[Top] [All Lists]

Re: [Amps] How to read the 3-500Z spec sheet?

To: Jeff Blaine AC0C <>, AMPS <>
Subject: Re: [Amps] How to read the 3-500Z spec sheet?
From: Larry <>
Date: Sun, 23 May 2010 11:51:55 -0700
List-post: <">>
On 23-May-10 10:45 AM, Jeff Blaine AC0C wrote:
> Of course, a real IMD test requires a 2 -tone source and you can download
> those applications on the web free of charge.

Wrong answer for amplifier testing. While you can approximate proper 
"two-tone" testing with a sound card tone source when evaluating a 
transceiver, a LOT more is required for accurate and technically correct 
amplifier testing.

To do accurate IMD (and more correctly OIP3) testing on an amp, you NEED 
two separate clean signal sources. This means two exciters that are 
known to be very clean and free from harmonics (much greater than 60 dB 
down) plus a high power combiner and usually a set of bandpass filters 
at each of the tone frequencies. Plus, just to keep everything happy, a 
bunch of attenuators sprinkled around the bench.

Anything less and you are only testing the source(s) and not the amp. 
Some time back, W8JI detail the correct test setup for amplifier testing 
and I think it's on his web site someplace. Anything less and you are 
just fooling your self.


Larry - W7IUV
DN07dg - central WA

Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>