[Elecraft] K2 Encoder problems continue.

[Geoffrey Mackenzie-Kennedy]

Nidge,

Thanks for your reply.

Unfortunately I do not know enough about Hamradio Deluxe nor its interface 
with the K2, but rightly or wrongly I assume that if the radio works 
properly under computer control, then the MCU (U6) is working as it should 
during this mode of control.

I cannot shake my hunch that something is pulling down to near ground either 
the ENC A or the ENC B lines (or both) when the MCU is in place. If the 
encoder is an optical type, then under such a fault condition I would not be 
too surprised if the voltage on ENC RD also dropped to near ground - which 
is what you have measured at U3 pin 14. It would be worthwhile to make some 
resistance measurements between these three lines and ground, with the power 
off - MCU in place and MCU removed.

Not to be overlooked is the possibility that the fault might be mechanical. 
For instance if a small sliver of solder had worked its way into the MCU's 
socket, it might create a short when the MCU chip is in place - but "open" 
when the chip is removed.

Good luck.

73,
Geoff
GM4ESD


On Saturday, April 17, 2010, at 11:13 PM, Nidge (Nigel Smith) wrote:

> Hi Don and Geoff
>
> Thanks for the replies both.
>
> First of all Geoff: I'm afraid I don't have a scope here anymore.  I did
> remove the MCU
> and checked the voltages, and this time on pin 14 of U3 I had the correct
> voltage close
> to 3.8V, with the MCU inserted it was below 100mV.

> The radio, when connected to Hamradio Deluxe works fine under computer
> control, both
> on receive and transmit.  The filters are off but that's because I'm 
> unable
> to fine tune them
> as the encoder isn't working.