Re: [Repeater-Builder] Sinclair dipole phasing harness
Nate Duehr wrote: I am not an expert, but most of the Sinclair stuff I've used had the elements welded in place. These are the HD models (heavy-duty) They also make them welded in the Low PIM models... no moving parts to make noise... Interesting. I was wondering what was different about the low PIM models. I should have guessed they would be welded construction. I wonder if they also use different types of coax in the harness? I have often wondered if single copper braid cables weren't a potential source of noise, especially as they get older? I think you're right in the lower-end Sinclair line, there are elements that are just bolted to a mast Correct. I am not an expert either, but have seen quite a few of these in various configurations and spent some time perusing the product line, wishing I could buy a new one. Some have the dipoles just a few inches from the mast, and are field adjustable for offset or omni pattern. For offset, all dipoles go on one side of the mast. For omni they go on opposite sides or spiral around the mast. These models generally seem to have a bandwidth of about 10 MHz, eg. they come in 142-152, 152-162 MHz models, etc. Some have the dipoles roughly a quarter wavelength from the mast, all on one side, and are intended to provide an offset pattern only. These usually cover 138-174 MHz. Some have the dipoles roughly a half wavelength from the mast, all on one side, and are intended to provide and elliptical pattern. These usually cover 138-174 MHz. There are also a few that have pairs of dipoles side by side, with spacing somewhat less than a quarter wavelength. These are field adjustable for elliptical or omni, and the ones I've seen (and owned) were 138-174 MHz. There very likely may be others that I am not familiar with, these are just some observations I have made. I'll take the expensive antenna, any day... over farting around with a lower quality one! I would if I could! Maintaining a repeater is becoming a full time job. Much of the time that goes into it is directly related to farting around trying to keep something on the air and working reasonably well with a zero budget. But one does what one can. If it was just another repeater serving an area that already had several repeaters sitting idle, I'd have walked away from it in frustration long ago! Paul N1BUG Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Sinclair dipole phasing harness
Hi Burt, Did I hear my name mentioned??? Maybe just ESP:-) Yes you did, Great Sinclair dipole guru! :-) I got the dipole drawing from your new web site. Thanks! That part I'm clear on, but still a bit confused on the phasing harness. I would suggest that you don't even consider putting the harnass inside the mast (unless Harold can tell us how Sinclair does it). Put the harness on the outside of the mast like the SRL210A4. Uh, yeah, I hear that. I like the idea of the internal harness, but I just spent 3 hours getting the old harness *out* of the mast. I can't imagine how it was put *in* there. To combine the impedances on a 4 bay Sinclair array is simple. Divide the dipoles into pairs and parallel them. This gives 25 ohms. Then add an electrical quarter wave of 50 ohm coax (RG-213/U) to transform it to 100 ohms. Combine the matching coax from each pair in parallel to give 50 ohms. Then you can connect your feedline at any length from this latter 50 ohm connection. Here is a crude drawing of what I think you are saying: http://www.n1bug.com/dipoleharness1.jpg Points X and Y are the 100 ohm points created by adding an electrical quarter wave of RG-213 coming out of the 25 ohm point where two dipoles are connected in parallel. But points X and Y are physically several feet apart. That being said, I think the coax that joins those points at the final parallel junction (to connect to the feedline) would have to be a multiple of an electrical half wavelength in order to repeat the 100 ohms at the other end (thus ending up with 50 ohms when you parallel them)? If so, I'm still confused on how they did this for both cardioid and bidirectional versions of this antenna with the harness inside the mast. Required physical lengths would be different due to the different dipole spacing from the mast. One can only work with physical lengths that fit inside the mast (I guess?) but this seems to clash with the electrical length required for impedance matching. It's a non-issue since I have no way of getting a new harness inside the mast. With an external harness I can just coil up or loop any extra length required for matching reasons. But I'd still like to understand how they did it. :-) In any case, the phasing harness on my 210C4 was done differently. It uses a combination of RG-213/U and RG-63B/U in the harness itself. Here is a sketch of it: http://www.n1bug.com/210C4harness.jpg Here, if we assume points X and Y are 100 ohms, point Z (where the feedline attaches) would fall somewhere between 50 ohms and 78 ohms, depending on the electrical length of the RG-63B/U coax connecting them. I'm trying to look up the velocity factor of RG-63B/U (part PE, part air dielectric), but having no luck so far. All of which seems completely different from the picture at http://forum.radioamateur.ca/index.php?topic=2245.0 where there appears to be just a quarter wave section of coax off each side of point Z to the T for each pair of dipoles. I don't know how that was physically possible given the dipole spacing. I think we can safely assume I'm missing something here. :-) Paul N1BUG Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Sinclair dipole phasing harness
I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh On 5/18/10, N1BUG p...@n1bug.com wrote: Hi Burt, Did I hear my name mentioned??? Maybe just ESP:-) Yes you did, Great Sinclair dipole guru! :-) I got the dipole drawing from your new web site. Thanks! That part I'm clear on, but still a bit confused on the phasing harness. I would suggest that you don't even consider putting the harnass inside the mast (unless Harold can tell us how Sinclair does it). Put the harness on the outside of the mast like the SRL210A4. Uh, yeah, I hear that. I like the idea of the internal harness, but I just spent 3 hours getting the old harness *out* of the mast. I can't imagine how it was put *in* there. To combine the impedances on a 4 bay Sinclair array is simple. Divide the dipoles into pairs and parallel them. This gives 25 ohms. Then add an electrical quarter wave of 50 ohm coax (RG-213/U) to transform it to 100 ohms. Combine the matching coax from each pair in parallel to give 50 ohms. Then you can connect your feedline at any length from this latter 50 ohm connection. Here is a crude drawing of what I think you are saying: http://www.n1bug.com/dipoleharness1.jpg Points X and Y are the 100 ohm points created by adding an electrical quarter wave of RG-213 coming out of the 25 ohm point where two dipoles are connected in parallel. But points X and Y are physically several feet apart. That being said, I think the coax that joins those points at the final parallel junction (to connect to the feedline) would have to be a multiple of an electrical half wavelength in order to repeat the 100 ohms at the other end (thus ending up with 50 ohms when you parallel them)? If so, I'm still confused on how they did this for both cardioid and bidirectional versions of this antenna with the harness inside the mast. Required physical lengths would be different due to the different dipole spacing from the mast. One can only work with physical lengths that fit inside the mast (I guess?) but this seems to clash with the electrical length required for impedance matching. It's a non-issue since I have no way of getting a new harness inside the mast. With an external harness I can just coil up or loop any extra length required for matching reasons. But I'd still like to understand how they did it. :-) In any case, the phasing harness on my 210C4 was done differently. It uses a combination of RG-213/U and RG-63B/U in the harness itself. Here is a sketch of it: http://www.n1bug.com/210C4harness.jpg Here, if we assume points X and Y are 100 ohms, point Z (where the feedline attaches) would fall somewhere between 50 ohms and 78 ohms, depending on the electrical length of the RG-63B/U coax connecting them. I'm trying to look up the velocity factor of RG-63B/U (part PE, part air dielectric), but having no luck so far. All of which seems completely different from the picture at http://forum.radioamateur.ca/index.php?topic=2245.0 where there appears to be just a quarter wave section of coax off each side of point Z to the T for each pair of dipoles. I don't know how that was physically possible given the dipole spacing. I think we can safely assume I'm missing something here. :-) Paul N1BUG Yahoo! Groups Links
Re: [Repeater-Builder] Sinclair dipole phasing harness
The ones going to the third 'T' should be the same length to avoid out-of-phase issues. Joe M. Larry Horlick wrote: I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh On 5/18/10, *N1BUG* p...@n1bug.com mailto:p...@n1bug.com wrote: Hi Burt, Did I hear my name mentioned??? Maybe just ESP:-) Yes you did, Great Sinclair dipole guru! :-) I got the dipole drawing from your new web site. Thanks! That part I'm clear on, but still a bit confused on the phasing harness. I would suggest that you don't even consider putting the harnass inside the mast (unless Harold can tell us how Sinclair does it). Put the harness on the outside of the mast like the SRL210A4. Uh, yeah, I hear that. I like the idea of the internal harness, but I just spent 3 hours getting the old harness *out* of the mast. I can't imagine how it was put *in* there. To combine the impedances on a 4 bay Sinclair array is simple. Divide the dipoles into pairs and parallel them. This gives 25 ohms. Then add an electrical quarter wave of 50 ohm coax (RG-213/U) to transform it to 100 ohms. Combine the matching coax from each pair in parallel to give 50 ohms. Then you can connect your feedline at any length from this latter 50 ohm connection. Here is a crude drawing of what I think you are saying: http://www.n1bug.com/dipoleharness1.jpg Points X and Y are the 100 ohm points created by adding an electrical quarter wave of RG-213 coming out of the 25 ohm point where two dipoles are connected in parallel. But points X and Y are physically several feet apart. That being said, I think the coax that joins those points at the final parallel junction (to connect to the feedline) would have to be a multiple of an electrical half wavelength in order to repeat the 100 ohms at the other end (thus ending up with 50 ohms when you parallel them)? If so, I'm still confused on how they did this for both cardioid and bidirectional versions of this antenna with the harness inside the mast. Required physical lengths would be different due to the different dipole spacing from the mast. One can only work with physical lengths that fit inside the mast (I guess?) but this seems to clash with the electrical length required for impedance matching. It's a non-issue since I have no way of getting a new harness inside the mast. With an external harness I can just coil up or loop any extra length required for matching reasons. But I'd still like to understand how they did it. :-) In any case, the phasing harness on my 210C4 was done differently. It uses a combination of RG-213/U and RG-63B/U in the harness itself. Here is a sketch of it: http://www.n1bug.com/210C4harness.jpg Here, if we assume points X and Y are 100 ohms, point Z (where the feedline attaches) would fall somewhere between 50 ohms and 78 ohms, depending on the electrical length of the RG-63B/U coax connecting them. I'm trying to look up the velocity factor of RG-63B/U (part PE, part air dielectric), but having no luck so far. All of which seems completely different from the picture at http://forum.radioamateur.ca/index.php?topic=2245.0 where there appears to be just a quarter wave section of coax off each side of point Z to the T for each pair of dipoles. I don't know how that was physically possible given the dipole spacing. I think we can safely assume I'm missing something here. :-) Paul N1BUG Yahoo! Groups Links repeater-builder-fullfeatu...@yahoogroups.com mailto:repeater-builder-fullfeatu...@yahoogroups.com
Re: [Repeater-Builder] Sinclair dipole phasing harness
You're right, Joe. They are both labeled the same, so they are the same length but can be any odd 1/4 wavelength. lh On 5/18/10, MCH m...@nb.net wrote: The ones going to the third 'T' should be the same length to avoid out-of-phase issues. Joe M. Larry Horlick wrote: I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh On 5/18/10, *N1BUG* p...@n1bug.com paul%40n1bug.com mailto: p...@n1bug.com paul%40n1bug.com wrote: Hi Burt, Did I hear my name mentioned??? Maybe just ESP:-) Yes you did, Great Sinclair dipole guru! :-) I got the dipole drawing from your new web site. Thanks! That part I'm clear on, but still a bit confused on the phasing harness. I would suggest that you don't even consider putting the harnass inside the mast (unless Harold can tell us how Sinclair does it). Put the harness on the outside of the mast like the SRL210A4. Uh, yeah, I hear that. I like the idea of the internal harness, but I just spent 3 hours getting the old harness *out* of the mast. I can't imagine how it was put *in* there. To combine the impedances on a 4 bay Sinclair array is simple. Divide the dipoles into pairs and parallel them. This gives 25 ohms. Then add an electrical quarter wave of 50 ohm coax (RG-213/U) to transform it to 100 ohms. Combine the matching coax from each pair in parallel to give 50 ohms. Then you can connect your feedline at any length from this latter 50 ohm connection. Here is a crude drawing of what I think you are saying: http://www.n1bug.com/dipoleharness1.jpg Points X and Y are the 100 ohm points created by adding an electrical quarter wave of RG-213 coming out of the 25 ohm point where two dipoles are connected in parallel. But points X and Y are physically several feet apart. That being said, I think the coax that joins those points at the final parallel junction (to connect to the feedline) would have to be a multiple of an electrical half wavelength in order to repeat the 100 ohms at the other end (thus ending up with 50 ohms when you parallel them)? If so, I'm still confused on how they did this for both cardioid and bidirectional versions of this antenna with the harness inside the mast. Required physical lengths would be different due to the different dipole spacing from the mast. One can only work with physical lengths that fit inside the mast (I guess?) but this seems to clash with the electrical length required for impedance matching. It's a non-issue since I have no way of getting a new harness inside the mast. With an external harness I can just coil up or loop any extra length required for matching reasons. But I'd still like to understand how they did it. :-) In any case, the phasing harness on my 210C4 was done differently. It uses a combination of RG-213/U and RG-63B/U in the harness itself. Here is a sketch of it: http://www.n1bug.com/210C4harness.jpg Here, if we assume points X and Y are 100 ohms, point Z (where the feedline attaches) would fall somewhere between 50 ohms and 78 ohms, depending on the electrical length of the RG-63B/U coax connecting them. I'm trying to look up the velocity factor of RG-63B/U (part PE, part air dielectric), but having no luck so far. All of which seems completely different from the picture at http://forum.radioamateur.ca/index.php?topic=2245.0 where there appears to be just a quarter wave section of coax off each side of point Z to the T for each pair of dipoles. I don't know how that was physically possible given the dipole spacing. I think we can safely assume I'm missing something here. :-) Paul N1BUG Yahoo! Groups Links repeater-builder-fullfeatu...@yahoogroups.comRepeater-Builder-fullfeatured%40yahoogroups.com mailto:repeater-builder-fullfeatu...@yahoogroups.comRepeater-Builder-fullfeatured%40yahoogroups.com
Re: [Repeater-Builder] Sinclair dipole phasing harness
Thanks. That makes sense and should work out quite well for a harness external to the mast. Of course the quarter wave of 125 ohm coax will still be required inside each dipole, but the use of all 50 ohm coax beyond that point simplifies construction. Apparently Sinclair had different ways of doing it, perhaps depending on the exact model. Or maybe they changed the harness design at some point. Paul N1BUG Larry Horlick wrote: I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh
Re: [Repeater-Builder] Sinclair dipole phasing harness
On the drawing it does not show any 125 ohm cable, but I think what you are saying is that from the feedpoint of the folded dipole, inside the tubing there is a 1/4 wavelength piece of 125 ohm cable (about 13.5 inches at 2m) that is joined to 50 ohm cable. What we see exiting the tube (opposite the feedpoint) is the 50 ohm stuff. If this is correct it fully explains a drawing on the previous page showing a cross section of a single element folder dipole. \ lh On 5/18/10, N1BUG p...@n1bug.com wrote: Thanks. That makes sense and should work out quite well for a harness external to the mast. Of course the quarter wave of 125 ohm coax will still be required inside each dipole, but the use of all 50 ohm coax beyond that point simplifies construction. Apparently Sinclair had different ways of doing it, perhaps depending on the exact model. Or maybe they changed the harness design at some point. Paul N1BUG Larry Horlick wrote: I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh
Re: [Repeater-Builder] Sinclair dipole phasing harness
On 5/18/2010 12:29 PM, Larry Horlick wrote: I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. Yes, I believe this is correct. Whenever I've looked, notice that the omni versions are 1/2 wave spacing from the mast, and the cartioid are 1/4 wave spacing from the mast, in almost all of Sinclair's product line. Nate WY0X
Re: [Repeater-Builder] Sinclair dipole phasing harness
That's correct. The folded dipole impedance is 300 ohms. The 1/4 wavelength of 125 ohm coax transforms that down close to 50 ohms. This 1/4 wavelength matching section is completely inside the dipole itself. The transition to 50 ohm cable occurs somewhere near the top of the folded dipole, so we see the 50 ohm cable exiting the dipole. In my dipoles the 125 ohm cable is RG-63B/U which, owing to its partly air dielectric, no doubt has a higher velocity factor than solid dielectric coax. So the section is somewhat longer than 13.5 inches. I'm still trying to find a reference to the exact velocity factor of RG-63B/U. It sounds like you have some very interesting (and rare) Sinclair documentation there! Paul N1BUG Larry Horlick wrote: On the drawing it does not show any 125 ohm cable, but I think what you are saying is that from the feedpoint of the folded dipole, inside the tubing there is a 1/4 wavelength piece of 125 ohm cable (about 13.5 inches at 2m) that is joined to 50 ohm cable. What we see exiting the tube (opposite the feedpoint) is the 50 ohm stuff. If this is correct it fully explains a drawing on the previous page showing a cross section of a single element folder dipole. \ lh On 5/18/10, *N1BUG* p...@n1bug.com mailto:p...@n1bug.com wrote: Thanks. That makes sense and should work out quite well for a harness external to the mast. Of course the quarter wave of 125 ohm coax will still be required inside each dipole, but the use of all 50 ohm coax beyond that point simplifies construction. Apparently Sinclair had different ways of doing it, perhaps depending on the exact model. Or maybe they changed the harness design at some point. Paul N1BUG Larry Horlick wrote: I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Sinclair dipole phasing harness
Indeed. Most of it is hand written, and come from Sinclair training material. These are copies, not originals and for the life of me I cannot remember where I got. I'm thinking it was given to me by one the Sinclair gurus in Aurora when I dropped in one day to pick up some invar rods for a Q202 duplexer that I was given. Anyway this guy came out of the shop and we had a short discussion about various Sinclair products. He took out to the plant floor and after went back to his office. He was a production manager and hand drew in front of me several curves for different filters. It turned into a 3 hour training session for me. He covered so much material that I retained only a fraction. He was very knowedgeable and extremely passionate about his work and the product. I ultimately walked away with 4 rods, gratis, and he followed up with a phone call a couple of weeks later to see if I was successful in refirbishing the duplexer. This was Feb of 1990 and the list price of the rods, then, were $18.50 ea. lh On 5/18/10, N1BUG p...@n1bug.com wrote: That's correct. The folded dipole impedance is 300 ohms. The 1/4 wavelength of 125 ohm coax transforms that down close to 50 ohms. This 1/4 wavelength matching section is completely inside the dipole itself. The transition to 50 ohm cable occurs somewhere near the top of the folded dipole, so we see the 50 ohm cable exiting the dipole. In my dipoles the 125 ohm cable is RG-63B/U which, owing to its partly air dielectric, no doubt has a higher velocity factor than solid dielectric coax. So the section is somewhat longer than 13.5 inches. I'm still trying to find a reference to the exact velocity factor of RG-63B/U. It sounds like you have some very interesting (and rare) Sinclair documentation there! Paul N1BUG Larry Horlick wrote: On the drawing it does not show any 125 ohm cable, but I think what you are saying is that from the feedpoint of the folded dipole, inside the tubing there is a 1/4 wavelength piece of 125 ohm cable (about 13.5 inches at 2m) that is joined to 50 ohm cable. What we see exiting the tube (opposite the feedpoint) is the 50 ohm stuff. If this is correct it fully explains a drawing on the previous page showing a cross section of a single element folder dipole. \ lh On 5/18/10, *N1BUG* p...@n1bug.com mailto:p...@n1bug.com wrote: Thanks. That makes sense and should work out quite well for a harness external to the mast. Of course the quarter wave of 125 ohm coax will still be required inside each dipole, but the use of all 50 ohm coax beyond that point simplifies construction. Apparently Sinclair had different ways of doing it, perhaps depending on the exact model. Or maybe they changed the harness design at some point. Paul N1BUG Larry Horlick wrote: I have a drawing from Sinclair that shows 4 stacked folded dipoles (it does not indicate an antenna model) using all 50 ohm cable. So using the 210C4 harness picture from the link below as a template, this is how it's done: Feedlines from dipole A, B, C, and D are any length, but identical. A and B go to a tee, C and D go to another tee. The feedlines from the output (if I am allowed to use that rather crude term!) of these tees are any odd 1/4 wavelength (but do not have to be the same) and go to a 3rd tee. The output of this tee is 50 ohms. I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. lh Yahoo! Groups Links
Re: [Repeater-Builder] Sinclair dipole phasing harness
I can't speak specifically of Sinclair, most all of the models I've used will do either omni or cardioid by moving the elements. The spacing from the mast stays the same. Joe M. Nate Duehr wrote: On 5/18/2010 12:29 PM, Larry Horlick wrote: I suspect that the harness does not affect the pattern, but rather it is the dipole to mast spacing. Yes, I believe this is correct. Whenever I've looked, notice that the omni versions are 1/2 wave spacing from the mast, and the cartioid are 1/4 wave spacing from the mast, in almost all of Sinclair's product line. Nate WY0X
Re: [Repeater-Builder] Sinclair dipole phasing harness
On May 18, 2010, at 6:17 PM, MCH wrote: I can't speak specifically of Sinclair, most all of the models I've used will do either omni or cardioid by moving the elements. The spacing from the mast stays the same. Joe M. I am not an expert, but most of the Sinclair stuff I've used had the elements welded in place. These are the HD models (heavy-duty) ... they cost more, but the usually outlast the repeater gear, or match it for longevity. If they have the internal harness, and the hardline run to them is done right for weatherproofing, they're damn near indestructible. They also make them welded in the Low PIM models... no moving parts to make noise... I think you're right in the lower-end Sinclair line, there are elements that are just bolted to a mast, and you might even be able to buy the antenna without the mast, and provide your own. I'm not a big fan of those. But the welded/HD models are spendy up-front. I do think you get what you pay for, though. On a site where hoisting and dealing with a 4-bay wasn't going to be all that much difference in real-world coverage over a 2-bay, two clubs went together out here last winter and bought two 2-element HD VHF versions. They were BEEFY... but they didn't survive the dude who ran over both of them with a forklift at a warehouse somewhere between here and Canada... THAT was fun... insurance claims (by the shipper) and having to order two more out-of-stock antennas, and wait, and wait... and wait... But the end result was well worth it. The antennas are up, and working great. The last one at that site had an external harness, and lasted 10 years... in some nasty mountain-top wind, snow, ice conditions... plus baking in the high-altitude sun (UV rays) for all that time. What finally killed it WAS the Sun... the harness became so brittle that no amount of electrical tape and painting with sealant could save it. And none of us had the time to do what someone here is doing... re-harnessing it. We got quite a bit better than list price, but I think list is just over $400... for $40 a year... I'll take the expensive antenna, any day... over farting around with a lower quality one! ;-) Time is worth something... -- Nate Duehr, WY0X n...@natetech.com facebook.com/denverpilot twitter.com/denverpilot
Re: [Repeater-Builder] Sinclair dipole phasing harness
Hi Paul Did I hear my name mentioned??? Maybe just ESP:-) Some time ago the ISP I originally used merged with anther. I had files on another ISP (rocler.qc.ca) but dropped it due to a dispute concerning SPAM filtering. All my files that I kept have been moved to my own domain website (gorum.ca) where I have better control over it. The old NEDA packet files are on another site that I use. The folded dipole clone info is at: http://www.gorum.ca/fdipolev.htm or download fdipolev.gif from the gorum.ca site. (Sometimes the link gets redirected to sedoparking.com which I have trouble getting rid of.) I would suggest that you don't even consider putting the harnass inside the mast (unless Harold can tell us how Sinclair does it). Put the harness on the outside of the mast like the SRL210A4. You do have it right that there is a matching piece of 125 ohm coax (RG-63/U) inside the dipole. This makes the impedance of each dipole 50 ohms. To combine the impedances on a 4 bay Sinclair array is simple. Divide the dipoles into pairs and parallel them. This gives 25 ohms. Then add an electrical quarter wave of 50 ohm coax (RG-213/U) to transform it to 100 ohms. Combine the matching coax from each pair in parallel to give 50 ohms. Then you can connect your feedline at any length from this latter 50 ohm connection. That takes care of the impedance but you first must match the phase of the rf signal at each dipole. Failure to consider the phase matching will result in a really messed up vertical pattern (unless you are very very lucky). Matching the phase simply means that the electrical wavelength along each feedline path to each dipole has to be as close to equal as possible. They don't have to be any particular wavelength, just so long as they are all equal electrically. Saying this is easy, measuring the wavelength is not easy and requires some speciallized test equipment. I don't know how others measure electrical wavelength, possibly using a network analyzer (which I don't have). What I use is an old HP803A VHF RF Bridge fed with a signal generator and a spectrum analyzer as a null detector. The other essential component of this setup is a Z-Theta Chart which looks sort of like a Smith Chart. See: http://www.gorum.ca/z-theta-8x11.gif On the chart, the resistance and reactance components of the impedance are plotted on the inside of the chart and a line drawn between them will intersect the relative electrical wavelength around the perimeter. The wavelength can be measured to better than 0.002. There is an HP application note that explains the process in detail. I could scan it if anyone is interested. The wavelength on the feedlines of each of the dipoles is measured and the shortest one selected. The other feedlines are then shortened by the necessary incremental length to make them all electrically equal. Of course this has to be done as a first step before paralleling the feedlines. That is my experience. Others may have different ways to achieve the same end result. Burt VE2BMQ N1BUG wrote: Me again. I just got handed a potential project. I am looking for information on the phasing harness for Sinclair VHF 4-bay dipole arrays with the coax inside the mast. I want to know types of coax and lengths so I can understand the matching. I could use info on both the bidirectional and cardioid versions, but especially cardioid. The harness lengths must be different in order to cram it inside that mast. Burt? Or anyone can shed some light on this? (I was thinking Burt had some info on a web site somewhere, but I can't seem to find it) I am aware of the 125 ohm quarter wave section inside Sinclair dipoles, but want to know about the rest of the harness. I am wanting to attempt the difficult or, maybe, impossible... I am trying to figure out if it would be possible to use dipoles from an SRL235-2 to rebuild what is believed to be and SRL214, and at the same time convert the antenna from bidirectional to cardioid pattern. I would be constructing my own harness. I think this might be possible, if I can find out how the phasing harness for the SRL214/cardioid version was made. Any info out there? Paul N1BUG Yahoo! Groups Links
