[Elecraft] 12 volt PA

[David Gilbert]

I don't find emergency backup to be a very compelling argument for 
sticking with a 12 volt PA design.  I don't see why it would require a 
commercial system to provide backup for a ham rig, and I don't think it 
would be significantly more expensive to string four smaller capacity 
batteries in series instead of one larger 12 volt battery.  Charging 
could be done at 48 volts, or at 12 volts with the batteries in parallel.

My guess is that the only reason we still see 12 volt rigs is because 
they make mobile and portable use more convenient, which of course was 
Elecraft's roots anyway.  Possibly even that will go away eventually ... 
the automotive manufactures have for some time been exploring higher 
voltage (42 volts or something like that if I remember correctly) 
systems because of the increasing current requirements (requiring 
heavier wiring) of today's expanding vehicle electronics.  That was 
actively being discussed a dozen years ago, though, so most likely the 
voltage overshoot issues (relays and motors have a lot of inductance) 
have proven difficult to overcome.

73,
Dave   AB7E



On 4/15/2010 10:56 AM, Phil Kane wrote:
> On 4/15/2010 8:25 AM, Wes Stewart wrote:
>
>    
>> For the life of me I can't understand why radios continue to be
>> designed around an automobile storage battery when fewer than 1%
>> will ever operate in a mobile environment.
>>      
>    For those of us who insist that our communications gear operate
>    when the mains power goes off, the 12V DC battery system is the
>    most reasonable backup.  Few if any of us have the resources to
>    install a commercial 48V battery system  - which is the
>    commercial standard currently - or the 40 KW backup generator
>    or solar array which is what is needed (but don't have) to run
>    my house "off the grid".
>
>    For communications backup purposes we don't use "automobile
>    storage batteries" which are designed for a large current draw
>    for a short time (engine cranking) and relatively little current
>    draw afterward while the alternator picks up the load.  Deep-cycle
>    totally sealed batteries are the standard for communication
>    backup systems of this capacity.
>
>    My engineering firm designs commercial communication sites
>    primarily for the public safety community and such backup
>    power systems are a very important part of what we do for our
>    clients.
>
> --  73 de K2ASP - Phil Kane
>      Elecraft K2/100   s/n 5402
>
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