[Elecraft] KPA-500 270V ERR

[David Gilbert]

That sounds odd to me.  True PIN diodes are current actuated devices.  
The carrier lifetimes are long enough that the devices are "on" even if 
the signal peaks exceed the voltage of the control current ... as long, 
of course, as the control current exceeds the signal current.

On the other hand, I've heard that Elecraft has sometimes used regular 
switching diodes instead of PINs, and for those you need a voltage that 
exceeds the peak voltage of whatever you're switching.

Both types of diodes have their place ... using one where the other 
works better is not good practice.

73,
Dave   AB7E



On 8/26/2021 11:33 AM, Fred Jensen wrote:
> I think the 270 V circuit is DC bias for the PIN diodes in the TR-switch.
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> On 8/26/2021 10:32 AM, Chuck Chandler wrote:
>> My KPA-500 has been running great for several years.  Recently I 
>> noticed it
>> was making the occasional extra "click" or "thunk" upon powering up or
>> down.  Usually it would "click" when powered up and again when powered
>> down, but recently a few seconds after the first click there would be
>> another one, maybe more of a thunk sound.
>>
>> This afternoon I turned it on and when I pushed the Operate/Standby 
>> button
>> I got a fault light and the 270V ERR message on the display. The menu HV
>> option shows 68.4V, varying a bit, on my 240V line.  I put it on the 
>> bench
>> and opened up the top cover.  There is a smell of overheated components,
>> maybe burnt but more like too hot.
>>
>> I've submitted the contact form on the Elecraft support page. Any
>> suggestions?  For now, I'm running barefoot...
>>
>> 73 de Chuck, WS1L
>>
>>
>
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