Anyone using the Wholehouse 3 transmitter beware. First picture is taken with spectrum analyzer beside the Wholehouse antenna operating as it came out of the box without "secret" power increase and the second picture is taken from the Decade MS-100 from right beside the antenna. Notice the Decade second and third harmonic is well within the limits set out by the FCC and ISED and look how bad the Wholehouse is! And I didn't look above 350 mHz but I'm sure more harmonics there also.
Transmitter was on 89.9 and second harmonic is at 179.9 mHz and third at 269.7mHz and so on... This up in the TV bands. Fortunately nothing was in the aircraft band. The other stuff crammed together with the fundamental 89.9 are the other FM stations in the band that would all be seen if I zeroed in on 88-108 mHz in high resolution.
KDX has a Wholehouse 2 Transmitter which is rarely put on the air but is kept on hand as a backup in case better FM transmitters are out of service. We ordinarily use several frequencies in the educational band below 91.9 but when used in that region the Wholehouse 2 floods the whole lower FM band with spikes and spurs making it impossible to use other channels. We found that operating in the upper band the Wholehouse 2 does not have the same problem, and we located a channel to use when needed. It sounds good and also has the secret switch to boost output.