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About a year ago the NAB commissioned a lab study on the field strengths of many of the FM part 15 transmitters. Here’s the link:
In this you will find the list of the units tested and a graph which shows how their field strengths compared with the FCC limit of 48 dBuV/m (equivalent to 251 uV/m) at 3 meters.
Calculating backwards, the CCrane unit produced a field strength of 100 uV/m so if this is representative of your unit it is hard to explain the very short range you reported. Even with reflections, moving the receiver around should produce a signal.
The data presentation in the report makes it difficult to compare the field strengths as we are used to discussing since the graph is in dBuV/m at 3 meters. Since dB is a log function, the data are compressed and a unit with double the field strength of another will appear only 6 dBuV/m higher. Though it doesn’t appear to be the case on the graph, there are very large differences in FS of the devices tested.
If you are interested, you can pick the dBuV/m off the tables or graphs and convert to uV/m.
uV/m = 10^-6 (10^(dBUv/20))
For example, 48 dBuV/m converts as
uV/m = 10^-6 (10^(48/20)) = 251 uV/m.
That being said, the results of Rich’s suggestion of a outdoor “free range” test may be interesting.