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Re: [linrad] OH0 June 12: Rx/Tx measurements

A friend of mine(Rod VK6KRG) devised a test using a "comb" of strong 
signals across the band of interest.
The mixer performance is affected by the total energy it has to absorb 
from unwanted signals and a single strong interfering signal may not be 
as rigorous a test as some HF band conditions, or multiple pager signals 
on 148 MHz, or even TV line oscillator noise for example.
I think he used a sharp square wave oscillator at about 20 KHz followed 
by a bandpass filter at the band of interest to give multiple strong 
signals at 20 KHz spacing. With this setup, even signals at -5 to -10 
dBm were enough to overwhelm a good mixer. The idea has been (or will 
be) in QEX - some of the details above may be wrong but you get the idea


Leif Åsbrink wrote:

>Hi All,
>Like for last years VHF meeting I will bring equipment
>this year to measure dynamic range properties of amateur
>Those of you who go there and have a modern rig (one that
>is still available on the market) please bring it if you
>can. I am interested in collecting data from several different
>units of the same model for a Dubus article about typical 
>performance of modern amateur equipment.
>The big problems are sideband noise in Tx and Rx as well as
>keying clicks and splatter in SSB mode. I am interested
>in collecting more data like what you can find here:
>Leif  /  SM5BSZ