[1000mp] MK5 cw transmit lockup on 40 & 80m

[Jim Smith]

Paul,

Is your key plugged into the front panel jack of the MkV or the rear?  
If in the front, try moving it to the rear.  The front panel jacks seem 
to provide a relatively easy path for RF Feedback to get into the rig.

You might also try, as a temporary measure, removing everything from the 
front panel jacks and see if that fixes the problem.

I had the same problem which was solved (as in Pete's suggestion) by 
putting a capacitor between the collector of the keying interface 
transistor and ground right at the output of the interface. 

73 de Jim Smith   VE7FO

Paul Ash wrote:

>Hello All,
>
>I am experiencing a somewhat strange problem 
>with my MK5. For contesting, I use my PC to key
>the rig in CW mode. What I am finding is
>when running on 40 or 80m (with 500W or more
>out of my Henry 3K) the transmitter will lock 
>"keyed" as soon as I attempt to send any characters.
>I have to pull the key jack plug from the front of the rig
>to get the MK5 to switch back to RX. This problem is
>certainly frequency dependent, no problems at all above 40m.
>The rig operates normally if I use paddles to key the rig.
>I do use the PC for normal CAT via the serial port. 
>
>I have tried ferrites on the key line. I have the rig and the PC 
>connected to the same power strip. Everything in the shack
>is connected to the same single point station ground. 
>
>I pulled the serial cable and it has no effect.
>
>Rig works fine in SSB.
>
>I am using a simple parallel port interface with
>just a 2n2222 and 1k resistor. Should I be considering
>something else?
>
>I called Yaesu and the tech there has no clue, not even a guess as
>to the problem.
>
>Any ideas?
>
>Tnx and 73,
>
>Paul N1PA
>
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