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The decision of which boat anchor receiver(s) to own is seldom based on performance alone. A combination of favored manufacturer, period of manufacture, features, collectability or even just 'looks' often rank higher on the priority list than receiver performance. Even if one were interested in performance specs much of the available information is subjective as few receivers manufactured prior to the mid 70s have undergone standardized testing. Hard data on minimum discernable signal (MDS), blocking and two-tone IMD dynamic range is interesting to some operators and important in an historical context as it shows the progression of receiver development.
This is an ongoing project to test receivers manufactured prior to the mid 70s and document their performance. The first round of receivers tested is from my collection and all have been electrically restored, aligned and perform to all factory listed specifications. As more receivers are tested the results will be added to the list.
A change in measurement technique for boat anchor receivers vs. present-day receivers was deemed appropriate. Modern receivers have adequate gain and exhibit noise floor levels of -136 to -139 dBm with their rf gain controls set at maximum and are normally tested in that configuration. Boat anchor receivers typically have significantly more gain than needed and require that the RF gain controls be reduced to prevent i-f and detector stage overload. It's interesting to note that most of these receivers exhibited noise floors of -143 to -146 dBm at full gain!
An explanation of the test procedure and what constitutes a 'good' receiver can be found at Receiver Measurement Basics.
In addition to the receiver MDS and dynamic range measurements tests, recovered AM signal to noise, AM frequency response and AM distortion have been added to the battery of tests. Due to the amount of data collected, individual receiver pages were created and are available at the links below. A quick comparison of receiver dynamic range can still be found below the receiver list.
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