Ok, folks, surely there are several of you who know what your rigs design is. What do some of the newer, higher priced and lower priced rigs use in their audio chains for amps and preamps? Do they have sophisticated feedback networks to equalize the amplitudes over the passband or are they simple amplifiers? Jose, I am not arguing that there aren't better ways to do things. What I am saying, is that amateur radios have not always done it the best way, but instead the most inexpensive way. Perhaps some of the newer more expensive rigs have better solutions but I'll bet the lower end ones don't. What does your current rig have for an audio chain prior to the balanced modulator? Is it optimized to handle wide bandwidth multi-tone digital signals, and not just in the audio but through out? If not, then the decision on what modem design would be recommended must take this into account. If one of the objectives is wide acceptance, then one must take into account the capabilities of a wide number of amateur radios. Jim WA0LYK --- In [email protected], [EMAIL PROTECTED] wrote: > > Quoting jgorman01 <[EMAIL PROTECTED]>: > > > Op amps may very well be a good solution for a very linear > > amplifier. However, my point is how many current amateur radios use > > this much more expensive solution in their audio chains? > > You would be surprised to find them used in many ham transceivers in the > last 20 years. > > > My transceivers are dated, as I suspect many hams are, but not so old > > that they couldn't have used op amps for a very fine wide bandwidth > > amp. I'll be honest, I also don't know what kind of phase shift > > problems op amps will have even if the amplitude variations are > > minimized. > > > On the other hand, it has been a while since I investigated op amps > > and they had some issues. At the time, there were none offered that > > could deal adequately with a balanced modulator (RF mixer) either > > because of the toroids used in a balanced modulator nor could they > > provide the +7 dBm or higher powers needed for this purpose. > > I think that power is the least important issue in a balanced modulator. > For some time MC1496's, diode quads and CMOS switches have given very > good carrier suppression and high linearity, which are key issues for > a balanced modulator, delivering about 0 dBm. Power can be raised with > an amplifier stage after the balanced modulator. At this point, I > would not sacrifice any of those parameters for power. > > > Bipolars were the best solution for this type of need. In addition, > > power supply requirements, i.e., +12/-12 volts to get good common > > mode rejection was also needed. > > The available devices nowadays have solved many of those limitations, > including devices designed for a single supply. Besides, it is not > that difficult to generate the -Vee voltage with a small switching > regulator inside a shielded case. > > Jose, CO2JA > > > > > > ---------------------------------------------------------------- > This message was sent using IMP, the Internet Messaging Program. > > > > __________________________________________ > > XIII Convención Científica de Ingeniería y Arquitectura > 28/noviembre al 1/diciembre de 2006 > Cujae, Ciudad de la Habana, Cuba > http://www.cujae.edu.cu/eventos/convencion >
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> 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/
