[Elecraft] KPA-500 270V ERR

[jerry]

Using 1N4007's and 1N5208's ( I could have the last # wrong ) as "Poor 
Man PIN
diodes" is pretty established practice in the amateur community.  Look 
up
W6JL on QRZ.com.  He has an extensive article about it on his page 
there.

Also Hans Summers of qrp-labs uses them in his 50W QSK amplifier.

   Apparently, these kilovolt rectifiers behave very much like PIN 
diodes,
at speed.

                - Jerry KF6VB



On 2021-08-26 11:46, David Gilbert wrote:
> 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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