Using a tuner to get rid of BCB problems often works quite well. That's a good suggestion because most of the time it works, although there are cases where it might not work as well or can even make things worse.
The typical T-network tuner is a highpass configuration and will generally reject lower frequency signals at a more rapidly increasing attenuation than above the tuner frequency. Most link coupled tuners are actually a "bandpass" circuit, not a highpass. In all cases we should remember the exact suppression characteristics depend on the impedances presented by the radio and the antenna system at the undesired frequency to the network. There are cases where a tuner (of nearly any type) can actually increase the level of an undesired out-of-band signal, even though that same tuner looks good into a 50-ohm resistor from a 50-ohm source. It is the characteristics of the antenna, tuner, and radio as a combination of impedances at the **unwanted** signal frequency that determine the real attenuation.....not how it acts into 50-ohm loads from infinite bandwidth 50-ohm sources found in models. <<Anyway, the advantage I'm talking about is that when properly adjusted, a link-coupled tuner acts as a high-pass filter. This means that it provides additional rejection of AM broadcast stations in the 530 - 1710 kHz band. This is really important to many hams, particularly when they live close to one of these high-powered transmitters which are always on and have plenty of potential for causing problems in the receiver.>> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
