Are you using a Kenwood TL-922A amp?

Dave, do not hook up the PTT output of your 6300 to the Tl922A! Doing so will destroy the keying transistor in the 6300. The 922 has 100 VDC on its key line input. You will need a hardware interface between the 6300 and the amp PTT input. Ameritron makes an interface or you could make your own with a small 12 volt relay. No need to hook up the ALC with a Flex, just don't overdrive the amp.

I agree with all of that. I had a 922A for a couple of years and used it with my 5000 and 6300. It served me well. If I remember, I paid around $900 for it about four years ago. Now, if you're getting a real good deal, go for it. However, I can't say enough in praise of the Elecraft KPA500 when used with a Flex. If you couple it with a KAT500 tuner, it's like having a 500-watt transceiver. Virtually no tuning required. I worked a lot of DX and busted through a few pileups with my 922A. It's a solid amp. I finally parted mine out when the capacitors got too old and failed.

Marty,
Unless someone has modified your 922 to include a low voltage keying circuit internally to the amp, you should NOT be doing what your doing.  you MUST use a separate keying relay that is designed for the higher voltages found in the TL-922.  If you don't, it is only a matter of time before you fry the keying circuit in your 3000.

MFJ (Ameritron) sells a very inexpensive keying circuit model ARB-704.   You can also find cables on ebay that have the relay built into the cable that are capable of handling the voltage.