[Elecraft] K3 #00626 - help with KPA3 Rev B schematic

[Ted G7BQM]

Thanks to those who contacted me.  Nobody seems to have a Rev B Schematic!

The possibility of an exchange unit has not materialised so as the KPA3 is still mine, I decided a bit of disassembly was in order before taking it to be serviced.

Findings upon removal for testing:

C43 and C44 passed testing with a Peak LCR45 - refitted

R27 OK - refitted

D7,8 & 9 OK with Peak DCA75 - replaced since I could get these and they are very cheap

D10 Pin Diode tested as ‘no component’ with Peak DCA75 and multimeter shows open circuit

The MA4P4006B-402 600V Pin Diode does not appear to be available for sale in the UK, but I am checking with the service centre.

Conclusions:

One fault found, need to repair that before further testing.  Since I do not know the history of the unit, which was a Silent Key sale, there is no information about the likely cause of this failure.

Many thanks once again - I will post the final outcome on the reflector, once all is working again.


73, Ted G7BQM




> On 23 Feb 2019, at 12:14, Ted G7BQM <tedg7bqm at fastnet.co.uk> wrote:
> 
> Hello All,
> 
> I have recently acquired an early K3 which needs tidying and checking over.  So far all appears to be OK except for the KPA3 which gives no RF output but the rig draws 14 Amps regardless of the power setting.  The LPA is working fine with up to 12 W RF out and a max current draw of 4 A.
> 
> Visual checking of the KPA3 board reveals nothing amiss but also shows considerable component differences compared to the only schematic I could find on the Elecraft website - the Rev C version.
> 
> If any of you early adopters have a .PDF schematic for the KPA3 Rev B, I would be most grateful for an electronic copy.
> 
> 73, Ted G7BQM  (with quite a lot of Elecraft stuff!)
> 
> 
> 
> 
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