[TenTec] Filters, amps and IMD, etc

[Mike Hyder -N4NT-]

IMD is the product of two or more signals.  3rd order IMD is a signal's 
fundamental mixing with the second harmonic of another signal...

For this reason, a 10dB attenuation in the line will attenuate the desired 
signal by that much but will attenuate the intermodulation distortion 
products by much more.

Amplification works in the opposite way.  It brings up one signal but brings 
up the IMD products more than it does the one signal.  In addition, if the 
amplifier is not perfectly linear, it serves to accentuate the harmonic 
products and worsen the problem (see paragraph 1 above).

I have just exceeded my knowledge.

73, Mike N4NT

----- Original Message ----- 
From: "Randy K4QO" <k4qo at earthlink.net>
To: <tentec at contesting.com>
Sent: Thursday, July 28, 2005 11:50 PM
Subject: [TenTec] Filters, amps and IMD, etc


If the amp that kicks in at the tighter bandwidths is the problem, why
not just adjust the gain of that amp down a bit.  Wouldn't that improve
the IMD without resorting to 3rd party filters?  Or is it that ANY
additional amp stages, regardless of gain causes the IMD to get worse?

Iquiring minds wanna know!

73,
Randy
K4QO