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Electronics"},"subtitle":{"type":"html","$t":""},"link":[{"rel":"http://schemas.google.com/g/2005#feed","type":"application/atom+xml","href":"https:\/\/la3za.blogspot.com\/feeds\/posts\/default"},{"rel":"self","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/-\/QRP?alt=json-in-script\u0026max-results=5"},{"rel":"alternate","type":"text/html","href":"https:\/\/la3za.blogspot.com\/search\/label\/QRP"},{"rel":"hub","href":"http://pubsubhubbub.appspot.com/"},{"rel":"next","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/-\/QRP\/-\/QRP?alt=json-in-script\u0026start-index=6\u0026max-results=5"}],"author":[{"name":{"$t":"Sverre Holm"},"uri":{"$t":"http:\/\/www.blogger.com\/profile\/08306221557326542499"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"26","height":"32","src":"\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEirIUQ4__tBn8iuiGzcRlJEOroeUKkNCZ2mN2DM3rs_2pPUFGIs7a2EtYWIiOikqsFchk8w4XaHx_XyS1g_-i8Kmu46zrppNaF1Xeh-omtKQqjq9tEzjhEobips8DmSvw\/s1600\/sverreholm20.jpg"}}],"generator":{"version":"7.00","uri":"http://www.blogger.com","$t":"Blogger"},"openSearch$totalResults":{"$t":"18"},"openSearch$startIndex":{"$t":"1"},"openSearch$itemsPerPage":{"$t":"5"},"entry":[{"id":{"$t":"tag:blogger.com,1999:blog-2554001380039969960.post-1293514117370270407"},"published":{"$t":"2022-06-23T12:16:00.015+02:00"},"updated":{"$t":"2022-09-12T10:25:53.952+02:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"antenna tuner"},{"scheme":"http://www.blogger.com/atom/ns#","term":"QRP"}],"title":{"type":"text","$t":"Reversing the inductor in the Chinese QRP antenna tuner makes all the difference"},"content":{"type":"html","$t":"\u003Cp\u003E\u003C\/p\u003E\u003Cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003E\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEh2FgtklX5g5nbVzGJmItzxCK1CnqRuB6seFB_W97JZC34B46zWzH2tRZsmh5FuwcuahPRQ-RB09Va6rdrinBxqNfwtL7m4iG61qxWNVJEWj-a3JDZ8Y6pNjJpxvFyfgO3YIuvQ5sCBOcZ8DjzaA5dEx6NaSWRkRd2I4izAQLh4cG3Ko77-dCR10qDz\/s4001\/ChinaTunerLA3ZA.jpg\" style=\"clear: right; float: right; margin-bottom: 1em; margin-left: 1em;\"\u003E\u003Cimg border=\"0\" data-original-height=\"2767\" data-original-width=\"4001\" height=\"221\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEh2FgtklX5g5nbVzGJmItzxCK1CnqRuB6seFB_W97JZC34B46zWzH2tRZsmh5FuwcuahPRQ-RB09Va6rdrinBxqNfwtL7m4iG61qxWNVJEWj-a3JDZ8Y6pNjJpxvFyfgO3YIuvQ5sCBOcZ8DjzaA5dEx6NaSWRkRd2I4izAQLh4cG3Ko77-dCR10qDz\/s320\/ChinaTunerLA3ZA.jpg\" width=\"320\" \/\u003E\u003C\/a\u003E\u003C\/div\u003ELike many I was disappointed with the Chinese antenna tuner kit \"QRP manual days\" back in 2014 and I never really got it to work.\u0026nbsp;\u003Cp\u003E\u003C\/p\u003E\u003Cp\u003EThat was even after I had replaced the two polyvaricon capacitors. The two screws for mounting each of the variable capacitors were too long. The result was that they interfered with the moving plates of the capacitor and I ruined both of them. There was no warning of this in the manual, so beware anyone who buys this kit.\u003C\/p\u003E\u003Cp\u003EDespite fixing this, it didn't really tune anything. I later learned that it probably works for low bands like 80 m as it is, but I didn't notice that. I thought maybe the toroid core of the inductor was of inferior quality, but never really investigated it, so it sat unused on the shelf for 7-8 years.\u003C\/p\u003E\u003Cp\u003E\u003Cspan\u003E\u003C\/span\u003E\u003C\/p\u003E\u003Ca name='more'\u003E\u003C\/a\u003ERecently, however I learnt that there is an error in the instructions which makes all the difference: The order of the taps in the inductor should be reversed. In this way, one can get the small inductance value consisting of only a single turn at position A of the rotary switch. Prior to this fix, the inductor starts with 10 turns at position A, and this is too much except for the lower bands like 80m.\u0026nbsp;\u003Cp\u003E\u003C\/p\u003E\u003Cp\u003EThis is explained in this video by \u003Ca href=\"https:\/\/www.youtube.com\/watch?v=JceLhTV28oI\" target=\"_blank\"\u003EKP4MD, Carol, from 7 July 2021\u003C\/a\u003E starting from about 10 minutes. The particular frame that shows this is reproduced here also.\u003C\/p\u003E\u003Cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003E\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEgoOwo99HOseVt6f0_syGdOIY95_K4ObFaHxx5cH03uZ55iLKzw6qx-Pez4AedFBsgRH4g1GXdSbsSm9_QOk6dN47XdwTkG3AYpKv2gVy3XiSy4WoXo2_fnjr9nNbMUJndq8xpUkUSeDYlWk4uJosLf57nzJyx4PyZEZCh_E-Yw-C2jzAd5ljOdnxAf\/s1600\/ChineseATU-ReverseCoil.jpg\" style=\"margin-left: 1em; margin-right: 1em;\"\u003E\u003Cimg border=\"0\" data-original-height=\"1200\" data-original-width=\"1600\" height=\"300\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEgoOwo99HOseVt6f0_syGdOIY95_K4ObFaHxx5cH03uZ55iLKzw6qx-Pez4AedFBsgRH4g1GXdSbsSm9_QOk6dN47XdwTkG3AYpKv2gVy3XiSy4WoXo2_fnjr9nNbMUJndq8xpUkUSeDYlWk4uJosLf57nzJyx4PyZEZCh_E-Yw-C2jzAd5ljOdnxAf\/w400-h300\/ChineseATU-ReverseCoil.jpg\" width=\"400\" \/\u003E\u003C\/a\u003E\u003C\/div\u003E\u003Cbr \/\u003E\u003Cp\u003EWhat I did was to desolder all 12 or so connections from the inductor to the rotary switch - be careful not to melt the plastic around the switch contacts. I actually did that and had to disassemble it in order to get it back in working order. Then I unwound the wire from the toroid core and rewound it in the opposite direction. And then resoldered it back.\u003C\/p\u003E\u003Cp\u003EThat made the trick, now it tunes 20 m also!\u003C\/p\u003E\u003Cp\u003EBy the way, the odd name for this tuner seems to be a \u003Ca href=\"http:\/\/m1kta-qrp.blogspot.com\/2014\/05\/comments-on-chinese-atu.html\" target=\"_blank\"\u003Emistranslation from Chinese. It should have been the more prosaic \"Manual antenna tuner kit\".\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cbr \/\u003E\u003C\/p\u003E"},"link":[{"rel":"replies","type":"application/atom+xml","href":"https:\/\/la3za.blogspot.com\/feeds\/1293514117370270407\/comments\/default","title":"Post Comments"},{"rel":"replies","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2022\/06\/reversing-inductor-on-chinese-qrp.html#comment-form","title":"2 Comments"},{"rel":"edit","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/1293514117370270407"},{"rel":"self","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/1293514117370270407"},{"rel":"alternate","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2022\/06\/reversing-inductor-on-chinese-qrp.html","title":"Reversing the inductor in the Chinese QRP antenna tuner makes all the difference"}],"author":[{"name":{"$t":"Sverre Holm"},"uri":{"$t":"http:\/\/www.blogger.com\/profile\/08306221557326542499"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"26","height":"32","src":"\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEirIUQ4__tBn8iuiGzcRlJEOroeUKkNCZ2mN2DM3rs_2pPUFGIs7a2EtYWIiOikqsFchk8w4XaHx_XyS1g_-i8Kmu46zrppNaF1Xeh-omtKQqjq9tEzjhEobips8DmSvw\/s1600\/sverreholm20.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEh2FgtklX5g5nbVzGJmItzxCK1CnqRuB6seFB_W97JZC34B46zWzH2tRZsmh5FuwcuahPRQ-RB09Va6rdrinBxqNfwtL7m4iG61qxWNVJEWj-a3JDZ8Y6pNjJpxvFyfgO3YIuvQ5sCBOcZ8DjzaA5dEx6NaSWRkRd2I4izAQLh4cG3Ko77-dCR10qDz\/s72-c\/ChinaTunerLA3ZA.jpg","height":"72","width":"72"},"thr$total":{"$t":"2"}},{"id":{"$t":"tag:blogger.com,1999:blog-2554001380039969960.post-7162961718702131322"},"published":{"$t":"2019-09-14T17:15:00.000+02:00"},"updated":{"$t":"2019-09-16T22:36:46.146+02:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Morse"},{"scheme":"http://www.blogger.com/atom/ns#","term":"QRP"}],"title":{"type":"text","$t":"QRPGuys LA3ZA Zero Beat Indicator"},"content":{"type":"html","$t":"\u003Ctable cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"float: right; margin-left: 1em; text-align: right;\"\u003E\u003Ctbody\u003E\n\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEiWfo-F0O-5Qj7vivQWg-GtGKji_KqLWuLnj5DeGQZwcmQWqZhke57JBcXzdRo_i1p7SHUbJGaaz6pp87Vw8u9wrEtXIGfaXU_cf1INlmWHnxS2LY9q-RXo6z8GPIFhhAjqcVkhD_xKoRI\/s1600\/LA3ZA-QRPGuys.jpg\" imageanchor=\"1\" style=\"clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;\"\u003E\u003Cimg border=\"0\" data-original-height=\"600\" data-original-width=\"753\" height=\"254\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEiWfo-F0O-5Qj7vivQWg-GtGKji_KqLWuLnj5DeGQZwcmQWqZhke57JBcXzdRo_i1p7SHUbJGaaz6pp87Vw8u9wrEtXIGfaXU_cf1INlmWHnxS2LY9q-RXo6z8GPIFhhAjqcVkhD_xKoRI\/s320\/LA3ZA-QRPGuys.jpg\" width=\"320\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\n\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EImage: \u003Ca href=\"http:\/\/qrpguys.com\/\" target=\"_blank\"\u003EQRPGuys.com\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\n\u003C\/tbody\u003E\u003C\/table\u003E\nSome time ago QRPGuys approached me and asked if they could make the low-power zero-beat indicator\u0026nbsp;that I made many years ago available as a kit. I was surprised and very honored by this request. It's been available from them for a while now and here is a description from their page:\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003Cblockquote class=\"tr_bq\"\u003E\n\u003Ci\u003EThe QRPGuys LA3ZA Zero Beat Indicator gives you a visual indication when you are tuned to the callers frequency, based on the tone of the received signal you hear on your transceiver. The theory is simple. The device takes into account the amount of built-in offset your transceiver has, usually around 300-800Hz, and illuminates an led when it detects that specific tone you hear when you are tuned to transmit on the callers specific frequency.\u003C\/i\u003E\u003Cbr \/\u003E\n\u003Ca name='more'\u003E\u003C\/a\u003E\u003C\/blockquote\u003E\n\u003Cblockquote class=\"tr_bq\"\u003E\n\u003Ci\u003EIt incorporates a CMOS LMC567 Tone Decoder IC that compares the audio tone you are receiving to a calibrated tone you determine during the setup, then illuminates an LED when that frequency is met. The board can be used outboard with the 3.5mm audio jack with it’s self-contained battery supply or mounted inside in a smaller configuration, and run from any 2.0V – 9.0V max. source from inside the transceiver using the auxiliary audio input. It is a low power device and uses less than 1mA to power the circuitry. The device will detect and respond to a\u0026nbsp; tone of ~300-1000Hz.\u003C\/i\u003E\u0026nbsp;\u003C\/blockquote\u003E\n\u003Cblockquote class=\"tr_bq\"\u003E\n\u003Ci\u003EA web search will show these devices have been around for a number of years and Sverre, LA3ZA, upgraded an older TTL design to CMOS technology and has given us permission to provide it as a kit.\u003C\/i\u003E\u003C\/blockquote\u003E\n\u003Cbr \/\u003E\nMy original circuit is in the post \u003Ca href=\"http:\/\/la3za.blogspot.com\/2002\/04\/qrp-zero-beat-indicator-for-elecraft-k2.html\" target=\"_blank\"\u003EQRP Zero-beat indicator for the Elecraft K2\u003C\/a\u003E\u0026nbsp;(2002), and a revised one in the post \u003Ca href=\"http:\/\/la3za.blogspot.com\/2009\/09\/k2-fixed-level-audio-output.html\" target=\"_blank\"\u003EK2 Fixed Level Audio Output\u003C\/a\u003E\u0026nbsp;(2009). The main difference from the kit version is that I have 220 ohms in series with 470 uF from the output pin 8 to ground. It adds a little hang to the LED light making it less agile. This is something I found more pleasing to look at, but which QRPGuys decided to skip. My zero-beat indicator in action can be seen in this \u003Ca href=\"https:\/\/www.youtube.com\/watch?v=XkR4VJ6j0Hg\u0026amp;list=PLD717EA55E194C71F\" target=\"_blank\"\u003EYouTube video\u003C\/a\u003E.\u003Cbr \/\u003E\n\u003Cbr \/\u003E\nI think they made a really nice kit out of this and am very happy with the result.\u0026nbsp;A full description is on\u0026nbsp;\u003Ca href=\"https:\/\/qrpguys.com\/la3za-zero-beat-indicator\" target=\"_blank\"\u003Ethe QRPGuys website\u003C\/a\u003E. And no, I will not make any profit from this, but please go ahead and buy the kit from them anyway!\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003Cbr \/\u003E\nThis blog post first appeared on the\u0026nbsp;\u003Ca href=\"https:\/\/la3za.blogspot.com\/2019\/09\/qrpguys-la3za-zero-beat-indicator.html\" target=\"_blank\"\u003ELA3ZA Radio \u0026amp; Electronics Blog\u003C\/a\u003E."},"link":[{"rel":"replies","type":"application/atom+xml","href":"https:\/\/la3za.blogspot.com\/feeds\/7162961718702131322\/comments\/default","title":"Post Comments"},{"rel":"replies","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2019\/09\/qrpguys-la3za-zero-beat-indicator.html#comment-form","title":"0 Comments"},{"rel":"edit","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/7162961718702131322"},{"rel":"self","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/7162961718702131322"},{"rel":"alternate","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2019\/09\/qrpguys-la3za-zero-beat-indicator.html","title":"QRPGuys LA3ZA Zero Beat Indicator"}],"author":[{"name":{"$t":"Sverre Holm"},"uri":{"$t":"http:\/\/www.blogger.com\/profile\/08306221557326542499"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"26","height":"32","src":"\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEirIUQ4__tBn8iuiGzcRlJEOroeUKkNCZ2mN2DM3rs_2pPUFGIs7a2EtYWIiOikqsFchk8w4XaHx_XyS1g_-i8Kmu46zrppNaF1Xeh-omtKQqjq9tEzjhEobips8DmSvw\/s1600\/sverreholm20.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEiWfo-F0O-5Qj7vivQWg-GtGKji_KqLWuLnj5DeGQZwcmQWqZhke57JBcXzdRo_i1p7SHUbJGaaz6pp87Vw8u9wrEtXIGfaXU_cf1INlmWHnxS2LY9q-RXo6z8GPIFhhAjqcVkhD_xKoRI\/s72-c\/LA3ZA-QRPGuys.jpg","height":"72","width":"72"},"thr$total":{"$t":"0"}},{"id":{"$t":"tag:blogger.com,1999:blog-2554001380039969960.post-7312847672369172891"},"published":{"$t":"2019-04-24T14:51:00.003+02:00"},"updated":{"$t":"2019-06-27T13:01:11.943+02:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"QRP"},{"scheme":"http://www.blogger.com/atom/ns#","term":"QRPLabs"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Ultimate 3"},{"scheme":"http://www.blogger.com/atom/ns#","term":"WSPR"}],"title":{"type":"text","$t":"The Ultimate WSPR Spot - part 2"},"content":{"type":"html","$t":"\u003Cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003E\n\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEgwTwmjs20p2fK4Z17cVm2fudOiiMoM3hyphenhyphenybbp4yETKuhGzmGjr-mzJfnG62QnRaAQwLiiBbosgWXUQ87tTrSYyyEUTNCbvVe8VXs8Ot9c6PTm89h55NmQSIPfRActR4kyshou0sl_rPJo\/s1600\/U3-U3S-LA3ZA.jpg\" imageanchor=\"1\" style=\"clear: right; float: right; margin-bottom: 1em; margin-left: 1em;\"\u003E\u003Cimg border=\"0\" data-original-height=\"589\" data-original-width=\"1600\" height=\"117\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEgwTwmjs20p2fK4Z17cVm2fudOiiMoM3hyphenhyphenybbp4yETKuhGzmGjr-mzJfnG62QnRaAQwLiiBbosgWXUQ87tTrSYyyEUTNCbvVe8VXs8Ot9c6PTm89h55NmQSIPfRActR4kyshou0sl_rPJo\/s320\/U3-U3S-LA3ZA.jpg\" width=\"320\" \/\u003E\u003C\/a\u003E\u003C\/div\u003E\nBeing spotted by the designer of my WSPR transmitter must be the ultimate WSPR spot! Perhaps only surpassed by being spotted by the designer of the mode himself, K1JT, Joe\u0026nbsp;as I was \u003Ca href=\"https:\/\/la3za.blogspot.com\/2015\/05\/the-ultimate-wspr-spot.html\" target=\"_blank\"\u003Efour years ago.\u003C\/a\u003E\u003Cbr \/\u003E\n\u003Cbr \/\u003E\nIt is Hans, G0UPL, of \u003Ca href=\"https:\/\/www.qrp-labs.com\/\" target=\"_blank\"\u003EQRPLabs\u003C\/a\u003E who is the designer of both my U3 to the left (turned off) and the U3S to the right. The latter was the active transmitter at the time of the spot below.\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003Ctable cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"float: left; margin-right: 1em; text-align: left;\"\u003E\u003Ctbody\u003E\n\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEho6d436Zmt85xmSsXRdfyKxKO8Hcs1iGlp7U3MR6VPvPD7_ONsWE5g0QAWmdM5DZ45eRH3cre5WHqGqNl9WgxFfa3vPgeZqBnyVIm9LLhqThGb-rE-w_VLcxyOZ4qD6Zq3SGvfEobVCK0\/s1600\/G0UPL.png\" imageanchor=\"1\" style=\"clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;\"\u003E\u003Cimg border=\"0\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEho6d436Zmt85xmSsXRdfyKxKO8Hcs1iGlp7U3MR6VPvPD7_ONsWE5g0QAWmdM5DZ45eRH3cre5WHqGqNl9WgxFfa3vPgeZqBnyVIm9LLhqThGb-rE-w_VLcxyOZ4qD6Zq3SGvfEobVCK0\/s640\/G0UPL.png\" width=\"90%\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\n\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003E\u003Cbr \/\u003E\u003C\/td\u003E\u003C\/tr\u003E\n\u003C\/tbody\u003E\u003C\/table\u003E\n\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003Cbr \/\u003E\nBy the way, this is a line from VK2TPM, Peter's excellent \u003Ca href=\"https:\/\/itunes.apple.com\/au\/app\/wspr-watch\/id532487317?mt=8\" target=\"_blank\"\u003EWSPR Watch app for Ipod\u003C\/a\u003E.\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003Cbr \/\u003E"},"link":[{"rel":"replies","type":"application/atom+xml","href":"https:\/\/la3za.blogspot.com\/feeds\/7312847672369172891\/comments\/default","title":"Post Comments"},{"rel":"replies","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2019\/04\/the-ultimate-wspr-spot.html#comment-form","title":"0 Comments"},{"rel":"edit","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/7312847672369172891"},{"rel":"self","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/7312847672369172891"},{"rel":"alternate","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2019\/04\/the-ultimate-wspr-spot.html","title":"The Ultimate WSPR Spot - part 2"}],"author":[{"name":{"$t":"Sverre Holm"},"uri":{"$t":"http:\/\/www.blogger.com\/profile\/08306221557326542499"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"26","height":"32","src":"\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEirIUQ4__tBn8iuiGzcRlJEOroeUKkNCZ2mN2DM3rs_2pPUFGIs7a2EtYWIiOikqsFchk8w4XaHx_XyS1g_-i8Kmu46zrppNaF1Xeh-omtKQqjq9tEzjhEobips8DmSvw\/s1600\/sverreholm20.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEgwTwmjs20p2fK4Z17cVm2fudOiiMoM3hyphenhyphenybbp4yETKuhGzmGjr-mzJfnG62QnRaAQwLiiBbosgWXUQ87tTrSYyyEUTNCbvVe8VXs8Ot9c6PTm89h55NmQSIPfRActR4kyshou0sl_rPJo\/s72-c\/U3-U3S-LA3ZA.jpg","height":"72","width":"72"},"thr$total":{"$t":"0"}},{"id":{"$t":"tag:blogger.com,1999:blog-2554001380039969960.post-7603880085087424040"},"published":{"$t":"2017-12-27T10:44:00.002+01:00"},"updated":{"$t":"2019-04-25T19:42:23.526+02:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"QRP"},{"scheme":"http://www.blogger.com/atom/ns#","term":"QRSS"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Ultimate 3"},{"scheme":"http://www.blogger.com/atom/ns#","term":"WSPR"}],"title":{"type":"text","$t":"QRSS experiments: FSKCW and Slow Hell"},"content":{"type":"html","$t":"These last few days I've been experimenting with my \u003Ca href=\"https:\/\/www.qrp-labs.com\/\" target=\"_blank\"\u003EQRPLabs\u003C\/a\u003E Ultimate 2 and Ultimate 3s transmitting on 7 MHz. In addition to WSPR, the modes transmitted have been FSKCW with 6 second long dots, and Slow Hell with 17 second long characters. The result as received this morning can be seen on the display from the grabber of Les, G3VYZ in Northumberland, UK. This is a stack of 6 consecutive 10 second frames as can be found on the QRSS \u003Ca href=\"http:\/\/www.swharden.com\/qrss\/plus\/\" target=\"_blank\"\u003Egrabber site of AJ4VD\u003C\/a\u003E.\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\n\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEhJ8dUVYDcQrcHByUBmlBQ_59Q6oe0poLw99zrHtQY7HmRNcLVgRPg8nFD_sgFSSO913oS782g2uQ55z72ATt9ipwhtJY3H_LN0s_JOtn1A205iZZbIjnagydNwNvwAYwahyr08ZVCOJ9Y\/s1600\/stack_G3VYZ3_1514365882.jpg\" imageanchor=\"1\" style=\"margin-left: auto; margin-right: auto;\"\u003E\u003Cimg border=\"0\" data-original-height=\"379\" data-original-width=\"914\" height=\"165\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEhJ8dUVYDcQrcHByUBmlBQ_59Q6oe0poLw99zrHtQY7HmRNcLVgRPg8nFD_sgFSSO913oS782g2uQ55z72ATt9ipwhtJY3H_LN0s_JOtn1A205iZZbIjnagydNwNvwAYwahyr08ZVCOJ9Y\/s400\/stack_G3VYZ3_1514365882.jpg\" width=\"400\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\n\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFSKCW and Slow Hell reception of LA3ZA at G3VYZ\u003C\/td\u003E\u003C\/tr\u003E\n\u003C\/tbody\u003E\u003C\/table\u003E\n\u003Cbr \/\u003E\nMy signal is on 7,039.870 kHz and has been set up with a FSK shift of 6 Hz. Power output was 0.2 W and the distance is about 890 km.\u003Cbr \/\u003E\n\u003Cbr \/\u003E\nIt works but the reception is much less reliable than for WSPR, which is not so unexpected. At the same time the WSPR signal was received all around Northern Europe (G, GM, DL, ON, OE, LX, LA, OY, OH, PA, SM) as well as on the Canary Islands, 3930 km away.\u003Cbr \/\u003E\n\u003Cspan id=\"goog_1949834655\"\u003E\u003C\/span\u003E\u003Cspan id=\"goog_1949834656\"\u003E\u003C\/span\u003E\u003Cbr \/\u003E"},"link":[{"rel":"replies","type":"application/atom+xml","href":"https:\/\/la3za.blogspot.com\/feeds\/7603880085087424040\/comments\/default","title":"Post Comments"},{"rel":"replies","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2017\/12\/qrss-experiements-fskcw-and-slow-hell.html#comment-form","title":"0 Comments"},{"rel":"edit","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/7603880085087424040"},{"rel":"self","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/7603880085087424040"},{"rel":"alternate","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2017\/12\/qrss-experiements-fskcw-and-slow-hell.html","title":"QRSS experiments: FSKCW and Slow Hell"}],"author":[{"name":{"$t":"Sverre Holm"},"uri":{"$t":"http:\/\/www.blogger.com\/profile\/08306221557326542499"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"26","height":"32","src":"\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEirIUQ4__tBn8iuiGzcRlJEOroeUKkNCZ2mN2DM3rs_2pPUFGIs7a2EtYWIiOikqsFchk8w4XaHx_XyS1g_-i8Kmu46zrppNaF1Xeh-omtKQqjq9tEzjhEobips8DmSvw\/s1600\/sverreholm20.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEhJ8dUVYDcQrcHByUBmlBQ_59Q6oe0poLw99zrHtQY7HmRNcLVgRPg8nFD_sgFSSO913oS782g2uQ55z72ATt9ipwhtJY3H_LN0s_JOtn1A205iZZbIjnagydNwNvwAYwahyr08ZVCOJ9Y\/s72-c\/stack_G3VYZ3_1514365882.jpg","height":"72","width":"72"},"thr$total":{"$t":"0"}},{"id":{"$t":"tag:blogger.com,1999:blog-2554001380039969960.post-5889152080151110039"},"published":{"$t":"2016-11-27T21:39:00.001+01:00"},"updated":{"$t":"2017-10-11T22:46:44.068+02:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Low-pass"},{"scheme":"http://www.blogger.com/atom/ns#","term":"QRP"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Ultimate 3"}],"title":{"type":"text","$t":"Even better low-pass filters for transmitters"},"content":{"type":"html","$t":"The last issues of QEX have featured two interesting articles by Gary Cobb, G3TMG. He outlines the advantage of using Zolotarev designs for the harmonic suppression filters of transmitters, giving even better suppression of the second harmonic than the more common Chebyshev or quasi-elliptic filters.\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003Ctable cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"float: right; text-align: right;\"\u003E\u003Ctbody\u003E\n\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEiDlRZofPlKk8pmuv9RE2MoeH9cRddIOwHGLay3Kp8lEIhKg4d3rlHzwH4ySbL8mGx7inyApiRZfFo7n_O7EYE7qch_LnnnOjHF0bWb-XL9de96hz2sv9zVmuVk05QPeip9Sa18mYnbkxc\/s1600\/Chebyshev.jpg\" imageanchor=\"1\" style=\"clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;\"\u003E\u003Cimg border=\"0\" height=\"121\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEiDlRZofPlKk8pmuv9RE2MoeH9cRddIOwHGLay3Kp8lEIhKg4d3rlHzwH4ySbL8mGx7inyApiRZfFo7n_O7EYE7qch_LnnnOjHF0bWb-XL9de96hz2sv9zVmuVk05QPeip9Sa18mYnbkxc\/s320\/Chebyshev.jpg\" width=\"320\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\n\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EChebyshev low-pass filter from the GQRP data sheet (issue 1)\u003C\/td\u003E\u003C\/tr\u003E\n\u003C\/tbody\u003E\u003C\/table\u003E\nMy interest in this was triggered by the test of the Ultimate 3 QRSS\/WSPR kit from QRP Labs in the Nov 2016 QST. The review was positive overall, but it was remarked that the \u003Ca href=\"http:\/\/www.qrp-labs.com\/ultimate3\/u3info\/harmonics.html\" target=\"_blank\"\u003Eharmonic suppression does not meet FCC requirements (-43 dBc or better)\u003C\/a\u003E. I am not sure whether this is due to PCB layout issues, or if better filters can alleviate it, but I note that the design uses the simplest filter of the ones I have listed here.\u003Cbr \/\u003E\n\u003Cbr \/\u003E\nThe evolution of filters for use for harmonic suppression follows at least these three steps:\u003Cbr \/\u003E\n\u003Ca name='more'\u003E\u003C\/a\u003E\u003Col\u003E\n\u003Cli\u003EChebyshev type I filters with equiripple in the passband and a monotonically falling, maximally flat stopband. A 7-pole version with three inductors and four capacitors in a pi-network has been around for a while, in e.g. the \u003Ca href=\"http:\/\/www.gqrp.com\/harmonic_filters.pdf\" target=\"_blank\"\u003Eold recommendation from the GQRP club\u003C\/a\u003E. It was based on the QST paper \"Low-pass filters for amateur radio transmitters,\" Ed Wetherhold, W3NQN, Dec. 1979. Two designs for a 20 m filter were given there:\u003Cbr \/\u003E\n1) Max. ripple in passband: 0.00731 dB, attenuation at 28 MHz: 40.7 dB\u003Cbr \/\u003E\n1) Max. ripple in passband: 0.00960 dB, attenuation at 28 MHz: 34.5 dB\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003C\/li\u003E\n\u003Cli\u003E\u003Ctable cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"float: right; margin-left: 1em; text-align: right;\"\u003E\u003Ctbody\u003E\n\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEjOZ6e4gdDvvaiAdkvFlzk9NNMlJzC5J2he_F0-xLjVnt0SwqgmWzS7KopczYpICpjDRvDHt1w1u1NlC0SPIh1e0C2lksiaJ6KxqtCjV2ykOy4Ahua56LhxpRI8UW4dpuPiVcsZRwm5ir4\/s1600\/CWAZ.jpg\" imageanchor=\"1\" style=\"clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;\"\u003E\u003Cimg border=\"0\" height=\"90\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEjOZ6e4gdDvvaiAdkvFlzk9NNMlJzC5J2he_F0-xLjVnt0SwqgmWzS7KopczYpICpjDRvDHt1w1u1NlC0SPIh1e0C2lksiaJ6KxqtCjV2ykOy4Ahua56LhxpRI8UW4dpuPiVcsZRwm5ir4\/s320\/CWAZ.jpg\" width=\"320\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\n\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003ESecond-harmonic optimized low-pass filter from the \u003Cbr \/\u003E\nGQRP data sheet (issue 2)\u003C\/td\u003E\u003C\/tr\u003E\n\u003C\/tbody\u003E\u003C\/table\u003E\nAn improved stopband was the topic of W3NQN's article \"\u003Ca href=\"https:\/\/www.arrl.org\/files\/file\/Technology\/tis\/info\/pdf\/9902044.pdf\" target=\"_blank\"\u003ESecond-harmonic optimized low-pass filters\u003C\/a\u003E\" in QST Feb. 1999. Here there is one additional capacitor as the central inductor is made into a parallel resonance which gives a zero in the stopband, based on an idea by \u003Ca href=\"http:\/\/www.tonnesoftware.com\/miscellany.html\" target=\"_blank\"\u003EJim Tonne, WB6BLD\u003C\/a\u003E. The design goal is that this zero should be at the second harmonic frequency. W3NQN proposed to call this a Chebyshev filter with a zero (CWAZ) filter, but it is more correct to call it a quasi- or pseudo-elliptic filter as remarked by G3TMG. It increases the attenuation at the second-harmonic in the 20 m design to better than 60 dB. This design is the basis for the \u003Ca href=\"http:\/\/www.gqrp.com\/technical2.htm\" target=\"_blank\"\u003Ecurrent (Issue 2) G-QRP technical sheet\u003C\/a\u003E. This would also be interesting to test in the QRP Labs Ultimate 3 transmitter kit.\u003Cbr \/\u003E\n\u003Cbr \/\u003E\n\u003C\/li\u003E\n\u003Cli\u003E\u003Ctable cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"float: right; margin-left: 1em; text-align: right;\"\u003E\u003Ctbody\u003E\n\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEg5HuAivx7nbg60hJtaLKDTwSE2iOFxnVMM9_M8oHoQ6_j1LgJHg2Aaogrj6TSWj8EX_f1bu8DoqlBseNUyRjDjBqfuDBN5CXDIB3gT5TTKDkypo9K0mw_YINO9M60TFdm99G26UqaNeb4\/s1600\/Zolotarev.jpg\" imageanchor=\"1\" style=\"clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;\"\u003E\u003Cimg border=\"0\" height=\"150\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEg5HuAivx7nbg60hJtaLKDTwSE2iOFxnVMM9_M8oHoQ6_j1LgJHg2Aaogrj6TSWj8EX_f1bu8DoqlBseNUyRjDjBqfuDBN5CXDIB3gT5TTKDkypo9K0mw_YINO9M60TFdm99G26UqaNeb4\/s320\/Zolotarev.jpg\" width=\"320\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\n\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EZolotarev low-pass filter from the Nov\/Dec 2016 QEX article\u003C\/td\u003E\u003C\/tr\u003E\n\u003C\/tbody\u003E\u003C\/table\u003E\nG3TMG in the new QEX articles has noticed that the passband is over-specified in the above filters as the lower 60% or so of the passband is unused. The Zolotarev design allows for more passband ripple in this part where it does not matter. The advantage is even better stopband attenuation. A measured example for a 60 m filter has a passband ripple of \u003Cstrike\u003E0.17\u003C\/strike\u003E\u0026nbsp;0.04 dB, an insertion loss of 0.17 dB,\u0026nbsp;and a stopband attenuation at the second harmonic of 71 dB. This filter has the same component count as the previous one, but the filter is no longer symmetric like the two previous ones. The increase in second-harmonic suppression is not as great as the going from the first filters to the second, but should still be worth the effort.\u003C\/li\u003E\n\u003C\/ol\u003E\n\u003Cdiv\u003E\nThe papers, which are well worth reading, are:\u003C\/div\u003E\n\u003Cdiv\u003E\n\u003Cul\u003E\n\u003Cli\u003EGary Cobb, G3TMG, Zolotarev low-pass filter design, QEX, July\/Aug 2016.\u003C\/li\u003E\n\u003Cli\u003EGary Cobb, G3TMG, A more efficient low-pass filter, QEX, Nov\/Dec 2016.\u003C\/li\u003E\n\u003C\/ul\u003E\n\u003Cdiv\u003E\n\u003Cbr \/\u003E\u003C\/div\u003E\n\u003Cdiv\u003E\nThe post \"\u003Ca href=\"http:\/\/la3za.blogspot.no\/2016\/11\/even-better-low-pass-filters-for.html\" target=\"_blank\"\u003EEven better low-pass filters for transmitters\u003C\/a\u003E\"\u0026nbsp;first appeared on the\u0026nbsp;\u003Ca href=\"http:\/\/la3za.blogspot.no\/\"\u003ELA3ZA Radio \u0026amp; Electronics Blog.\u003C\/a\u003E\u003C\/div\u003E\n\u003C\/div\u003E\n"},"link":[{"rel":"replies","type":"application/atom+xml","href":"https:\/\/la3za.blogspot.com\/feeds\/5889152080151110039\/comments\/default","title":"Post Comments"},{"rel":"replies","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2016\/11\/even-better-low-pass-filters-for.html#comment-form","title":"0 Comments"},{"rel":"edit","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/5889152080151110039"},{"rel":"self","type":"application/atom+xml","href":"https:\/\/www.blogger.com\/feeds\/2554001380039969960\/posts\/default\/5889152080151110039"},{"rel":"alternate","type":"text/html","href":"https:\/\/la3za.blogspot.com\/2016\/11\/even-better-low-pass-filters-for.html","title":"Even better low-pass filters for transmitters"}],"author":[{"name":{"$t":"Sverre Holm"},"uri":{"$t":"http:\/\/www.blogger.com\/profile\/08306221557326542499"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"26","height":"32","src":"\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEirIUQ4__tBn8iuiGzcRlJEOroeUKkNCZ2mN2DM3rs_2pPUFGIs7a2EtYWIiOikqsFchk8w4XaHx_XyS1g_-i8Kmu46zrppNaF1Xeh-omtKQqjq9tEzjhEobips8DmSvw\/s1600\/sverreholm20.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEiDlRZofPlKk8pmuv9RE2MoeH9cRddIOwHGLay3Kp8lEIhKg4d3rlHzwH4ySbL8mGx7inyApiRZfFo7n_O7EYE7qch_LnnnOjHF0bWb-XL9de96hz2sv9zVmuVk05QPeip9Sa18mYnbkxc\/s72-c\/Chebyshev.jpg","height":"72","width":"72"},"thr$total":{"$t":"0"}}]}});