Arutelud PMR teemadel

[Stupiduser]

Mida targemad persoonid arvavad lällarist Cobra MT725?

[Landy]

Vaadates tehnilisi parameetreid, siis tegu täiseti tavalise PRM käsijaamaga, mida me võistlustel kasutanud oleme.

Up to 3 KM Range (dependent on terrain)
8 Channel Operation - licence free
38 Sub Channels - remove interference
Incoming Call Alert - noisy environments
Stylish rubberised design - for comfort
Illuminated LCD - night use
Rider to Pillion Intercom Facility - intercom
Channel Scan - group work
10 Channel Memory + memory scan
VOX (voice activation) - handsfree use
Baby Monitor - long range
Power Saver - extended use
Roger Beep Tone - user friendly
Vibra alert - ideal for noisy places


Package Includes :

Two Radios
Charger unit
Rechargeable Batteries
Belt clips
User manual
Durable travel case

[Landy]

Lisaks veel:

Cobra Microtalk MT725-2VP (UK)

Set Reviewed: Cobra Microtalk MT-725-2VP (UK), supplied in a twin pack with Ni-MH rechargeable batteries and a combined twin desktop mains charger.

NOTE that the MT-725 is also sold in twin packs WITHOUT the charger and rechargeable battery packs - the package reviewed here and rated accordingly is specifically the MT725-2VP (The 'VP suffix standing for 'Value Pack'), which DOES come with the charger and batteries. The latter are also available separately as options.

Cobra is o­ne of the great, evocative names in hobby radio, perhaps remembered with particular fondness by a certain generation for whom Cobra were the ultimate in CB radios, and it is still possible to buy CB sets bearing the Cobra logo. I was looking forward to seeing what they'd been up to o­n PMR446.

First Impressions

These are the first Cobra 446 radios I've had through my hands and my initial reaction (after hacking them out of their almost impenetrable plastic capsule) was - hmmmm... very nice indeed. Like most of the contemporary rival Motorolas, their styling puts them more in the class of 'cool sports accessory' rather than serious communications gear, but that isn't necessarily a bad thing and there's none of the dreaded silver to be seen here. The tactile feel, weight and size is roughly o­n a par with current Motorolas too, so if you like the way the T5522 (for example) feels in your hand, you'll like these too.

The front panel buttons offer the right balance between positive action and resistance to being pushed so that they are unlikely to be operated accidentally. I'm not too sure about the way three of them have been placed above the display, though, as it means that the display will be at least partly obscured by your fingers while you are operating them - better to always have the controls either below or to o­ne side of the display to prevent this from happening. o­ne positive effect of having the buttons spread all around the display is that they act as rubber standoffs which keep the display lens away from any surface the radio might be put down o­n, thereby reducing the chances of the lens getting scratched.

Since this review first appeared some visitors have noted that there seem to be at least two different display layouts o­n the various images of the MT725 to be found o­n the net. I don't know why that would be, but can confirm that the sets reviewed here had exactly the same display elements and layout as the units pictured above.

The radio's battery cover has unfortunately been borrowed from Motorola's current 'hatchback' phase but it has a much better clasp-type catch which is unlikely to spring open accidentally. The belt clip is removable for access to the battery compartment and can be left off to give the radio a completely smooth rear profile if you intend to be holding the radio in your hand the whole time, but even when it is fitted, the belt clip has a very low profile and very smooth, rounded edges so it doesn't make the radio awkward to hold. The overall flint-handaxe shape of the radio makes it impossible for it to be stood up o­n a flat surface, but it does feel extremely comfortable in the hand.

The manual which comes with the UK version is well written and clearly illustrated. Interestingly, it states that channels 1 and 2 may not be used in France, although I'm not sure whether that is still the case. The manual (English o­nly) is a fold out sheet, which does at least mean that if two of you buy a pair of these radios to split, the manual can be reproduced easily enough - unfortunately the drop in charger pod is a combined twin unit, which keeps costs down due to there o­nly being o­ne mains adaptor, but makes the package less attractive to two individual buyers. The package includes two 'filler' adaptors so that the packs can be charged in the desktop charger without the radios. The design of the drop-in charger and special battery packs is such that o­nly the special packs can be recharged in-radio via the desktop charger as it utilises extra contacts o­n the body of the special pack.

The time claimed for in-radio battery charging via the supplied desktop twin charger seems suspiciously fast, stated as a mere 3hrs. Those of you who have ruined Ni-MH batteries by overcharging them will also be relieved to hear that the manual states that the radios can be left o­n charge indefinitely without harming the batteries. The charging circuit presumably includes some kind of intelligence to make all of this possible.

There is also an -optional- mains wall charger which plugs straight into the charge/INT jack of the radio and charges the battery pack through the battery terminals of the radio. Charging time with this option is also 3hrs. The manual states that o­nly the official Cobra Ni-MH pack can be charged in the radio via this means although I'd tend to suspect that third-party AAA Ni-MH cells of a similar mAH rating could be recharged too. I didn't have the optional wall charger to try, though, so don't take my word for it.

Battery life with the radio permanently o­n scan is rather short - just several hours, proof, I suppose, that the auto power saving mode (which is disabled during scan) does do a useful job. o­ne rather negative impression that I got was that the supplied Ni-MH battery packs seemed to self-discharge very quickly when the sets were in storage. Although this always does seem to be an issue with Ni-MH batteries in particular, these o­nes seem noticeably poor in that respect.

If you manage to get caught short, the radio can, as usual, be run from standard AAA dry cells, four in this case.

Quick features list:

Buttons are Call, Lock, Mode, Power, Volume up/down, Channel up/down, MONitor/Backlight and PTT.

8 Channels, 38 CTCSS (can be turned off), Roger Beep (Can be turned off), Calltone (Choice of 5), Call alert/Vibra-alert (more about this below), Key beep (Can be turned off), Keylock, Scan, **CTCSS decode and show**, Battery level indicator (four segments), Power saving mode (Automatic), Baby Monitor mode, Dual-Watch (more below), Dual - User Intercom feature (More below). 'Range Extender' mode (more below).

Features in detail:

Channels/CTCSS

Each channel has its CTCSS code individually defined, and may be programmed with CTCSS off. There is no global CTCSS o­n/off control.

SCAN and CTCSS SCAN.

This is where this initially rather fine looking radio starts to look a little bit clunky. If you paid any attention to the list of buttons above, you'll have noticed that SCAN isn't among them. In fact, you have to go four steps into the menu (four presses of MODE) to get to the root of the scan menu, then press the channel UP or channel DOWN button in order to set it off scanning. This is really rather poor - it would have been better if, given the control layout provided, SCAN had been invoked by pressing and holding down either channel UP or channel DOWN from normal operating mode.

SCAN disregards the CTCSS settings for each channel when in scan mode, so it will halt o­n any transmission o­n any channel with or without CTCSS. Strangely, the Volume up/down buttons don't work while in scan mode, so if SCAN stops o­n a rather quiet transmission, you can't just jog the volume up a couple of notches while the radio is paused o­n the transmission to hear what's being said.

CTCSS decode-and-show is still much too rare and so it's always good to see it o­n any set we are loaned for review, but again, the implementation here is a bit peculiar. If you've got a T6222, a T5522, or a Telcom TE-150 or variant, then you know how CTCSS decode and show should be done - if the radio halts o­n a signal when in scan mode, it should then automatically launch into CTCSS ident mode and display the code (if any) found. If you press PTT briefly while the radio is halted o­n a transmission and showing an identified CTCSS code, the radio should adopt that channel and CTCSS code.

Cobra have chosen to make CTCSS scan a feature which has to be manually invoked and can o­nly be carried out o­n o­ne channel at a time, so you can either:

Scan all channels for all transmissions, or -

Scan o­ne channel for CTCSS codes.

If you want to identify the inbound CTCSS tone o­n a signal that SCAN has stopped o­n, you have to press MODE then the channel-up or channel-down button to switch the set into 'Now scan this channel for CTCSS' mode. If the signal is still o­n-air by the time you do all that, it will decode and show the incoming CTCSS tone. If the signal then disappears for a bit, the unit resumes scanning for CTCSS codes o­n the channel it stopped o­n, and continues to do so indefinitely - it never resumes channel scanning and instead continues to cycle through all the possible CTCSS codes looking for inbound CTCSS o­n whatever channel it originally stopped o­n.

In practice, this is so limiting and inconvenient that in the end, I just didn't use it, preferring to use my T6222 to search for traffic that I then listened to with the Cobra. Poor implementation aside, I'm sorry to say that I also found the operation of the CTCSS-ident feature to be a little inconsistent, so if I had it doing a CTCSS scan, it would sometimes offer up different codes o­n successive 'overs' from the same individual transmitting, whereas the T6222 either identified the same code every time, or didn't show anything if it wasn't sure because the transmission was too short or there was interference present.

If the MT725 does stop o­n a particular channel during scan, and you do successfully identify the inbound CTCSS tone, you can make the radio adopt both the channel and the identified CTCSS tone by pressing PTT while both are displayed o­n the screen. The radio then falls back into normal operating mode with the relevant channel and code selected. So the 'capture' part, at least, does work in the conventionally expected fashion.

CALLTONE and ALERT

Nothing to explain about this, surely? Well, yes there is. Usually, you'd have o­ne or more audio tone sequences which can be sent as modulated audio -from- the -transmitting- radio to the receiving radio. They normally sound like a phone ringing or a simple musical sequence.

At first glance the Cobra has this too, but upon closer inspection it doesn't work in the normal way. Each radio has a set of calltones to choose from (five in this case), but the radios don't actually TRANSMIT the calltone as audio - they transmit some kind of control signal (which sounds like a low frequency burbling sound) which tells the RECEIVING radio to either sound its selected calltone or activate its vibra-alert device.

If you're using two Cobra radios this works fine, but if you press CALL with the intention of waking up someone who is using another manufacturer's radio, all they will hear is a weird burbling noise. ...Just something you need to bear in mind if you plan to use these with other makes of radio.

ROGER BEEP is a fairly fast low-mid-hi beep which sounds quite pretty the first half dozen or so times you hear it. After that, you'll be pleased to find you can turn it off. KEY BEEPS can also be turned off.

VOX has five levels of sensitivity, and works with or without an external accessory plugged in. The radio continues to transmit until two seconds of silence have elapsed.

BABY MONITOR - Uses the same sensitivity level setting as for VOX, but the radio keeps transmitting for ten seconds rather than two. o­nce it drops out of transmit, there is also a ten second re-arm delay during which further sounds will not cause the radio to transmit. The merits or otherwise of using a very public, relatively long range system like PMR446 for baby monitoring can be debated at length but if you do buy these radios primarily for this purpose, you can at least use them as walkie talkies o­n other occasions, whereas a dedicated baby monitor is o­nly ever a baby monitor (and occasional alien detector)

DUAL WATCH - Designates a particular channel and code to be 'watched' and when this feature is enabled the unit periodically jumps away from whatever channel/code combination you are listening to and has a quick listen o­n the alternative combination defined as the Dual Watch channel. If it finds activity there it pauses so you can listen to it, otherwise it returns to the primary channel and code. If you really do have an application where incoming traffic from two groups or two individuals using different channels and codes is of equal importance to you, then this will be useful. SCAN o­n the MT725 stops o­n all signals regardless of the CTCSS settings programmed in each channel, so Dual Watch does at least offer a way to 'scan' two of the eight channels, each with a specific code to watch for. If conventional split-frequency RF repeaters are ever allowed o­n 446, you could set the radio's primary channel to the repeater's input channel and the Dual Watch channel to the repeater's output channel, so the MT725 is 'repeater ready'.

BATTERY METER - four segments, so you can see a definite progression as the batteries get weaker, which makes it easier to anticipate just exactly when they will die o­n you.

KEYLOCK has its own dedicated button - hold down for two seconds to invoke/revoke keylock. Unusually, the keys LOCKED include the power o­n/off button. I would usually prefer the power switch to be excluded so the radio can be left with the settings locked between uses.

INTERCOM - I can tell you what this does, but I didn't have the necessary audio accessories and adaptors to try it out, so I can't say what is is actually like in use. It allows two users each with their own headset/mike to talk to each other and to use the radio as a radio, and is (I would imagine) primarily aimed at motorcycle riders and their passengers. I appreciate that many of you would have liked a more detailed discussion of this relatively rare feature, but that wasn't possible without the relevant audio accessories.

MONITOR - Cobra manual jargon calls this AUTOSQUELCH OFF, but it's what we all know as Squelch defeat/CTCSS squelch defeat. A momentary press of the MON button turns the backlight o­n for 10 seconds. Holding it down for more than a second, but no longer than 5 seconds, makes it act as a conventional defeat-while-pressed MONitor button. Holding it down for 5 seconds or more engages the...

MAXIMUM RANGE EXTENDER.

Ever since I saw this mentioned in Cobra spec lists, I've wanted to know exactly what this does and how it does it. If it's possible to enhance the range in some way, why not just do it all the time? Is it a genuine technical enhancement, like a switchable RF preamplifier? I'm sure you will be itching to know. I know I was.

What it does is... ...It locks the squelch defeat o­n until you press the MON button again.

While there's no denying that this will indeed enable you to hear signals which are so weak they won't normally make it though the squelch, I think it is a rather massive example of marketing kidology to give this facility such a prepostorously grand title. Squelch Defeat Lock is what it is - yes, it will enable you to hear weaker signals than you would otherwise, but at the cost of having to endure very loud no-signal hiss in between transmissions from the other operator.

Performance:

I played around with these for a few days and then used them properly for a period of about 8 hours to keep in touch with a friend at the Royal International Air Tattoo (Airshow) in Gloucestershire. They worked very well for this purpose and gave us the freedom to split up and wander about looking at the various attractions individually without getting hopelessly and permanently separated in the very large crowd. As expected there was considerable use of 446 at the event and we were grateful to have CTCSS. RAF Fairford covers a fairly vast area and and has a very long runway and so it's easy to get close to the 'standard' 446 range limit just by going to opposite ends of the field. We o­nly really got out of range o­nce, and that was when I trudged what felt like a good mile back to the car to collect something. When the other radio's signal started to slide beneath the squelch just before I reached the car I looked over in the direction of the main venue and realised there was a fairly prominent rise which was concealing not o­nly the airfield, but the wings and lower fuselages of some of the very large aircraft parked in the static displays near the runway. We therefore had nothing like line of sight and the other radio was no more than 3ft above the ground, so I was quite happy to have reached the range limit under the circumstances. The batteries were quite low by the end of the day but the radios had been o­n all day and transmitting quite a lot, so I didn't think that was unreasonable, especially considering the fact that we had had the volume flat out all day long.

Audio quality from the units is good, but was tested to the limit at Fairford where it wasn't really loud enough to be heard over the nearly continuous jet noise and the commentary squawking from the PA speakers all over the field, and we spent a lot of time with the radios glued to our ears. In more normal circumstances the audio output from the units is more than adequate.

I also took the MT725s with me o­n a more recent week-long trip to Orkney. Bad weather and lack of time prevented me from making it up o­nto the highest ground (On Hoy) to attempt any serious DX contacts, but I did hear some commercial traffic in and around Kirkwall and Stromness, and even occasional transmissions somewhere around my B&B in the underpopulated west central area of the Orkney mainland, so if there was traffic to be heard, the Cobras generally managed to pick it up, intercepting everything that my T6222 did and perhaps a little more.

Back home and just listening around, I did gain the informal impression that in terms of sensitivity, the MT725s were at least at the high end of average. The o­nly way to be sure was to carry out a proper walk test and comparison with a known set.


The comparison set in this case was the Oregon Scientific TP-326 that I normally use as a comparison set, the reason being (as always) that this is the most sensitive set that I personally own. Also along for the ride was the Xtreme Slimtalk SL-01P which I had for review at the same time. For this particular test I used a slightly different test transmitter, a real PMR446 radio set to its low (50mW) output power. I then walked away from it across open country until, at a distance of 2.5km from the transmitter, the TP326 and SL01P both began to struggle to receive the test transmission. To my immense surprise, the test transmitter signal continued to sail through the squelch o­n the Cobra MT-725 no matter where and which way up I held it. I had to lie it o­n the ground to get it to lose the signal. Of all the consumer 446 sets that I have either owned or reviewed, the Cobra MT725, or at least this particular example of o­ne, is the most sensitive that I have seen to date. While I was testing this set Dean was hard at work o­n the very similar MT-525 and it's interesting to see that he felt his example of that set was just averagely good in this respect, when I'd have bet good money that both sets were virtually identical inside with the exception of their processor firmware. Whether they are or not, the results for the MT725 range test must remain as found.

Conclusion:

Lovely to look at and to hold, the Cobra MT-725 surprised me with its great receive performance in the range walk test, and if there hadn't been anything else to detract from it the radio would have scored very highly indeed. Unfortunately, scanning and in particular the CTCSS decode-and-show are poorly implemented and really spoil an otherwise very good radio. Scan should be immediately accessable, not buried away four levels deep in the menu, and CTCSS decode is so awkward to use that you probably won't use it. You definitely should not buy this radio if CTCSS decode is your primary requirement - there are other radios, some mentioned above, which do it properly.

Rating this radio is also difficult due to the apparent wide variation in price. As noted at the start of the review, you have to be careful to check that you are buying what you really want because you can buy the MT725 in twinpacks without a charger or batteries, but the package reviewed and rated here is the MT725-2VP version which DOES come with batteries and a charger. After a quick look around o­n the net the general price for this package at the time of writing (November 2004) seems to be around 65 GBP for the pack, placing them nicely alongside their obvious rival, the Motorola T5522. The Motorola has properly implemented, reliable CTCSS decode and that ought to put it streets ahead, but o­n the evidence of this example, the Cobra MT725s stretch the range that little bit further and they do have Vibracall if you really need it. They narrowly escape a deduction for trying to pass off the 'Maximum Range Extender' as something far more wonderful than it actually is. The final score is therefore eight out of ten.

My thanks to PAMA UK for the loan of the sets reviewed.

[K.Kotkas]

Kas on point terve manual 2ra trykkida ? 2kki arvaks midagi omast kogemustest, mitte ei refereeriks kasutusjuhendit, mida kodanik kindlasti isegi lugeda oskab.

[Arto]

Mida targemad persoonid arvavad lällarist Cobra MT725?

Meie kasutame ning midagi halba pole veel märganud, ainuke jama on peakomplektiga, seda pole veel normaalselt saanud hääle järgi lülitama!

[uaz469]

2kki arvaks midagi omast kogemustest, mitte ei refereeriks kasutusjuhendit,.............

Mul endal just need samad "Cobra MT725-2VP" kasutada,olen igati rahul!
CB Foorimist sai ka juhendi/skeemi,kuidas neile korralikum antenn külge pookida (muidugi aja- ja materjali puudumisel on jäänud see antennipookimine unarusse):!:
Niiet,mina olen igati rahul nendega.

[seff]

CB Foorimist sai ka juhendi/skeemi,kuidas neile korralikum antenn külge pookida.........


pane see link siis ka siia kirja kuidas neid tuunida...

endal ka samasugused lällarid ja täitsa toimivad

[uaz469]

no kui kellelgi veel seda Cobra pemari antennipookimis linki vaja, siis:
http://cbfoorum.pri.ee/viewtopic.php?t=238

ja andke siis teada kah, kuidas õnnestus!

[414 AVM]

Landy, seleta palun lahti, miks PMR jaamad paremad on kui CB omad (peale Sinu oma ärihuvi muidugi). Mul on Alan 42 Multi, toimib ka suvalise katuseroikaga suht kauge maa taha, aga üha rohkem on safaritel nõutud PMR .

[reimo]

Vastan, miks mina ostsin: CB on kasutatav puhatlt autos, ehk siis ainult safaritel (minu puhul), PMRiga saab ka nädala sees tööd teha (ei pea ühe kaabli otsa juurest teise hlistama või jooksma), samuti naisega seenele minnes jms oludes kasutada.
Viimasel Cherosafari jätkusõidu ajal oli küll seis, et PMRiga polnud eriti midagi teha, kogu suhtlus käis CB kaudu. Või siis ei suutnud minu jaam midagi vastu võtta. Kui ise üksi mudasse jäin, siis sain kellegiga sidet, aga kvaliteet oli nii kehv, et ei saanud aru, kellega ja kus kolonni otsas rääkisin, lõpuks telefon aitas:)

[Landy]

Landy, seleta palun lahti, miks PMR jaamad paremad on kui CB omad (peale Sinu oma ärihuvi muidugi). Mul on Alan 42 Multi, toimib ka suvalise katuseroikaga suht kauge maa taha, aga üha rohkem on safaritel nõutud PMR .

Ega nad polegi paremad, nad on veidi teiseks kasutusalaks. (Nagu sai ja leib). CB kasutab 27MHZ kandeala ja PMR 466 Mhz. Ühelgi safaril pole need NÕUTUD.

Väikesed, odavad ja kerged ning mõnus kasutada väikesel territooriumil. Normaalne levi kuni 1km vahemaa taha.
Vastupidiselt auto jaamadele saab neid kasutada kus ja millal iganes. Matkates, seenel, suusatmas, kanuutams jne. olles. Võimalus lisada ka hands-free. Kasutatakse ka ehitustel ja väiksemtel väliüritustel.
Mõnus kasutada pisikestel safritel, pikkade kolonnide puhul ei pruugi algus ja lõpp enam tieneteist kuulda. Ka Piloodi-Vintsmann suhtlemisel heaks on PMR abimeheks.
CB eelis ongi pikad vahemaad, selgem heli ja rohekem kanaleid ja muud lisavõimlused.

[fagott]

Vaata,huvitav,kuidas sa oma Alan 42-ga võistluste ajal punkti otsides metsas ringi jooksed?Peale safarite on ka olemas võistlused,kus pole CB-ga midagi teha.On muidugi olemas CB käsijaamad,aga selle metsas mutta kaotamise järgne emotsioon erineb oluliselt PMR kaotuse järgsest Viimane lihtsalt taskulambiga samas hinnaklassis...

[Raitz]

Eh ma mulisen ka PMR-i kohapealt
Tõsi mul on alati Cobrad olnud, aga siin nende koopiad, seega pole hullu.
Seinad mõjutavad levi väga. Üks toas, teine autos versioonis oli normaalne kuuldavus kuni 1km.
Üks hoovis, teine autos oli normaalne kuuldavus 2km
õu-õu lahenduse puhul olen ise suht avatul maastikul ka 5km saanud, aga noh, üle 2km pole mõtet nendele loota üldiselt.
Cobradele on Kiivrikomplekte (saab omavahel suhelda ka kiivrit peast võtmata). Käed vabad süsteeme, nagu moba oma. Mul on uuemal Cobral seinaladija 2le (mitte dokk, vaid analoogilne mobla laadijale). Kuna autos nagunii 12->220 adapter, siis käiks hädapärast see lahendus ka, kindlasti on ka 12v laadijaid olemas, aga peamine on see, et paljud mudelid kasutavad AAA patareisid, või pulkakusid. Mis on eriti bro lahendus, taskust uued sisse ja elu läheb edasi.
On ka akuga asju, aga neist olen ise eemale hoidnud.
Kuna vahel on rattaga sõites nad samuti taskus, siis ükski padukas pole neist jagu saanud, seega natuke vett neid ei heiduta.
Aga mis peamine, nad on odavad
Pole masendust kui upub, kaob või lihtsalt katki läheb.
(viimast pole mul ette tulnud)

[FlammablE]

Autos mingi CB jaam olemas. Mis kanalil tavaliselt metsas suhtlus käib?
Kas keegi oskab soovitada mõnda PMR, millel veidi valjem heli? Võibolla hakkab tõesti kuulmine kaduma, aga mootorimüra ja metsas tavaliselt valitseva suure segaduse tõttu on saatjatest vähe kasu. Enamasti ei pane tähelegi, et keegi sinuga meeleheitlikult suhelda soovib.
PMR suureks plussiks minu silmis on just võimalus auto ja mingil põhjusel autost välja pekstud vintsmani/rajaleidja vaheline suhtlus. CB käsijaamad hakkavad seal 2k ja üles= harrastajale veidi kallis lõbu, eriti kui kasutajal kombeks tihedamini mülkasse ära uppuda

[Landy]

Autos mingi CB jaam olemas. Mis kanalil tavaliselt metsas suhtlus käib?

Abiks:
http://forum.4x4.ee/viewtopic.php?t=474 ... rekkamehed