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The definitive CCR thread... why you won't really save anything.


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#41 WPXM352

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Posted 25 January 2020 - 03:38 PM

Many years back, before these CCR became the rage, it was a common complaint of ham users of Japanese handhelds that when replacing the factory supplied "rubber duckie" antenna with a 5/8 wave dipole or a base station antenna that the receiver sensitivity would erode. 

 

This was quickly identified as being a combination of both poor RF front end selectivity and poor dynamic range and IMD .

 

It would be interesting to subject these CCR radios as well as known good commercial grade radios to the rigorous testing of TIA603D.

 

Lacking the complete facilities to do so, it occurred to me that a UHF TEM cell could be put to use to combine a desired signal (12dB SINAD reference) and undesired noise spectrum (rejection notched at desired) from an amplified noise diode generator to perform a Noise Power Ratio test of these various radios having integral antennas. This set up could be used to quantitatively measure radios and rank them on a dB scale of best to worst. 

 

This setup would simulate the "real world" environment of powerful emitters in and out of band of the receiver.


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#42 gman1971

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Posted 25 January 2020 - 04:32 PM

Well said. 

 

Many years back, before these CCR became the rage, it was a common complaint of ham users of Japanese handhelds that when replacing the factory supplied "rubber duckie" antenna with a 5/8 wave dipole or a base station antenna that the receiver sensitivity would erode. 

 

This was quickly identified as being a combination of both poor RF front end selectivity and poor dynamic range and IMD .

 

It would be interesting to subject these CCR radios as well as known good commercial grade radios to the rigorous testing of TIA603D.

 

Lacking the complete facilities to do so, it occurred to me that a UHF TEM cell could be put to use to combine a desired signal (12dB SINAD reference) and undesired noise spectrum (rejection notched at desired) from an amplified noise diode generator to perform a Noise Power Ratio test of these various radios having integral antennas. This set up could be used to quantitatively measure radios and rank them on a dB scale of best to worst. 

 

This setup would simulate the "real world" environment of powerful emitters in and out of band of the receiver.






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