[1000mp] Question to those using the INRAD Roofing filter

[Thomas Beltran]

> Could someone please tell me what a "roofing" filter is ??   I am not
> familiar with that term.
>
It is essentially the First IF filter, setting the maximum bandwidth for the
radio.  In the Mark V, like George's (and mine) with the Inrad Front-End
mod, the Roofing filter mod replaces that front-end mod.  The mod goes after
the stock, 12 khz. 4 pole crystal filter.  It is a 4 khz., 6 pole crystal
filter, with a small amp that more than compensates for insertion loss.
Since it sets the maximum bandwidth, one must use the sub-receiver to listen
to FM.

About all I can say about the filter is that my radio sounds much "cleaner."
And, when other hams in the area are on the air (usually 17 meters), I have
to tune within a few khz. before I get the de-sensing - prior to the mod, I
would get the de-sensing within 15 - 18 khz., so that is quite an
improvement.  In other words, I actually have to hunt a bit :)  I live in
the San Fernando Valley (NE of downtown Los Angeles), and I have quite a few
neighors who run the legal limit.  I almost never use the noise blanker, but
recently, the occasion arose, and it seemed to work very effectively.  Tom
W6EIJ