Today I put the Coaxial Dynamics RF meter on the two FM transmitters. I used "slugs" in the meter specifically made for my purposes, as slugs for these frequencies and these low powers are not very common. Power read from antenna connection to ground on circuit boards inside the transmitters.
The Decade CM-10 gave a solid 2 mW out. Nothing else to test.
The Whole House 3.0 gave 2.2 mW on the USA setting.
On the "secret" Canadian setting the power jumped to a whopping 310 mW output!
Readings taken at frequency of 92.7, into a 50 ohm dummy load. Can't say for certain that 50 ohms is the actual design impedance output but it's pretty much the standard and either way the relative readings would be accurate.
Worth noting that I was testing the WH 3.0 with brand new batteries. When plugging in the power supply (not the one included, as that didn't work) there was a slight increase in output, maybe a meter needle worth. The USB supplies are 5 volts, the batteries make 4.5 so that little half a volt pumps it up just a little.
Now, remember this can have some bearing on the final field strength of course, but it's how the antenna uses the RF power to get it into space, and especially how other cables are connected and arranged. These readings were taken with nothing connected to the transmitters except power, and the WH 3.0 was also tested on just batteries with no power connected with similar results. Not that I was expecting any changes as this was with the meter hard wired to the outputs.
So, that's that.
I know have two FM transmitters for sale at half price. I believe the WH 3.0 is spoken for. The Decade CM-10 is up for grabs at half price, $100 + shipping.
TIB