EMRFD Message Archive 14345

Message Date From Subject
14345 2017-09-22 07:38:25 Hans Summers PIN diode T/R switch

Hi all

See these around, from time to time... and now I note Elecraft have one in their new 1500W amplifier KPA1500. My question is this. I know if you have simple back-to-back diodes at a receiver input you are degrading the IMD performance (IP3). Presumably this is NOT happening when PIN diodes are used in a T/R switch as in the KPA1500. Why not?

73 Hans G0UPL
http://qrp-labs.com

14346 2017-09-22 08:00:18 Russell Shaw Re: PIN diode T/R switch

14347 2017-09-22 18:44:09 Ashhar Farhan Re: PIN diode T/R switch

well, we haven't measured the IMD with those in the path. i suspect it has a measurable degradation over the quadrature detector's own IMD.

- f

14345	2017-09-22 07:38:25	Hans Summers	PIN diode T/R switch
Message	Date	From	Subject
Hi all See these around, from time to time... and now I note Elecraft have one in their new 1500W amplifier KPA1500. My question is this. I know if you have simple back-to-back diodes at a receiver input you are degrading the IMD performance (IP3). Presumably this is NOT happening when PIN diodes are used in a T/R switch as in the KPA1500. Why not? 73 Hans G0UPL http://qrp-labs.com
14346	2017-09-22 08:00:18	Russell Shaw	Re: PIN diode T/R switch

14347	2017-09-22 18:44:09	Ashhar Farhan	Re: PIN diode T/R switch
well, we haven't measured the IMD with those in the path. i suspect it has a measurable degradation over the quadrature detector's own IMD. - f