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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