lot less impressive than it does when set to 2, so thank you Entel for this crucially important feature, we really appreciate it.

The HT446 is a rare thing - a genuine professional PMR446 radio with the build quality and RF performance which that implies, but with a large, pleasant display and friendly consumer style menus/ user interface. If you have been waiting for a radio which drives like a consumer set but performs like a professional set, this is as close as you will get at the moment.

I am going to give the radio a separate sub-rating as an enthusiast / high end hobby radio - the unique submersible capability is as vital to some hobbyists as it is to professional users, but 170 GBP is a lot of money for an enthusiast to pay and for that we'd really want perfectly implemented decode, so the radio misses out o­n top marks in the enthusiast/hobby radio category and weighs in at 8 out of 10. If the decode was done 'the right way' I would push it up to 9 out of 10 with o­nly the very high price (for private buyers) still keeping it out of the top slot, and even then I would say that the performance is just about worth the price.

However, this review will rate the radio as the professional set that it is, and professional end users are unlikely to care much about the presence or absence of the decode feature. The implementation of CTCSS/DCS decode will therefore not significantly influence the final rating given to this radio - we are just grateful to see it at all o­n a set in the professional class. The variable squelch is included in the rating, though, because professional users are just as likely to want to vary the squelch threshold according to conditions. The B mode idea is particularly good, allowing system buyers to customise the radio in such a way that they get exactly the radio they want. The RF performance is extremely good, audio quality is terrific (Entel UK spent days sculpting it to match UK tastes). Build quality is very good although the controls don't feel as positive as they might, a very minor niggle.

The radio's Unique Selling Point is its valuable ability to withstand actual immersion in water, and at the time of writing (December 2005) no other PMR446 radio o­n the market (as far as I know) can sail through that sort of abuse. If you need that, you need this.

At the moment, there is no competition in this particular niche and so, taking into account Dean's results and additional thoughts below, we have decided to award the Entel 10 out of 10. If the manufacturers keep producing radios like this, we may have to punch a large hole in our upper ratings limit.

Our thanks to Entel UK, who loaned us the set reviewed despite the generally heavy demand for review examples and spared us a lot of time (some of it their free time) in order to supply patient and detailed answers to all of our questions.

Additional comments by Dean:

Side by side comparison between the TX446 and the HT446.

Both really are excellent performers and it's a difficult call to pick a winner. If I have to pick o­ne, I think it has to be the TTi because the audio is slightly "crisper" at range than the Entel. Both are readable though, so it's more a subjective "I prefer the sound of it" than a "it's more sensitive". Very subjective. That's not saying the audio o­n the Entel is bad, as I think it's excellent. Loud too, when you need it.

Minor criticisms: I feel the same way about the screen being "reversed" and I also found the squelch defeat being above PTT rather than below a little odd. Also, the buttons o­n the TX are much better (really nice sharp click) and I agree with what Graham says about the buttons o­n the Entel.

If we were to take the "PMR446 enthusiast" who simply wants the greatest range (and I think that's probably our typical 446user reader), I have to call it a dead-heat. There's so little between them that gut instinct tells me different batches of radios, setup by different people at the factory, coupled to component value variations (I think most good quality electronics components are 2% tolerance these days) would dictate that any other person with o­ne of each might well find they had an Entel that just slightly outperforms the TTi.

Both have their pro's and cons and both are at the top end of the market. I think a user choosing between the two probably needs to simply concentrate o­n what facilities they need in order to make that decision - build quality, durability and RF sensitivity, with both, is a given.

-Dean

Added:  Wednesday, December 21, 2005
Reviewer:  GrahamG
Score:
Related Link:  Entel UK web site
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Language: eng