[Elecraft] Problems with Top Ten Decoder?

[Dan Levin]

I'm having an odd problem with two brand new Top Ten decoders and two
different K3's.  In each case, the decoder is having problems pulling up the
band data lines coming in from the K3.  All four band data lines measure at
5 volts without the K3 connected (thanks to the decoder's pull-up
resistors), but only between 1.6 and 2.1 volts with the K3 connected (on
lines that should be "on" - lines that should be "off" read zero volts).
Turns out that isn't a high enough voltage for the decoder chip to read
properly, so the band decoder doesn't work.

I strongly suspect operator error, but can't figure out what I am doing
wrong.

Hints?

                     ***dan, K6IF