All, Reference : http://www.mix-sig.com/Msi5data12.pdf
Repeater Builder (the company) may be interested in building this up and making it available as a add on unit. We had looked at this some time ago, but felt the concept was not understood by our community to the degree that the product would be very successful. We have found that education of the folks interested in the AP-50 has been a challenge at best. Sure, better sounding repeaters has resulted since the release of this little device, but I doubt we'll ever sell enough to make it worth the effort of getting it all together and making it available to the general builder. How many of you would really buy a PL filter like this? For those not knowing what the AP-50 is, it's a high quality audio processor that takes place of the stock (blob) that exists in many commercial radios that are commonly available and made into repeaters like the MASTR II and MICOR. Here is some online reference: http://www.repeater-builder.com/products/ My thanks go out to Virgil W0INK for his most excellent work. Kevin Custer > The best PL filter I ever saw was one I built out of a digital SCF > design a couple of years ago. I realize that the paper is referencing > commonly available products, but I wish someone would make this thing > up for sale. > > Here is a link to the data sheet: > > http://www.mix-sig.com/Msi5data12.pdf > > This thing had essentially flat response from 110% of Fc to the top of > the voice band. The cutoff below was superb in the elliptic mode. If > Fc was set to 300Hz, tones at 255Hz were 30 dB down. It got better > with lower frequencies, and everything below 200Hz was 70+ dB down. If > set to Fc of 275Hz, everything was flat above 300, and 234Hz was 30dB > down, and everything below 180 Hz was better than 70 dB down. > > The neat thing is it is totally adjustable and can be built with only > two 8 pin ICs and a few cheap parts (caps and resistors). If all of > your PL tones are in the lower ranges, Fc can be set to 200Hz (or > lower), giving fuller sounding voice audio while still rejecting tones > below 170Hz by 30dB or more, a lot more as you go lower. > > Joe
