[BC] Spurious and Harmonic output of AM TX

[John Lyles]

Jim is correct in that to get FCC type notification, the transmitter must be capable of meeting the suppression limits, standalone. If a tuner is required to make a transmitter meet the FCC R&R, then it has to be included in the submittal data for type notification and should be part of the transmitter, or included with the system as provided to the broadcaster. Larger FM and TV transmitters had external coaxial harmonic filters, and those were included in the data taking to meet the specs.  

Dependence on the ATU to make transmission equipment meet the spurious and harmonic requirements is not allowed. Also, besides conducted emissions, radiated emissions must also be compliant with the rules and regs. This is usually called the 'cabinet radiation' measurement and it is a real concern as harmonic currents can cause significant leakage across the joints and seams of the cabinet, if they are not RF tight. 

John


 
> >> No. You will be going through your usual antenna coupler. It will 
> >> provide sufficent harmonic suppression,
> >> i.e., 43 + 10 log (power in watts), especially considering your 
> >> harmonics will already be 40 dB down.
> 
> I am under the impression that in the USA transmitters
> have to meet spurious output regulations  *at the output
> of the transmitter*.  Hence relying on the coupler to do
> anything beyond matching would be folly.
> 
> - JimT
>