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

[DaveL G3TJP]

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
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Alan D. Wilcox, W3DVX]

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
[hidden email] <mailto:[hidden email]>
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
>
>  
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Alan D. Wilcox, W3DVX]

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
[hidden email] <mailto:[hidden email]>
http://WilcoxEngineering.com
Williamsport, PA 17701

------------------------------------------------------------------------
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"
> <[hidden email]>
> To: <[hidden email]>
> Cc: "David Lankshear" <[hidden email]>
> 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
>> [hidden email] <mailto:[hidden email]>
>> 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

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com