Radio permanently on charger to monitor

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mmc-dsm
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Radio permanently on charger to monitor

Post by mmc-dsm »

Hi,

This maybe an odd question but here's what I want to do.

I have an old Visar I would like to use on my office desk only to monitor a frequency; I would keep it open on the charger permanently. Also, the radio has an old battery than can barely hold charge.

Would I have any trouble?

Thanks!
RadioSouth
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Re: Radio permanently on charger to monitor

Post by RadioSouth »

Did the same thing with a HT600 for quite a while. I think the bottom line is as long as the charger is running in trickle mode and the battery is passing the power thru you'll be OK IMHO. I did read once that Motorola recommends against transmitting while radio is in charger.
mmc-dsm
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Re: Radio permanently on charger to monitor

Post by mmc-dsm »

No TX, RX only.
tvsjr
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Re: Radio permanently on charger to monitor

Post by tvsjr »

I'd be careful... eventually the battery will totally croak and turn into a big-arse resistor, generating heat. Wiggly and Wobbly (W&W) sells an acceptable battery eliminator for Visar (also good for KVL3K) that would be a better solution.
mmc-dsm
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Re: Radio permanently on charger to monitor

Post by mmc-dsm »

I took a look at the battery eliminator but I would have to buy a 12v power supply.
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escomm
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Re: Radio permanently on charger to monitor

Post by escomm »

mmc-dsm wrote:I took a look at the battery eliminator but I would have to buy a 12v power supply.
Better than your office burning down??
mmc-dsm
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Re: Radio permanently on charger to monitor

Post by mmc-dsm »

Sure!

I didn't think we were talking as important of a heat as a fire hazard when it was mentionned.
tvsjr
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Re: Radio permanently on charger to monitor

Post by tvsjr »

What are you trying to monitor? If you're looking for a 1 channel, RX only radio, there are any number of mobile radios that would do the job properly. Hell, if you don't have anything on the splinter channels either side of your intended frequency, an old non-narrowbandable Maxtrac, GM300, etc. would work great. Find a throwdown 12V supply (I have an old laptop power supply that produces 12V @ 2A... nice and small, great for testing... just installed a two-pin Moto power connector on it) and you're golden. Stick a rubber duck on the antenna. Much less klugey than a Visar.
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Bill_G
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Re: Radio permanently on charger to monitor

Post by Bill_G »

Or a cheap scanner.
mmc-dsm
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Re: Radio permanently on charger to monitor

Post by mmc-dsm »

Those are good ideas.

I'm just in cheap mode right now and didn't want to buy anything; just use what I have on hand.

Also, needed a radio with MDC decode to mute as much as possible the MDC sequence as it is used on the frequency I'm monitoring. (Can't stand MDC...)
Will
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Re: Radio permanently on charger to monitor

Post by Will »

You may, depending the model of the charger, throttle it back so you do not croak the battery.
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Bill_G
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Re: Radio permanently on charger to monitor

Post by Bill_G »

mmc-dsm wrote:Those are good ideas.

I'm just in cheap mode right now and didn't want to buy anything; just use what I have on hand.

Also, needed a radio with MDC decode to mute as much as possible the MDC sequence as it is used on the frequency I'm monitoring. (Can't stand MDC...)
In that case, stick with Plan A. Can't go wrong. The battery will eventually die. Go get an aquarium thermal sticker so you can tell when the battery is well above room temp.
mmc-dsm
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Re: Radio permanently on charger to monitor

Post by mmc-dsm »

I solved my problem...

Found an AC adapter (7.5V 700mA) in a parts bin I have. Soldered the wires directly onto the battery pins on the back of the Visar.

Works like a charm. Thank you all for your inputs.
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Bill_G
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Re: Radio permanently on charger to monitor

Post by Bill_G »

That's going to blow up. There's nothing to limit the current even if it is only 3/4 of an amp.

Wait - never mind - you meant you soldered to the radio battery contacts, not to the battery itself. Carry on.
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tsunami_australia
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Re: Radio permanently on charger to monitor

Post by tsunami_australia »

That is essentially what a battery eliminator does anyway so should be fine. The fire brigade I was in some years ago had a couple of crappy Kenwoods (30yo or so) sold to them as new (don't get me started about what moron couldn't tell the difference). Anyway long story short the batteries end up failing and they rarely saw use as they were too big and bulky for on the fireground. I as equipment officer was ordered to throw them in the bin and come up with the wise idea of ripping the battery cells out and converting them for 12v use and equipping them in the tankers (which the fire control was too tightwad to buy radios for which was an issue at times) with a full external whip antenna (bnc connectors for the antennas).

Ripped the cells out, soldered in a 7v 2a reg with some other bits, hooked to external whip, screwed to the centre of the cab via custom home made bracket and used the speaker mic as a mic. It worked a treat and was heralded a HUGE success and the best use for the useless things yet. Now whilst the visar may be too small to rip out the cells and house a trannie the story is the same as what you've done so your story should by all means work too :). Interestingly enough I was told that my work was rather quite a buzz the next time the tanker went out of area on a huge fire because of the range that handheld could achieve and how well it worked :).
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Bill_G
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Re: Radio permanently on charger to monitor

Post by Bill_G »

Amazing how long your legs get with a little elevation.
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mikegilbert
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Re: Radio permanently on charger to monitor

Post by mikegilbert »

My first commercial radio was a Kenwood TK-340 back in the late '90s. When the battery started to die in 2001, I didn't have the money to buy a new one at the time. Turns out my Radio Shack radar detector's DC cord was a direct fit for the 12V barrel plug input on the side of the radio. Combined with a mag-mount, it was a slick little mobile.
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nukedude
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Re: Radio permanently on charger to monitor

Post by nukedude »

Bill_G wrote:
mmc-dsm wrote:Those are good ideas.

I'm just in cheap mode right now and didn't want to buy anything; just use what I have on hand.

Also, needed a radio with MDC decode to mute as much as possible the MDC sequence as it is used on the frequency I'm monitoring. (Can't stand MDC...)
In that case, stick with Plan A. Can't go wrong. The battery will eventually die. Go get an aquarium thermal sticker so you can tell when the battery is well above room temp.
Great idea on the aquarium sticker. Need a few of those for some of my home science projects.

Used to use an HT1250 to monitor with it in the cradle all the time, the battery swelled and made a mess of melted electronics and plastic. Also melted the vinyl wood looking veneer of one Realistic floor speaker it was all sitting on.
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Bill_G
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Re: Radio permanently on charger to monitor

Post by Bill_G »

nukedude wrote:
Bill_G wrote:
mmc-dsm wrote:Those are good ideas.

I'm just in cheap mode right now and didn't want to buy anything; just use what I have on hand.

Also, needed a radio with MDC decode to mute as much as possible the MDC sequence as it is used on the frequency I'm monitoring. (Can't stand MDC...)
In that case, stick with Plan A. Can't go wrong. The battery will eventually die. Go get an aquarium thermal sticker so you can tell when the battery is well above room temp.
Great idea on the aquarium sticker. Need a few of those for some of my home science projects.

Used to use an HT1250 to monitor with it in the cradle all the time, the battery swelled and made a mess of melted electronics and plastic. Also melted the vinyl wood looking veneer of one Realistic floor speaker it was all sitting on.
Yeah. They're cheap and cheerful. Easy way to monitor an individual piece of equipment.
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