Hi All, There are designs for 2 meter high performance receiving solutions on the SM5BSZ VHF/Linrad webpages.
http://www.sm5bsz.com http://www.nitehawk.com/sm5bsz/ http://www.nitehawk.com/linrad_dat/ 73 Rein W6?PA)ZN johanmaas2001 wrote: >Hi, > >I found recently a chip of maxim; the max2314. > >Input is possible from 40 -150 Mc and delivers an IQ signal. > >Maybe this will help in getting to VHF. > >73 Johan PA3GSB > > >--- In [email protected], KY1K <[EMAIL PROTECTED]> wrote: > > >>Hi Alberto, >> >>I've seen that switch, and it looks like the dead short or the 50 >> >> >ohm > > >>termination is a problem. Since the switch does not present a high >>impedance during the time it's open, there is no way to avoid >> >> >having > > >>it discharge (or drain) the integrating caps, so they can't >> >> >function > > >>as a sample and hold. >> >>Also notice that the turn on vs turn off time varies, it turns on >> >> >in > > >>3.6 nS and it turns off in 5.8nS. This isn't going to work well >> >> >since > > >>1 cycle of 144 MHz is 7 nS. While the switch passes 144 MHz, it >> >> >won't > > >>turn on and turn off fast enough to be usable at 144 MHz. >> >>IF (and it's a big IF) we could slow down the on time transition, >> >> >it > > >>might be usable. If it would turn on in 5.8 nS and turn off in 5.8 >>nS, it would be good, provided the other switches could operate >> >> >with > > >>the same on and off times (switching times are all consistent). >> >>I've chatted with AD about these issues, there is no way to burn >> >> >out > > >>the 50 ohm resistors to effectively remove them from the circuit. >>There is no comparable analog switch made by them that does >> >> >function > > >>properly (for us). They are NOT planning or designing a suitable >> >> >switch. > > >>I talked to a friend who designs cmos about the consistency >> >> >problem. > > >>It is a relatively simple task to equalize the switching times IF >>'adjustability' is a design goal. But, it is very expensive to make >>the masks necessary to do the fabrication of the parts. Without a >>major demand for switches with consistent (equalized) on/off times, >> >> >a > > >>suitable switch will never be built. >> >>I have some ideas about how to control the switching speeds and >> >> >would > > >>love to chat with anyone interested in QSD at vhf. Talk to me off >>list, as the subject might be off topic for this group. >> >>Art >> >> >>At 06:13 AM 10/23/2005, you wrote: >> >> >> >>>I know that a few of you are considering the idea of building a QSD >>>directly at 144 MHz. I have just received an Analog Device >>> >>> >bullettin > > >>>with the specs of a new high speed analog switch. >>> >>>Maybe it is worth investigating its suitability for that >>> >>> >application. > > >>http://www.analog.com/UploadedFiles/Data_Sheets/847169922ADG901_2_b.p >> >> >df > > >>>73 Alberto I2PHD >>> >>> >>> >>> >>> >>> >>>Yahoo! Groups Links >>> >>> >>> >>> >>> >>> > > > > > > > > >Yahoo! Groups Links > > > > > > > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
