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Re: QRPGuys DSB Digital Transceiver
With all the controversy surrounding this kit I am sorry I even purchased it. It's sitting here waiting to be assembled. I suppose I'll throw the PCB boards away and keep the parts for future projects. With so many problems surrounding dsb (other than simplicity) I cannot understand why the qrpguys put this kit out. In retrospect I would have paid extra just to have a proper SSB signal after reading all the comments in this thread.
Randy AB9GO |
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Re: Phasing SSB Transceiver: Homebrew w/o a scope?
Having built both a phasing receiver and many filter rigs, I think a single conversion filter rig is easier.? ? Why not build a single conversion superhet receiver first.?Good luck? 73? Bill N2CQR
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On Sunday, November 3, 2019, 11:56:46 AM EST, ajparent1/kb1gmx <kb1gmx@...> wrote:
FYI the QCX receiver is a image rejecting design (phasing) for SSB changing a few resistors in the audio filter (from CW band width to SSB) and it sounds very good. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: QRPGuys DSB Digital Transceiver
Correct. My bad.
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Mike K5ESS -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of David Ryeburn Sent: Saturday, November 2, 2019 8:43 PM To: [email protected] Subject: Re: [qrp-tech] QRPGuys DSB Digital Transceiver On 2019-11-02 2:18 p.m., K5ESS via Groups.Io wrote: My rational is that with a RIT or transmitted frequency offset the baseband audio would have the upper and lower sidebands separated by the offset frequency No, by double the amount of offset. If you move the inserted carrier up x Hz at the receiver, the upper sideband signal's audio decreases x Hz while the lower sideband signal's audio increases x Hz. > instead of overlapping. David VE7EZM and AF7BZ |
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Re: QCX-40 Working...Sort of...
ajparent1/kb1gmx
Left button issues suggest R44 or the button as right button and rotary encoder
are on the same path (to MPU pin 26. Each button encodes as a different voltage into an analog pin to reduce the number of pins needed. So likely wrong part in R44 or button rotated 90 degrees or soldering issues. If left works and long press is not working then it likely user error. Long press is long and no bounces. The difference in how the button works is firmware in the MPU and unlikely that tiny bit of could would fail and everything else works. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: Phasing SSB Transceiver: Homebrew w/o a scope?
ajparent1/kb1gmx
FYI the QCX receiver is a image rejecting design (phasing) for SSB changing a
few resistors in the audio filter (from CW band width to SSB) and it sounds very good. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: Phasing SSB Transceiver: Homebrew w/o a scope?
ajparent1/kb1gmx
Simple, a scope is over used. Often not required or at best a handy tool.
I build mine using mostly my ears and a good DMM. If you have EMRFD the miniR2 design is pretty much precooked and a just build it. the R2pro is also same thing just build to a higher performance. The math is if you want to do ground up or understand the reason it works. generally its good to read the text around it as it explains whats going on without the hoary math. The QST published a bunch of years back MicroR2 as a good RX and they had a matching TX. I've built both on a board and dead bug. The KK7B are my prefered designs but I'vebuilt some of the minimal and lower performing designs and found they were quite adequate. There are others is the RSGB compendiums and a few old school designs but generally they are fussier to build. The key is if they want 1% parts (resistors) do it. Same for caps. The tool I found most handy was the AADE LCII or similar. The few critical inductances and caps were easily matched or checked. As to tune-up. A signal on the air and tune across it if the other sideband is no existent (cant be found or ever very weak compared to the desired one) its good. If things are done (adjusted) right you can tell. IT depends on if you into CW or SSB as the Dan Tayloe designs for CW were also good. Also CW only needs the Good RX and if your doing SSB the TX is really just the RX with all the paths going the other way. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: Phasing SSB Transceiver: Homebrew w/o a scope?
Bob Macklin
QRP Labs has a QSD receiver and a phasing module to go with it.
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Once you understand how the phasing SSB Rx works you might be able to figure out how to do a phasing QSE. Bob Macklin K5MYJ Seattle, Wa. "Real Radios Glow In The Dark" ----- Original Message -----
From: "Ryan Flowers" <geocrasher@...> To: <[email protected]> Sent: Saturday, November 02, 2019 6:01 PM Subject: [qrp-tech] Phasing SSB Transceiver: Homebrew w/o a scope? Hello everyone, This is my inaugural post here in the QRP-Tech group. I have done a lot of hacking on the BITX40, and feel that i understand it fairly well. I also have homebrewed a DC receiver. I've written about that all on my blog in case anyone cares to read it, . I followed the digital DSB thread with great interest, and if you read my site you'll see I've written on the subject. Part of the discussion that piqued my interest was a post in which it was explained how a simple SSB transceiver could be built using phasing. I don't fully understand phasing (the math in EMFRD is waaaay over my head) but it looks like if one does the math right (using online calculators?) it would be simple enough to design and construct. And thus my question emerges. I don't own a scope although if intend to eventually. But lets say I don't, and I want to homebrew the simplest SSB transceiver design: A direct conversion receiver with a phasing filter to the audio amp, with the same filter used in reverse to strip the sideband going to the PA. Allison (Who I am hoping will shed some light on this subject!) mentioned it would be pretty simple, which I understand to be a very relative term :p What designs exist, and could they be built without a scope? That is my question. -- Ryan Flowers W7RLF |
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Re: QRPGuys DSB Digital Transceiver
On 2019-11-02 2:18 p.m., K5ESS via Groups.Io wrote:
My rational is that with a RIT or transmitted frequency offset the baseband audio would have the upper and lower sidebands separated by the offset frequency No, by double the amount of offset. If you move the inserted carrier up x Hz at the receiver, the upper sideband signal's audio decreases x Hz while the lower sideband signal's audio increases x Hz. instead of overlapping.David VE7EZM and AF7BZ |
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Phasing SSB Transceiver: Homebrew w/o a scope?
Hello everyone,
This is my inaugural post here in the QRP-Tech group. I have done a lot of hacking on the BITX40, and feel that i understand it fairly well. I also have homebrewed a DC receiver. I've written about that all on my blog in case anyone cares to read it, . I followed the digital DSB thread with great interest, and if you read my site you'll see I've written on the subject. Part of the discussion that piqued my interest was a post in which it was explained how a simple SSB transceiver could be built using phasing. I don't fully understand phasing (the math in EMFRD is waaaay over my head) but it looks like if one does the math right (using online calculators?) it would be simple enough to design and construct. And thus my question emerges. I don't own a scope although if intend to eventually. But lets say I don't, and I want to homebrew the simplest SSB transceiver design: A direct conversion receiver with a phasing filter to the audio amp, with the same filter used in reverse to strip the sideband going to the PA. Allison (Who I am hoping will shed some light on this subject!) mentioned it would be pretty simple, which I understand to be a very relative term :p What designs exist, and could they be built without a scope? That is my question. -- Ryan Flowers W7RLF |
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Re: QRPGuys DSB Digital Transceiver
ajparent1/kb1gmx
Only when the Receiver cannt hear the other sideband at all.
However add an offset and your computer is the receiver and the software filters are quite narrow. It can work. It is a very narrow case of SDR as the computer and software are the detector and the IF though at audio range has the requisite filters. No one ever said that a Superhet had to have a IF at some high frequency it could easily be 2khz for narrow band work. That is why what you propose for narrow digital signals can work. by introducing a frequency offset and using a narrow filter to select the desired sideband. So yes it can work and likely does for that reason. Just that the solution is still the same but the means tends to obscure the actual action The yabut is that apparently everyone is running high stability oscillator to be exactly on frequency and that makes the right offset an issue. Of course if the other end is using a SSB radio then the issue it moot as he is stripping the unwanted image. Likely the case. I'd use a simple image rejecting mixer scheme and that is passive cheap and effective enough. Used both ways it also would reduce the offending unwanted sideband by 20-30db. It works both ways to like equipped radio for voice work. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: QRPGuys DSB Digital Transceiver
Allison,
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No I have not tried it but I¡¯m only making the claim for the FT8 digital mode not voice. My rational is that with a RIT or transmitted frequency offset the baseband audio would have the upper and lower sidebands separated by the offset frequency instead of overlapping. WSJT should then be able to decode the upper sideband while ignoring the lower sideband which would not decode. Mike K5ESS -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of ajparent1/kb1gmx Sent: Saturday, November 2, 2019 3:19 PM To: [email protected] Subject: Re: [qrp-tech] QRPGuys DSB Digital Transceiver Mike, Have you actually tried it. I have in an early attempt to make a simple 10M DSB HT pair. The RX was a simple direction conversion to minimize parts. Both crystal controlled so no issue with frequency and no usable copy either. Yet a SSB radio as a receiver worked just fine. Ended up dumping the idea and would later do it SSB with the usual crystal filter. However with a offset and the relatively narrow signal they other guy might find you only due to the narrow processing window. However you then have to appear where he is listening which may not help. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: QRPGuys DSB Digital Transceiver
ajparent1/kb1gmx
Mike,
Have you actually tried it. I have in an early attempt to make a simple 10M DSB HT pair. The RX was a simple direction conversion to minimize parts. Both crystal controlled so no issue with frequency and no usable copy either. Yet a SSB radio as a receiver worked just fine. Ended up dumping the idea and would later do it SSB with the usual crystal filter. However with a offset and the relatively narrow signal they other guy might find you only due to the narrow processing window. However you then have to appear where he is listening which may not help. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: QRPGuys DSB Digital Transceiver
I think two DSB transceivers can communicate via FT8 quite well as long as their carrier frequencies differ by a couple hundred Hz or they apply a couple of hundred Hz of RIT if their transmitted carrier frequencies are identical.
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Mike K5ESS -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Hans Summers Sent: Friday, November 1, 2019 2:36 AM To: [email protected] Subject: Re: [qrp-tech] QRPGuys DSB Digital Transceiver Mike K5ESS: Yes, no problem with receiving a DSB signal, as long as you are receiving it on an SSB receiver. It is DSB at both ends which is the problem. As far as I can think of, of all the many modes amateurs send to each other, DSB is the only one where you can't work someone else who also has a DSB transceiver. Bob K5MYJ: If you add a BFO to a general coverage receiver you end up with effectively a DSB receiver, don't you? In which case don't all the same DSB-DSB problems apply? I don't see how it can work at all, let alone sound better than SSB... and regarding modes (this topic is about DSB FT8) I'm not a big FT8 fan (never tried it, no particular inclination to do so) but... FT8 is certainly considered a weak signals mode, in the CW/PSK31 class. Allison KB1GMX: you hit many nails on many heads in a very short space of time. As usual! All agreed :-) 73 Hans G0UPL |
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Re: QRPGuys DSB Digital Transceiver
ajparent1/kb1gmx
Nick,
"Well, I'd like to weigh in and give DSB a little love. It seems to me to be a great way to generate a "phone" signal with minimal circuitry. And the gain you get by going from AM with carrier to DSB is huge. There are various ways of describing it, but when you consider the fact that the peak to average power in speech is maybe 15 dB and the carrier is there all the time, even when you aren't talking, the efficiency gain is big." What???? AM is less efficient than SSB by an easy 9db, the carrier is only there to be an effective BFO do the audio recovery. The carrier is baggage that heats the final all the time you talk. DSB is not AM, the other station still needs a BFO to recover the signal and enough selectivity to reject the other sideband. Thread creep, comment: We are talking about DSB in the CW segment of any band. Not SSB or AM or even DSB in the phone segment of any band. With all that said. IN the space where phone is nominally permitted its all ok. I run AM on the usual watering holes and even 10M for fun. DSB is doable as well there but please be mindful your still as wide as a AM signal carrier or no. I've had people say you can't run AM here (14.286) in the 20M watering hole, and they could not cite band plan or FCC rule prohibiting it other than I was not in the CW space. That last thing is the fact that CW segments are not phone segments and wide signals are at objectionable and in cases likely a rule violation. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: QRPGuys DSB Digital Transceiver
Well, I'd like to weigh in and give DSB a little love. It seems to me to be a great way to generate a "phone" signal with minimal circuitry. And the gain you get by going from AM with carrier to DSB is huge. There are various ways of describing it, but when you consider the fact that the peak to average power in speech is maybe 15 dB and the carrier is there all the time, even when you aren't talking, the efficiency gain is big. I'm not sure why two DSB stations can't work each other, but it's fascinating. My interest in DSB was raised by this web post from KL7R: Whether it's advisable to pass DSB through the HW-8's amplifier chain or not, I don't know, but I admire the way Mike just did it. SSDRA has some example diode balanced modulators for generating DSB in figure 11, page 185. These days I feel like I have to append a bunch of disclaimers after saying I like a certain circuit or design: As a ham and homebrewer, I often build simple circuits for the fun of it. I just want to see 'em work briefly before putting them on the pile and moving on to the next thing. I'm not claiming that the Pixie II, Tuna Tin, 1929 type 27 Blooper or similar items are state of the art or should be part of any ham's "main station". Phone signals wider than SSB should generally be used when bands aren't crowded and/or at low power levels. But I have no beef with those AM enthusiasts out there. No opinion on DSB FT8 except that the same considerations regarding crowding and power levels might apply here as well. 73 & happy modulating, Nick, WA5BDU |
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Re: QRPGuys DSB Digital Transceiver
Mike K5ESS: Yes, no problem with receiving a DSB signal, as long as you are
receiving it on an SSB receiver. It is DSB at both ends which is the problem. As far as I can think of, of all the many modes amateurs send to each other, DSB is the only one where you can't work someone else who also has a DSB transceiver. Bob K5MYJ: If you add a BFO to a general coverage receiver you end up with effectively a DSB receiver, don't you? In which case don't all the same DSB-DSB problems apply? I don't see how it can work at all, let alone sound better than SSB... and regarding modes (this topic is about DSB FT8) I'm not a big FT8 fan (never tried it, no particular inclination to do so) but... FT8 is certainly considered a weak signals mode, in the CW/PSK31 class. Allison KB1GMX: you hit many nails on many heads in a very short space of time. As usual! All agreed :-) 73 Hans G0UPL |
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Re: QRPGuys DSB Digital Transceiver
Bob Macklin
DSB can be received on a GC receiver that has a BFO.
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And it can sound better than SSB. For weak signal stuff you really need CW or maybe something like PSK. I like OLD GC receivers with sliderule dials and TUBES. Bob Macklin K5MYJ Seattle, Wa. "Real Radios Glow In The Dark" ----- Original Message -----
From: "ajparent1/kb1gmx" <kb1gmx@...> To: <[email protected]> Sent: Thursday, October 31, 2019 7:19 PM Subject: Re: [qrp-tech] QRPGuys DSB Digital Transceiver DSB only works if the other guy has SSB RX. Simple as that. Doesn't make any difference what the information is so long as you can ignore the other sideband. The other problem with DSB is if your putting out 5W, 2.5 of it is in the other sideband that only contributes QRM and you don't listen to it. The circuits are simple but the wasted power is high. It is why DSB pops up, gets a little air, and tends to die over the years. Going a small step further makes SSB, filters have gotten cheap, mixers to convert frequencies are simpler and cheap, and the former toughest nut to crack was the VFO is now replaced by a simple and flexible digital system that is cheap. No excuses that made it harder exist anymore. If for any reason superhet system is complicated then phasing using analog components you can easily make a SSB receiver (QCX for example) and the circuits if turned around in the TX direction also makes good SSB. I think Juma is the only one that did a tranceiver that way commercially. However many hobbyists have done it (at least me) and it works well. Again the VFO that was a pain before is now replaced by a very good digital system just like the one in QCX. Oh, if full analog is not interesting, the computer can do the analog part digitally and pump it into the required hardware and Viola SoftRock RX/TX. Quality SSB, very little RF hardware, and you need to computer anyway. That can do FT-8 and most anything else. SDR! Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: QRPGuys DSB Digital Transceiver
ajparent1/kb1gmx
DSB only works if the other guy has SSB RX. Simple as that. Doesn't
make any difference what the information is so long as you can ignore the other sideband. The other problem with DSB is if your putting out 5W, 2.5 of it is in the other sideband that only contributes QRM and you don't listen to it. The circuits are simple but the wasted power is high. It is why DSB pops up, gets a little air, and tends to die over the years. Going a small step further makes SSB, filters have gotten cheap, mixers to convert frequencies are simpler and cheap, and the former toughest nut to crack was the VFO is now replaced by a simple and flexible digital system that is cheap. No excuses that made it harder exist anymore. If for any reason superhet system is complicated then phasing using analog components you can easily make a SSB receiver (QCX for example) and the circuits if turned around in the TX direction also makes good SSB. I think Juma is the only one that did a tranceiver that way commercially. However many hobbyists have done it (at least me) and it works well. Again the VFO that was a pain before is now replaced by a very good digital system just like the one in QCX. Oh, if full analog is not interesting, the computer can do the analog part digitally and pump it into the required hardware and Viola SoftRock RX/TX. Quality SSB, very little RF hardware, and you need to computer anyway. That can do FT-8 and most anything else. SDR! Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: QRPGuys DSB Digital Transceiver
Hans,
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I don't think there will be any problem decoding a DSB FT8 signal. As an example, if you have your transmitter set to 14.074 and you have WSJT set for transmit at 1 kHz, the upper sideband will occupy a 50 Hz. Segment centered about the 1 kHz. mark on the waterfall display. The lower sideband will occupy a 50 Hz segment that is centered 1 kHz below the lower end of the waterfall display and will be ignored. Correct my thinking if I'm wrong. No argument with the other issues discussed. Mike K5ESS -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Hans Summers Sent: Thursday, October 31, 2019 1:09 AM To: [email protected] Subject: Re: [qrp-tech] QRPGuys DSB Digital Transceiver Hi Todd Of course, your wasted-power argument applies even more to AM thanYes... true! But the topic was DSB not AM or a comparison of every other possible mode and how efficient it is and various other advantages and disadvantages... Yes AM is inefficient and takes too much bandwidth. The advantage of AM is that non-technical non-ham people can tune it easily, hence the suitability for broadcast applications, whereas with SSB we amateurs have to tune accurately to avoid making our QSO correspondent sound like Donald Duck. But at least, an AM station can work another AM station! I think DSB is alone (as far as I can think of) in being the only mode where you can't work another station using the same mode! Therefore it isn't just inefficient and interfering, but also inconsistent [if widely adopted]. Too many unpleasant negative "in"'s hi hi. Steve WB6TNL... additional to what Allison said... if the two DSB stations are perfectly aligned then cancellation will occur; if they are a few Hz off, then what this will mean is, each FT8 tone will be ghosted those few Hz away, at the same amplitude, by its equal and opposite counterpart from the unwanted sideband. Faced with TWO tones to decode this will seriously confuse the FT8 decoder. You might be able to get away with it if the difference is small (a Hz, for example) but then that will probably mess things up due to partial cancellation; and if the difference is more than a few Hz then the FT8 decoder would detect and decode two equal tones where it is only expecting one. Result: no decode, or at the very least, greatly reduced probability of decode. 73 Hans G0UPL |
Randy.AB9GO
Nick Kennedy
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