Help interpreting tuner specs
Those all look like fine numbers, except that I'm a little uncertain about the 50db quieting points. The 0.5uv mono sensitivity seems too good to be true for 50db quieting. And while I believe 22uv is a fine number for stereo, I'm a little uncertain because most tuner specs these days use dbf units rather than uv. Hopefully someone else will comment further on those two numbers. Regards, -- Al |
I did some calculations on the 50db quieting numbers, to convert them to dbf (decibels above a femtowatt, which is a quadrillionth of a watt). If the tuner's antenna input is 75 ohms (i.e., a coaxial connector), 50 db quieting occurs at: Mono: 5dbf Stereo: 38dbf If the tuner's antenna input is 300 ohms (i.e., screw terminals that accept 300 ohm twinlead), 50 db quieting occurs at: Mono: -1dbf Stereo: 32dbf The stereo numbers appear reasonably decent but not exceptional. The mono numbers, as I indicated above, appear to be too good to be true, and I suspect represent a mistake. You can find the numbers for a great many tuners here: http://www.fmtunerinfo.com/specs.html Regards, -- Al |
I agree with Al, these look like extremely good numbers. I find measured sensitivity numbers a bit difficult to correlate on my own test bench, and there are a few sources of possible error. First, many FM generators (like my old Sound Technology 1000A) have a 50-ohm output, so you need to use a matching network for proper calibration of the output into either a 75-ohm or a 300-ohm antenna input, and add the attenuation of this network to the signal-level dial calibration. Second, I find that there are a handful of RF-noisy devices around my bench, and sometimes don't feel like turning them all off to get a super-precise measurement. And there's the matter of the disparity of your mono vs. stereo readings - if the composite or pilot modulation level on the signal generator is off a bit, then it will show up here. But if your tuner is indeed acheiving the performance you describe . . . it's working just fine. |
I have recently rekindled my interest in audio components. I was an avid hobbyist in the late 70's, early 80's. I have the Carver tx11 tuner (FM only) and used it at Marlboro College in southern Vermont, hooked it up to regular radio shack or whatever dipole antenna stretched across the wall. This tuner is amazing. My receivers of the day in this decade were Technics, JVC, Harmon Kardon, Denon. Their tuner sections were vastly inferior. I picked up Long Island fm from Marlboro, Vermot. I could differetiate between many classic rock stations close together on the dial out of Worcester, Mass(WAAF), Hartford , Ct(10.9, wccc?), New Haven Ct (WPLR), etc. |
