Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
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page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Best solution for RF protection Posted: Sun Jan
11, 2009 10:13 pm
Joined: Fri Jan 26, 2007
I've got a specification that allows as much
as +20 dBm into a receive input but many LNAs can't take that much power
without ruining the amplifier. Is there some kind of diode circuit that
can be used for protection against such a RF input without creating
distortion at a reasonably lower level? My input is relatively low frequency
Post subject: Posted: Fri Jan 23, 2009 3:18 am
Joined: Fri Jan 26, 2007 2:40 am
Post subject: Posted: Fri Jan 23, 2009 12:47 pm
Joined: Fri Feb 17, 2006 12:07 pm
There are one or two bits of data missing before I can
get my addled head around this one.
Is the frequency of the +20dBm
signal very close to weaker signals you are trying to detect/decode?
And is it at a fixed frequency or anywhere in the range?
+20dBm signal pulsed or continuous?
Are the weaker signals spread
over a random spectrum from 1-30MHz?
I would certainly look around
for bomb-proof front-end amplifiers, such as the approach using transmit
transistors with a measured and adequately low noise factor as the first
stage. This approach has been shown to yield very high IP3 figures.
At bottom, life is all about
and blowing out.
Post subject: Posted:
Mon Jan 26, 2009 5:58 pm
Joined: Fri Jan
26, 2007 2:40 am
The frequency is anywhere in the 1-30
MHz range. This is NOT a performance spec so much as it is a "damage"
spec. Another words we don't have to receive anything in particular
while this is going on.
I think the damage spec is "continuous".
The one thing that is tough here is that most gain block amps
I see have absolute max inputs no more than +18 dBm (most MiniCircuits
amps have +13 dBm). It's hard enough just finding an amp that will work
in this range anymore (due to most focus on the higher ranges) let alone
an absolute max this high. Therefore some sort of circuitry is needed.