RE: [Repeater-Builder] DB224A new harness
Wow Kb0wlf From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of allan crites Sent: Friday, February 19, 2010 10:34 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] DB224A new harness Tom, Perhaps you could enlighten everyone who read these discussions with your success in modifying a DB224 from the 150-162 range to the 220-225 range. You are the first I have ever heard of having done this. I know I would be particularly interested in the harness transmission lines used and their lengths, and their characteristic impedance's. I would also be interested in the impedance measurements made of the dipole configuration after being modified, how you determined the appropriate coax transformation impedance's, and how you compensated for the positive and negative reactances which appear as the freq. is varied from the center freq. to the band edges in each transformation. Would you also include the instrumentation used for your designs? If you employed the use of a Smith Chart in your calculations can you provide a copy showing the impedance response curve vs. freq. for the range 220-225 MHz or whatever you measured? There are no loops on a DB224, only folded dipoles. Loops are circular, dipoles are linear. Allan Crites WA9ZZU --- On Fri, 2/19/10, Tom Manning af...@bellsouth.net wrote: From: Tom Manning af...@bellsouth.net Subject: Re: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Friday, February 19, 2010, 9:15 PM ? Hello Allan As you note it would take a good deal of work to go from 154 to 220Mhz. Yes the loops would have to be shortened and the harness would have to be be reworked-shortened. This would be easier than changing to 144Mhz. I have done this twice in the past. 73 de Tom Manning - Original Message - From: allan crites http://us.mc822.mail.yahoo.com/mc/compose?to=wa9...@arrl.net To: Repeater-Builder@ http://us.mc822.mail.yahoo.com/mc/compose?to=repeater-buil...@yahoogroups.com yahoogroups. com Sent: Thursday, February 18, 2010 5:47 PM Subject: Re: [Repeater-Builder] DB224A new harness Tom I would certainly be interested in knowing just how a 150-162 MHz DB224 could be easily be modified to cover 220. The dipoles would need to be physically shortened and the matching harness would need to be completely redesigned. What magic do you have in your bag of tricks to manage this? Allan Crites WA9ZZU --- On Thu, 2/18/10, Tom Manning af...@bellsouth. NET wrote: From: Tom Manning af...@bellsouth. NET Subject: Re: [Repeater-Builder] DB224A new harness To: Repeater-Builder@ yahoogroups. com Date: Thursday, February 18, 2010, 4:58 PM Hello Andrew and Norm If you are trying to figure out the lengths needed for 144-148Mhz I can measure what you need to know but not in a hurry. I have a DB products antenna that is cut for the two meter band that I ordered from DB Products about 10 years ago. What I need to know is the measurements for 220Mhz. I also have several DB224a's that have been removed due to problems. These could easily be modified to cover 220Mhz. 73 de Tom Manning, AF4UG - Original Message - From: NORM KNAPP http://us.mc822.mail.yahoo.com/mc/compose?to=nkn...@twowayradio.net To: Repeater-Builder@ http://us.mc822.mail.yahoo.com/mc/compose?to=repeater-buil...@yahoogroups.com yahoogroups. com Sent: Wednesday, February 17, 2010 10:35 PM Subject: RE: [Repeater-Builder] DB224A new harness The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm _ _ __ From: Repeater-Builder@ yahoogroups. com http://us.mc822.mail.yahoo.com/mc/compose?to=repeater-buil...@yahoogroups.com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@ yahoogroups. com http://us.mc822.mail.yahoo.com/mc/compose?to=Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio. net http://us.mc822.mail.yahoo.com/mc/compose?to=nknapp%40twowayradio.net wrote: From: NORM KNAPP nkn...@twowayradio. net http://us.mc822.mail.yahoo.com/mc/compose?to=nknapp%40twowayradio.net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@ yahoogroups. com http://us.mc822.mail.yahoo.com/mc/compose?to=Repeater-Builder%40yahoogroups.com Date: Wednesday, February 17, 2010, 3:57 PM
RE: [Repeater-Builder] DB224A new harness
Howdy, Not intended to disrupt the thread here,,but on the 220 comments. Ron KG5BZ just climbed a tower in Austin to measure loops (and spacing I hope) on an old 220 ham cut DB product. He told me he already had the original 220 harness specs from DB. I offered to help him get the info together to be posted to the group. I will try to follow-up with him to share the info. 73 Don Kirchner W5DK From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tom Manning Sent: Thursday, February 18, 2010 4:58 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] DB224A new harness Hello Andrew and Norm If you are trying to figure out the lengths needed for 144-148Mhz I can measure what you need to know but not in a hurry. I have a DB products antenna that is cut for the two meter band that I ordered from DB Products about 10 years ago. What I need to know is the measurements for 220Mhz. I also have several DB224a's that have been removed due to problems. These could easily be modified to cover 220Mhz. 73 de Tom Manning, AF4UG - Original Message - From: NORM KNAPP mailto:nkn...@twowayradio.net To: Repeater-Builder@yahoogroups.com Sent: Wednesday, February 17, 2010 10:35 PM Subject: RE: [Repeater-Builder] DB224A new harness The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm From: Repeater-Builder@yahoogroups.com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio.net mailto:nknapp%40twowayradio.net wrote: From: NORM KNAPP nkn...@twowayradio.net mailto:nknapp%40twowayradio.net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever you feed the antenna with). Last night I connected the Sitemaster up again and I noticed the the SWR will come down some when I firmly secure the harness to the mast with the metal tape. How far down remains to be seen. I will keep you posted. 73 and thanks! de N5NPO Norm image001.jpg
Re: [Repeater-Builder] DB224A new harness
Hello Allan As you note it would take a good deal of work to go from 154 to 220Mhz. Yes the loops would have to be shortened and the harness would have to be be reworked-shortened. This would be easier than changing to 144Mhz. I have done this twice in the past. 73 de Tom Manning - Original Message - From: allan crites To: Repeater-Builder@yahoogroups.com Sent: Thursday, February 18, 2010 5:47 PM Subject: Re: [Repeater-Builder] DB224A new harness Tom I would certainly be interested in knowing just how a 150-162 MHz DB224 could be easily be modified to cover 220. The dipoles would need to be physically shortened and the matching harness would need to be completely redesigned. What magic do you have in your bag of tricks to manage this? Allan Crites WA9ZZU --- On Thu, 2/18/10, Tom Manning af...@bellsouth.net wrote: From: Tom Manning af...@bellsouth.net Subject: Re: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Thursday, February 18, 2010, 4:58 PM Hello Andrew and Norm If you are trying to figure out the lengths needed for 144-148Mhz I can measure what you need to know but not in a hurry. I have a DB products antenna that is cut for the two meter band that I ordered from DB Products about 10 years ago. What I need to know is the measurements for 220Mhz. I also have several DB224a's that have been removed due to problems. These could easily be modified to cover 220Mhz. 73 de Tom Manning, AF4UG - Original Message - From: NORM KNAPP To: Repeater-Builder@ yahoogroups. com Sent: Wednesday, February 17, 2010 10:35 PM Subject: RE: [Repeater-Builder] DB224A new harness The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm _ _ __ From: Repeater-Builder@ yahoogroups. com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@ yahoogroups. com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio. net wrote: From: NORM KNAPP nkn...@twowayradio. net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@ yahoogroups. com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever you feed the antenna with). Last night I connected the Sitemaster up again and I noticed the the SWR will come down some when I firmly secure the harness to the mast with the metal tape. How far down remains to be seen. I will keep you posted. 73 and thanks! de N5NPO Norm
Re: [Repeater-Builder] DB224A new harness
Tom, Perhaps you could enlighten everyone who read these discussions with your success in modifying a DB224 from the 150-162 range to the 220-225 range. You are the first I have ever heard of having done this. I know I would be particularly interested in the harness transmission lines used and their lengths, and their characteristic impedance's. I would also be interested in the impedance measurements made of the dipole configuration after being modified, how you determined the appropriate coax transformation impedance's, and how you compensated for the positive and negative reactances which appear as the freq. is varied from the center freq. to the band edges in each transformation. Would you also include the instrumentation used for your designs? If you employed the use of a Smith Chart in your calculations can you provide a copy showing the impedance response curve vs. freq. for the range 220-225 MHz or whatever you measured? There are no loops on a DB224, only folded dipoles. Loops are circular, dipoles are linear. Allan Crites WA9ZZU --- On Fri, 2/19/10, Tom Manning af...@bellsouth.net wrote: From: Tom Manning af...@bellsouth.net Subject: Re: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Friday, February 19, 2010, 9:15 PM Hello Allan As you note it would take a good deal of work to go from 154 to 220Mhz. Yes the loops would have to be shortened and the harness would have to be be reworked-shortened. This would be easier than changing to 144Mhz. I have done this twice in the past. 73 de Tom Manning - Original Message - From: allan crites To: Repeater-Builder@ yahoogroups. com Sent: Thursday, February 18, 2010 5:47 PM Subject: Re: [Repeater-Builder] DB224A new harness Tom I would certainly be interested in knowing just how a 150-162 MHz DB224 could be easily be modified to cover 220. The dipoles would need to be physically shortened and the matching harness would need to be completely redesigned. What magic do you have in your bag of tricks to manage this? Allan Crites WA9ZZU --- On Thu, 2/18/10, Tom Manning af...@bellsouth. NET wrote: From: Tom Manning af...@bellsouth. NET Subject: Re: [Repeater-Builder] DB224A new harness To: Repeater-Builder@ yahoogroups. com Date: Thursday, February 18, 2010, 4:58 PM Hello Andrew and Norm If you are trying to figure out the lengths needed for 144-148Mhz I can measure what you need to know but not in a hurry. I have a DB products antenna that is cut for the two meter band that I ordered from DB Products about 10 years ago. What I need to know is the measurements for 220Mhz. I also have several DB224a's that have been removed due to problems. These could easily be modified to cover 220Mhz. 73 de Tom Manning, AF4UG - Original Message - From: NORM KNAPP To: Repeater-Builder@ yahoogroups. com Sent: Wednesday, February 17, 2010 10:35 PM Subject: RE: [Repeater-Builder] DB224A new harness The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm _ _ __ From: Repeater-Builder@ yahoogroups. com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@ yahoogroups. com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio. net wrote: From: NORM KNAPP nkn...@twowayradio. net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@ yahoogroups. com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my
RE: [Repeater-Builder] DB224A new harness
Norm I need you to do two more things: 1) Tell me where the measurements of the lengths of the coax were made to, were they to the edge of the molded tee block, or to the center of the block, and at the splice to the different coax cables, was the measurement to the center of the splice or at the edge of the shrink tubing? 2) I used Z measured data from a DB 224A (for the 150-162 range) in my inventory, of the physical dimensions of the dipole. Would you confirm the dipole dimensions of the antenna you are using, everything including the spacing to the mtg pipe, the overall length, the length from the center mounting bracket to each end of the dipole and the dimension of the center to center of the folded section. I want to confirm that I am using correct data in my calculations. Only one dipole dims. are necessary. A dwg would be nice. From first go around the Smith Chart, it appears that to use or modify the O.C. stub to optimize the impedance matching for use at 144-148 Mhz may be unwise. I'm leaning towards adding a Tee adapter with stub at the feed point connector, and if necessary modifying the length of the 106.5, 50 Ohm feed line coax. If you somehow modify the O.C. stub and your results are worse, then you have essentially destroyed the matching harness usefulness. Please also advise the type of connector used at the feed-point, N or UHF. WA9ZZU --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio.net wrote: From: NORM KNAPP nkn...@twowayradio.net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Wednesday, February 17, 2010, 10:35 PM The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm _ _ __ From: Repeater-Builder@ yahoogroups. com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@ yahoogroups. com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio. net wrote: From: NORM KNAPP nkn...@twowayradio. net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@ yahoogroups. com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever you feed the antenna with). Last night I connected the Sitemaster up again and I noticed the the SWR will come down some when I firmly secure the harness to the mast with the metal tape. How far down remains to be seen. I will keep you posted. 73 and thanks! de N5NPO Norm
Re: [Repeater-Builder] DB224A new harness
Thanks Allen. All coax harness measurements are center of moldings or splices. The dipoles are supposed to be standard db224a elements. I will have to measure them and get back to you on that. All connectors are N type. Thanks again Norm - Original Message - From: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com To: Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com Sent: Thu Feb 18 08:49:47 2010 Subject: RE: [Repeater-Builder] DB224A new harness Norm I need you to do two more things: 1) Tell me where the measurements of the lengths of the coax were made to, were they to the edge of the molded tee block, or to the center of the block, and at the splice to the different coax cables, was the measurement to the center of the splice or at the edge of the shrink tubing? 2) I used Z measured data from a DB 224A (for the 150-162 range) in my inventory, of the physical dimensions of the dipole. Would you confirm the dipole dimensions of the antenna you are using, everything including the spacing to the mtg pipe, the overall length, the length from the center mounting bracket to each end of the dipole and the dimension of the center to center of the folded section. I want to confirm that I am using correct data in my calculations. Only one dipole dims. are necessary. A dwg would be nice. From first go around the Smith Chart, it appears that to use or modify the O.C. stub to optimize the impedance matching for use at 144-148 Mhz may be unwise. I'm leaning towards adding a Tee adapter with stub at the feed point connector, and if necessary modifying the length of the 106.5, 50 Ohm feed line coax. If you somehow modify the O.C. stub and your results are worse, then you have essentially destroyed the matching harness usefulness. Please also advise the type of connector used at the feed-point, N or UHF. WA9ZZU --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio.net wrote: From: NORM KNAPP nkn...@twowayradio.net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Wednesday, February 17, 2010, 10:35 PM The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm _ _ __ From: Repeater-Builder@ yahoogroups. com http://us.mc822.mail.yahoo.com/mc/compose?to=Repeater-Builder%40yahoogroups.com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@ yahoogroups. com http://us.mc822.mail.yahoo.com/mc/compose?to=Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio. net http://us.mc822.mail.yahoo.com/mc/compose?to=nknapp%40twowayradio.net wrote: From: NORM KNAPP nkn...@twowayradio. net http://us.mc822.mail.yahoo.com/mc/compose?to=nknapp%40twowayradio.net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@ yahoogroups. com http://us.mc822.mail.yahoo.com/mc/compose?to=Repeater-Builder%40yahoogroups.com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever
Re: [Repeater-Builder] DB224A new harness
Hello Andrew and Norm If you are trying to figure out the lengths needed for 144-148Mhz I can measure what you need to know but not in a hurry. I have a DB products antenna that is cut for the two meter band that I ordered from DB Products about 10 years ago. What I need to know is the measurements for 220Mhz. I also have several DB224a's that have been removed due to problems. These could easily be modified to cover 220Mhz. 73 de Tom Manning, AF4UG - Original Message - From: NORM KNAPP To: Repeater-Builder@yahoogroups.com Sent: Wednesday, February 17, 2010 10:35 PM Subject: RE: [Repeater-Builder] DB224A new harness The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm From: Repeater-Builder@yahoogroups.com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio.net wrote: From: NORM KNAPP nkn...@twowayradio.net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever you feed the antenna with). Last night I connected the Sitemaster up again and I noticed the the SWR will come down some when I firmly secure the harness to the mast with the metal tape. How far down remains to be seen. I will keep you posted. 73 and thanks! de N5NPO Norm
Re: [Repeater-Builder] DB224A new harness
Tom I would certainly be interested in knowing just how a 150-162 MHz DB224 could be easily be modified to cover 220. The dipoles would need to be physically shortened and the matching harness would need to be completely redesigned. What magic do you have in your bag of tricks to manage this? Allan Crites WA9ZZU --- On Thu, 2/18/10, Tom Manning af...@bellsouth.net wrote: From: Tom Manning af...@bellsouth.net Subject: Re: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Thursday, February 18, 2010, 4:58 PM Hello Andrew and Norm If you are trying to figure out the lengths needed for 144-148Mhz I can measure what you need to know but not in a hurry. I have a DB products antenna that is cut for the two meter band that I ordered from DB Products about 10 years ago. What I need to know is the measurements for 220Mhz. I also have several DB224a's that have been removed due to problems. These could easily be modified to cover 220Mhz. 73 de Tom Manning, AF4UG - Original Message - From: NORM KNAPP To: Repeater-Builder@ yahoogroups. com Sent: Wednesday, February 17, 2010 10:35 PM Subject: RE: [Repeater-Builder] DB224A new harness The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm _ _ __ From: Repeater-Builder@ yahoogroups. com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@ yahoogroups. com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio. net wrote: From: NORM KNAPP nkn...@twowayradio. net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@ yahoogroups. com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever you feed the antenna with). Last night I connected the Sitemaster up again and I noticed the the SWR will come down some when I firmly secure the harness to the mast with the metal tape. How far down remains to be seen. I will keep you posted. 73 and thanks! de N5NPO Norm
RE: [Repeater-Builder] DB224A new harness
I just recieved 2 new DB224A harnesses from Andrew. They were made in Mexico (no surprise there, they have been making them there for some time). Curious if you had any problems ordering them, and if I may ask, what did they run you? I need it to work on 147.225/147.825. I got a 1.68:1 on 147.225mhz and better than 1.5:1 on 147.825mhz. Any one seem to think I might improve this a bit if I spread the loops out a bit? What would be the ideal spacing for 147.225mhz? I know a DB224E would be better, but this one has to do. So you started with a DB224E, but installed a DB224A harness on it? Or was this a DB224A to begin with? Altering the vertical spacing (within reason) will likely have little effect on the VSWR. One curious thing is there is a new feature on this harness. There is a 25 VB-8 open ended stub down the main feed line about 12.5 from where the two halves of the harness come together... Yes, it is open. What is this all about? I saw the same thing on a recent DB404 UHF dipole array from Andrew. I didn't see the open stub until I was already at the site with the tower crew so I didn't get a chance to dissect/analyze it further. Could I extend it to get the match to improve at lower frequencies? Without knowing its specific function, it's hard to say what effect extend the length would have. --- Jeff WN3A
RE: [Repeater-Builder] DB224A new harness
I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamination in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever you feed the antenna with). Last night I connected the Sitemaster up again and I noticed the the SWR will come down some when I firmly secure the harness to the mast with the metal tape. How far down remains to be seen. I will keep you posted. 73 and thanks! de N5NPO Norm winmail.dat
RE: [Repeater-Builder] DB224A new harness
I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio.net wrote: From: NORM KNAPP nkn...@twowayradio.net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever you feed the antenna with). Last night I connected the Sitemaster up again and I noticed the the SWR will come down some when I firmly secure the harness to the mast with the metal tape. How far down remains to be seen. I will keep you posted. 73 and thanks! de N5NPO Norm
RE: [Repeater-Builder] DB224A new harness
The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50 ohm and the VB-11 is 75 ohm. I hope that is the info you needed. It would be great if you could figure out what the open stub is for and can we use that for adjustments. If you need more info, let me know. 73 Norm From: Repeater-Builder@yahoogroups.com on behalf of allan crites Sent: Wed 2/17/2010 9:29 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] DB224A new harness I tried to work backwards on a Smith Chart from the dipole to the 1/2 WL O.C. stub to determine a reason for the stub but it appears the unknown coax types are causing erroneous and confusing answers. Can you confirm the coax types shown on your diagram? a. --- On Wed, 2/17/10, NORM KNAPP nkn...@twowayradio.net wrote: From: NORM KNAPP nkn...@twowayradio.net Subject: RE: [Repeater-Builder] DB224A new harness To: Repeater-Builder@yahoogroups.com Date: Wednesday, February 17, 2010, 3:57 PM I got the harnesses at no charge from Andrew. I contacted customer support and told them I had 3 fairly new DB224's (2 a models and a b model) that had water intrusion/contamina tion in the harness where they were supposedly seal by the factory. I offered pictures and they accepted. Upon seeing the photos they asked that I give them serial numbers and requested I send the defective harnesses to them. I did and they offered and I accepted replacement harnesses. The two db224's that I have (personally) are the A models. The B model belongs to my shop. I often end up with abandoned and or defective db224's and other antennas as I work for a two way land mobile dealer/shop. Unfortunately, I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an occasional DB224b. Hats off to Andrew for shipping me free replacement harnesses. I am still gonna ScotchKote those moldings regaurdelss. If you look at the attached photoes from my initial post, you will see that the open 25 VB-8 (50 ohm) stub is 12.5 from the T where the top half and bottom halves of the harness come together, down the main feed to the hardline (or whatever you feed the antenna with). Last night I connected the Sitemaster up again and I noticed the the SWR will come down some when I firmly secure the harness to the mast with the metal tape. How far down remains to be seen. I will keep you posted. 73 and thanks! de N5NPO Norm winmail.dat
