[WriteLog] More Sloppy Keying

Mon Jun 21 23:38:33 EDT 2004

On 2004年6月22日 03:17:56 -0000, arholub wrote:
>Was just thinking about the keying levels out of a laptop as compared to a 
desktop. 
I've specifically looked at the keying levels on two of my IBM laptops with a DC 
coupled scope. One has a built-in serial port (T22) and the other, a T41, uses a 
B&B Electronics PCMCIA dual serial port card. Both put out more than enough to 
very solidly key the NPN interverter (sometimes called a level shifter) that needs to 
sit between the computer and the radio's keying line. I have several inverters built 
up, all identical, that use a 2N4123 transistor that I had a lot of in my junk box. So 
far, I have used it to key a TS850, Omni V, K2, and TS790A. 
Jim K9YC