I've worked with the Audioplex sensor and it works very well hooked up to Xantech or Audioplex IR connecting blocks.
In most systems it is not necessary to use anything but the standard frequency model. Most (95%) remote controls in the North American market issue a 40khz carrier wave, the largest exception is RCA, who most frequently use a 56khz carrier. If your system includes european gear however, all bets are off. Many european component manufacturers utilize carrier frequencies that are far too high to be compatible with Xantech or Audioplex sensors of any type. Oyvind, you should check with the manufacturers you are using in this job. See if the remote control carrier frequency is between 32khz and 44khz.
An explanatory note on the Plasma problem: The reason we have so much conflicting advice here is that the interference is both EMI and Optical.
Metal shielding (and a good ground, guys!) can reduce EMI to nothing. Optical interference only occurs when the Plasma is ON, so simply telling your customer to avoid using a picture in their home theater... Whoops, I guess that wasn't as funny as I thougt. Anyway, optical interference can be beaten two ways. Simply make the opening of the sensor more opaque or smaller, that will reduce the amount of interference but will also lower the range. The other way is the way the Audioplex and the Xantech CFL sensor works. They have found that the plasmas output a ton of interference centered around 40khz. So the pulse pattern gets through the repeater system to the component and can be counted, but the component will not recognize the pulse pattern since the carrier frequency is jammed. Audioplex and Xantech strip the carrier, thus removing all of the interfering noise from the plasma, then generate an artificial carrier that looks fine to the av components.
The methods vary a little in terms of installation. The Xantech will only work at one frequency, but you can adjust the frequency on the sensor itself (thus on a job with both Sony 40khz and RCA56khz, you might be able to find an inbetween spot that works), Audioplex make fixed frequency versions so a mixed system you have to use two sensors.
