Re: Testing Crystal Filters maximum dbm

iz oos
 

I would add the same question for ceramic filters and resonators.


Il 22/ott/2019 11:21, "iz oos via Groups.Io" <and2oosiz2=gmail.com@groups.io> ha scritto:

Great advices and explanation Allison! What about testing SAW filters, is there a so stringent limit to - 10dbm (like crystal filters) to test them safely?


Il 21/ott/2019 18:17, "ajparent1/KB1GMX" <kb1gmx@...> ha scritto:
Iz,

think about that.... 
-10dbm is about .1milliwatt,  +16dbm is 40milliwatts or about 400 times greater power.

Crystal filter and crystals in singular use generally have a max power of about
1mW (0dbm) for most while some of the older slab rocks in FT243 cases could
take much more.

Why the limit, two things its mechanical vibration and the consequence is heat.
Too much heat and crystals crack or lead bonds fail.

I have swept filters and generally I use -10dbm for safety. Since the average filter is 
about 3-8db loss that is more than enough drive to see a signal on the other side.
So a source side 20db attenuator is pretty much required.  Also the source
impedance is then solidly known making it easier to add the needed transformer
or network to match the input of the filter.  You will likely have to have the same
network to match the detector side as well.

Allison

Join BITX20@groups.io to automatically receive all group messages.