Need some help please
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Hello all.
I have been working on K2/100 #4684. It worked beautifully in a QSO with my brother on 40m last weekend until the power out went to 0. Doing some troubleshooting with the procedures in the manual this is what I came up with. I started with the receiver and those measurements were within reason. I moved on to Transmitter Basic Voltage checks and recorded these voltages. These are all on the basic K2 with the SSB adapter removed and jumpers for J9 and 10 and C167 installed. D6 Anode on tx - *.25V* D7 Anode on tx - *7.9V* Actual Power Output - *0.3W* I moved on to the ALC voltage checks. Power Control Test - *4.97V *Not even close. ------------------------------------------------------------ Transmit Mixer, Buffer, Band-Pass Filter, T-R Switch * *Xmit Mixer Output - *.212 Vrms* Buffer Output - *1.9 Vrms* Band-Pass Filter Output - *0.056 Vrms *T-R Switch #1 Output - *0.057 Vrms* All way too high. ---------------------------------------------------------------------- Pre-Driver, Driver, PA. Pre-Driver Output - *0.170 Vrms* Driver Input - *0.024 Vrms* Driver Output - *4.07 Vrms* PA Input - Q7 - *.94 Vrms *Q8 - *1.08 Vrms *RF Detector Input - *0.0 Vrms * Not good at all! I checked D9 and it is a 1N5711 and it is installed correctly. ------------------------------------------------------------------------------------ PA Transistor Tests. Both flunk with very low resistances. DMM positive lead on Bases I get about *.65 Ohms* to the collector and emitter. DMM negative lead on Bases I get about *1.7 Ohms *to collector and emitter. I checked the hardware and thermal pads for both Q7 and Q8 and they're all in great shape. No mis-alignments of shoulder washers or thermal pads. No torn thermal pads etc..... Which component or components are bad.? I suspect I'm going to be buying new finals possibly a driver and 1N5711 diode. The voltages are all haywire after the pre-driver Q5. Thanks for your help. -- R. Kevin Stover ACØH Reclaim Your Inbox! http://www.mozilla.org/products/thunderbird _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Has anyone been successful in pushing the K2 beyond the 70 WPM external
keying limit for CW operation? Does it adhere to spec (70 WPM) or differ in practice? Anyone try any hardware or firmware mods to bump up the speed? I'd love for this great high performance CW rig (or even the K1 or KX1, despite the QRPish nature of them) to be able to handle up to 100 WPM. --Andrew, NV1B _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by ac0h
Kevin,
>From the resistance readings on Q7 and Q8 you appear to have shorted final transistors. I'm not certain how it happened, they are quite hardy transistors. If you havn't already, repeat the resistance measurements with the heat sink removed on the chance that you just have a short to the heat sink. Then remove the transistors to confirm that they are indeed shorted - the board resistance readings should be restored to about normal if the finals are indeed the problem. The 'too high' RF voltage readings that you obtained at the transmit mixer, buffer etc. are not a problem - that is the normal reaction of the K2 when it does not sense output power, it just increases the level in an attempt to boost the output higher. You likely do not have a failing D9 - it just does not have any RF to detect, but having an extra on hand is not a big deal. The real challenge will be to determine why they failed - there may be something in the KPA100 input that is not right, or you did not have the base K2 heat sink in contact with the tabs of Q7 and Q8, or ??, just guesses here - but excessive heat is normally the killer of solid state devices, the question is 'how did it get so hot'. 73, Don W3FPR > -----Original Message----- > > Hello all. > > I have been working on K2/100 #4684. > It worked beautifully in a QSO with my brother on 40m last weekend until > the power out went to 0. > Doing some troubleshooting with the procedures in the manual this is > what I came up with. > > I started with the receiver and those measurements were within reason. > I moved on to Transmitter Basic Voltage checks and recorded these > voltages. > These are all on the basic K2 with the SSB adapter removed and jumpers > for J9 and 10 and C167 installed. > > D6 Anode on tx - *.25V* > D7 Anode on tx - *7.9V* > Actual Power Output - *0.3W* > > I moved on to the ALC voltage checks. > > Power Control Test - *4.97V *Not even close. > ------------------------------------------------------------ > Transmit Mixer, Buffer, Band-Pass Filter, T-R Switch > * > *Xmit Mixer Output - *.212 Vrms* > Buffer Output - *1.9 Vrms* > Band-Pass Filter Output - *0.056 Vrms > *T-R Switch #1 Output - *0.057 Vrms* > > All way too high. > ---------------------------------------------------------------------- > Pre-Driver, Driver, PA. > > Pre-Driver Output - *0.170 Vrms* > Driver Input - *0.024 Vrms* > Driver Output - *4.07 Vrms* > PA Input - Q7 - *.94 Vrms > *Q8 - *1.08 Vrms > > *RF Detector Input - *0.0 Vrms * Not good at all! I checked D9 and it > is a 1N5711 and it is installed correctly. > ------------------------------------------------------------------ > ------------------ > PA Transistor Tests. Both flunk with very low resistances. > > DMM positive lead on Bases I get about *.65 Ohms* to the collector and > emitter. > DMM negative lead on Bases I get about *1.7 Ohms *to collector > and emitter. > > I checked the hardware and thermal pads for both Q7 and Q8 and they're > all in great shape. No mis-alignments of shoulder washers or thermal > pads. No torn thermal pads etc..... > > Which component or components are bad.? I suspect I'm going to be buying > new finals possibly a driver and 1N5711 diode. The voltages are all > haywire after the pre-driver Q5. > > Thanks for your help. > > -- > R. Kevin Stover ACØH > > Reclaim Your Inbox! > http://www.mozilla.org/products/thunderbird > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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W3FPR - Don Wilhelm wrote:
> Kevin, > >>From the resistance readings on Q7 and Q8 you appear to have shorted final > transistors. I'm not certain how it happened, they are quite hardy > transistors. > > If you havn't already, repeat the resistance measurements with the heat sink > removed on the chance that you just have a short to the heat sink. Then > remove the transistors to confirm that they are indeed shorted - the board > resistance readings should be restored to about normal if the finals are > indeed the problem. > > The 'too high' RF voltage readings that you obtained at the transmit mixer, > buffer etc. are not a problem - that is the normal reaction of the K2 when > it does not sense output power, it just increases the level in an attempt to > boost the output higher. > > You likely do not have a failing D9 - it just does not have any RF to > detect, but having an extra on hand is not a big deal. > > The real challenge will be to determine why they failed - there may be > something in the KPA100 input that is not right, or you did not have the > base K2 heat sink in contact with the tabs of Q7 and Q8, or ??, just guesses > here - but excessive heat is normally the killer of solid state devices, the > question is 'how did it get so hot'. > > 73, > Don W3FPR > > Thanks for the reply Don, I sent the same mail to Elecraft and got pretty much the same reply. I have no idea how they got smoked. I've never transmitted with the rig without the heat sink, as far as I know. It could be that the finals never made very good contact with the heatsink. Maybe Elecraft should consider a spacer of some sort to make sure the tabs of those transisitors are flat and parallel with the heatsink before they get soldered. Aftre taking the hardware apart this morning and lloking closely, the shoulder washer on Q7 seems to have been overheated and melted slightly. It didn't want to come out of the tab. How much lead length should you have on the top side of the board when Q7 and Q8 are installed correctly? Thanks. -- R. Kevin Stover ACØH Reclaim Your Inbox! http://www.mozilla.org/products/thunderbird _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Andrew Moore-4
On Feb 22, 2005, at 11:43 AM, Andrew Moore wrote: > Has anyone been successful in pushing the K2 beyond the 70 WPM external > keying limit for CW operation? At 60 wpm, each element is 20 ms long. Given a 5 ms rise and fall time (assuming you've made the key-click mod), that's only 10ms of full-power signal. Going much faster than this may be impractical. Certainly the initial element is going to get clipped severely, and the K2 does not support CW PTT to prevent this. (This is probably a good request for the next revision of firmware -- but it would mean the internal keyer would be disabled) 100 wpm, elements are only 12 ms long - barely 2 ms at full output. At that speed, I'd begin to wonder about the group delay response of the remote receiver's filters.... > Does it adhere to spec (70 WPM) or > differ in practice? Anyone try any hardware or firmware mods to bump > up > the speed? I'd love for this great high performance CW rig (or even > the > K1 or KX1, despite the QRPish nature of them) to be able to handle up > to > 100 WPM. Here's my question - what person can copy 100 wpm? Only a handful of people in the world can copy 60 wpm! If this is meant for machine copy, then perhaps it is time to look at the lesson learned by the early HF RTTY users in the 1950s. At the time, FSK wasn't legal. These guys were running RTTY using OOK. It worked, but copy was poor. In theory, FSK has a 2 dB advantage over OOK in the presence of Gaussian noise. PSK has an additional 2 dB advantage over FSK. The bottom line -- if you are looking to run a 100 wpm data link on HF, there are a lot more robust methods of modulation than OOK - CW. FSK is gobs better, and you can run it up to 300 baud (using CW keying between mark and space, this would be 360 wpm, as 60 wpm is 50 baud) Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email] Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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> Here's my question - what person can copy 100 wpm? Only a handful of
> people in the world can copy 60 wpm! I'd guess it's a larger group than you might think -- though I'd agree those folks are few and far between. I've run into a handful than can copy 100, and I remember about 10 years ago I was in disbelief when a guy on a 2m repeater told me he could do over 100, so I put him on the spot and cranked up my computer's CW speed to 100, asked him a question in CW over the repeater, and he answered. Holy cow. > The bottom line -- if you are looking to run a 100 wpm data link on HF Nope, this is for copy in the head. For some reason when I listen to folks QSO at 60 or 70 or higher, it just gets me really motivated, and all the enjoyment I experienced when I started fiddling with radios comes right back again (i.e., "you mean you can talk to someone on the other side of the world, in real time, with less power than it takes to light a 10 watt bulb?!) It's great stuff. Having a machine copy it takes *all* the magic away for me. Sending of course needs a keyboard. Anyway, thanks for the comments, particularly the timing stuff. You really do need to be sending to someone with a very capable receiver. (hmm... hopefully a K2). You bring up a good point about a firmware PTT tweak -- it doesn't sound like a horribly complicated thing to implement, but then again, I don't know anything about the K2's firmware. I wonder if one could just hack the hardware to somehow keep TX engaged, even if it means manually throwing a switch -- equivalent to the PTT method but instead going right to the hardware. After all, we have the schematics (er, or I will once I order my new K2! :) Thanks, --Andrew, NV1B .. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Andrew Moore-4
> 100 wpm, elements are only 12 ms long - barely 2 ms at full > output. At that speed, I'd begin to wonder about the group > delay response of the remote receiver's filters.... I once asked about this on the Ten Tec reflector during a discussion of high speed CW, but some of the high-speed guys there assured me that they routinely copied 100 wpm without apparently being bothered by filter effects. I had a hard time believing this. They must use pretty wide filters to avoid the ringing or group delay effects that you mention, Bill. But they really didn't tell me for sure. > Here's my question - what person can copy 100 wpm? Only a handful of > people in the world can copy 60 wpm! > You and I think alike... this was my exact next question to the guys. But again, they just sort of shrugged me off and never indicated that they thought they were pushing any limit of human ability. In fact, one guy told me that there is an entire group of folks who gets together on 40 meters at 100+ wpm! Around 7032 if I remember correctly. I've never heard them. At this speed Ted McElroy's world record, set back in the 1930s, should be threatened, but I don't know what is up with that. I believe-- though I am not sure-- that actually writing down (or typing) what you copy is really difficult at that speed. In other words, it is actually easier to simply copy in the head. McElroy's greatest achievement was evidently being able to produce a hard copy of what he heard. Regards, Al W6LX _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Bill Coleman-2
When I was a novice, Cecil WA5SFZ, could copy 60WPM on a Mill, which was
a typewriter version of a RTTY keyboard (all uppercase). Cecil smoked a pipe, a habit he picked up when copying news for press agencies (UPI?), as one of the perks of the job was free pipe-lighting service to keep the operators hands always on the keyboard. On Tue, 22 Feb 2005 10:05 am, Bill Coleman wrote: > Here's my question - what person can copy 100 wpm? Only a handful of > people in the world can copy 60 wpm! _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Andrew Moore-4
Andrew, NV1B wrote:
I've run into a handful than can copy 100, and I remember about 10 years ago I was in disbelief when a guy on a 2m repeater told me he could do over 100, so I put him on the spot and cranked up my computer's CW speed to 100, asked him a question in CW over the repeater, and he answered. Holy cow. ----------- He ought to get hold of Guinness and a few others and claim his fame. As the record books stand today, the world's record for code reception "by ear" was set on July 2, 1939 by Ted R. McElroy, giving him the title of Official Champion Radio Operator at the Asheville Code Tournament in North Carolina. The latest information I can find says that his record of 75.2 wpm has stood ever since. That's "head copy" of course. When the test began, McElroy is reported to have astounded the audience by calmly sipping a cup of coffee then lighting an cigarette while the transmission blasted away before sitting down at the mill (typewriter with all cap letters specifically for copying CW). Then he is reported to have kept typing 15 minutes after the transmission ended to finish transcribing the entire text. Obviously, a good memory was helpful! I'm a little surprised that McElroy's official record hasn't been challenged. Is anyone out there aware of any official records kept today? Guinness doesn't seem to list a CW record. As others pointed out, the K2 is designed with a specific rise and fall time when keying CW that keeps the bandwidth occupied to a minimum at typical keying speeds, but which begins to limit the efficiency and readability of CW at super-high speeds. That's pretty typical of modern "CW" rigs. High speed CW (HSCW) is, as far as I've read, all done via SSB. That is, the rig isn't keyed, but the CW is sent by a tone injected into the audio (microphone) input of an SSB rig. That produces a "CW" signal consisting of a single transmitted frequency, since no carrier and only one sideband is transmitted. The transmit frequency is offset from the carrier by the frequency of the modulating tone. Computers are used to generate the keyed CW tone and record the received signals. Live operators still read the stuff, but only after it's been slowed down to a suitable "human" speed. This CW sometimes gets to astronomical speeds. A "ping" of signal produced by a meteor trail often is less than one second, but complete exchanges are sometimes done in a ping or two! Even slowed down, it's not easy copy usually. Mega-warble, noise and fragmentary bits of signal way below the noise level make copy at least as much a challenge as any other mode. The greater than 2 kHz bandwidth of a SSB rig is adequate to pass the keying and sidebands produced by HSCW. Instead of sidebands some tens of Hz from the carrier like most of us generate keying our K1's, K2's and KX1's in CW mode, high speed CW sidebands can extend several hundred Hz out from the "carrier" (modulating) frequency. The keying speeds, in words per minute, run from 100 to 800 wpm, typically, although I've heard of speeds up to 3,200 wpm (16,000 characters per minute) being used. A K2 with the SSB option is certainly capable of doing it. Just add an Elecraft XV transverter and join the meteor scatter crowd straining for pings... Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Andrew Moore-4
On Feb 22, 2005, at 1:16 PM, Andrew Moore wrote: >> Here's my question - what person can copy 100 wpm? Only a handful of >> people in the world can copy 60 wpm! > > I'd guess it's a larger group than you might think -- though I'd agree > those folks are few and far between. I've run into a handful than can > copy 100, and I remember about 10 years ago I was in disbelief when a > guy on a 2m repeater told me he could do over 100, so I put him on the > spot and cranked up my computer's CW speed to 100, asked him a question > in CW over the repeater, and he answered. Holy cow. Color me skeptical. I wonder if it is a "mind reading" trick. I wonder how accurate a computer sending CW would be at 100 wpm -- or how well it would sound passing through a repeater. The highest official CW speed was about 74 wpm, a record that was set decades ago and never overturned. If there's so many people who can copy north of 60 wpm, why has this record never been broken? >> The bottom line -- if you are looking to run a 100 wpm data link on HF > > Nope, this is for copy in the head. For some reason when I listen to > folks QSO at 60 or 70 or higher, it just gets me really motivated, and > all the enjoyment I experienced when I started fiddling with radios > comes right back again Where are these 60 wpm and higher operators? The highest speed CW I hear is just north of 40 wpm -- during contests. I knew a couple of blind hams who ran the WV Novice Net almost three decades ago. They'd plug along at 5 wpm, close the net, then crank their keyboards to 50 wpm and have a QSO right there. But that's 50 wpm, not 70. > You bring up a good point about a firmware PTT > tweak -- it doesn't sound like a horribly complicated thing to > implement, but then again, I don't know anything about the K2's > firmware. It's something that's been brought up often enough by contesters. Whenever the next firmware revision comes out, it's something to anticipate. > I wonder if one could just hack the hardware to somehow keep TX > engaged, > even if it means manually throwing a switch -- equivalent to the PTT > method but instead going right to the hardware. After all, we have the > schematics (er, or I will once I order my new K2! :) There is a modification to do this, implementing CW PTT: <http://www.qsl.net/w3fpr/ptt_input_for_the_elecraft_k2.htm> Bill Coleman, AA4LR, PP-ASEL Mail: [hidden email] Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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> Color me skeptical. I wonder if it is a "mind reading" trick. I wonder
> how accurate a computer sending CW would be at 100 wpm -- or how well > it would sound passing through a repeater. Not mind reading (he corrected me on my grammar too), nor machine copy (what are the chances he happened to have a CW reader then and there, or that the repeater and his own rx didn't distort such a high speed signal to the point at which a machine couldn't copy?) Copy at 100 isn't like at 20 or 25 where you copy 100%. I don't think these guys are necessarily copying (or even trying to copy) 100% at these rates -- just enough to carry on a conversation. At these rates the entire conversation is more -- well, conversational -- less rigid, more fluid and spontaneous, "seat of the pants" sort of stuff. It's just amazing to listen to them. Tom (Chester), W4BQF, is a good example. Frequently on 40m flying along at over 70. He's not the only one, just the one I hear most often. Given the number of people I've heard who can do 50 to 70 with ease, what I find hard to believe is that 74 is the official record. Maybe they mean 74 with the ability to reproduce it, 100%, on paper. At speeds of 75 or more, I don't know that there's an easy way to prove you hear what you hear. The best way I can see is to simply have a long conversation with someone at that rate, and the proof will be in the pudding, or however that saying goes. It will quickly become obvious whether or not the op is copying for real. > decades ago and never overturned. If there's so many people who can > copy north of 60 wpm, why has this record never been broken? I'd like to know! Again I suspect it's because of the way they determine "success." > Where are these 60 wpm and higher operators? The highest speed CW I > hear is just north of 40 wpm -- during contests. They seem to be centered around 7.030 to 7.033 kHz in the evenings. The "Chicken Fat Operators" (CFO), a bunch of high speed ops, used to be very active there, but activity has died down alot starting around 10 years ago, about the time I got hooked on high speed and joined them. They're still out there though. Their roster must be over 1,000 members by now. I think about the only requirement for joining up was that you could carry on a QSO at 40 wpm or higher. Proof was by getting on the air with two members and QSO'ing with them in this manner. I'm just getting back HF after a while off (having kids will do that to you; where did the time (and money) go?!), and one of my priorities, if not my highest, is to get the speed back up (when I went inactive last, it was somewhat comfortable around 50 to 55, pushing at 60, and liked to practice at 70). One thing for sure, it does take practice. It's real, and it's possible, and more important, it's a blast. Way more fun than Thanks for pointing me to the PTT mod -- I took a look. Really need to order my K2... _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Ron D'Eau Claire-2
...
> have astounded the audience by calmly sipping a cup of coffee then lighting > an cigarette while the transmission blasted away before sitting down at the > mill (typewriter with all cap letters specifically for copying CW). Then he > is reported to have kept typing 15 minutes after the transmission ended to > finish transcribing the entire text. I suspect that's exactly why the "official" record stands -- these guys aren't transcribing -- just conversing -- which, from what I know about them, is much more the point rather than boasting (no disrespect intended to McElroy -- quite an achievement on his part). > High speed CW (HSCW) is, as far as I've read, all done via SSB. That is, the > rig isn't keyed, but the CW is sent by a tone injected into the audio > (microphone) input of an SSB rig. That produces a "CW" signal consisting of > a single transmitted frequency, since no carrier and only one sideband is > transmitted. This sounds interesting. I've never heard much about it. Are high speed CW ops using this in lieu of "the real thing" to get around rigs' limitations? Since it's on SSB, I assume it's not legal down in the conventional CW portion of the band. It sounds like it could be an easy way for QRQ CW to operate from any rig in the 70 to 100 range, or so. --Andrew, NV1B .. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Andrew Moore-4
In a message dated 2/22/2005 2:51:15 PM Eastern Standard Time, Bill Coleman <[hidden email]> writes:
>On Feb 22, 2005, at 1:16 PM, Andrew Moore wrote: >The highest official CW speed was about 74 wpm, a record >that was set >decades ago and never overturned. If there's so many people >who can >copy north of 60 wpm, why has this record never been broken? That was a record for hard copy - McElroy pounded out the copy on a *manual* typewriter! "Head copy" is a different animal. The folks who can copy 80-100 wpm or whatever aren't pounding keyboards with every received letter; they're listening to the code like someone talking. How fast can the average person carry on a verbal conversation vs. transcribing one? In highspeed contest operation, you're only looking for information in bursts - usually just call and report, maybe section/country. What McElroy was doing was for minutes at a time. -- For comparison, consider the test for US Navy Radioman "A" class (IIRC) circa 1958: 24 wpm 5 character code groups, copied on a manual typewriter (mill). Passing grade was a maximum of 3 errors. In an hour. 73 de Jim, N2EY _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Andrew Moore-4
Andrew Moore wrote:
> > > This sounds interesting. I've never heard much about it. Are high > speed CW ops using this in lieu of "the real thing" to get around rigs' > limitations? Since it's on SSB, I assume it's not legal down in the > conventional CW portion of the band. It sounds like it could be an easy > way for QRQ CW to operate from any rig in the 70 to 100 range, or so. > > --Andrew, NV1B Most software for the digital modes include both "sound card" CW and hard keyed CW. You can't tell the difference on the air unless the op doesn't know the sidetone frequncy of his rig and has the frequency in the software set wrong. There won't be any QSK with "sound card CW" either. Up until I built a keying interface for my TS-520 thats how I ran CW. Hamscope or MixW and a rigblaster. Another happy benefit of audio injected CW, really afsk, is that there are no key clicks to be heard and you don't have to worry about rise and fall times of the keying waveform. -- R. Kevin Stover ACØH Reclaim Your Inbox! http://www.mozilla.org/products/thunderbird _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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On Tue, 2005-22-02 at 14:59 -0600, R. Kevin Stover wrote:
> Another happy benefit of audio injected CW, really afsk, is that there > are no key clicks to be heard and you don't have to worry about rise and > fall times of the keying waveform. Wouldn't that depend on the audio waveform fed into the SSB transmitter? I would expect an audio signal with small rise and fall times and/or poor waveform shaping would still cause keyclicks. Am I wrong, and if so, why? -- 73, Brian VE7NGR _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Andrew Moore-4
Andrew, NV1B, wrote:
This sounds interesting. I've never heard much about it. Are high speed CW ops using this in lieu of "the real thing" to get around rigs' limitations? Since it's on SSB, I assume it's not legal down in the conventional CW portion of the band. It sounds like it could be an easy way for QRQ CW to operate from any rig in the 70 to 100 range, or so. ------------------ It's legal CW even though it's generated in SSB mode since only the single frequency is transmitted, but I doubt if real HSCW be welcome (or legal) on the HF CW bands because of the bandwidth. A CW signal, like any signal, has sidebands that occupy a bandwidth directly proportional to the data rate. If a CW signal is received on a too-narrow filter, the keying is lost: either the signal appears as steady noise or a steady tone ('ultimate' filter ringing!). For a normal CW transmission at some tens of WPM the bandwidth needed is very small - only in the tens of Hz or less. HSCW at hundreds of words per minute can require hundreds of Hz of bandwidth. That is on a receiver using conventional CW filters it'd be heard as a strange tone with very noisy, wide sidebands extending a long way on both sides of the carrier frequency! The keying may not be at all evident. But for something in the middle, >50 WPM and up, keying a tone into the mic jack in SSB mode may be the way to go to avoid the shaping built into the rig. The K2 lets you define the receive filters separately from the transmit filter in SSB, so you can still have the flexibility of the K2's selectable receive CW filters while transmitting using a keyed tone in SSB mode. If you get really interested in pursuing it after you build your K2, jump on here or contact elecraft directly. Wayne, the principal designer for the K2, is always interested in new mods and uses for the rig and he's quick to offer help and advice. There are a number of very talented and experienced engineers on the reflector here who have contributed greatly to the development of improvements for the K2 over the years who may be able to offer their help as well. The support you get is one of the most valuable benefits of owning an Elecraft rig. The only possible issue I can think of is that in SSB mode, the frequency display is the carrier frequency. So, if you tuned it up on 7030.00 kHz and used a 500 Hz tone to key the rig, the actual transmit frequency would be 500 Hz above or below the displayed xmit frequency - that is either 7029.05 or 7030.05 kHz, depending upon which sideband you are using. The K2 has RIT and full SPLIT operation, so you can adjust the receiver tuning independently of the transmit frequency, so that shouldn't be a serious issue. I am certain that McElroy's record is for solid hard copy. That was back in the days when a human being was an essential part of a manual "RTTY" or "TOR" system designed for precise hard copy. The human's job was to convert the sounds in the phones into precise strokes on the keys to make the right letters! "Head copy" was not considered a very useful achievement. It'd be interesting to see verifiable demonstrations of the sort of speeds that are being achieved without hard copy. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by ac0h
R. Kevin Stover wrote:
> Another happy benefit of audio injected CW, really afsk, is that there > are no key clicks to be heard and you don't have to worry about rise and > fall times of the keying waveform. The extent of the sidebands (and therefore the rise/fall times and the maximum speed that can be transmitted) are limited by the width of the ssb filter. A signal generated this way can be quite clicky -- I would consider a 3 KHz wide CW signal way too wide. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Vic wrote:
The extent of the sidebands (and therefore the rise/fall times and the maximum speed that can be transmitted) are limited by the width of the ssb filter. A signal generated this way can be quite clicky -- I would consider a 3 KHz wide CW signal way too wide. ------------- Yeah! On the CW bands at least. Some of the HSCW might need that! You bring up a good point I missed in my reply earlier. If using keyed audio to produce CW, then the waveform produced by the keying source is very important to avoid clicks. Kevin Stover said "...audio injected CW, really afsk,..." Isn't afsk really audio frequency-shift keying as commonly used for RTTY on VHF? The signal produced by a well-adjusted SSB rig with a pure keyed tone injected will be pure CW, undetectable from any other CW signal. The things to be concerned about to achieve that, other than a decent keying waveform on the audio signal, are adequate carrier and opposite sideband suppression. On the CW bands, any carrier or other sideband leak would be simply a "spurious" emission and would have to meet all the FCC requirements for the level of such emissions. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Ron D'Eau Claire-2
>The only possible issue I can think of is that in SSB mode, the frequency
>display is the carrier frequency. Well ... I would caution folks to be careful, I can think of a few other Part 97 problems when generating CW (in a CW sub-band) feeding keyed audio into an SSB transmitter. A "pure" audio sine wave into a zero-distortion, zero noise SSB Tx chain will indeed generate a single frequency signal if the carrier is suppressed so to non-existence. Unfortunately, carriers are not totally suppressed, Tx SSB generation chains are not distortionless and noiseless, audio oscillators (and sound cards) do not always produce exact sine waves, often there is low level hum in all the coupling circuitry, and, unless you start and stop the sine wave exactly at a zero crossing, you will generate some strange stuff that might not qualify as 0.1A1 emissions (or whatever it is called today - I guess I show my age). My laptop's soundcard with MixW and the RigBlaster seems to generate acceptable RTTY despite all of this because there are sidebands around the two tones as a result of the FSK. All of the undesired products are in there too, but it seems to pass the "Part 97 test" for RTTY. QUESTION: At 600 Hz (the default K2 sidetone?), the period of one cycle is 1.667 ms. How many cycles does it take for the normal human ear (that would not include either of mine! to distinguish a dot from a dash? I think the second ticks on WWV are 5 cycles of a 1KHz signal in length? Fred K6DGW Auburn CA CM98lw Ron D'Eau Claire wrote: > > Andrew, NV1B, wrote: > This sounds interesting. I've never heard much about it. Are high speed CW > ops using this in lieu of "the real thing" to get around rigs' limitations? > Since it's on SSB, I assume it's not legal down in the conventional CW > portion of the band. It sounds like it could be an easy way for QRQ CW to > operate from any rig in the 70 to 100 range, or so. > > ------------------ > deleted </conservebandwidth> _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Ron D'Eau Claire-2
> > Kevin Stover said "...audio injected CW, really afsk,..." > > Isn't afsk really audio frequency-shift keying as commonly used for RTTY on > VHF? > > The signal produced by a well-adjusted SSB rig with a pure keyed tone > injected will be pure CW, undetectable from any other CW signal. The things > to be concerned about to achieve that, other than a decent keying waveform > on the audio signal, are adequate carrier and opposite sideband suppression. > On the CW bands, any carrier or other sideband leak would be simply a > "spurious" emission and would have to meet all the FCC requirements for the > level of such emissions. > > Ron AC7AC > > AFSK is audio-frequency-shift keying and that's what the majority of Hams using the sound card for RTTY on HF are using. Check me if I'm wrong but if the sound card produces a pure sine wave audio signal of say 600Hz how would you distinguish that from a hard keyed CW signal unless it's got harmonics spread out over the 2.5Khz audio bandpass? How do the rise and fall times of the SSB and CW waveforms compare? Isn't SSB, even with VOX delay turned all the way down, a lot slower than CW? If the SSB rise and fall times are slower than CW how do you get clicks? I would agree that nobody in their right mind would cut loose with 800wpm HSCW on the HF bands becasue of the bandwidth used. I can't remember the old formula for figuring the bandwidth for CW signals of any arbitary speed. -- R. Kevin Stover ACØH Reclaim Your Inbox! http://www.mozilla.org/products/thunderbird _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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