[Elecraft] Question: Over-voltage protection (OVP) for K2, K1

[Alan D. Wilcox]

Dave,
Were I to do the high-power model, I'd probably use the same Anderson 
power-pole connectors as in the K2/100 simply to retain compatibility 
with everything else.
Alan
	Alan D. Wilcox, W3DVX
570-321-1516
alan at wilcoxengineering.com <mailto:alan at wilcoxengineering.com>
http://WilcoxEngineering.com
Williamsport, PA 17701

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David Lankshear wrote:
> Hi Alan.
>
> Well, the K2/100's cable has an inline fuse at the PSU end, if 
> constructed in accordance with Elecraft's instructions although a 
> separate, faster blow fuse could be incorporated into the crowbar box.
>
> I must confess that I'd originally thought of incorporating a 
> crowbar-in-a-box, but the idea was swamped with other things and I 
> simply haven't done anything about it - until you jogged my memory.
>
> I have two linear and one switchmode power supply here; all are 
> capable of supplying 13v8 at 30 amps plus so supply fuses are 
> important to me.  All of the units are capable of providing some 
> variation in output voltage by internal adjustment.  I would be 
> concerned if the voltage crept up a little but not outside the 
> supply's parameters, which might cause the K2/100 to draw nearer 30A 
> on transmit.
>
> The crowbar could be permanently fitted in line and connectors could 
> be as simple as two hefty strips of PCB to which the input and output 
> leads are soldered.   If it's a hefty beast, it might find favour with 
> users of other equipment that are supplied at 12v and many amps - (the 
> "universal" crowbar?)
>
> 73  DaveL  G3TJP
>
> ----- Original Message ----- From: "Alan D. Wilcox" 
> <alan at wilcoxengineering.com>
> To: <elecraft at mailman.qth.net>
> Cc: "David Lankshear" <dave at lanks.plus.com>
> Sent: Tuesday, October 30, 2007 12:32 AM
> Subject: Re: [Elecraft] Question: Over-voltage protection (OVP) for 
> K2, K1
>
>
>> Dave,
>> If I were to do an OVP for a K2/100 ...
>> 1. Different connectors,
>> 2. A circuit breaker (a 20+ A supply would cause serious damage 
>> without  a fuse or breaker),
>> 3. Change OVP-12 to the OVP-24 (20A continuous, 30A intermittent),
>> 4. Bigger case, probably metal to act as heat sink (just in case).
>>
>> I would expect a 20-30A supply to have protection, so the above 
>> wouldn't be necessary. HOWEVER, the supply that inspired the project 
>> to start with was just such a supply, so maybe such an OVP would be a 
>> good idea. Hmmm.
>>
>> Alan
>> Alan D. Wilcox, W3DVX
>> 570-321-1516
>> alan at wilcoxengineering.com <mailto:alan at wilcoxengineering.com>
>> http://WilcoxEngineering.com
>> http://www.eham.net/reviews/detail/6768 ... for Client Comments
>> Williamsport, PA 17701
>>
>> ------------------------------------------------------------------------
>> David Lankshear wrote:
>>> That's fine for a barefoot K2, Alan, but what about the K2/100?
>>>
>>> Re Matt's comment - surely you don't need current sense resistors 
>>> for an over VOLTAGE trip?  Generally, the minimum component count 
>>> for a brute force crowbar is 4.  SCR, zener, resistor, capacitor.
>>>
>>> 73  DaveL  G3TJP