[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Many thanks... makes it hard for me to be rotten all the time when people are nice. s. Ken Decker wa6...@... wrote: Skipp, Here's the WA1ZDX info www.ccdx.org/zedyx/mods/db212.htm Actually this one is on Repeater Builder http://www.repeater-builder.com/db/db-212-assembly-and-mounting-instructions-(andrew).pdf Spec from Andrew on the DB212 http://www.stealth.ae/plugins/custompages/detinf.php?id=322id_categories=115 More Andrew info http://www.hol4g.com/webpdf/DBB_CAT29-PG318-319_01.PDF Info on modifying a DB201 and DB212 for 10 and 6 meters http://www.xanaduu.com/db201/ Ken WA6OSB
[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Skipp, Here's the WA1ZDX info www.ccdx.org/zedyx/mods/db212.htm Actually this one is on Repeater Builder http://www.repeater-builder.com/db/db-212-assembly-and-mounting-instructions-(andrew).pdf Spec from Andrew on the DB212 http://www.stealth.ae/plugins/custompages/detinf.php?id=322id_categories=115 More Andrew info http://www.hol4g.com/webpdf/DBB_CAT29-PG318-319_01.PDF Info on modifying a DB201 and DB212 for 10 and 6 meters http://www.xanaduu.com/db201/ Ken WA6OSB
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
First, don't expect to land exactly where you expect simply by adjusting the lengths to a specific dimension. You really need to place the antenna on a tower to adjust properly and use an antenna analyzer. The length of feedline from each antenna remains the same. You need to shorten the length of 35-ohm cable that attaches to the tee and heads toward your radio. This needs to be 1/4 wave taking the velocity factor of the cable into effect. Chuck - Original Message - From: wa6ifi dave_novo...@comcast.net To: Repeater-Builder@yahoogroups.com Sent: Wednesday, November 18, 2009 12:04 AM Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) I have a 2 loop DB212-2 which is cut for 48 MHz. I want to use it for a 6M repeater on 53.13. I've shortened the loops to about 53. Do I need to shorten the length of the coax which runs from the antenna to the T? What should be the length of the cable that runs from the T to the feedline (cable C in instruction flyer. Thanks, Dave Novotny, WA6IFI --- In Repeater-Builder@yahoogroups.com, Jeff DePolo j...@... wrote: I have dimensional data for both Decibel and Celwave lowband folded dipoles *somewhere*. If there's interest I'll hunt for them. I think the Celwave design (with the stingers) would be easier to fabricate - no bending involved. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025 Sent: Sunday, November 15, 2009 10:57 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) Chuck Kelsey wb2edv@ wrote: FYI - Sinclair got the extra bandwidth by stager tuning the antenna element from the 1/4-wave matching transformer that is inside the element. The trade-off was a decrease in return loss (higher VSWR). Chuck WB2EDV Maybe... maybe not. I swept one just a short time back and the return loss was about 15.6 dB, which makes it a very nice usable animal. I've also had one in parts and the matching coax length was what I would have expected. Somewhere in my notes I have all the construction information recorded like I did on the Decibel Antennas... I've got a Decibel Loop at the old shop somewhere... if I can easily get it up high enough to throw a sweep on it I can report the results back. I'll have another HP Digital Sender (auto feed pdf scanner) on line within the month... then you'll have more information to chew over. cheers, s. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release Date: 11/15/09 07:50:00 Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.707 / Virus Database: 270.14.71/2510 - Release Date: 11/17/09 14:26:00
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Chuck Kelsey wrote: First, don't expect to land exactly where you expect simply by adjusting the lengths to a specific dimension. You really need to place the antenna on a tower to adjust properly and use an antenna analyzer. grin Reminds me of my first experience with a Cushcraft AFM-4DA (4 bay exposed dipole array for 2M) about 30 years ago. I put it on a nice galvanized mast and mounted it to a tall building free and clear of anything. While the antenna worked - it really didn't perform any better than a 5/8 wave ground plane. I realized that optimum gain was not being achieved because the dipoles were spaced around the galvanized support and weren't really in phase to help each other out. OK, no problem, I'll put them in a line all above one another. WOW, the gain in the direction where the dipoles were facing was fantastic - so, I fixed the gain problem - BUT I created another problem. The null in the opposite direction was so deep that the system didn't work where I needed it to (I really needed omni coverage - I couldn't suffer with a null anywhere). OK, no problem, I'll put the elements on a FIBERGLASS pole. I bought a hefty fiberglass pipe and carefully mounted the Cushcraft array to it - mounting all of the dipoles above one another will retain the gain, and the fiberglass pipe won't create a null - problem solved right? NOPE - a rubber duck would have performed better! What happened? This type of array REQUIRES the element to be in the presence of a metallic mast - otherwise the impedance of the element isn't close to 50 ohms. I didn't have the ability then to measure return loss or actual impedance of the individual dipoles, but I can guarantee you it wasn't close to 50 ohms. The antenna didn't work and the reflected power was awful. I used a Bird and hand-held to feed one dipole - while moving the distance between the dipole and the metal mast pipe - sure enough, when you got to the distance the mount was designed to give, the reflected was at a minimum. SO The distance between the antenna and the support varies the port impedance. Bought a Sinclair SRL-229 (super stationmaster type) and life went on Certainly on low band the concern of the elements exactly above on another is of a lesser concern because the difference in phase angle is likely less - so obtaining good low angle gain in an omni directional pattern is doable. Kevin Custer
[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Dave, I found some info on DB212 cable lengths doing a Google search. A website by WA1ZYX has a couple of pages on modifying the DB212 for 6 meters and also cable lengths/matching and spacing of the folded dipoles. No info on changing element spacing from tower leg. This could affect the pattern. Also found a 4 page article by Decibel Products titled DB212 Series. Good info on antenna patterns. BTW, I've got a NOS DB225 cut for 75.70 MHz. This is like a DB212 with a director. It's got all the measurements for spacing for director, etc so this probably will be critical. I was thinking of trying to extend the elements for 6 meters. Has anyone done this on a DB225? Ken WA6OSB
[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Hi Ken, I'd be interested in the web page url for the WA1ZYX web page and the other information if you'd be willing to share it? I have a DB-212 cut and working on 6m and the same type of antenna on 2m with the director. I will as time allows document those antennas and make that information available to the group. s. Ken Decker wa6...@... wrote: Dave, I found some info on DB212 cable lengths doing a Google search. A website by WA1ZYX has a couple of pages on modifying the DB212 for 6 meters and also cable lengths/matching and spacing of the folded dipoles. No info on changing element spacing from tower leg. This could affect the pattern. Also found a 4 page article by Decibel Products titled DB212 Series. Good info on antenna patterns. BTW, I've got a NOS DB225 cut for 75.70 MHz. This is like a DB212 with a director. It's got all the measurements for spacing for director, etc so this probably will be critical. I was thinking of trying to extend the elements for 6 meters. Has anyone done this on a DB225? Ken WA6OSB
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
If'n I remember correctly... Fred Vobbe built his own 6m loop antennas for his repeater array - maybe someone could arm-twist him for his story about the antennas and harness. (Sorry Fred - I know you'se busy...) At 06:28 PM 11/16/09 -, you wrote: Yes please Jeff... thanks skipp Jeff DePolo j...@... wrote: I have dimensional data for both Decibel and Celwave lowband folded dipoles *somewhere*. If there's interest I'll hunt for them. I think the Celwave design (with the stingers) would be easier to fabricate - no bending involved. --- Jeff WN3A - Adam -
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Yep I have 2 6 meter repeaters I would be interested in the data to build a few DB-212 antennas Neal KA2CAF --- On Tue, 11/17/09, Adam T. Cately atcat...@bright.net wrote: From: Adam T. Cately atcat...@bright.net Subject: Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) To: Repeater-Builder@yahoogroups.com Date: Tuesday, November 17, 2009, 6:45 AM If'n I remember correctly... Fred Vobbe built his own 6m loop antennas for his repeater array - maybe someone could arm-twist him for his story about the antennas and harness. (Sorry Fred - I know you'se busy...) At 06:28 PM 11/16/09 -, you wrote: Yes please Jeff... thanks skipp Jeff DePolo j...@... wrote: I have dimensional data for both Decibel and Celwave lowband folded dipoles *somewhere*. If there's interest I'll hunt for them. I think the Celwave design (with the stingers) would be easier to fabricate - no bending involved. --- Jeff WN3A - Adam - Yahoo! Groups Links repeater-builder-fullfeatu...@yahoogroups.com
[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
I have a 2 loop DB212-2 which is cut for 48 MHz. I want to use it for a 6M repeater on 53.13. I've shortened the loops to about 53. Do I need to shorten the length of the coax which runs from the antenna to the T? What should be the length of the cable that runs from the T to the feedline (cable C in instruction flyer. Thanks, Dave Novotny, WA6IFI --- In Repeater-Builder@yahoogroups.com, Jeff DePolo j...@... wrote: I have dimensional data for both Decibel and Celwave lowband folded dipoles *somewhere*. If there's interest I'll hunt for them. I think the Celwave design (with the stingers) would be easier to fabricate - no bending involved. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025 Sent: Sunday, November 15, 2009 10:57 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) Chuck Kelsey wb2edv@ wrote: FYI - Sinclair got the extra bandwidth by stager tuning the antenna element from the 1/4-wave matching transformer that is inside the element. The trade-off was a decrease in return loss (higher VSWR). Chuck WB2EDV Maybe... maybe not. I swept one just a short time back and the return loss was about 15.6 dB, which makes it a very nice usable animal. I've also had one in parts and the matching coax length was what I would have expected. Somewhere in my notes I have all the construction information recorded like I did on the Decibel Antennas... I've got a Decibel Loop at the old shop somewhere... if I can easily get it up high enough to throw a sweep on it I can report the results back. I'll have another HP Digital Sender (auto feed pdf scanner) on line within the month... then you'll have more information to chew over. cheers, s. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release Date: 11/15/09 07:50:00
[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Yes please Jeff... thanks skipp Jeff DePolo j...@... wrote: I have dimensional data for both Decibel and Celwave lowband folded dipoles *somewhere*. If there's interest I'll hunt for them. I think the Celwave design (with the stingers) would be easier to fabricate - no bending involved. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025 Sent: Sunday, November 15, 2009 10:57 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) Chuck Kelsey wb2edv@ wrote: FYI - Sinclair got the extra bandwidth by stager tuning the antenna element from the 1/4-wave matching transformer that is inside the element. The trade-off was a decrease in return loss (higher VSWR). Chuck WB2EDV Maybe... maybe not. I swept one just a short time back and the return loss was about 15.6 dB, which makes it a very nice usable animal. I've also had one in parts and the matching coax length was what I would have expected. Somewhere in my notes I have all the construction information recorded like I did on the Decibel Antennas... I've got a Decibel Loop at the old shop somewhere... if I can easily get it up high enough to throw a sweep on it I can report the results back. I'll have another HP Digital Sender (auto feed pdf scanner) on line within the month... then you'll have more information to chew over. cheers, s. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release Date: 11/15/09 07:50:00
[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
If you're building a Low-Band Loop Antenna from scratch... forget the DB-212 and copy the Sinclair Version. The Sinclair Low-Band loop has a lot wider band-width and it's pretty much the same design... if properly done easier to construct hardware wise. s. cruizzer77 atlant...@... wrote: Thanks for the info. Somewhere else I read that from the mount to the outer edge the length should be 51 inches, this will be about the same as 52.5 inches from center to outer edge. But to build one from scratch I need more info, radius of the loop, diameter of the tube, coupling etc. Of course these can be calculated from formulas, but as the DB212 seems to be a particular good design it would be interesting to know. --- In Repeater-Builder@yahoogroups.com, JOHN MACKEY jmackey@ wrote: I converted one about 15 years ago for use on 6 meters. It measured 52.5 inches from center to outer edge. -- Original Message -- Received: Sat, 14 Nov 2009 10:41:05 AM PST From: cruizzer77 atlantis7@ To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB-212 detailed info wanted Does anyone have detailed info about the DB-212 antenna (converted to 6m) that make it possible to build one from scratch? All the measures and info about the mount and feed point are interesting in the first place. 73 de Martin HB9TZW
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
FYI - Sinclair got the extra bandwidth by stager tuning the antenna element from the 1/4-wave matching transformer that is inside the element. The trade-off was a decrease in return loss (higher VSWR). Chuck WB2EDV - Original Message - From: skipp025 skipp...@yahoo.com To: Repeater-Builder@yahoogroups.com Sent: Sunday, November 15, 2009 10:15 AM Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) If you're building a Low-Band Loop Antenna from scratch... forget the DB-212 and copy the Sinclair Version. The Sinclair Low-Band loop has a lot wider band-width and it's pretty much the same design... if properly done easier to construct hardware wise. s. cruizzer77 atlant...@... wrote: Thanks for the info. Somewhere else I read that from the mount to the outer edge the length should be 51 inches, this will be about the same as 52.5 inches from center to outer edge. But to build one from scratch I need more info, radius of the loop, diameter of the tube, coupling etc. Of course these can be calculated from formulas, but as the DB212 seems to be a particular good design it would be interesting to know. --- In Repeater-Builder@yahoogroups.com, JOHN MACKEY jmackey@ wrote: I converted one about 15 years ago for use on 6 meters. It measured 52.5 inches from center to outer edge. -- Original Message -- Received: Sat, 14 Nov 2009 10:41:05 AM PST From: cruizzer77 atlantis7@ To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB-212 detailed info wanted Does anyone have detailed info about the DB-212 antenna (converted to 6m) that make it possible to build one from scratch? All the measures and info about the mount and feed point are interesting in the first place. 73 de Martin HB9TZW Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.707 / Virus Database: 270.14.66/2504 - Release Date: 11/15/09 02:50:00
[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Chuck Kelsey wb2...@... wrote: FYI - Sinclair got the extra bandwidth by stager tuning the antenna element from the 1/4-wave matching transformer that is inside the element. The trade-off was a decrease in return loss (higher VSWR). Chuck WB2EDV Maybe... maybe not. I swept one just a short time back and the return loss was about 15.6 dB, which makes it a very nice usable animal. I've also had one in parts and the matching coax length was what I would have expected. Somewhere in my notes I have all the construction information recorded like I did on the Decibel Antennas... I've got a Decibel Loop at the old shop somewhere... if I can easily get it up high enough to throw a sweep on it I can report the results back. I'll have another HP Digital Sender (auto feed pdf scanner) on line within the month... then you'll have more information to chew over. cheers, s.
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
I've seen some return loss figures in the 30-40 dB range on the Decibel antenna. However, sweep one and report back. Chuck WB2EDV - Original Message - From: skipp025 skipp...@yahoo.com To: Repeater-Builder@yahoogroups.com Sent: Sunday, November 15, 2009 10:57 AM Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) Chuck Kelsey wb2...@... wrote: FYI - Sinclair got the extra bandwidth by stager tuning the antenna element from the 1/4-wave matching transformer that is inside the element. The trade-off was a decrease in return loss (higher VSWR). Chuck WB2EDV Maybe... maybe not. I swept one just a short time back and the return loss was about 15.6 dB, which makes it a very nice usable animal. I've also had one in parts and the matching coax length was what I would have expected. Somewhere in my notes I have all the construction information recorded like I did on the Decibel Antennas... I've got a Decibel Loop at the old shop somewhere... if I can easily get it up high enough to throw a sweep on it I can report the results back. I'll have another HP Digital Sender (auto feed pdf scanner) on line within the month... then you'll have more information to chew over. cheers, s.
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
The low-band loop from Sinclair (SRL 110) was not nearly as wide band as the Hi band (SRL210) and UHF models (SRL310). The latter were designed to be mounted either half wave or quarter wave from the tower or mast. In the case of the low band loop a half wave would have put the loop 10 ft from the mast, which would be structually unsound. The SRL110 were normally mounted about 3 ft or so from the mast which is 1/8 wave. This would result in a lower impedance (200 ohms loop impedance) requiring 93 ohm coax as an internal matching transformer (the SRL210 and 310 series use 125 ohm matching coax). It also would be much more sensitive to spacing from the mast or tower. At least that has been my experience with the low band loops. Burt VE2BMQ Chuck Kelsey wrote: FYI - Sinclair got the extra bandwidth by stager tuning the antenna element from the 1/4-wave matching transformer that is inside the element. The trade-off was a decrease in return loss (higher VSWR). Chuck WB2EDV - Original Message - From: skipp025 skipp...@yahoo.com To: Repeater-Builder@yahoogroups.com Sent: Sunday, November 15, 2009 10:15 AM Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) If you're building a Low-Band Loop Antenna from scratch... forget the DB-212 and copy the Sinclair Version. The Sinclair Low-Band loop has a lot wider band-width and it's pretty much the same design... if properly done easier to construct hardware wise. s. cruizzer77 atlant...@... wrote: Thanks for the info. Somewhere else I read that from the mount to the outer edge the length should be 51 inches, this will be about the same as 52.5 inches from center to outer edge. But to build one from scratch I need more info, radius of the loop, diameter of the tube, coupling etc. Of course these can be calculated from formulas, but as the DB212 seems to be a particular good design it would be interesting to know. --- In Repeater-Builder@yahoogroups.com, JOHN MACKEY jmackey@ wrote: I converted one about 15 years ago for use on 6 meters. It measured 52.5 inches from center to outer edge. -- Original Message -- Received: Sat, 14 Nov 2009 10:41:05 AM PST From: cruizzer77 atlantis7@ To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB-212 detailed info wanted Does anyone have detailed info about the DB-212 antenna (converted to 6m) that make it possible to build one from scratch? All the measures and info about the mount and feed point are interesting in the first place. 73 de Martin HB9TZW Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.707 / Virus Database: 270.14.66/2504 - Release Date: 11/15/09 02:50:00 Yahoo! Groups Links
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
I was hoping that Burt would chime in. Chuck WB2EDV - Original Message - From: Burt Lang b...@gorum.ca To: Repeater-Builder@yahoogroups.com Sent: Sunday, November 15, 2009 11:57 AM Subject: Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) The low-band loop from Sinclair (SRL 110) was not nearly as wide band as the Hi band (SRL210) and UHF models (SRL310). The latter were designed to be mounted either half wave or quarter wave from the tower or mast. In the case of the low band loop a half wave would have put the loop 10 ft from the mast, which would be structually unsound. The SRL110 were normally mounted about 3 ft or so from the mast which is 1/8 wave. This would result in a lower impedance (200 ohms loop impedance) requiring 93 ohm coax as an internal matching transformer (the SRL210 and 310 series use 125 ohm matching coax). It also would be much more sensitive to spacing from the mast or tower. At least that has been my experience with the low band loops. Burt VE2BMQ
RE: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
I have dimensional data for both Decibel and Celwave lowband folded dipoles *somewhere*. If there's interest I'll hunt for them. I think the Celwave design (with the stingers) would be easier to fabricate - no bending involved. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025 Sent: Sunday, November 15, 2009 10:57 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212) Chuck Kelsey wb2...@... wrote: FYI - Sinclair got the extra bandwidth by stager tuning the antenna element from the 1/4-wave matching transformer that is inside the element. The trade-off was a decrease in return loss (higher VSWR). Chuck WB2EDV Maybe... maybe not. I swept one just a short time back and the return loss was about 15.6 dB, which makes it a very nice usable animal. I've also had one in parts and the matching coax length was what I would have expected. Somewhere in my notes I have all the construction information recorded like I did on the Decibel Antennas... I've got a Decibel Loop at the old shop somewhere... if I can easily get it up high enough to throw a sweep on it I can report the results back. I'll have another HP Digital Sender (auto feed pdf scanner) on line within the month... then you'll have more information to chew over. cheers, s. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release Date: 11/15/09 07:50:00
