Topband: Unofficial archive of the works from the early pioneers of Amateur Radio's digital communications era
What is CCW? Amateur Radio Coherent CW was invented by Ray Petit, W7GHM. He is also the inventor of Clover now manufactured by HAL Communications. The first amateur QSO was by Andy McCaskey, WA7ZVC using a Ten-Tec PM-1. CCW was promoted by Chas. Woodson (Woody), W6NEY a professor at Stanford University. Woody published a newsletter in the early 1970's. Ade Weiss, W0RSP wrote some articles in CQ and Woody, W6NEY publish a series of articles in QST in 1979 - 1981 period. In February 1994 VE2IQ published his circuit for CCW using a PC and DSP techniques. Peter Lamb, G3IRM wrote a newsletter on CCW techniques in the early 1990's. CCW moved on to BPSK techniques and is presently being used on 80 meters. A lot of this work, software, etc. is available on the web. The ARRL had information in the 1980's handbooks and still has some material in the current issues. Amateur CCW was developed before we had nice microprocessors, DSP and other current technology. It's been around for 25 years, is only as complex as an SSB transmitter, and certainly within the building ability of all most all amateurs. One does not need power ... it is a QRPp mode. CCW is slow ... 12 wpm CW. You need a good freq standard, but today we can use GPS timing (see TAPR web site). It works in noise and under poor conditions and has been proven to work on the ham bands. See all that here. https://midnightdesignsolutions.com/ccw/ 73 JC N4IS -Original Message- From: Topband On Behalf Of JC Sent: Monday, December 24, 2018 6:46 PM To: 'K4SAV' ; topband@contesting.com Subject: Re: Topband: FT8 - How it really works Jerry The new mode FT8 is not all that new, actually, there are several aspects to consider, like detect the signal, decode the signal detected, make a decision to accept the decoded signal. The improvement on signal to noise ratio concept is very old, just the internet made it possible with time synchronization. The decode uses new algorithms and some very intelligent way to guest the decoded signal. Check this out. 1975 Sept QST; Coherent cw test! Experiments show 20 db Signal Boost over QRM, http://www.arrl.org/files/file/Technology/tis/info/pdf/7509026.pdf The improvement on signal to noise ratio is just because a narrow bandwidth. The gates opens at the right millisecond window. On FSK the secret salvage is time synchronization. You can record the audio and play it back, the decode will happen only if you synchronize the time of the recording with the time in ms of the PC clock. I did that, and it worked, I have a SDR QS1R and using HDSDR software to record the I/Q file, RF file. I used to record rare DX expedition signal and the bandwidth is 50 KHz, I can see the FT8 guys on 1840, My question was , can I decode them from the digital file recorded several month ago? I started plaining the file at the top of the second count, and voalah!!!, The WSJT-X decoded several station, weak as -21 db. The weak signals are there, buried in the noise on my old digital recorded file. Then I decided to test my HWF, the practical result measuring cw signal is that the signal to noise increase around 20 db, 10 db due the directivity RDF 11.5 and another 10 db from the polarization filter. The Horizontal WF attenuation on vertical signals is over -90 db. The manmade noise vertical polarized is reduced below the MDS of the receiver and cannot be amplified by the receiver. The IC-7800 has two identical receivers. I connected my HWF on receiver MAIN and the TX antenna on the receiver SUB, I installed two instances of the WSJTX program, one for each receiver. After 15 minutes the number of decodes on the HWF was 20 or times more than the vertical full size vertical, my TX antenna 120 Ft high. Signals decoded around -21 db on the vertical was decoded on the HWF 0 to +1 db. Signals less the -5db decoded on the HWF was not decoded using the vertical, The HWF was decoding hundreds of signals that would be -40 db on the decode using the vertical. I think the s/n reported by the program as ball part is actually very good and close to the real s/n improvement of 2 Hz BW, depending on the mode. The only real way to increase signal to noise ratio is increasing the directivity of the RX antenna, more real RDF means real signal to noise ratio improvement. I used real because it is very easy to destroy the directivity with integration, leaking, intermodulation, low noise figure etc. One bad concept, bidirectional unterminated beverage with two lobes one in the back and one front, it just does not work because the RDF is 6 db down a terminated beverage. Same for BOG's the RDF is bad, a K9AY works better because has more RDF. A simple Flag can deliver 9 db RDF is tis easy to hide too. Two Flags in phase 11.5 db and four Flags 14 db RDF, and a very clean pattern besides real broadband from 1 MHz to 10 MHz As you can see on the ARRL 1975 article, there is nothing new about improvement of signal to noise ratio reducing
Re: Topband: FT8 - How it really works
Jerry The new mode FT8 is not all that new, actually, there are several aspects to consider, like detect the signal, decode the signal detected, make a decision to accept the decoded signal. The improvement on signal to noise ratio concept is very old, just the internet made it possible with time synchronization. The decode uses new algorithms and some very intelligent way to guest the decoded signal. Check this out. 1975 Sept QST; Coherent cw test! Experiments show 20 db Signal Boost over QRM, http://www.arrl.org/files/file/Technology/tis/info/pdf/7509026.pdf The improvement on signal to noise ratio is just because a narrow bandwidth. The gates opens at the right millisecond window. On FSK the secret salvage is time synchronization. You can record the audio and play it back, the decode will happen only if you synchronize the time of the recording with the time in ms of the PC clock. I did that, and it worked, I have a SDR QS1R and using HDSDR software to record the I/Q file, RF file. I used to record rare DX expedition signal and the bandwidth is 50 KHz, I can see the FT8 guys on 1840, My question was , can I decode them from the digital file recorded several month ago? I started plaining the file at the top of the second count, and voalah!!!, The WSJT-X decoded several station, weak as -21 db. The weak signals are there, buried in the noise on my old digital recorded file. Then I decided to test my HWF, the practical result measuring cw signal is that the signal to noise increase around 20 db, 10 db due the directivity RDF 11.5 and another 10 db from the polarization filter. The Horizontal WF attenuation on vertical signals is over -90 db. The manmade noise vertical polarized is reduced below the MDS of the receiver and cannot be amplified by the receiver. The IC-7800 has two identical receivers. I connected my HWF on receiver MAIN and the TX antenna on the receiver SUB, I installed two instances of the WSJTX program, one for each receiver. After 15 minutes the number of decodes on the HWF was 20 or times more than the vertical full size vertical, my TX antenna 120 Ft high. Signals decoded around -21 db on the vertical was decoded on the HWF 0 to +1 db. Signals less the -5db decoded on the HWF was not decoded using the vertical, The HWF was decoding hundreds of signals that would be -40 db on the decode using the vertical. I think the s/n reported by the program as ball part is actually very good and close to the real s/n improvement of 2 Hz BW, depending on the mode. The only real way to increase signal to noise ratio is increasing the directivity of the RX antenna, more real RDF means real signal to noise ratio improvement. I used real because it is very easy to destroy the directivity with integration, leaking, intermodulation, low noise figure etc. One bad concept, bidirectional unterminated beverage with two lobes one in the back and one front, it just does not work because the RDF is 6 db down a terminated beverage. Same for BOG's the RDF is bad, a K9AY works better because has more RDF. A simple Flag can deliver 9 db RDF is tis easy to hide too. Two Flags in phase 11.5 db and four Flags 14 db RDF, and a very clean pattern besides real broadband from 1 MHz to 10 MHz As you can see on the ARRL 1975 article, there is nothing new about improvement of signal to noise ratio reducing the bandwidth. On the article, the test was CW at 12 wpm and 9 Hz filter BW , no ring using WWV as time source for the synchronization. That was state of the art back in the early 70's, almost 50 years ago. 73's JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of K4SAV Sent: Monday, December 24, 2018 3:10 PM To: topband@contesting.com Subject: Re: Topband: FT8 - How it really works Although I have finished my FT8 testing, there is one final thought I would like to leave with you, and also to correct one statement I made earlier. Someone thought FT8 measured the noise in the interval when the FT8 signals were off, and I replied that would result in a real S/N number. That is not true as you will see in the info below. You would get a real S/N number if the RF was sampled, but not if the audio is sampled. I spent many years designing electronic circuits professionally, so I still think that way. So for a few minutes lets think about a circuit that can decode something below the noise floor .If you think about FT8 or anything similar, from a designers point of view, you suddenly realize that making a statement of "the circuit can decode down to X dBs below the noise floor" is almost an impossible task, that is, if you are talking RF noise floor as most people will be assuming. Since you will be dealing with audio, not RF, the receiver will convert the RF into audio and compress it into something that has a lot less dynamic range. How much less? Say the volume is set to a level such that the strongest signals do not clip, then how far down is the
Re: Topband: FT8 - How it really works
Chuck, I suspect something wasn’t quite right with your setup? At my QTH in W3 I can hear multiple FT8 signals on 1840kc USB (2.4khz bandwidth) from before my sunset until after sunrise. They are whining/droning carriers for 13 seconds every 15 seconds. Only for that less than 2 seconds every 15 seconds do I hear just band noise, at all other times I hear multiple FT8 signals just fine. And the computer can decode more signals than I can hear. Tim N3QE > On Dec 24, 2018, at 4:17 PM, Chuck Dietz wrote: > > I think I understand much of what you are saying, but I know that I was on > 160 meter FT=8 two nights ago with the speaker up fairly loud. I only heard > noise. I set the AGC off and adjusted the RF gain so that it did not > overload. Still no hint of any signals, but I decoded two stations! > > Just sayin’. > > Chuck W5PR > > Sent from Mail for Windows 10 > > From: K4SAV > Sent: Monday, December 24, 2018 2:10 PM > To: topband@contesting.com > Subject: Re: Topband: FT8 - How it really works > > Although I have finished my FT8 testing, there is one final thought I > would like to leave with you, and also to correct one statement I made > earlier. Someone thought FT8 measured the noise in the interval when > the FT8 signals were off, and I replied that would result in a real S/N > number. That is not true as you will see in the info below. You would > get a real S/N number if the RF was sampled, but not if the audio is > sampled. > > I spent many years designing electronic circuits professionally, so I > still think that way. So for a few minutes lets think about a circuit > that can decode something below the noise floor .If you think about FT8 > or anything similar, from a designers point of view, you suddenly > realize that making a statement of "the circuit can decode down to X dBs > below the noise floor" is almost an impossible task, that is, if you are > talking RF noise floor as most people will be assuming. > > Since you will be dealing with audio, not RF, the receiver will convert > the RF into audio and compress it into something that has a lot less > dynamic range. How much less? Say the volume is set to a level such > that the strongest signals do not clip, then how far down is the noise? > You can expect that to vary on each band too. > > Now comes a real complication. If you were taking samples in the RF > world, you could see the noise level on your S meter and estimate it > relative to the strongest signals. However your circuit will be dealing > with audio. Surprisingly, when the signals disappear, the receiver AGC > voltage drops and the receiver gain increases. That produces a lot more > audio signal. The audio noise in the case of no signals becomes higher > than the audio level for strong signals if you are using USB bandwidth > and receiving something similar to FT8. That condition is not nearly as > pronounced when using a narrow CW bandwidth. Even if you put the > receiver into AGC slow mode it won't hold for the 3 seconds when FT8 is > off, so you still get the increased audio in the off period. Then there > will be a sudden increase in audio when the first signal reappears, > until the ACG kicks in and lowers it. This happens even with fast AGC > selected. It's fast enough that you don't notice it when listening, but > if you put a scope on it you can see it. Yeah, all that surprised me > too when first thinking about it. Take a close listen and see if you > agree. If you can't hear it, put it on a scope or anything that displays > an audio waveform and it will become very obvious. > > If you made a statement that this circuit can decode X dBs below the > noise floor, most people will be thinking RF noise floor. So what is it > in the audio world that represents the noise floor in the RF world, and > what would your statement mean? > > Of course you could turn off the AGC and decrease the receiver RF gain > and that would make the audio very low when the signals disappear. That > would also severely limit the dynamic range for your circuit since you > would no longer have the compression supplied by the receiver.. Your > circuit would have to cover a much wider dynamic range, similar to what > a receiver does. So your circuit would need what? maybe 100 dB dynamic > range to cover the strongest signals to the weakest noise floor, > forgetting about decoding below the noise floor. Actually that wouldn't > really happen because receivers can't produce a dynamic range of 100 dB > in the audio. They may do it in the RF world, but not in audio. > Receivers have no need to do that. > > Jerry > _ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: FT8 - How it really works
Hi, we use 4ports-RX-splitter https://www.ebay.com/itm/4-WAY-HF-ANTENNA-SPLITTER-COMBINER-RX-0-1-50-MHz-SO-239-connectors/322564884873?hash=item4b1a5d8989:g:JJ4AAOxyM89Sbujo:rk:1:pf:0 73! de Eugene RA0FF http://www.qsl.net/ra0ff/ >Вторник, 25 декабря 2018, 8:17 +11:00 от Chuck Dietz : > >I think I understand much of what you are saying, but I know that I was on 160 >meter FT=8 two nights ago with the speaker up fairly loud. I only heard noise. >I set the AGC off and adjusted the RF gain so that it did not overload. Still >no hint of any signals, but I decoded two stations! > >Just sayin’. > >Chuck W5PR > >Sent from Mail for Windows 10 > >From: K4SAV >Sent: Monday, December 24, 2018 2:10 PM >To: topband@contesting.com >Subject: Re: Topband: FT8 - How it really works > >Although I have finished my FT8 testing, there is one final thought I >would like to leave with you, and also to correct one statement I made >earlier. Someone thought FT8 measured the noise in the interval when >the FT8 signals were off, and I replied that would result in a real S/N >number. That is not true as you will see in the info below. You would >get a real S/N number if the RF was sampled, but not if the audio is >sampled. > >I spent many years designing electronic circuits professionally, so I >still think that way. So for a few minutes lets think about a circuit >that can decode something below the noise floor .If you think about FT8 >or anything similar, from a designers point of view, you suddenly >realize that making a statement of "the circuit can decode down to X dBs >below the noise floor" is almost an impossible task, that is, if you are >talking RF noise floor as most people will be assuming. > >Since you will be dealing with audio, not RF, the receiver will convert >the RF into audio and compress it into something that has a lot less >dynamic range. How much less? Say the volume is set to a level such >that the strongest signals do not clip, then how far down is the noise? >You can expect that to vary on each band too. > >Now comes a real complication. If you were taking samples in the RF >world, you could see the noise level on your S meter and estimate it >relative to the strongest signals. However your circuit will be dealing >with audio. Surprisingly, when the signals disappear, the receiver AGC >voltage drops and the receiver gain increases. That produces a lot more >audio signal. The audio noise in the case of no signals becomes higher >than the audio level for strong signals if you are using USB bandwidth >and receiving something similar to FT8. That condition is not nearly as >pronounced when using a narrow CW bandwidth. Even if you put the >receiver into AGC slow mode it won't hold for the 3 seconds when FT8 is >off, so you still get the increased audio in the off period. Then there >will be a sudden increase in audio when the first signal reappears, >until the ACG kicks in and lowers it. This happens even with fast AGC >selected. It's fast enough that you don't notice it when listening, but >if you put a scope on it you can see it. Yeah, all that surprised me >too when first thinking about it. Take a close listen and see if you >agree. If you can't hear it, put it on a scope or anything that displays >an audio waveform and it will become very obvious. > >If you made a statement that this circuit can decode X dBs below the >noise floor, most people will be thinking RF noise floor. So what is it >in the audio world that represents the noise floor in the RF world, and >what would your statement mean? > >Of course you could turn off the AGC and decrease the receiver RF gain >and that would make the audio very low when the signals disappear. That >would also severely limit the dynamic range for your circuit since you >would no longer have the compression supplied by the receiver.. Your >circuit would have to cover a much wider dynamic range, similar to what >a receiver does. So your circuit would need what? maybe 100 dB dynamic >range to cover the strongest signals to the weakest noise floor, >forgetting about decoding below the noise floor. Actually that wouldn't >really happen because receivers can't produce a dynamic range of 100 dB >in the audio. They may do it in the RF world, but not in audio. >Receivers have no need to do that. > >Jerry >_ >Searchable Archives: http://www.contesting.com/_topband - Topband Reflector > >_ >Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: FT8 - How it really works
I think I understand much of what you are saying, but I know that I was on 160 meter FT=8 two nights ago with the speaker up fairly loud. I only heard noise. I set the AGC off and adjusted the RF gain so that it did not overload. Still no hint of any signals, but I decoded two stations! Just sayin’. Chuck W5PR Sent from Mail for Windows 10 From: K4SAV Sent: Monday, December 24, 2018 2:10 PM To: topband@contesting.com Subject: Re: Topband: FT8 - How it really works Although I have finished my FT8 testing, there is one final thought I would like to leave with you, and also to correct one statement I made earlier. Someone thought FT8 measured the noise in the interval when the FT8 signals were off, and I replied that would result in a real S/N number. That is not true as you will see in the info below. You would get a real S/N number if the RF was sampled, but not if the audio is sampled. I spent many years designing electronic circuits professionally, so I still think that way. So for a few minutes lets think about a circuit that can decode something below the noise floor .If you think about FT8 or anything similar, from a designers point of view, you suddenly realize that making a statement of "the circuit can decode down to X dBs below the noise floor" is almost an impossible task, that is, if you are talking RF noise floor as most people will be assuming. Since you will be dealing with audio, not RF, the receiver will convert the RF into audio and compress it into something that has a lot less dynamic range. How much less? Say the volume is set to a level such that the strongest signals do not clip, then how far down is the noise? You can expect that to vary on each band too. Now comes a real complication. If you were taking samples in the RF world, you could see the noise level on your S meter and estimate it relative to the strongest signals. However your circuit will be dealing with audio. Surprisingly, when the signals disappear, the receiver AGC voltage drops and the receiver gain increases. That produces a lot more audio signal. The audio noise in the case of no signals becomes higher than the audio level for strong signals if you are using USB bandwidth and receiving something similar to FT8. That condition is not nearly as pronounced when using a narrow CW bandwidth. Even if you put the receiver into AGC slow mode it won't hold for the 3 seconds when FT8 is off, so you still get the increased audio in the off period. Then there will be a sudden increase in audio when the first signal reappears, until the ACG kicks in and lowers it. This happens even with fast AGC selected. It's fast enough that you don't notice it when listening, but if you put a scope on it you can see it. Yeah, all that surprised me too when first thinking about it. Take a close listen and see if you agree. If you can't hear it, put it on a scope or anything that displays an audio waveform and it will become very obvious. If you made a statement that this circuit can decode X dBs below the noise floor, most people will be thinking RF noise floor. So what is it in the audio world that represents the noise floor in the RF world, and what would your statement mean? Of course you could turn off the AGC and decrease the receiver RF gain and that would make the audio very low when the signals disappear. That would also severely limit the dynamic range for your circuit since you would no longer have the compression supplied by the receiver.. Your circuit would have to cover a much wider dynamic range, similar to what a receiver does. So your circuit would need what? maybe 100 dB dynamic range to cover the strongest signals to the weakest noise floor, forgetting about decoding below the noise floor. Actually that wouldn't really happen because receivers can't produce a dynamic range of 100 dB in the audio. They may do it in the RF world, but not in audio. Receivers have no need to do that. Jerry _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: FT8 - How it really works
Although I have finished my FT8 testing, there is one final thought I would like to leave with you, and also to correct one statement I made earlier. Someone thought FT8 measured the noise in the interval when the FT8 signals were off, and I replied that would result in a real S/N number. That is not true as you will see in the info below. You would get a real S/N number if the RF was sampled, but not if the audio is sampled. I spent many years designing electronic circuits professionally, so I still think that way. So for a few minutes lets think about a circuit that can decode something below the noise floor .If you think about FT8 or anything similar, from a designers point of view, you suddenly realize that making a statement of "the circuit can decode down to X dBs below the noise floor" is almost an impossible task, that is, if you are talking RF noise floor as most people will be assuming. Since you will be dealing with audio, not RF, the receiver will convert the RF into audio and compress it into something that has a lot less dynamic range. How much less? Say the volume is set to a level such that the strongest signals do not clip, then how far down is the noise? You can expect that to vary on each band too. Now comes a real complication. If you were taking samples in the RF world, you could see the noise level on your S meter and estimate it relative to the strongest signals. However your circuit will be dealing with audio. Surprisingly, when the signals disappear, the receiver AGC voltage drops and the receiver gain increases. That produces a lot more audio signal. The audio noise in the case of no signals becomes higher than the audio level for strong signals if you are using USB bandwidth and receiving something similar to FT8. That condition is not nearly as pronounced when using a narrow CW bandwidth. Even if you put the receiver into AGC slow mode it won't hold for the 3 seconds when FT8 is off, so you still get the increased audio in the off period. Then there will be a sudden increase in audio when the first signal reappears, until the ACG kicks in and lowers it. This happens even with fast AGC selected. It's fast enough that you don't notice it when listening, but if you put a scope on it you can see it. Yeah, all that surprised me too when first thinking about it. Take a close listen and see if you agree. If you can't hear it, put it on a scope or anything that displays an audio waveform and it will become very obvious. If you made a statement that this circuit can decode X dBs below the noise floor, most people will be thinking RF noise floor. So what is it in the audio world that represents the noise floor in the RF world, and what would your statement mean? Of course you could turn off the AGC and decrease the receiver RF gain and that would make the audio very low when the signals disappear. That would also severely limit the dynamic range for your circuit since you would no longer have the compression supplied by the receiver.. Your circuit would have to cover a much wider dynamic range, similar to what a receiver does. So your circuit would need what? maybe 100 dB dynamic range to cover the strongest signals to the weakest noise floor, forgetting about decoding below the noise floor. Actually that wouldn't really happen because receivers can't produce a dynamic range of 100 dB in the audio. They may do it in the RF world, but not in audio. Receivers have no need to do that. Jerry _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Three Port Rx antenna splitter
Corrected the autotransformer turns/tap on the 2-way splitter examples... http://no3m.net/wp-content/uploads/2018/12/splitters.png On 12/24/18 1:57 PM, Eric NO3M wrote: Frank If you really want a 3-port splitter, see here: http://no3m.net/wp-content/uploads/2018/12/splitter-3.png Two more common alternatives using 2-port splitters: http://no3m.net/wp-content/uploads/2018/12/splitters.png 73 Eric NO3M On 12/24/18 8:00 AM, Frank VO1HP wrote: Does anyone have a schematic for a 75ohm three port splitter using #73 binocular cores. I have those on hand. Need to feed beverage to two TS590SG’s and Skimmer SDR in CQWW160. 73 Frank VO1HP _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Three Port Rx antenna splitter
Frank If you really want a 3-port splitter, see here: http://no3m.net/wp-content/uploads/2018/12/splitter-3.png Two more common alternatives using 2-port splitters: http://no3m.net/wp-content/uploads/2018/12/splitters.png 73 Eric NO3M On 12/24/18 8:00 AM, Frank VO1HP wrote: Does anyone have a schematic for a 75ohm three port splitter using #73 binocular cores. I have those on hand. Need to feed beverage to two TS590SG’s and Skimmer SDR in CQWW160. 73 Frank VO1HP _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Three Port Rx antenna splitter
Hi Frank, I don't know anything about 3-way splitters, but if I were in your situation I think I would sacrifice 1 dB and make a 4-way splitter using 3x 2-way splitters. 2-way is much more commonly used and documented, and quite probably easier to achieve than 3-way. The 4th port is simply terminated in a load, of course. 73, Greg, ZL3IX On 2018-12-25 02:00 a.m., Frank VO1HP wrote: Does anyone have a schematic for a 75ohm three port splitter using #73 binocular cores. I have those on hand. Need to feed beverage to two TS590SG’s and Skimmer SDR in CQWW160. 73 Frank VO1HP _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Morning Openings to Europe from Oregon
All, As Tree noted I've been able to get into Eastern Central and Norther Europe this past week. Truly a very rare case from this far south. The northern guys have an hour more darkness than at my latitude. The openings have been somewhat spotty. I do not rely on RBN spots. Most RBN do not have good low noise RX antennas and do very little to tell me if my signal is making it to the desired areas. For me it's all new! Maybe, the updates and tuning of the antenna system have played a roll. However, I think more than that the fact that I've retired since the last solar cycle has had more impact. But then I don't know as I've listened to N7UA and VE6WZ work many that I could not hear even in my very low noise environment. This morning LA1MFA had a good low QSB signal for several hours. I was spotted by R3LA but did not hear nay other callers. R0SR and UA4HBW in the log earlier this week on the dreaded mode. All of these contacts have been polar direction. Signs are we are in for a great solar minimum. Here is hope that conditions will be favorable for the Stew Perry next weekend! Tip, If you think band is open call CQ! 73 All, Merry Christmas and Happy New Year! Bob, W7RH -- W7RH DM35OS It has become appallingly obvious that our technology has exceeded our humanity. Albert Einstein _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Three Port Rx antenna splitter
Does anyone have a schematic for a 75ohm three port splitter using #73 binocular cores. I have those on hand. Need to feed beverage to two TS590SG’s and Skimmer SDR in CQWW160. 73 Frank VO1HP -- Sent from Gmail Mobile _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: RF in the DX Eng. NCC-1 (and a fix)
Merry Christmas and Happy New Year: On 160 m. (probably due to the close proximity to my inverted L) my NCC-1 rx antenna phasing box would snap crackle and pop on transmit, most likely the result of RF getting into the nine relay coils inside. If you employ phased rx antennas and a tx antenna, all in a small space, running over 1 KW you may have noticed this also. The stock box has some small bypass caps on the DC supply line in, and the T/R control line in, but they were not enough to keep RF out entirely. The fix for me was a small 100 micro-Henry choke inside the box in series with the floating center of the T/R line, along with a 0.015 mfd cap on the cold side of the choke to ground, and a pair of the same chokes in series with the DC +,- supply line into the box at its entrance. The DC supply jack has an adequate amount of stock bypass capacitance so I didn't add any more. 0.1 mfd if I remember correctly. These fixes quieted the NCC-1 down for me and were a lot easier than trying to bypass each relay coil to ground with capacitors. 73 Rob K5UJ _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
