A friend of mine expressed concerned about radiation and possible harmonics.
My feeling are
1.That the harmonics should be suppressed before they leave the transmitter
2. Any radiation is of little concern since TVI etc is no longer a concern.
I welcome all thoughts on the matter.
Carl
WA1KPD
Hi Carl,
Yes, the harmonics SHOULD be handled by the transmitter. If they are down -40dB or so, the FCC will most likely not hear you. Depending on the antenna, feedline and freq, there can be another 10-40 dB of ANTENNA harmonic suppression available. (on the harmonic freqs using a coax ant)
Generally, the more complex the tuner, the more harmonic suppression. A simple parallel floating "JJ" style tuner with one cap and coil may be good for only -25dB additional suppression. The more complex split capacitor designs with capacitors to ground may give us -40dB or more at the harmonic freqs. If more suppression is not needed, then why bother?
I have always used the simple floating design because the harmonic suppression of my rigs is good - a pi-network usually sees to that.
In your case it should be easy to measure your stock second and third harmonic suppression using a local RX or SDR receiver (TX into a dummy load) to see if you even have a problem to begin with.
Yes, TVI is not an issue anymore unless the neighbor has rusted cable connectors or some issue that causes diode rectification or poor shielding. In that case, most any rig, good or bad harmonic suppression, will tear them up.
But bottom line, do everything "textbook" and it will all add in the proper direction to give cumulative good results. Measurements are key.
T