hdsint
Newbie level 1
mechanical tuners impedance measurement
Hello.
I have a number of LDMOS rf fets that I wish to validate both the input
and output impedance of.
My test fixture consists of a block of aluminumn with N connectors on
each end "Grounding is very good" and a small pcb to mount the device on.
The pcb is nothing more than a input printed line and a output printed line
1 inch long. Biasing of the gate and drain is achieved via a 400nh smd inductor
and a .1uf cap to ground on the dc supply side.
Anyway I have been looking for some manual tuners so as to present the
correct impedance to device but cant seem to locate anything thats suitable for
use from 70Mhz to 200Mhz. Would anyone have a source for these tuners ?
As an alternative I could make them instead. Would anyone have any insight
as to whats in these mechanical tuners. I was thinking its nothing more than a
pi filter with two variable caps and one inductor but I am not 100% sure.
I have a hp vna at this end to check the results and a small metal shop to fabricate
the tuners if I have to make them. The test fixture is break apart style so I can
measure the complex impedance when the device is removed.
Thanks Paul.
Hello.
I have a number of LDMOS rf fets that I wish to validate both the input
and output impedance of.
My test fixture consists of a block of aluminumn with N connectors on
each end "Grounding is very good" and a small pcb to mount the device on.
The pcb is nothing more than a input printed line and a output printed line
1 inch long. Biasing of the gate and drain is achieved via a 400nh smd inductor
and a .1uf cap to ground on the dc supply side.
Anyway I have been looking for some manual tuners so as to present the
correct impedance to device but cant seem to locate anything thats suitable for
use from 70Mhz to 200Mhz. Would anyone have a source for these tuners ?
As an alternative I could make them instead. Would anyone have any insight
as to whats in these mechanical tuners. I was thinking its nothing more than a
pi filter with two variable caps and one inductor but I am not 100% sure.
I have a hp vna at this end to check the results and a small metal shop to fabricate
the tuners if I have to make them. The test fixture is break apart style so I can
measure the complex impedance when the device is removed.
Thanks Paul.
