[Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp
Re: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
Skipp - Looking at the cabling - TX side is normal; but the receive side looks to be wired as 2 - 3 can duplexers in parallel. How does this improve rejection? Seems that IF you needed the parallel duplexers to handle a LOT of tx power, that would be okay, but does it help on the receive side? Just wondering . . . Chas, KS3Z --- skipp025 [EMAIL PROTECTED] wrote: Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp Yahoo! Groups Links (Yahoo! ID required) mailto:[EMAIL PROTECTED] Yahoo! oneSearch: Finally, mobile search that gives answers, not web links. http://mobile.yahoo.com/mobileweb/onesearch?refer=1ONXIC
Re: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
And they only approached 100 dB... Chuck WB2EDV - Original Message - From: skipp025 [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, May 28, 2007 3:02 AM Subject: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due... Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp Yahoo! Groups Links
Re: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
It would seem like the middle and right columns were originally a simple duplexer, then they added the left column to that. If you can trust the labeling, the bottom left is the TX input and the top right is the RX input. The middle and left columns have shorted loop stubs attached to each cavity. These are stuffed down between the cavities and you can see the shorted ends on a couple. The right column doesn't have these stubs. The signal path seems to go from the bottom middle column, up to the top middle, then over to the top left and down to the bottom left. The blue sticker shown seems to be for the 152-153 MHz range, although that could have been for just the left column's cavities. It only shows one pass freq and one reject freq; a duplexer would have a high-pass and a low-pass; this looks more like a specially designed filter than a real duplexer, although there are labels on the top middle and top right cavities indicating RX and TX respectively. It's strange that the left and middle columns are configured differently, with short pieces of coax between the TEE fittings and the cavities in the middle column that are not present on the left column. Bob M. == --- skipp025 [EMAIL PROTECTED] wrote: Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos more. http://mobile.yahoo.com/go?refer=1GNXIC
Re: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
What no one has mentioned yet is that the cans all appear to be NOTCH cans. DB had some variations of the notches that were skewed to one side of the notch or the other. It is possible that this was speced as a special product to take out specific freq ranges while leaving a wide open pass range. If nothing else it should be a good source of notch cans. Milt N3LTQ - Original Message - From: skipp025 [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, May 28, 2007 3:02 AM Subject: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due... Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp Yahoo! Groups Links
Re: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
I too was trying to figure out the harness. I've never seen something like this before. I also saw only 3 cans in the transmit side. This must be a low power duplexer, as these appear to be only a notch devices and there are only 3 cans to notch out the transmitter noise from getting into the receiver. The six cans on the receive side probably are tuned to notch the transmitter frequency out of the receiver. Any transmitter noise that is on the receiver input would not be filtered out in the receiver cans. 73, Joe, K1ike -- Original message -- From: Charles Schmell [EMAIL PROTECTED] Skipp - Looking at the cabling - TX side is normal; but the receive side looks to be wired as 2 - 3 can duplexers in parallel. How does this improve rejection? Seems that IF you needed the parallel duplexers to handle a LOT of tx power, that would be okay, but does it help on the receive side? Just wondering . . . Chas, KS3Z ---BeginMessage--- Skipp - Looking at the cabling - TX side is normal; but the receive side looks to be wired as 2 - 3 can duplexers in parallel. How does this improve rejection? Seems that IF you needed the parallel duplexers to handle a LOT of tx power, that would be okay, but does it help on the receive side? Just wondering . . . Chas, KS3Z --- skipp025 [EMAIL PROTECTED]com wrote: Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp Yahoo! Groups Links (Yahoo! ID required) mailto:Repeater-Builder-fullfeatured@yahoogroups.com __Yahoo! oneSearch: Finally, mobile search that gives answers, not web links. http://mobile.yahoo.com/mobileweb/onesearch?refer=1ONXIC ---End Message---
[Repeater-Builder] Re: When 4, 6 or 8 Cavities just won't due...
Here is another possibility, it could be a standard duplexer with two receive outputs. The cans could be Bp Br, using a High Q caps in the loops. I really cant tell. --- In Repeater-Builder@yahoogroups.com, skipp025 [EMAIL PROTECTED] wrote: Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp
Re: [Repeater-Builder] Re: When 4, 6 or 8 Cavities just won't due...
they are all notch Cavities merrill KG4IDD Coy Hilton wrote: Here is another possibility, it could be a standard duplexer with two receive outputs. The cans could be Bp Br, using a High Q caps in the loops. I really cant tell. --- In Repeater-Builder@yahoogroups.com, skipp025 [EMAIL PROTECTED] wrote: Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp Yahoo! Groups Links
[Repeater-Builder] Re: OT: Need to find a product to develop goodwill at a tower site(s)
It appears that you know what you or the company wants so a suggestion on making it work. Pager receivers work well in this type of application, and they can be had now for nearly free. Attach it to a DTMF board of your choosing, and you have what you ask for. It's obvious that the company has already looked for what they are asking from you, but can't find it. It may also be a test of your technical ability to solve simple problems. I have seen this before when the group doesn't know ones abilities. 73 and good luck! AC0Y --- In Repeater-Builder@yahoogroups.com, [EMAIL PROTECTED] wrote: Hello to All, I am starting to develop a future ham repeater relation with a tower site(s) owner and recently got a request for something unusual. The company has a fleet of VHF radio equipped vehicles. They want to pull up to a site, enter a touch-tone sequence on the mike, and open a security gate at the site. I could kludge together something, but would rather find something commercially available. Anytime I have kludged something together, I have ended up having to repair it for longer that I expected. Something with a VHF receiver, TT decode and relay contact output would be great. Any ides if this is even made commercially? I know that some fire/ambulance departments use a similar idea to open and close the firehouse door. Some also have the ability to control traffic control lights on their way to a situation. 73, Joe, k1ike
RE: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
It started out as a stock six-cavity notch duplexer (I have one of these in storage - I think it's a DB-4021?). Let me explain that part (the stock duplexer) first. Before I get into it, realize that some notch cavities are asymmetrical in terms of the notch response - they have somewhat of a high-pass *or* low-pass characteristic to them. That is, the insertion loss above the notch frequency may be a few dB more than it is below the notch. To start with, the three cavities on the right are one side of the duplexer, and the three in the middle are the other side. Easy enough. The three cavities on the right have traditional tees right on the loops. The three in the middle have the cavities stood off what would normally be a tee using a length of coax. In other words, instead of the tee along the length of the harness being attached directly to the cavity loop, there is a short piece of coax between the tee and the cavity loop. By standing the cavity off by a length of cable (typically 1/4 wave), the high-pass or low-pass characteristic of the cavity is flipped. So, if we assume the right three cavities were high-pass, the middle three would be low pass using this technique. Now, to get back to the stubs. They are added right at the cavity tee to provide additional notch depth and enhance the high-pass/low-pass response. Depending on the length of the cable, they can look like either L or C in parallel with the loop. So, that explains the duplexer. That leaves the three cavities on the left. Those are just more notch cavities, again with the stubs to enhance the response. HOWEVER, like Bob, what bothers me is that these three extra cavities are configured without the standoff coax between the tee and the cavity, thereby making them the same pass-response configuration as the RIGHT three cavities, whereas they should be configured the same as the MIDDLE three cavities. Not sure what to make of that...my guess would be that it doesn't work right... --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Bob M. Sent: Monday, May 28, 2007 8:04 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due... It would seem like the middle and right columns were originally a simple duplexer, then they added the left column to that. If you can trust the labeling, the bottom left is the TX input and the top right is the RX input. The middle and left columns have shorted loop stubs attached to each cavity. These are stuffed down between the cavities and you can see the shorted ends on a couple. The right column doesn't have these stubs. The signal path seems to go from the bottom middle column, up to the top middle, then over to the top left and down to the bottom left. The blue sticker shown seems to be for the 152-153 MHz range, although that could have been for just the left column's cavities. It only shows one pass freq and one reject freq; a duplexer would have a high-pass and a low-pass; this looks more like a specially designed filter than a real duplexer, although there are labels on the top middle and top right cavities indicating RX and TX respectively. It's strange that the left and middle columns are configured differently, with short pieces of coax between the TEE fittings and the cavities in the middle column that are not present on the left column. Bob M. == --- skipp025 [EMAIL PROTECTED] wrote: Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp __ __Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos more. http://mobile.yahoo.com/go?refer=1GNXIC Yahoo! Groups Links No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.472 / Virus Database: 269.8.0/821 - Release Date: 5/27/2007 3:05 PM
[Repeater-Builder] Re: D-Star demo
This brings some questions to mind. none of the D-STAR repeaters that I know of (ICOM) have the ability to do FM repeat, If the repeaters, antennas and the rest of the equipment weren't the same or nearly the same and coo-located how can the test be fair? Also the D-Star is narrow band with respect to the standard Fm repeater. With digital either it's there or it's not. Granted digital is a good way to go but it is way too pricy right now for me to think of purchasing I'll stick with my FM machines for now. AC0Y --- In Repeater-Builder@yahoogroups.com, Ron Wright, Skywarn Coodinator [EMAIL PROTECTED] wrote: hi all, In the FILES section of this board is a Weak Sig D-Star demon by WB9WZB. Most impressive test. Can anyone give details of the test...was same rig with power levels and antennas used in the test??? 73, ron, n9ee/r
Re: [Repeater-Builder] Re: D-Star demo / P25-ALNICO-AOR-MOTOTRBO-ICOM Digital Voice
I too have tried to find out what equipment was used during the Weak signal D-STAR versus FM.mp3 demo which is posted under the Files sections of the Illinoisdigitalham yahoo group. I too first inquired to Mark (WB9QZB), he had then asked me to contact John (KC5ZRQ) directly. I received the following reply from John, and when I answered his question as to which recording I was referring to, I never received an answer or another reply. Coy, if you happen to receive a reply, can you please forward me a copy? I just recorded a Mototrbo weak signal audio comparison last night and plan to post it to the hamradio-dv.org web site. But when I do, I would also like to post a weak signal D-Star audio comparison with it, and up to this point, I cannot use KC5ZRQ's since I do not know the facts behind it. For that reason, a friend of mine is thinking of working with me possibly today to record our own D-Star weak signal comparison. Coy, please keep me posted as to your findings, or I'll let you know when our audio clip is up on the hamradio-dv.org website. Also, if anyone is interested, there are sample recordings of ALINCO, AOR, ICOM, and MOTOTRBO (AOR is the only weak signal at this time) on the home page of http://www.hamradio-dv.org . I am interested in adding a list of '''Amateur Radio''' digital voice related links (Alinco, AOR, ICOM, MOTOTRBO, P25, and any other open source / published digital voice protocols). I would appreciate any links that you believe would fill the above requirements. Be it a personal, club, or corporate web site, just as long as it has pertinent information on Amateur Radio Digital Voice protocols and or systems, I welcome them. I do somewhat frown on Digital Voice protocols which require a personal computer, juggling sound card connections, using two sound cards, or wrestling all the interconnecting cables on ones desk. I look forward to checking out your web sites and or links. Please send them directly to [EMAIL PROTECTED] Have Fun Thanks ! Paul Metzger K6EH - From: [EMAIL PROTECTED] Subject:Re: Super! Finally A D-Star Recording! Date: March 2, 2007 13:58:18 PST To: [EMAIL PROTECTED] I have several recordings. Please specify the filename. John, KC5ZRQ - Original Message - From: Paul Metzger [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, March 02, 2007 3:51 PM Subject: Super! Finally A D-Star Recording! Could you please inform me of all aspects of the the newly uploaded audio file to Yahoo? Range, Power, Antennas, Radios, Narrow//Wide Band, etc etc etc. If going through different repeaters, please list every item of hardware that makes up the repeaters, antenna patterns, losses, including the effective receive sensitivity of each systems receiver. I might want to add this to the N6DVA Digital Voice Amateur Radio Association Web Site at http://www.hamradio-dv.org Would you mind if I did such a thing? I've been waiting for some to conduct this very same experiment and record it just as you have. I already have an Analog/Audio comparison of the AOR units, I sure would like to have one of the D-Star line as well. Thank you for your time and consideration. Paul Metzger K6EH The Digital Voice Amateur Radio Association http://www.hamradio-dv.org N6DVA --- From: [EMAIL PROTECTED] Subject:Re: Super! Finally A D-Star Recording vs Analog FM! Date: March 3, 2007 08:27:40 PST To: [EMAIL PROTECTED] The file is; Weak Signal D-STAR versus FM.mp3 Comparison of a Weak D-STAR Signal versus a Weak FM Signal Paul Metzger K6EH Digital Voice Amateur Radio Association http://www.hamradio-dv.org N6DVA --- --THE END --- On May 28, 2007, at 06:55, Coy Hilton wrote: This brings some questions to mind. none of the D-STAR repeaters that I know of (ICOM) have the ability to do FM repeat, If the repeaters, antennas and the rest of the equipment weren't the same or nearly the same and coo-located how can the test be fair? Also the D-Star is narrow band with respect to the standard Fm repeater. With digital either it's there or it's not. Granted digital is a good way to go but it is way too pricy right now for me to think of purchasing I'll stick with my FM machines for now. AC0Y --- In Repeater-Builder@yahoogroups.com, Ron Wright, Skywarn Coodinator [EMAIL PROTECTED] wrote: hi all, In the FILES section of this board is a Weak Sig D-Star demon by WB9WZB. Most impressive test. Can anyone give
Re: [Repeater-Builder] D-Star demo
Sorry Coy, I referred to you several times within the context of my last e-mail to the group. It should have been Ron Wright (N9EER). On May 27, 2007, at 07:47, Ron Wright, Skywarn Coodinator wrote: hi all, In the FILES section of this board is a Weak Sig D-Star demon by WB9WZB. Most impressive test. Can anyone give details of the test...was same rig with power levels and antennas used in the test??? 73, ron, n9ee/r Yahoo! Groups Links
RE: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
* Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp * The description says it was for an amateur project that was never completed, and I can see why. This setup has three notch cans in the transmit side, and 6 notch cans in the receive side. As described, yes, the insertion loss would be pretty low, however with no band pass protection for the front end of the receiver, you better be on your own hilltop with no one else around. I don't think this custom assembly qualifies much as a duplexer, but it is a nice assembly of notch cavities. * 73 N7HQR,_._,___
Re: [Repeater-Builder] Re: D-Star demo
If you want a fair test, find a P25 machine and barrow a radio. The P25 machines have the ability to do mixed mode (that is conventional FM and digital) and would be a better machine to compare digital versus analog on the same frequency using the same infrastructure. Dan KA8YPY On May 28, 2007, at 9:55 AM, Coy Hilton wrote: This brings some questions to mind. none of the D-STAR repeaters that I know of (ICOM) have the ability to do FM repeat, If the repeaters, antennas and the rest of the equipment weren't the same or nearly the same and coo-located how can the test be fair? Also the D-Star is narrow band with respect to the standard Fm repeater. With digital either it's there or it's not. Granted digital is a good way to go but it is way too pricy right now for me to think of purchasing I'll stick with my FM machines for now. AC0Y --- In Repeater-Builder@yahoogroups.com, Ron Wright, Skywarn Coodinator [EMAIL PROTECTED] wrote: hi all, In the FILES section of this board is a Weak Sig D-Star demon by WB9WZB. Most impressive test. Can anyone give details of the test...was same rig with power levels and antennas used in the test??? 73, ron, n9ee/r Yahoo! Groups Links
Re: [Repeater-Builder] Re: D-Star demo
You mean analog audio vs. digital audio, both are conventional FM in this application. Gary Dan Blasberg wrote: If you want a fair test, find a P25 machine and barrow a radio. The P25 machines have the ability to do mixed mode (that is conventional FM and digital) and would be a better machine to compare digital versus analog on the same frequency using the same infrastructure. Dan KA8YPY On May 28, 2007, at 9:55 AM, Coy Hilton wrote: This brings some questions to mind. none of the D-STAR repeaters that I know of (ICOM) have the ability to do FM repeat, If the repeaters, antennas and the rest of the equipment weren't the same or nearly the same and coo-located how can the test be fair? Also the D-Star is narrow band with respect to the standard Fm repeater. With digital either it's there or it's not. Granted digital is a good way to go but it is way too pricy right now for me to think of purchasing I'll stick with my FM machines for now. AC0Y --- In Repeater-Builder@yahoogroups.com, Ron Wright, Skywarn Coodinator [EMAIL PROTECTED] wrote: hi all, In the FILES section of this board is a Weak Sig D-Star demon by WB9WZB. Most impressive test. Can anyone give details of the test...was same rig with power levels and antennas used in the test??? 73, ron, n9ee/r Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] Re: D-Star demo
Coy, it seems you are confusing technologies here. D-Star repeaters and the analog repeater systems you are accustomed to are all FM and all conventional. D-Star is a digital audio format, that's all. It still operates on an FM carrier. What I think you mean to say is that the D-Star repeaters do not pass an analog audio FM signal as well as a D-Star digital audio FM signal. I also wish they did this. In the U.S. land/mobile industry that uses the P25 digital audio format this is known as mixed mode (a term Motorola coined). I agree that Icom missed the boat when they did not build this feature into the new D-Star repeater systems. Perhaps they were unable to overcome some technical barrier, I don't know and they won't say (neither Icom or Icom America). Also, as you pointed out, D-Star digital voice is a narrowband signal occupying only about 6Khz vs. the 25Khz or so that amateur repeaters have often required to date. It is difficult to do a comparison between a digital audio system like D-Star and a conventional analog system so what my friends and I have done instead is we programmed several channels in our D-Star radios with the same simplex frequency only one channel is set for DV (D-Star digital voice) and another is set for narrowband analog while a third is set for wideband analog. We have performed numerous point-to-point (simplex) comparisons under varying conditions (day, night, clear, rain, dry, humid, etc.) so that we could each hear the differences for ourselves. Under some conditions analog works just fine and certainly sounds more natural but under other conditions, especially long distance, the digital voice can make communication more readily possible by audio compression and virtually eliminating the path noise that we usually hear on a distant analog signal. I frequently use P25 conventional, D-Star, and analog equipment and while the D-Star format and its error correction abilities may not be the best it does a very good job and I hope more amateurs explore this digital voice format and, I hope more amateur equipment manufacturers offer D-Star capable gear. Soon I hope to try out the European TETRA digital format for more comparison and education. These are the voice modes of tomorrow so I think it's in my best interests to learn them today. 73, Gary Coy Hilton wrote: This brings some questions to mind. none of the D-STAR repeaters that I know of (ICOM) have the ability to do FM repeat, If the repeaters, antennas and the rest of the equipment weren't the same or nearly the same and coo-located how can the test be fair? Also the D-Star is narrow band with respect to the standard Fm repeater. With digital either it's there or it's not. Granted digital is a good way to go but it is way too pricy right now for me to think of purchasing I'll stick with my FM machines for now. AC0Y --- In Repeater-Builder@yahoogroups.com, Ron Wright, Skywarn Coodinator [EMAIL PROTECTED] wrote: hi all, In the FILES section of this board is a Weak Sig D-Star demon by WB9WZB. Most impressive test. Can anyone give details of the test...was same rig with power levels and antennas used in the test??? 73, ron, n9ee/r
Re: [Repeater-Builder] Re: D-Star demo
duh..sorry, yep meant analog vs digital audioIt would help if I wake up before I respond. Dan KA8YPY On May 28, 2007, at 2:51 PM, Gary wrote: You mean analog audio vs. digital audio, both are conventional FM in this application. Gary Dan Blasberg wrote: If you want a fair test, find a P25 machine and barrow a radio. The P25 machines have the ability to do mixed mode (that is conventional FM and digital) and would be a better machine to compare digital versus analog on the same frequency using the same infrastructure. Dan KA8YPY On May 28, 2007, at 9:55 AM, Coy Hilton wrote: This brings some questions to mind. none of the D-STAR repeaters that I know of (ICOM) have the ability to do FM repeat, If the repeaters, antennas and the rest of the equipment weren't the same or nearly the same and coo-located how can the test be fair? Also the D-Star is narrow band with respect to the standard Fm repeater. With digital either it's there or it's not. Granted digital is a good way to go but it is way too pricy right now for me to think of purchasing I'll stick with my FM machines for now. AC0Y --- In Repeater-Builder@yahoogroups.com, Ron Wright, Skywarn Coodinator [EMAIL PROTECTED] wrote: hi all, In the FILES section of this board is a Weak Sig D-Star demon by WB9WZB. Most impressive test. Can anyone give details of the test...was same rig with power levels and antennas used in the test??? 73, ron, n9ee/r Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links
[Repeater-Builder] FW: VSWR Issues
At some point in this thread, someone mentioned that we need to install a circulator or isolator to prevent damage from high VSWR and help eliminate interference problems. What suggestions have ya'll got for a 30 watt machine? Mike WM4B _ From: Mike Besemer (WM4B) [mailto:[EMAIL PROTECTED] Sent: Saturday, May 26, 2007 10:02 AM To: Repeater-Builder@yahoogroups.com Cc: [EMAIL PROTECTED] Subject: VSWR Issues Greetings all, My club repeater system consists of a KRP-5000 feeding (what we think is) a DB-224 mounted on a watertower at about 140'. The feedline is about 170 feet of one-inch helix. We'd been getting some comments from users about decreased coverage, but had attributed most of them to the heavy foliage we're seeing now (we have the same issue every spring), but nonetheless last night the two of us on the technical committee went to the site to do some checking. (As a sidebar, my background is 24 years USAF as an avionics tech and my buddy works as a radio/radar tech for the FAA.) At the site, a quick power check revealed the problem. 9 watts forward, 3 watts back (checked from both sides of the cans). The transmitter output should be 30 watts. Checked the transmitter into a Comm Systems Analyzer and verified 8.6 watts from the transmitter. So. we know that the transmitter is toasted, no doubt from excessive reflected power. The next step was to put a TDR on the line. Everything appeared to be okay up to the antenna, but the termination point (antenna) looked pretty ragged. What does a DB-224 (or similar) antenna look like on a TDR? (We tried to print the TDR image so I could share it, but the printer was not cooperating.) I need to add that we DO NOT have access to the water tower. Previous club leadership pulled some fast ones on the county and we are forbidden from climbing the tower. Whatever needs to be done, we must use the same crew the county uses and pay all costs. Also, we're the only ones on the tower, so there is no routine maintenance done on the tower that we can piggy-back on. Bottom line. we need to figure out what we need to do and have everything in place if we need to hire a crew to come out and do the work for us. If I had access to the tower, I'd terminate the top of the hardline with a 50 ohm load and recheck the reflected power to verify that the feedline is good. I'd also check power at the top to see how much loss we had. (The antenna has been up there for more years than anyone can remember. we believe that the last time it was inspected was 1994.) The hardline itself looks very good, and we inspected the antenna as best we could from ground-level with a sighting scope and could not see anything obviously mucked up. I'm guessing that the feedline is okay but that the antenna is going to need either overhauled or replaced. and since we're going to have to pay for the rigging crew, replacing the antenna would probably be the cheapest route. Thoughts, suggestions? Did we miss anything obvious? Suggestions for a new antenna that will last as long as this one did? I hate to go to the membership with a 'we think this is what is wrong and we need to spend money', but without access to the tower we're pretty much hamstrung. Anybody got a TDR image of a DB-224 (or similar) that we can use for comparison? Thanks in advance, Mike WM4B
Re: [Repeater-Builder] FW: VSWR Issues
What you want is called an isolator. This is a circulator with the required RF load already attached. Telewave makes some that will work in the 2-meter ham band. http://www.telewave.com/pricelist/isolators.html Paul kb9wlc --- Mike Besemer (WM4B) [EMAIL PROTECTED] wrote: At some point in this thread, someone mentioned that we need to install a circulator or isolator to prevent damage from high VSWR and help eliminate interference problems. What suggestions have ya'll got for a 30 watt machine? Mike WM4B _ From: Mike Besemer (WM4B) [mailto:[EMAIL PROTECTED] Sent: Saturday, May 26, 2007 10:02 AM To: Repeater-Builder@yahoogroups.com Cc: [EMAIL PROTECTED] Subject: VSWR Issues Greetings all, My club repeater system consists of a KRP-5000 feeding (what we think is) a DB-224 mounted on a watertower at about 140'. The feedline is about 170 feet of one-inch helix. We'd been getting some comments from users about decreased coverage, but had attributed most of them to the heavy foliage we're seeing now (we have the same issue every spring), but nonetheless last night the two of us on the technical committee went to the site to do some checking. (As a sidebar, my background is 24 years USAF as an avionics tech and my buddy works as a radio/radar tech for the FAA.) At the site, a quick power check revealed the problem. 9 watts forward, 3 watts back (checked from both sides of the cans). The transmitter output should be 30 watts. Checked the transmitter into a Comm Systems Analyzer and verified 8.6 watts from the transmitter. So. we know that the transmitter is toasted, no doubt from excessive reflected power. The next step was to put a TDR on the line. Everything appeared to be okay up to the antenna, but the termination point (antenna) looked pretty ragged. What does a DB-224 (or similar) antenna look like on a TDR? (We tried to print the TDR image so I could share it, but the printer was not cooperating.) I need to add that we DO NOT have access to the water tower. Previous club leadership pulled some fast ones on the county and we are forbidden from climbing the tower. Whatever needs to be done, we must use the same crew the county uses and pay all costs. Also, we're the only ones on the tower, so there is no routine maintenance done on the tower that we can piggy-back on. Bottom line. we need to figure out what we need to do and have everything in place if we need to hire a crew to come out and do the work for us. If I had access to the tower, I'd terminate the top of the hardline with a 50 ohm load and recheck the reflected power to verify that the feedline is good. I'd also check power at the top to see how much loss we had. (The antenna has been up there for more years than anyone can remember. we believe that the last time it was inspected was 1994.) The hardline itself looks very good, and we inspected the antenna as best we could from ground-level with a sighting scope and could not see anything obviously mucked up. I'm guessing that the feedline is okay but that the antenna is going to need either overhauled or replaced. and since we're going to have to pay for the rigging crew, replacing the antenna would probably be the cheapest route. Thoughts, suggestions? Did we miss anything obvious? Suggestions for a new antenna that will last as long as this one did? I hate to go to the membership with a 'we think this is what is wrong and we need to spend money', but without access to the tower we're pretty much hamstrung. Anybody got a TDR image of a DB-224 (or similar) that we can use for comparison? Thanks in advance, Mike WM4B Luggage? GPS? Comic books? Check out fitting gifts for grads at Yahoo! Search http://search.yahoo.com/search?fr=oni_on_mailp=graduation+giftscs=bz
[Repeater-Builder] Re: D-Star demo
It would seem that I left out analog in none of the D-STAR repeaters that I know of (ICOM) have the ability to do ANALOG FM repeat. I'm not confused ..my fingers drop words at times;-) I was in paging for many years we did both...ANALOG and digital paging FSK NRZ...but D-STAR uses GSM, FSK and QPSK as well to send data, acording to the published standard that I have red. AC0Y --- In Repeater-Builder@yahoogroups.com, Gary [EMAIL PROTECTED] wrote: Coy, it seems you are confusing technologies here. D-Star repeaters and the analog repeater systems you are accustomed to are all FM and all conventional. D-Star is a digital audio format, that's all. It still operates on an FM carrier. What I think you mean to say is that the D-Star repeaters do not pass an analog audio FM signal as well as a D-Star digital audio FM signal. I also wish they did this. In the U.S. land/mobile industry that uses the P25 digital audio format this is known as mixed mode (a term Motorola coined). I agree that Icom missed the boat when they did not build this feature into the new D-Star repeater systems. Perhaps they were unable to overcome some technical barrier, I don't know and they won't say (neither Icom or Icom America). Also, as you pointed out, D-Star digital voice is a narrowband signal occupying only about 6Khz vs. the 25Khz or so that amateur repeaters have often required to date. It is difficult to do a comparison between a digital audio system like D-Star and a conventional analog system so what my friends and I have done instead is we programmed several channels in our D-Star radios with the same simplex frequency only one channel is set for DV (D-Star digital voice) and another is set for narrowband analog while a third is set for wideband analog. We have performed numerous point-to-point (simplex) comparisons under varying conditions (day, night, clear, rain, dry, humid, etc.) so that we could each hear the differences for ourselves. Under some conditions analog works just fine and certainly sounds more natural but under other conditions, especially long distance, the digital voice can make communication more readily possible by audio compression and virtually eliminating the path noise that we usually hear on a distant analog signal. I frequently use P25 conventional, D-Star, and analog equipment and while the D-Star format and its error correction abilities may not be the best it does a very good job and I hope more amateurs explore this digital voice format and, I hope more amateur equipment manufacturers offer D-Star capable gear. Soon I hope to try out the European TETRA digital format for more comparison and education. These are the voice modes of tomorrow so I think it's in my best interests to learn them today. 73, Gary Coy Hilton wrote: This brings some questions to mind. none of the D-STAR repeaters that I know of (ICOM) have the ability to do FM repeat, If the repeaters, antennas and the rest of the equipment weren't the same or nearly the same and coo-located how can the test be fair? Also the D-Star is narrow band with respect to the standard Fm repeater. With digital either it's there or it's not. Granted digital is a good way to go but it is way too pricy right now for me to think of purchasing I'll stick with my FM machines for now. AC0Y --- In Repeater-Builder@yahoogroups.com, Ron Wright, Skywarn Coodinator mccrpt@ wrote: hi all, In the FILES section of this board is a Weak Sig D-Star demon by WB9WZB. Most impressive test. Can anyone give details of the test...was same rig with power levels and antennas used in the test??? 73, ron, n9ee/r
RE: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due...
It looks to me that the extra cavities were added to a regular duplexer. The receive side has the T connector connected to the notch cavity thru a length of cable to make a pass band network along with the notch. This has the effect of skewing the normal pass of the notch filter on one side (making for a steeper notch on one side) and at the same time forming somewhat of a pass band filter with the length of cable between the filter and T. The extra stub I believe is used to try and make the notch steeper on one side so as not to overlap on the TX side with the close spacing. They may have reduced the coupling of the notches in order to try and make them steeper for the close spacing and then added the extra cavities to make up for the inadequate coupling in the primary filter cans. Or they may have just thought that more is better. Or they may have added the extra filters because of the botched job of trying to make a close space duplexer and not getting the cables right. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of skipp025 Sent: Monday, May 28, 2007 2:03 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due... Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp Yahoo! Groups Links
RE: [Repeater-Builder] When 4, 6 or 8 Cavities just won't do...
Gary, It may be that the duplexer was put together for a commercial application that has nothing whatsoever to do with Amateur Radio. The vendor does not specify what frequencies it is tuned to- a very serious omission. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Gary Schafer Sent: Monday, May 28, 2007 6:47 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due... It looks to me that the extra cavities were added to a regular duplexer. The receive side has the T connector connected to the notch cavity thru a length of cable to make a pass band network along with the notch. This has the effect of skewing the normal pass of the notch filter on one side (making for a steeper notch on one side) and at the same time forming somewhat of a pass band filter with the length of cable between the filter and T. The extra stub I believe is used to try and make the notch steeper on one side so as not to overlap on the TX side with the close spacing. They may have reduced the coupling of the notches in order to try and make them steeper for the close spacing and then added the extra cavities to make up for the inadequate coupling in the primary filter cans. Or they may have just thought that more is better. Or they may have added the extra filters because of the botched job of trying to make a close space duplexer and not getting the cables right. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] mailto:Builder%40yahoogroups.com ] On Behalf Of skipp025 Sent: Monday, May 28, 2007 2:03 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] When 4, 6 or 8 Cavities just won't due... Re: When 4, 6 or 8 Cavities just won't due... Another Ebay gem: DB PRODUCTS 9-CAVITY RADIO REPEATER DUPLEXER-100DB-HAM Ebay Item number: 250120910164 I don't know to be impressed or just laugh at all the hardware (number of cavities used). cheers, skipp
