K3, VHF Diversity
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I am in the process of implementing full diversity reception of 2M CW
EME signals. I will be using 2 each quad arrays of 2M long yagis, One horizontally polarized and the other vertically polarized. At and after the antennas' power dividers, there will be installed equal gain and NF LNAs, followed by equal lengths of Heliax Super Flex down to the shack. In the shack will be two identical phase locked (together) down converters that drive the K3 and it's Sub RX. This will result in one polarization in one ear and the other in the opposite ear. The TX upconverter and K3, will be locked to the same source. It will be an interesting on going experiment, to see if/how this affects and hopefully somewhat overcomes the polarization rotation and faraday/libration properties of EME received signals. Also planed, will be to feed both polarizations simultaneously, during TX, with a QRO+ PA. BTW, to date I don't use any computer control of the K3 ! I don't even allow any computers to be on when performing 2M EME operations, due to the residual broad band noise and birdies emitted by most . The availability of a none computer(external) controlled SDR receiver, among other features, is what sold me on the K3/P3SVGA system. Chuck, W7CS Message: 21 Date: Tue, 17 Feb 2015 22:09:08 -0800 From: Wayne Burdick <[hidden email]> To: Vic Rosenthal <[hidden email]> Cc: Elecraft Reflector <[hidden email]> Subject: Re: [Elecraft] [Elecraft_K3] Who said anything about removing diversity? That would *never* happen... Message-ID: <[hidden email]> Content-Type: text/plain; charset=us-ascii Diversity reception is characterized by perceived "phase precessing" between the two receivers' audio streams due to varying phases of the main and sub RF input signals. You don't want additional, unpredictable phase precessing on top of that due to the receivers themselves. Additive phase changes would sometimes make diversity reception less pleasant to listen to. Better to have the receivers locked together, eliminating a variable. Wayne N6KR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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On Wed,2/18/2015 11:25 AM, Chuck Smallhouse wrote:
> I don't even allow any computers to be on when performing 2M EME > operations, due to the residual broad band noise and birdies emitted > by most . Yes, that's a real problem. You may do better with older computers. My T2x and T4x-series Thinkpads will run (but won't charge) on 12VDC, which eliminates any noise from the switching power supply, but it doesn't help with noise radiated directly by the laptop. Newer computers seem to be noisier than these older ones. We discovered that on 6M/2M grid trip last fall. The T43s were quiet enough, but my partner's much newer one was pretty bad. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by W7CS
I'm curious about this ....
Is it a full duplex system or simplex (AKA are you listening while transmit?) From: Chuck Smallhouse <[hidden email]> To: [hidden email] Sent: Wednesday, February 18, 2015 2:25 PM Subject: [Elecraft] K3, VHF Diversity I am in the process of implementing full diversity reception of 2M CW EME signals. I will be using 2 each quad arrays of 2M long yagis, One horizontally polarized and the other vertically polarized. At and after the antennas' power dividers, there will be installed equal gain and NF LNAs, followed by equal lengths of Heliax Super Flex down to the shack. In the shack will be two identical phase locked (together) down converters that drive the K3 and it's Sub RX. This will result in one polarization in one ear and the other in the opposite ear. The TX upconverter and K3, will be locked to the same source. It will be an interesting on going experiment, to see if/how this affects and hopefully somewhat overcomes the polarization rotation and faraday/libration properties of EME received signals. Also planed, will be to feed both polarizations simultaneously, during TX, with a QRO+ PA. BTW, to date I don't use any computer control of the K3 ! I don't even allow any computers to be on when performing 2M EME operations, due to the residual broad band noise and birdies emitted by most . The availability of a none computer(external) controlled SDR receiver, among other features, is what sold me on the K3/P3SVGA system. Chuck, W7CS Message: 21 Date: Tue, 17 Feb 2015 22:09:08 -0800 From: Wayne Burdick <[hidden email]> To: Vic Rosenthal <[hidden email]> Cc: Elecraft Reflector <[hidden email]> Subject: Re: [Elecraft] [Elecraft_K3] Who said anything about removing diversity? That would *never* happen... Message-ID: <[hidden email]> Content-Type: text/plain; charset=us-ascii Diversity reception is characterized by perceived "phase precessing" between the two receivers' audio streams due to varying phases of the main and sub RF input signals. You don't want additional, unpredictable phase precessing on top of that due to the receivers themselves. Additive phase changes would sometimes make diversity reception less pleasant to listen to. Better to have the receivers locked together, eliminating a variable. Wayne N6KR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by W7CS
I guess I missed Chuck's posting on Feb.18th.
Harry: First your question the K3 is unable to operate in duplex as common ckts are used in the DSP (2nd IF) for both Tx and Rx. Only simplex operation is allowed. Chuck: A couple comments: I am already doing what you propose as far as receiving dual-pol, diversity eme signals: http://www.kl7uw.com/MAP65.htm I've posted this on the Elecraft Reflector, before. I had never considered running it for CW, which is what I think you are proposing. I guess that will work. You cannot use the 2nd IF to extract IQ baseband if you want to connect to digital sw. To do that you need to tap off both receiver's IF into a simple SDR like the LP-Pan feeding a four-port soundcard/computer. Transmitting to both polarity antennas will result in linear polarity of 45-degrees or 135-degrees, if split equally. You would be better to add a 90-degree phase line on one polarity to produce circular polarization. That will result in your signal being 3-dB weaker received by linear-pol antennas but will suffer no Faraday issues. Several DXpeditions have run this way to avoid dealing with Faraday. As long as you only run CW you do not need a computer (if you have moon pointing pre-printed). MAP65 requires a computer (of course) and is nearly immune to birdies (if not too thick). At present 95% of 2m-eme is digital. 73, Ed - KL7UW ----------- From: Harry Yingst via Elecraft <[hidden email]> To: Chuck Smallhouse <[hidden email]>, "[hidden email]" <[hidden email]> Subject: Re: [Elecraft] K3, VHF Diversity Message-ID: <[hidden email]> Content-Type: text/plain; charset=UTF-8 I'm curious about this .... Is it a full duplex system or simplex (AKA are you listening while transmit?) From: Chuck Smallhouse <[hidden email]> To: [hidden email] Sent: Wednesday, February 18, 2015 2:25 PM Subject: [Elecraft] K3, VHF Diversity I am in the process of implementing full diversity reception of 2M CW EME signals. I will be using 2 each quad arrays of 2M long yagis,? One horizontally polarized and the other vertically polarized.? At and after the antennas' power dividers, there will be installed equal gain and NF LNAs, followed by equal lengths of Heliax Super Flex down to the shack.? In the shack will be two identical phase locked (together) down converters that drive the K3 and it's Sub RX.? This will result in one polarization in one ear and the other in the opposite ear.? The TX upconverter and K3, will be locked to the same source. It will be an interesting on going experiment, to see if/how this affects and hopefully somewhat overcomes the polarization rotation and faraday/libration properties of EME received signals. Also planed, will be to feed both polarizations simultaneously, during TX, with a QRO+ PA. BTW, to date I don't use any computer control of the K3 !? I don't even allow any computers to be on when performing 2M EME operations, due to the residual broad band noise and birdies emitted by most .? The availability of a none computer(external) controlled SDR receiver, among other features, is what sold me on the K3/P3SVGA system. Chuck,? W7CS 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Yes I understand the K3 is a Non-Duplex radio.
Truthfully I have yet to really look at Sat Seriously and the last I really read up on it wasyears ago (up on one band down on another) So for some reason I had it stuck in my mindthat you had to listen to yourself (Duplex) Something I'll need to read up on again. Thank you From: Edward R Cole <[hidden email]> To: [hidden email] Sent: Thursday, February 19, 2015 12:19 AM Subject: Re: [Elecraft] K3, VHF Diversity I guess I missed Chuck's posting on Feb.18th. Harry: First your question the K3 is unable to operate in duplex as common ckts are used in the DSP (2nd IF) for both Tx and Rx. Only simplex operation is allowed. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by W7CS
That should work well Chuck. I know that SM5FRH had a similar system many years ago when he had his huge EME array. No computer required, just the brain doing the combining. I never tried that when I had my previous dual polarity array, I just had simple H or V switching, but I am planning to have polarity diversity this time on digital at least with a LinkRF IQ+ system. I may also try using it on CW with LINRAD and the same hardware.
I agree that you have to be very careful with choice of computers and power supplies when doing EME on VHF, or make the choice not to switch them on unless absolutely necessary. Before the advent of digital modes for EME I nearly always had all things switched off apart from an old NEC laptop similar to the Tandy Model 100 with an LCD display which was totally silent RF wise. The NEC was just for giving me Moon position, tracking of the moon being done manually. Gradually computers crept into the shack as we had nice tools available like FFT waterfall displays, the first popular one being AF9Y FFTDSP and later we had various DSP audio filtering programs added to the suite of essential utilities. Now of course we have the Internet and all that entails, including distractions while operating. I see photos of shacks with multiple computers and monitors and wonder how much the noise floor must be raised by all of that on VHF. I know Leif SM5BSZ wrote an article on the extreme measures he had to take with his computer to make it quiet for LINRAD use. I remember changing the clock crystal in my old PC to a lower frequency one so that the harmonic fell below the bottom of the band. Similarly I replaced the switched mode power supply in the PC to a model that had better filtering and the noise fell 10dB. Even a dB of extra noise can kill weak signal EME. The bottom ends of our VHF and UHF bands are now so full of birdies from computers etc that CW weak signal users have to move up the band from their traditional place. For most people there is no possibility of working in the bottom 20 or 30 kHz. I contrast that to when I (and much more so Chuck, who is one of the pioneers of EME) started on EME and there was no QRM at all, if you heard something it was another station. Sometimes it is nice to get away from it all and just have a radio, headphones and key. Good luck. 73 David Anderson GM4JJJ > On 18 Feb 2015, at 19:25, Chuck Smallhouse <[hidden email]> wrote: > > I am in the process of implementing full diversity reception of 2M CW EME signals. > > I will be using 2 each quad arrays of 2M long yagis, One horizontally polarized and the other vertically polarized. At and after the antennas' power dividers, there will be installed equal gain and NF LNAs, followed by equal lengths of Heliax Super Flex down to the shack. In the shack will be two identical phase locked (together) down converters that drive the K3 and it's Sub RX. This will result in one polarization in one ear and the other in the opposite ear. The TX upconverter and K3, will be locked to the same source. > > It will be an interesting on going experiment, to see if/how this affects and hopefully somewhat overcomes the polarization rotation and faraday/libration properties of EME received signals. > > Also planed, will be to feed both polarizations simultaneously, during TX, with a QRO+ PA. > > BTW, to date I don't use any computer control of the K3 ! I don't even allow any computers to be on when performing 2M EME operations, due to the residual broad band noise and birdies emitted by most . The availability of a none computer(external) controlled SDR receiver, among other features, is what sold me on the K3/P3SVGA system. > > Chuck, W7CS > > Message: 21 > Date: Tue, 17 Feb 2015 22:09:08 -0800 > From: Wayne Burdick <[hidden email]> > To: Vic Rosenthal <[hidden email]> > Cc: Elecraft Reflector <[hidden email]> > Subject: Re: [Elecraft] [Elecraft_K3] Who said anything about removing > diversity? That would *never* happen... > Message-ID: <[hidden email]> > Content-Type: text/plain; charset=us-ascii > > Diversity reception is characterized by perceived "phase precessing" between the two receivers' audio streams due to varying phases of the main and sub RF input signals. You don't want additional, unpredictable phase precessing on top of that due to the receivers themselves. Additive phase changes would sometimes make diversity reception less pleasant to listen to. Better to have the receivers locked together, eliminating a variable. > > Wayne > N6KR > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Elecraft mailing list
Hi Harry,
You are correct on satellite operation a full duplex rig is useful so you can net your signal on the other station as there you are for example transmitting up to space on 70cm and receiving the transponded signal on 2m. On high orbit satellites the slight delay is off putting if you listen to your own voice delayed and you can tend to stammer! However Chuck is writing about 144MHz moonbounce not OSCAR satellite operation. O moonbounce via "OSCAR 0" we can listen to our own signal, but don't need a full duplex rig to do that because of the 2.5 second delay of our own moon echo. Typically you hear a lot of echo testing which goes like this on CW at 15wpm: Transmit "OOOOO" with a huge ERP then back to receive a weak and watery "ooooo" if you are lucky and the gods are willing. Sometimes the shift in polarisation through the ionosphere (Faraday rotation) causes the signal to come back at 90 degrees to what you sent it up at and then you will generally hear nothing. This is where having dual receivers, one on Horizontal polarisation and the other on Vertical polarisation would help a lot. On 23cm and higher frequencies, moonbounce is generally transmitted on circular polarisation and even this requires a bit of thought because the mirror reflection off the moon converts right hand circular into left hand circular, so your antenna feed system to your dish has to cope with that. 73 David Anderson GM4JJJ > On 19 Feb 2015, at 07:32, Harry Yingst via Elecraft <[hidden email]> wrote: > > Yes I understand the K3 is a Non-Duplex radio. > Truthfully I have yet to really look at Sat Seriously and the last I really read up on it wasyears ago (up on one band down on another) So for some reason I had it stuck in my mindthat you had to listen to yourself (Duplex) Something I'll need to read up on again. > Thank you > > > > > From: Edward R Cole <[hidden email]> > To: [hidden email] > Sent: Thursday, February 19, 2015 12:19 AM > Subject: Re: [Elecraft] K3, VHF Diversity > > I guess I missed Chuck's posting on Feb.18th. > > Harry: > > First your question the K3 is unable to operate in duplex as common > ckts are used in the DSP (2nd IF) for both Tx and Rx. Only simplex > operation is allowed. > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Thank you,
I'm at the point in my life where my children are now adults, and while my jobkeeps me busy I now have a bit more time and funds to devote to hobbies. As a boy I spent a many hours reading the old handbooks older hams had givenme and dreaming, of being able to build all those interesting and exotic things. Later (while still in the Navy) I worked for a Two Way company where the Owner/Bosstook me under his wing (I owe much to that man) He gave me the confidence in my abilities. Though I spent the next 25 years in IT, my first love has always been radio and electronics. Now I just need time so I can build all those interesting and exotic things. From: David Anderson <[hidden email]> To: Harry Yingst <[hidden email]> Cc: Edward R Cole <[hidden email]>; "[hidden email]" <[hidden email]> Sent: Thursday, February 19, 2015 5:33 AM Subject: Re: [Elecraft] K3, VHF Diversity Hi Harry, You are correct on satellite operation a full duplex rig is useful so you can net your signal on the other station as there you are for example transmitting up to space on 70cm and receiving the transponded signal on 2m. On high orbit satellites the slight delay is off putting if you listen to your own voice delayed and you can tend to stammer! However Chuck is writing about 144MHz moonbounce not OSCAR satellite operation. O moonbounce via "OSCAR 0" we can listen to our own signal, but don't need a full duplex rig to do that because of the 2.5 second delay of our own moon echo. Typically you hear a lot of echo testing which goes like this on CW at 15wpm: Transmit "OOOOO" with a huge ERP then back to receive a weak and watery "ooooo" if you are lucky and the gods are willing. Sometimes the shift in polarisation through the ionosphere (Faraday rotation) causes the signal to come back at 90 degrees to what you sent it up at and then you will generally hear nothing. This is where having dual receivers, one on Horizontal polarisation and the other on Vertical polarisation would help a lot. On 23cm and higher frequencies, moonbounce is generally transmitted on circular polarisation and even this requires a bit of thought because the mirror reflection off the moon converts right hand circular into left hand circular, so your antenna feed system to your dish has to cope with that. 73 David Anderson GM4JJJ > On 19 Feb 2015, at 07:32, Harry Yingst via Elecraft <[hidden email]> wrote: > > Yes I understand the K3 is a Non-Duplex radio. > Truthfully I have yet to really look at Sat Seriously and the last I really read up on it wasyears ago (up on one band down on another) So for some reason I had it stuck in my mindthat you had to listen to yourself (Duplex) Something I'll need to read up on again. > Thank you > > > > > From: Edward R Cole <[hidden email]> > To: [hidden email] > Sent: Thursday, February 19, 2015 12:19 AM > Subject: Re: [Elecraft] K3, VHF Diversity > > I guess I missed Chuck's posting on Feb.18th. > > Harry: > > First your question the K3 is unable to operate in duplex as common > ckts are used in the DSP (2nd IF) for both Tx and Rx. Only simplex > operation is allowed. > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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