[Milsurplus] LS-454 with manpacks

[J. Forster]

How long was the 12 VDC applied? How stiff a source was the 12 V from? Do
you now get any sound at all from the speaker?

====

The transformer could fail a couple of ways:

If the current was high enough through the primary it could cause the
winding to open up like a fuse. In that case, the thing would now show OC
on an ohmmeter. This is a likely failure.

The other way is if the DC current was insufficient to open the winding,
but sufficient to roast it, eventually breaking down the insulation and
causing shorted turns. This would take some minutes at least and you would
almost certainly smell burning insulation. It would also take a
significant battery to supply the power to do this.

FWIW,
-John

======================





> I am pretty sure they are both 600 ohms
>
> 73 Eugene W2HX
>
>
> -----Original Message-----
> From: J. Forster [mailto:jfor at quik.com]
> Sent: Saturday, September 19, 2009 2:41 PM
> To: Eugene Hertz
> Cc: milsurplus at mailman.qth.net
> Subject: Re: [Milsurplus] LS-454 with manpacks
>
> Gene,
>
> Before hooking things up, did you check the spec'd load impedance for the
> radio and the input impedance for the speaker?  If so, what are they?
>
> -John
>
> =============
>
>
>> Hi all,
>>
>>
>>
>> Tried to connect an LS-454 to my PRC-174 today. What a failure! First, I
>> found out (the hard way) that the LS-454 has a different pin out. So I
>> moved
>> the wire from "E" to "B".
>>
>>
>>
>> But then the radio simply didn't have enough audio output power to power
>> this speaker. Surprising because on a H-189 the volume can make my ear
>> explode!  I wonder if I damaged the matching transformer inside the 454
>> after inadvertently applying 12V and ground to the 600 input? Anyone
>> know
>> the proper DC resistance for the 600 ohm input of the transformer?
>>
>>
>>
>> So I guess I will need to install a little audio amp. But worse, I will
>> need
>> to run a 3rd wire for supply voltage (in E 12V).  So it looks like a
>> whole
>> new cable will be required.
>>
>>
>>
>> Anyone have suggestions on how to best accomplish the goal of a speaker
>> on
>> an PRC?
>>
>>
>>
>> 73 Eugene W2HX
>>
>>
>>
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>
>
>
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