I have basically the same thing in my original testbed but I long ago ditched the INA device (I never was a big fan of the INA devices or their SSM predecessors in most applications, line level driver/receivers are an exception), they are noisy if you use them with anything less than 40db of gain and the noise really rises dramatically at 20db gain or less (This is inherent in all 'cross coupled' designs discrete or integrated) You are actually better off using a single differential op amp, especially if you are using a bipolar supply (There is a good reason few if any manufacturers show noise specs for single supply circuits in their datasheets, single supply circuits are noisier for low level, low impedance amplification) .... my main work on the 'backend' now consists of a diff opamp preceded by low noise pnp transistors **without** cross coupling them like in a INA or discrete equivelent (We don't need all that gain) ... Even a pair of 10 cent 2N4401's in front of a NE5532/4 will stomp about any of the expensive 'designer' low noise op amps ... Just ask the engineers at Soundcraft, Mackie, Yamaha, or Beringer who all use a pair of transistors ahead of the opamps in their professional balanced microphone preamps ... Problem is I'm at a standstill because my DDS's are too noisy to take advantage, hopefully the 995x based DDS Controller (David Brainerd's design) will be quiet and spur free enough to explore further
JR --- In soft_radio@yahoogroups.com, FRANCIS CARCIA <[EMAIL PROTECTED]> wrote: > > I built the double balanced Tayloe with the TI 3253 that words very well. The INA163s gain is X10 since my unit hangs off a 455 KHz IF. I put a 6 dB pad on the input to force 50 ohms. > This feeds my HPSDR set up in the low gain setting. The HPSDR in high gain mode requires lower op amp gain and high quality cable as an interface. It is very sensitive in the high gain mode but flatter frequency response. > BTW a soft rock 6 kit would have been a lot cheaper to do. frank > > Andreas Troschka <[EMAIL PROTECTED]> wrote: > jr_dakota wrote: > > A couple of pin for pin replacements are CBT3253 and FST3253 ... other > > numbers are SN74CBT3253 or 74CBT3253 or 74FST3253 > > > > All are essentially the same chip just different manufacturers ... The > > FST is Fairchild (USA) and the CBT is Philips (EU, Netherlands)... In > > your part of the world the Philips device may be the easiest to obtain > > > > JR > > > > --- In soft_radio@yahoogroups.com, "Adnan Yusuf" <mail_adnan85@> wrote: > >> i was making the sdr for the masses circuit. Unfortuately i couldnt > >> get the IC pi3b3253. However i got another ic named 74hc4052. The > >> problem that i am now having is that although both the ic's are > >> mux/demuxers with almost the same pins there are two pins that are > >> different in both the ics > >> > >> the pi3b3253 has 2 enables(one for high and one for low) > >> the 74hc4052 doesnt have this > >> > >> the 74hc4052 has a Vee pin while the pi3b3253 doesnot have this pin. > >> will i still be able to use this ic as an equivalent. > >> > >> please look at the link which provides the picture, it will make the > >> situation very clear. > >> http://img509.imageshack.us/my.php?image=67751722pt1.png > >> > >> please do reply. please take your time. i would be very greatful. > >> > >> yours > >> adnan yusuf > >> > > > > I'll underline that the mentioned pi3b3253 is a LVT (Low Voltage Technology) device working at 3.3Vcc with consequent logic voltage levels, differently from some other devices wrongly indicated on this thread as equivalents. > A direct substitution of such device with the indicated components can't be made without adaptation in the surrounding circuit. > > I don't know the device family used in the Tayloe circuit the 3253 is placed in (a pi5b3253, a 5Vcc level device exists too), of the receiver you mentioned, so it's up to you to verify this aspect and select the proper replacement. > > vy 73s de ik2wqi > > Andreas Troschka >
