jfw@ksr.com (John F. Woods) (05/20/91)
Having recently seen an advertisement for a "smart" antenna tuner, I
became curious about how they switch the inductances and capacitances
in and out of the circuit. Since the smart tuner claims to be good
for 300 watts, it would seem that they need switches that can
withstand several hundred volts when open, but the case seemed a bit
small for 11 high-voltage relays ("64 input capacitances, 32 output
capacitances, and 256 values of inductance"; 11 binary switches).
So, what are they likely to be using?mark@ve6mgs.uucp (Mark Salyzyn) (05/20/91)
In <3636@ksr.com> It was said: >Having recently seen an advertisement for a "smart" antenna tuner, I >became curious about how they switch the inductances and capacitances >in and out of the circuit. Since the smart tuner claims to be good >for 300 watts, it would seem that they need switches that can >withstand several hundred volts when open, but the case seemed a bit >small for 11 high-voltage relays ("64 input capacitances, 32 output >capacitances, and 256 values of inductance"; 11 binary switches). >So, what are they likely to be using? I have the `smart' tuner in question. Regular relays (well, higher quality that Radio Shack) are used. No Gold or Silver contacts. No special precautions on the input side of the Pi tuning network. The middle `L' of the tuning circuit has the inductors shorted by the contacts, most are toriod, but all, I am sure, have no mutual inductance. The output caps, however, have TWO separate relays with their contacts in series. This is where the voltage can get rather high. Have Fun. 73 de VE6MGS/Mark -sk-