[Flexradio] carrier on ssb
Hi, Just wanted to point out that the LO leakage has been handled from Tasa YU1LM a few years back succesfully in his designs. Specifically in his Avala-01 - http://yu1lm.qrpradio.com/AVALA-01%20AND%20ADTRX2-YU1LM.pdf you can suppress that 'carrier' by adjusting the bias voltages on I and Q of the QSE. That is not new and although all the reasons that Terry mentioned do exist, Tasa managed with this simple solution to tackle them, since some time now. I can testify this because my homebrew Avala and its carrier suppresion works lke a charm. Yet that feature is not existent in SDR-1K or in other homebrew QSEs. Probably something like it has to be in Flex-5K and in the new models. Just my 2c. 73, Christos SV1EIA ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
Re: [Flexradio] carrier on ssb
On 1/6/09 4:38 AM, Christos Nikolaou sv1...@gmail.com wrote: Hi, Just wanted to point out that the LO leakage has been handled from Tasa YU1LM a few years back succesfully in his designs. Specifically in his Avala-01 - http://yu1lm.qrpradio.com/AVALA-01%20AND%20ADTRX2-YU1LM.pdf you can suppress that 'carrier' by adjusting the bias voltages on I and Q of the QSE. That is not new and although all the reasons that Terry mentioned do exist, Tasa managed with this simple solution to tackle them, since some time now. I can testify this because my homebrew Avala and its carrier suppresion works lke a charm. Yet that feature is not existent in SDR-1K or in other homebrew QSEs. Probably something like it has to be in Flex-5K and in the new models. Since the F5K has the audio DAC and the QSE in the same box, they could have easily DC coupled it, which would make the adjustment possible without added parts (actually, fewer, no series capacitors).. I would guess (but do not know) that virtually all sound card and external audio interfaces have AC coupled outputs, so the SDR1K has to work with that. Jim, W6RMK ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
Re: [Flexradio] carrier on ssb
It is not actually a carrier but LO leakage from the commutator ic FST3253 and there is no adjustment you can make to null it on this implementation. I use sdr1k with the 100w PA and I have measured this leakage to be -20dbm @ 160m (70db below 100w)and 0dbm @ 10 m (50 db below 100w but only 30 db below 1w). While you transmit on ssb it is on your vfo frequency and at am/fm it is on vfo - if. You can also trace it during reception but with much lower level. 73 Christos ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
Re: [Flexradio] carrier on ssb
On 1/3/09 12:33 AM, Christos sv1...@otenet.gr wrote: It is not actually a carrier but LO leakage from the commutator ic FST3253 and there is no adjustment you can make to null it on this implementation. I use sdr1k with the 100w PA and I have measured this leakage to be -20dbm @ 160m (70db below 100w)and 0dbm @ 10 m (50 db below 100w but only 30 db below 1w). While you transmit on ssb it is on your vfo frequency and at am/fm it is on vfo - if. You can also trace it during reception but with much lower level. 73 Christos One might be able to null it if you have an audio interface with response down to DC? Or is it just leakage around the part, from the DDS output to the antenna output. (that is, if you were to disable the FST3253 so that it never turned on any of the switches, would you still get the feedthrough?) Is the F5K or the WonderRadio better or worse? (different PCB layout, different parts) Jim, W6RMK ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
Re: [Flexradio] carrier on ssb
-Original Message- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@flex-radio.biz]on Behalf Of Christos Sent: Saturday, January 03, 2009 3:33 AM To: FlexRadio biz Subject: Re: [Flexradio] carrier on ssb It is not actually a carrier but LO leakage from the commutator ic FST3253 and there is no adjustment you can make to null it on this implementation. I use sdr1k with the 100w PA and I have measured this leakage to be -20dbm @ 160m (70db below 100w)and 0dbm @ 10 m (50 db below 100w but only 30 db below 1w). While you transmit on ssb it is on your vfo frequency and at am/fm it is on vfo - if. You can also trace it during reception but with much lower level. 73 Christos ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ If it's exactly at the LO frequency, it's really both, as it should be considered an RF carrier (since it is) that is the direct result of LO leakage through the QSE. All QSE's have it, to a lesser or greater degree. SoftRocks, David Brainerd's QSE, the SDR-1000, and others have it, and it's measurable. I assume the Flex-5000 still uses a QSE, so it will also have it. Newer switch IC technologies, and careful design may have allowed them to improve on the leakage from the SDR-1000, however. The phase and amplitude adjustments of the I/Q signals can adjust the RF image level, but not the LO leakage, because they adjust only the audio/IF IQ signals, and are not in the LO carrier path. Since the LO is usually (always?) a set of digital signals that turn on and off the QSE switches themselves, adjusting them is difficult. The real issue may be how much power you are actually transmitting. Just as Christos says above. If you are running a SoftRock barefoot at one watt (+30dBm), and the LO leakage is 60dB down, you are radiating a signal at the LO freq at roughly -30dBm (.001 milli-Watt) in addition to your wanted signal at about +30dBm. It will probably not be heard too far away. But, if your are running 100W (+50dBm), the leakage is now around only -10dBm (0.1 milli-Watt), possible to hear much further. It's not always easy to get 60dB carrier suppression on some QSEs. More like 45dB on some (which is only 6 S-units). That would mean that your 1W rig (+30dBm) is putting out a -15dBm (0.032 milli-Watt) unwanted carrier. If you move to a 100W (+50dBm) rig, your unwanted carrier is now +5dBm!! That's 3.2mW. People have (rarely) worked great DX on HF with 3.2 milli-Watts. If (for example) you are being received at ten over S9, your LO leakage is S6 at that same location. Also, keep in mind that no simple filtering (LPF, BPF) can reduce either the LO leakage or image signals, since they are so close to the wanted signal. Running a KW (+60dBm) is even worse. With 45dB leakage, you are actually transmitting a LO leakage signal of +15dBm, or 32 milli-Watts! If you used a KW with 60dB leakage, you would be transmitting 0dBm (1 milli-Watt) of leakage signal. The LO leakage comes from many factors, such as: How balanced the resistance, impedance, and levels are around the QSE switch (we may have some control over this). How balanced the switches themselves inside the QSE IC or IC's are (no control, other than change the part). How balanced is the transformer used? number of turns, how even is the the twist between the two primaries, etc. Are the QSE clocks to the switches exactly 50% duty cycle, and no clock jitter? More? If you really wanted to, I think you could fine-tune some of this leakage out, but it would take some work, and your improvement would be limited. And yes, LO leakage can often there on receive as well. Even though your QSD is on receive, barring an active device in the receive path between the QSD and antenna, the LO leakage will be there. You are essentially transmitting a low-level signal to the antenna through the QSD switch. One reason why QSD/QSE rigs may have a problem at multi-rig operations. The good news is that any transmit amplifiers are not in circuit during receive, so the leakage is at a MUCH lower amplitude. I can easily hear the LO from the SDR rig on my old Icom 720, if I tune slightly off the SDR's frequency (Rx freq plus or minus I/Q IF freq). I was reminded of this just yesterday, while I was working with the SDR-1000 on 40, and happened to turn on the Icom (each radio using separate, perpendicular dipoles). Putting an active buffer in between the QSD and the antenna helps here. One common aftermarket board is the Z1 from Clifton Labs. Not needed as much on the SDR-1000 with the RFE board (it has a receive buffer/preamp), but recommended for SoftRocks and Brainerd receiver boards, especially if they are used to tap
Re: [Flexradio] carrier on ssb
You probably had a bad modulator chip (QSE). Please contact our service department for assistance. Regards, Gerald Gerald Youngblood, K5SDR President FlexRadio Systems 13091 Pond Springs Rd. #250 Austin, TX 78729 Phone: 512-535-4713 -Original Message- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of l...@bellsouth.net Sent: Thursday, January 01, 2009 6:56 PM To: FlexRadio@flex-radio.biz Subject: [Flexradio] carrier on ssb hi .i am having a problem with my flex 1000 i have a carrier on ssb and i get reports it has a carrier on the usb when it is running lsb. i also have a carrier when the radio is in the mox setting.can any help me? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
Re: [Flexradio] carrier on ssb
I've had that problem twice in the 1000 and it was due to a blown modulator chip. But you should contact Flex Radio direct and let them sort it out. Dave - N4DWK l...@bellsouth.net wrote: hi .i am having a problem with my flex 1000 i have a carrier on ssb and i get reports it has a carrier on the usb when it is running lsb. i also have a carrier when the radio is in the mox setting.can any help me? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
Re: [Flexradio] carrier on ssb
All normal unfortunately. The amount of carrier you have is another question. Others here can evaluate that once you determine how much rf carrier you have. This was an issue for me when I attempted to run a transverter for 6M then to amplify it. I had lots of amplifed carrier in SSB mode before speaking my first words. I hope this isn't the issue with the model 1500 coming out this spring. Regards Hulen K5HCS - Original Message - From: l...@bellsouth.net To: FlexRadio@flex-radio.biz Sent: Thursday, January 01, 2009 6:55 PM Subject: [Flexradio] carrier on ssb hi .i am having a problem with my flex 1000 i have a carrier on ssb and i get reports it has a carrier on the usb when it is running lsb. i also have a carrier when the radio is in the mox setting.can any help me? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ Internal Virus Database is out of date. Checked by AVG - http://www.avg.com Version: 8.0.176 / Virus Database: 270.10.0/1866 - Release Date: 12/27/2008 8:49 PM ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
[Flexradio] carrier on ssb
hi .i am having a problem with my flex 1000 i have a carrier on ssb and i get reports it has a carrier on the usb when it is running lsb. i also have a carrier when the radio is in the mox setting.can any help me? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
