[1000mp] W8JI INRAD roofing filter measurements

[Lou]

Hi Gary,

Good point. I'm not familiar with a specific definition for passive IMD
other than how you interpreted it.

The INRAD roofing filter has has passive components (the filter), but also
includes an amplifier "that compensates for the added insertion loss of the
filter" so in entirety is not passive.  Without schematics for the IC-7800
we don't know what components are getting switched in and out as the roofing
filters are selected. So, is the IMD (3r order in this case) caused by
passives or actives or both? Dunno...

Lou W7HV



-----Original Message-----
From: 1000mp-bounces at mailman.qth.net [mailto:1000mp-bounces at mailman.qth.net]
On Behalf Of Garry Shapiro
Sent: Wednesday, April 25, 2007 2:58 PM
To: All about Yaesu 1000mp
Subject: Re: [1000mp] W8JI INRAD roofing filter measurements

Lou:

Of course--but the quote specifically says "passive IMD in the filter", 
implying the nonlinearities are in the filter itself, rather than in the 
mixer preceding the filter. If there are nonlinearities in the amplifier 
section of the filter--and of course there will be to whatever 
extent--these are not "passive". I am trying to resolve whether this is 
semantics or an actual circuit phenomenon. Perhaps it did not translate 
exactly from the German.

Garry, NI6T