[Elecraft] K2/100 Locking Up in Data Mode

[Jim Campbell]

I discovered my problem. I hadn't constructed my opto-isolator device 
properly. I was using a standard circuit but a standard circuit wasn't 
designed for a K2. Once keyed, the K2 never returned to receive.

For the K2 to work correctly I had to add two diodes to the output of 
the opto-isolator and let the K2 auto-detect its presence. I found this 
by carefully reading the part of the K2 manual that tells how to 
interface it with a computer. The appropriate circuit is shown in Fig. 
8-1 on page 99 of the K2 Manual.

I successfully worked Holland, Ireland and a couple of stations in the 
US this evening using JT65-HF and 5 watts on 17 M. That's special to me 
because of the antenna that I am using. It is an 88 ft. dipole being fed 
by ladder line and averaging 12 ft. above the ground. It is also running 
through several tree canopies. Truly amazing! Thanks Elecraft for such a 
nice rig.

72,

Jim - W4BQP
K2/100 #2268 w/ 100W ATU

On 5/28/2012 12:10 AM, Jim Campbell wrote:
> I'm playing with JT65-HF. I have no problem with reception. When I send
> a message (48 seconds of key-down at 5 W) the message is sent correctly
> but after transmission stops the front panel controls are frozen. By
> frozen I mean that the only control that is effective on the front panel
> is the power switch. The dial doesn't change the frequency and all
> switch depressions are ignored.
>
> I built my own interface. The two audio lines (from radio to sound card
> and from sound card to radio are decoupled with small Radio Shack audio
> transformers. The keying line from the USB to serial dongle uses an
> opto-isolator for the decoupling. The audio level for the sound card to
> radio circuit is adjustable with a small potentiometer and is adjusted
> so the ALC just blinks the first bar. The data mode is enabled so that I
> see an "r" with a bar over it as the mode.
>
> All my radio gear uses 12 VDC and the 12 V side of the supply is
> isolated from the house ground. I have an 8 ft rod driven in the ground
> outside the radio room and all the antennas (coax shields) and -12 V are
> bonded to this ground.
>
> Any help will be appreciated.
>
> 72,
>
> Jim - W4BQP
>