Radio TECHNICAL Discussion

[djlewis]

And lastly, for those who insist on an M88:

http://www.ebay.com/...9#ht_797wt_1398

Interesting -- you're quite the eBay hound, Ern (that's a compliment).

BATTERY NOT TESTED OR GUARANTEED

$75 with shipping. Either I use my existing battery, which is in decent shape, or I buy a new one for $90 from WM. I guess the Uniden/WM unit looks better.

[jason]

David,

I disregarded the M72 because of its bulk, but now I'm not sure if it was any larger than the Uniden.

I HAVE seen an iCom battery clone on eBay for $15-20.

Yes, it'd be nice if Uniden somehow could squash a 2Ah Li-Ion into that small geometry...and I'll figure out a decent PFD shoulder mount....

Paddle Manchester w/ Leon next week?

Ern

The M88 and M72 are about the same volume just in a different shape. The M72 fits in the front pocket of my PFD (including all of the antena). Thus I don't have to worry about it falling off or impaling me in the eye.

[subaruguru]

David et al:

http://www.ebay.com/...9#ht_639wt_1399

Wish the Uniden battery was under $25....

Jason,

Good point (or lack of!).

[EEL]

You need to be careful about buying replacement batteries since Li-Ion batteries have a shelf life and are affected by heat. Unless the batteries have a recent manufacture date, they might not last long nor perform all that well. Their lifespan does depend on nature of use and device as well as storage and charging habits. This is why unless you will need an extra battery on a regular basis, it may not be a good idea to buy a spare battery just to have it around.

Ern,

I have no idea what you mean by noisy environment. Generally the spurious signals which affect a receiver's weak signal performance are generated by the receiver. That is why the test results for a receiver's minimum discernible signal typically don't tell you much about how well the receiver "hears" in the real world environment. In the real world environment the mixer stage is confronted with an array of signals not just a single freq. as in a testing situation. This can, depending upon the design of the receiver, result in noise which masks very weak signals so that in the real world you cannot hear weak signals which the minimum discernible signal test suggests you should be able to hear.

Personally I use NOAA WX stations as a decent test of how well a VHF handled "hears".

Ed Lawson

[subaruguru]

Ed,

On the contrary, rechargeable Li-ion batteries have extraordinarily-long shelf lives and almost no memory-charge effect...or whatever it's called, unlike Ni metal Hydride, alkalines, etc.

Further, the combination of test sensitivity (against a standard noise floor and freq res), selectivity, capture ratio, and spurious signal attenuation are sufficient to describe and compare FM tuners, as has been the case for a long time.

It's pretty simple, and most of the evolution of the science occurred post WWII until the peak of the designs exemplified by the great tuners of the late 70s and early 80s (plus the new baby Sony digital one).

But I'm unaware that internal spurious signal generation is an issue, unless it's a REALLY bad receiver design, or maybe has a really dirty Class D audio amp. Let's hope today's marine receivers are at least cleaner than that! I suspect they're pretty simple mostly-analogue designs with most of the production value going into the case, battery and design priority for ruggedness. Too bad open-box QA isn't anywgere as good as an average flat panel TV, though. The internet is littered with examples of out-of-box failures from all brands. Sheesh....

Best,

Ern

[EEL]

Ed,

On the contrary, rechargeable Li-ion batteries have extraordinarily-long shelf lives and almost no memory-charge effect...or whatever it's called,

You might find the information on sites such as battery university of interest.

Further, the combination of test sensitivity (against a standard noise floor and freq res), selectivity, capture ratio, and spurious signal attenuation are sufficient to describe and compare FM tuners, as has been the case for a long time.

It's pretty simple, and most of the evolution of the science occurred post WWII until the peak of the designs exemplified by the great tuners of the late 70s and early 80s (plus the new baby Sony digital one).

Whatever. I now understand your frame of reference is that of an audiophile.

Ed lawson

[ThomasL]

I bought a the Icom M92D and (being insecure) also purchased an additional battery. My 1st trip out with the radio ran about 6hrs, and, following the paddle, the charge indication on the radios LCD indicated it was still in the all bar fully charged condition.I was alone and did not transmit, but the GPS function was running. Obviously for a a day tourer like myself the 2nd battery was an unnecessary investment. As for the shelf life of L-ion batteries, I have multiple camera batteries dating back to 2004 that still hold a charge and who's performance has not diminished in spite of the fact that they have seen only sporadic use over time. They are far superior to the nicads of years past.

Tom

[subaruguru]

Jason,

I checked out Lisa H's M72 yesterday, and indeed, its slimness compensates well for taller height. And that 2Ah battery!

Certainly another great mid-priced ($200) option to the M88 or WM-VHF85/SH-75.

Somehow I missed it when dismissing the other bulkier iComs and SH rigs.

Tom,

I used the VHF85 yesterday for about 6 hours, maybe just a couple minutes total broadcast, but quite a bit more receiving chatter, and returned with 4/4 bars (supposedly "full") battery life remaining. So far so good.

Thanks to you both for the comments.

[EEL]

As for the shelf life of L-ion batteries, I have multiple camera batteries dating back to 2004 that still hold a charge and who's performance has not diminished in spite of the fact that they have seen only sporadic use over time.

Li-Ion and Lithium-Polymer batteries start to degrade from the moment of manufacture. How long it takes them to reach the point where they are considered to be a the end of their service life depends upon how they were stored and how they were charged before being stored for batteries that have never been used. For batteries in service, their life spans depend on how they are stored, how they are charged, how frequenly they are cycled and the nature of the charge-discharge cycles, and the type of application for which they are used. All I am saying is buying old stock batteries from discounters and buying a battery to sit unused as a spare in case the in service battery fails in the future is not a good idea.

Ed Lawson

[gyork]

For those who are concerned about consuming battery life from their radios, I performed a test with my 5-year-old ICOM 88 to simulate on-water usage. After FULLY CHARGING my Li-ion (3 bars, level 8.2), I set to monitor mode on DAY 1 for 8.5 h, making 2-3 transmits of 15 s or so, and 2 min of weather channel. On DAY 2: 3 bars, level 8.0, transmits/weather, 11 h. DAY 3: 3 bars, level 7.8, etc., 11 h. DAY 4: 3 bars, level 7.6, etc., 24 h. DAY 5: 2 bars, level 7.4, etc., 13.7 h. DAY 6: 1 bar, "low" flashing, level 7.2.

Summary: I assume that the radio will maintain a status of full or nearly-full charge (3 bars) for a minimum of 30.5 h (conservative; not sure when radio dipped from 3 to 2 bars during day 4 of testing), with ?possibly diminished transmit ability after 54.5 h (who can speak to this?). My limited understanding of Li-ion batteries suggests that one does not need to fully discharge them before recharging-IS THIS CORRECT? In an earlier post I suggested that my radio would last a full season of my limited paddling without recharging - I still stand by this. This would also support my recommendation to leave (fully-charged) radios ON for the full day(s) of group paddles-no worries!

Perhaps owners of different radio models will perform similar tests and post their results here?

[EEL]

My limited understanding of Li-ion batteries suggests that one does not need to fully discharge them before recharging-IS THIS CORRECT?

Gary:

Yes.

It is best to charge Li-Ion batteries before they have fully discharged (in theory you can discharge a Li-Ion to the point were the protection circuit will put it to "sleep" and then it cannot be charged) and best to store them only partially charged. In some situations it is suggested to let them become discharged every so often so the charge indicators stay accurate. Otherwise they tend to give inaccurate information about the state of a battery although the average user might not notice. From a technical perspective it is better to only partally charge them as opposed to fully charging them, but who does that? Not me for one.

As a practical matter most of these radios are quite impressive in terms of battery life both in longevity and operational duration per charge.

Ed Lawson

[ThomasL]

My perspective is that if a a potentially life saving instrument is involved, do the research and replace the battery whatever it's composition well prior to it's expected life potential.

Tom

[jason]

With every ICOM I have touched so far you can program the radio to display the battery Voltage on startup. This will give you a better view of the battery state then just the number of bars in the battery meter.

[billvoss]

From a technical perspective it is better to only partally charge them as opposed to fully charging them, but who does that? Not me for one.

I have heard, but can not confirm, that the greatest Li-Ion battery life is achieved storing the battery with roughly half a charge. This tidbit caused me to change my habit of fully recharging my radio when I got home, to fully recharging my radio the night before a paddle. Might just be superstition, but seems to work OK.

I purchased the optional AA battery carriage as a backup. It does not provide as much peek transmit power, and can only use disposable batteries. However, disposable batteries can easily last more than a season unused in my flare bag, and potentially save me from having to trigger my PLB.

[djlewis]

I bought the ICom M72 on eBay for $170 -- thanks Ern.

Reasoning -- The incredible 2000 mAh battery is worth the $70 (almost double the 1040 mAh on the WM) -- plus good reports about durability from everyone, except that the volume knob gets crudded with salt. But Lisa told me about Salt Away, which keeps hers in perfect working condition. If the battery is crappy, I'll use the still-good battery from the unit I ruined by not clearing volume knob of salt religiously. If it's a good battery, I'll have two 2000 mAh batteries! Even if the battery is crappy, I'll have a backup that will extend usage by something.

It's covered by the eBay warranty, so it has to work as a radio. If the battery is demonstrably crappy, I may even be able to get a refund from that -- I'll test it right away.

[PeterB]

I have an ICOM M72 and think its a great radio. it fits comfortably in the hand and in the pfd, the battery really holds a charge, and its worked whenever I've needed it to. I'm not very fastidious about maintaining it, and nothing has gone wrong with mine after 4 or so years.If I lost mine , I'd get another.

[djlewis]

I bought the ICom M72 on eBay for $170 -- thanks Ern.

Reasoning -- The incredible 2000 mAh battery is worth the $70 (almost double the 1040 mAh on the WM)...

Report on the used ICom M72 I bought on eBay... I used it on a paddle and it worked fine. It was on for 6 hours during the paddle with a bit of transmitting. Then Thursday evening around 8:00 I turned it on and have left it on since. Now, 44 hours later (total 50 hours), the battery indicator is still showing a full charge. Obviously I have not transmitted, but does it take more juice when there is incoming traffic? Do folks think this is what we can realistically expect on the water?

In any case, the battery on the used unit seems fine, and now I have a backup. But Ern told me that he talked to an ICom technician who said that it is not designed to have the battery removed and replaced very much -- that will degrade the seals. They figure the battery will just stay in place until it fails, years later. So that calls into question the intention to use the second battery to extend life on a longer trip. Sounds like under-engineering to me, and too bad. With judicious use of the on/off knob, it seems like one battery will go for up to a week's expedition, so I could get almost two weeks out of it with the second battery.

[EEL]

Obviously I have not transmitted, but does it take more juice when there is incoming traffic?

.......

With judicious use of the on/off knob, it seems like one battery will go for up to a week's expedition,

Yes to question and agree with estimate that if you do not use it much the batery should last for a week's trip.

In the specs there should be current draw number for transmitting, receiving with audio at full and standby which means radio is on, but not receiving a signal.

Standby draws least.

Ed Lawson

[djlewis]

Yes to question and agree with estimate that if you do not use it much the batery should last for a week's trip.

In the specs there should be current draw number for transmitting, receiving with audio at full and standby which means radio is on, but not receiving a signal.

Standby draws least.

Ed Lawson

65 total hours on standby and still showing all the bars.

Here are the specs

Current drain (at 7.5V DC)

Tx 6W output 1.7A typical Tx 5W output 1.5A typical Rx Internal SP 400mA typical (AF Max.) Rx External SP

200mA typical (AF Max.)

They don't show standby draw, but obviously it is under 30mA (at this point -- may go lower). I presume internal SP is the built-in speaker, and external SP is the add-on external speaker/mic.

Assuming 3 minutes/day of transmission, 30 of incoming traffic, mostly for weather reports, 6 hours on standby, I get a drain of about 400A/day, so maybe 5 days usage. But that could go a bit longer depending on the final estimate of standby draw.

-David

[djlewis]

Current drain (at 7.5V DC)

Tx 6W output -- 1.7A typical

Tx 5W output -- 1.5A typical

Rx Internal SP -- 400mA typical (AF Max.)

Rx External SP -- 200mA typical (AF Max.)

[EEL]

They don't show standby draw,

Odd they do not. My old, stalwart Standard has a standby current of 50mA which is typical for that brand. I do not know what the battery indicator is measuring, but I seriously dobut is is an accurate mesure of the battery's remaining capactiy. Most likely a mesure of its voltage output which is a rough guage so fair enough.

Assuming 3 minutes/day of transmission, 30 of incoming traffic, mostly for weather reports, 6 hours on standby, I get a drain of about 400A/day, so maybe 5 days usage. But that could go a bit longer depending on the final estimate of standby draw.

At the end of a recent 6 day trip my rado's battery indicator was still showing

full charge after being used about 40Min a day on average, one day for 5 hr. in the fog, and perhaps 3 min of transmitting. so I think your estimate is a good one.

To be technicalo. It is logical and reasonable to assume a 1200mA/Hr battery could supply 1200mA for an hour or some lesser current for a proportional amount, but that is not correct as you need to know how the manufacturer rates the battery to know how much current it will provide at what voltage over what period of time.

Ed Lawson

[djlewis]

It is logical and reasonable to assume a 1200mA/Hr battery could supply 1200mA for an hour or some lesser current for a proportional amount, but that is not correct as you need to know how the manufacturer rates the battery to know how much current it will provide at what voltage over what period of time.

That's why I guess it's good to measure actual burn-down time. At 75+ hours it finally lost a bar. So the effective drain rate -- on my kitchen counter, at room temp, with no incoming traffic -- seems to be about 20-25 mA/h. So my typical day above would take about 300mA, giving it 6+ days of usage on one battery charge. Pretty impressive.

--David

[djlewis]

Dead at around 80 hours. So around 22-23 mA/h.

[subaruguru]

....

In any case, the battery on the used unit seems fine, and now I have a backup. But Ern told me that he talked to an ICom technician who said that it is not designed to have the battery removed and replaced very much -- that will degrade the seals. They figure the battery will just stay in place until it fails, years later. So that calls into question the intention to use the second battery to extend life on a longer trip. Sounds like under-engineering to me, and too bad.

....

I acquired a non-working 4yr old M88 last week and decided to repair it, if possible. Initially it appeared that only the external battery terminals were compromised, and indeed one of them was broken off!

But removal of the battery showed salt deposits well past the inner "contact spring pins quartet" red o-ring, with subsequent corrosion and fracture of two of these pins.

iCom offers this part for $16, as well o-rings, etc.

Removing the antenna's very solid brass lock-nut took an hour of careful hammering...a truly difficult task, as it was indeed salt-frozen. Once removed, the cast frame can be slid out from the case, now showing that the damned contact mechanism is hard-soldered through its board. To get at removal then required desoldering the antenna lead and a ground shield...not a big deal with a small 40w iron and reading glasses.

Reassembly was straightforward. Care needs to be taken to reapply silicone sealant on the naked replacement contact assembly, and to regrease all seals...and maybe the antenna threads, too. (Note that you do NOT have to loosen nor remove the volume pot, as its pig-tailed to the board rather than solid-soldered on its pins. I also think that smearing some grease under the vol knob may be sufficient to prevent salt from crudding up the knob's operation...apparently a common complaint with the iComs.)

So far operation matches the new M88 I grabbed on eBay last week, so I think the refurb is perfect. It's fascinating to notice that the missing external battery contact is perhaps REDUNDANT, as the battery charges perfectly with only 3 contacts! This follows the logic of having redundant inner contacts too, as the 4 pins instantly combine at the pc board to only two paths.

So if iCom is so careful to design doubled battery contacts why does the thin inner 0-ring leak?!

Well, the iCom tech reasoned that users who remove the battery to rinse the radio simply abrade that o-ring, so that seepage eventually occurs. He cautioned that the battery should NEVER be removed except to replace it.

Hmmm....

My solution is to just smear some high-temp multi-grease on the o-ring both to act as a hydrophobic surface AND to allow battery removal without abrasion. We'll see how it goes....

It's interesting to note that the M72 uses a softer compressible seal that is MORE fragile in construction than the M88's o-ring, but being compliant it may offer a more secure seal until it gets scratched or torn from battery-removal "abuse".

So now I have a new West Marine VHF 85 (Uniden 75), and a pair of M88s. Oy....

[leong]

Never remove the battery to rinse the radio ... it's the battery to radio connection is what makes the system waterproof!