9H1FQ
12-06-2009, 04:37 PM
Have a look at this site:
http://server.oersted.dtu.dk/ftp/database/Data_CDs/Component_data/Maxim_2001/0003/APPNO038.HTM
http://server.oersted.dtu.dk/ftp/database/Data_CDs/Component_data/Maxim_2001/0003/APPNO038.HTM
View Full Version : SSB Modulator chip
9H1FQ
12-06-2009, 06:16 PM
see here
http://www.edn.com/article/CA46185.html
http://www.edn.com/article/CA46185.html
KB4QAA
12-07-2009, 07:00 AM
see here
http://www.edn.com/article/CA46185.html
Paul, This one is more to my personal liking. Despite the comments in application note, I think you would need to add a bit more filtering, but that is easy to do.
I'm sure more experience fellows are probably familiar with this or similar products, it it helpful to me.
Regards, Bill
http://www.edn.com/article/CA46185.html
Paul, This one is more to my personal liking. Despite the comments in application note, I think you would need to add a bit more filtering, but that is easy to do.
I'm sure more experience fellows are probably familiar with this or similar products, it it helpful to me.
Regards, Bill
G4LNA
12-07-2009, 07:18 AM
I've used Phasing type exciters for many years and you can't beat the audio quality you get from them, as Bill says the attenuation is not to great, I used to get -40db after careful tuning, but I gave it up because I kept having to remove the lids every other week to trim it up, even when using close tolerance components. Still, it was great fun and I used to get some great audio reports.
AB9LZ
12-07-2009, 11:45 AM
I've used Phasing type exciters for many years and you can't beat the audio quality you get from them, as Bill says the attenuation is not to great, I used to get -40db after careful tuning, but I gave it up because I kept having to remove the lids every other week to trim it up, even when using close tolerance components. Still, it was great fun and I used to get some great audio reports.
Building the phasing networks from close tolerance SMT chip caps and resistors makes this method practical again.
73 m/4
Building the phasing networks from close tolerance SMT chip caps and resistors makes this method practical again.
73 m/4
KA5S
12-07-2009, 12:01 PM
I commented there in "Phasing Sideband Revisited (http://p1k.arrl.org/cgi-bin/topdf.cgi?id=75636&pub=qst)"* that it should be possible to put a phasing SSB exciter on as few as two LSI devices.
*Members only
Yes, somewhere I have a B&W 2Q4.
Cortland
KA5S
*Members only
Yes, somewhere I have a B&W 2Q4.
Cortland
KA5S
G4LNA
12-07-2009, 02:22 PM
Sorry Cortland, I'm not a member so I can't read that.
I used a pair of MC1496 DBM's and they worked very well, but I still think it is a bit of a challenge trying to get the carrier and opposite sideband suppression better than -40db which you are still going to hear if the receive station is getting a strong signal from you, I agree though about the better stability components it would make life easier, I was using 0.1% tolerance components in the network. The phasing network has got to take on the same precautions that a VFO has and that is very difficult to do with the components mounted on the PCB open to the elements. I think if I was in the market to build one of these again I would seriously consider mounting the phasing network components in a temperature controlled environment to reduce any drift.
The other problem that I came across was to get the phase shift constant across the whole of the audio spectrum for speech, outside the useful spectrum the phase shift degrades drastically and this has an effect on the opposite sideband and you will get people complaining in pretty short order. To achieve the filtering I used some pretty tight audio bandpass filtering in the order of 24db per octave at below 300 and above 3KHz.
I used a pair of MC1496 DBM's and they worked very well, but I still think it is a bit of a challenge trying to get the carrier and opposite sideband suppression better than -40db which you are still going to hear if the receive station is getting a strong signal from you, I agree though about the better stability components it would make life easier, I was using 0.1% tolerance components in the network. The phasing network has got to take on the same precautions that a VFO has and that is very difficult to do with the components mounted on the PCB open to the elements. I think if I was in the market to build one of these again I would seriously consider mounting the phasing network components in a temperature controlled environment to reduce any drift.
The other problem that I came across was to get the phase shift constant across the whole of the audio spectrum for speech, outside the useful spectrum the phase shift degrades drastically and this has an effect on the opposite sideband and you will get people complaining in pretty short order. To achieve the filtering I used some pretty tight audio bandpass filtering in the order of 24db per octave at below 300 and above 3KHz.
K5UOS
12-07-2009, 05:01 PM
This was fairly recent Phasing SSB project in QST.
QST December 2006 had an article by KK7B, Rick Campbell, regarding phasing SSB. Rick is a co-author of Experimental Methods in RF Design.
http://www.arrl.org/qst/2006/12/campbell.pdf
Rick claims "more than 40dB below the energy in the desired sideband".
K5UOS
QST December 2006 had an article by KK7B, Rick Campbell, regarding phasing SSB. Rick is a co-author of Experimental Methods in RF Design.
http://www.arrl.org/qst/2006/12/campbell.pdf
Rick claims "more than 40dB below the energy in the desired sideband".
K5UOS
M0DSZ
12-10-2009, 08:04 AM
Unless you want a phasing generator I suggest an SA602 or SA612, originally from Philips.
N0SYA
12-13-2009, 06:35 PM
doing this in software could eliminate all drawbacks to the method
