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Posted: 4/11/2020 8:38:00 PM EDT
I'm going to try to brave the rain and storms to head over to central Missouri tomorrow to try to pick up an 8 can Sinclair R101GS low band duplexer. I downloaded the Repeaterbuilder modification instructions and it looks like quite a project. I have an HP8935 to tune it but I hate trying to sweat copper. That is the only part that concerns me (soldering the helix coils after cutting out a section). It's currently (or should be) on 48.56 / 49.040.
Not yet sure what to use for an antenna or actual repeater. Our site if all goes well we will have access to a 90 fott old ATT tower. It won't be too crazy tall but should be worth the effort. Some pics from the seller. Attached File Attached File Attached File Attached File Attached File |
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I'm thinking a couple of Syntor X9000s with either both or the transmit one running in headless configuration. Thoughts on what to use for a repeater other than that? I've had great luck with the receive of the X9000s mobile but not sure how they would do in this use.
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I have a low band GE MASTR II base station cabinet/rack mount unit... no idea what it would take to make it a repeater. If you want to drive east a few more hours
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Got the duplexer back home and to the repeater shack. I took all the guts out so I can work on it at home. The actual working parts aren't heavy but that cabinet is like a gun safe.
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$7,000 for a brand new RF Technology Eclipse 3 in Low Band...
Does Kansas use 1 Meg offsets or half Meg? |
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Hard to tell from the pics - how large is that cabinet or each of the cans?
I know their size is dictated by the physics involved. Just don’t know the equation to figure it. |
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Quoted: Quoted: You need any more Snytors? I think I have 2 in the shed. What kind? Regular, X, X9000? X9000. IIRC one is set up for 6 and 10, the other 2m. It's been several years since I've messed with them and at this point I'd be happy to send them to someone else who can use them. Yours for the cost of shipping. |
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Quoted: Hard to tell from the pics - how large is that cabinet or each of the cans? I know their size is dictated by the physics involved. Just don’t know the equation to figure it. View Quote The manual says 66.4" high, 22" wide and 210 lbs. I took all 8 out of the cabinet, here is one next to a mil rig and a Streamlight flashlight. They are smaller than regular lowband cans due to using a helical resonantor inside. Attached File |
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Depending on mounting locations, if top mount on the tower is available, a DB201 cut for your freq and mounted on a piece of pipe ~5' above the tower will be bulletproof, if side mount is required a DB212 modified to get down into 6m will work however may have a bit of a shadow on the opposite side of the tower from the antenna. Neither will give you any gain but both are bulletproof commercial antennas that will take a beating. What tower height are you working with?
If you had a tall enough tower, a multi element phased array could be pulled off using db212s positioned around the tower but that's more than what you probably want to mess with. I'm currently involved in building a 6m system locally, we will be using a GE MASTR II transceiver and PA but obtaining crystals for our freq split has proven to be difficult as most mfgs have dried up and the crystals we have tried have provided sub par performance. |
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Quoted: Depending on mounting locations, if top mount on the tower is available, a DB201 cut for your freq and mounted on a piece of pipe ~5' above the tower will be bulletproof, if side mount is required a DB212 modified to get down into 6m will work however may have a bit of a shadow on the opposite side of the tower from the antenna. Neither will give you any gain but both are bulletproof commercial antennas that will take a beating. What tower height are you working with? If you had a tall enough tower, a multi element phased array could be pulled off using db212s positioned around the tower but that's more than what you probably want to mess with. I'm currently involved in building a 6m system locally, we will be using a GE MASTR II transceiver and PA but obtaining crystals for our freq split has proven to be difficult as most mfgs have dried up and the crystals we have tried have provided sub par performance. View Quote The tower is a short ATT long lines tower. It's one of the fat squatty things with the big platform on top with the feed horns removed and those rings left around the corners. It's probably only about 80 ft tall but is on one of the higher elevation areas around here. We have a couple of repeaters there on VHF/UHF now. One is a high power MSF2000 connected to a ham split 4 bay dipole. It probably gets a 50 mile range. I think I should be able to mount it to the top with the rest at one of the rail corners. |
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Quoted: I think I should be able to mount it to the top with the rest at one of the rail corners. View Quote DB201 would be my choice as long as you can get it far enough away from the vhf/uhf antennas. You should be able to find one easily if you ask around, they were made for years and were widely used, unfortunately out of production now. Very simple, folded monopole ground plane design. The only issues I know of them having is the mounting clamp flange for the vertical element has a tendency to crack. Very easy to machine an adapter to use a stainless worm clamp though. I have some pics I can send you of what we did with our damaged one if you run across the same issue. |
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What do you guys make of this? I don't think it's lightning damage. The cables all look good and only that one spot looks like that. However, I haven't opened any other cans yet.
A previous modification? Bad solder joint someone tried to repair? Attached File Attached File Attached File EDIT: After looking at this guy's page again I guess it's just the way they are made. His factory joint there looks like shit too. I'm thinking there's nothing wrong with it and it's just the way it is. Mine is cleaner inside that his seem to be. https://www.qsl.net/va3ext/repeater.htm |
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Quoted: Haven't had a chance to dig through the shed yet. These 14 hour coronadays are killing me View Quote View All Quotes View All Quotes Quoted: Quoted: PM sent. Haven't had a chance to dig through the shed yet. These 14 hour coronadays are killing me Is all good. I've been busy too. Thanks |
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Love a nice set of cans! Last ones I messed with were on VHF hi band.
The small paging company I worked for back in the 90's was on VHF hi band and had several linked transmitters as well as some UHF control links. The owner also had a 6 meter simplex repeater on an old telco tower that @SVGA-1 has climbed. That one was a steel "ship's mast" tower with four arms. I think this is a Long Lines tower.? Located up on the Four Peaks ridge. Attached File Attached File Attached File It's got one hell of a view! |
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Quoted: Love a nice set of cans! Last ones I messed with were on VHF hi band. The small paging company I worked for back in the 90's was on VHF hi band and had several linked transmitters as well as some UHF control links. The owner also had a 6 meter simplex repeater on an old telco tower that @SVGA-1 has climbed. That one was a steel "ship's mast" tower with four arms. I think this is a Long Lines tower.? Located up on the Four Peaks ridge. https://www.AR15.Com/media/mediaFiles/108158/DSCN8133_JPG-1371087.JPG https://www.AR15.Com/media/mediaFiles/108158/DSCN8134_JPG-1371089.JPG https://www.AR15.Com/media/mediaFiles/108158/DSCN8132_JPG-1371091.JPG It's got one hell of a view! View Quote I'd love to own a platform tower like that. Easy to add antennas to, easy to climb with a 6 pack to watch the sun go down, not to mention easy to snipe from |
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Quoted: Love a nice set of cans! Last ones I messed with were on VHF hi band. The small paging company I worked for back in the 90's was on VHF hi band and had several linked transmitters as well as some UHF control links. The owner also had a 6 meter simplex repeater on an old telco tower that @SVGA-1 has climbed. That one was a steel "ship's mast" tower with four arms. I think this is a Long Lines tower.? Located up on the Four Peaks ridge. https://www.AR15.Com/media/mediaFiles/108158/DSCN8133_JPG-1371087.JPG https://www.AR15.Com/media/mediaFiles/108158/DSCN8134_JPG-1371089.JPG https://www.AR15.Com/media/mediaFiles/108158/DSCN8132_JPG-1371091.JPG It's got one hell of a view! View Quote Awesome view, that's the EXACT same tower design we are planning on putting it on, even the building is similar. Currently there are three UHF and one VHF repeater there. Attached File |
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How much trouble was it to get on that site? I have a Micor uhf repeater sitting in my bedroom doing nothing. Be nice to put it up at the 4 peaks site.
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Looked through the shed this morning and can't find the Syntors. Same story with a Spectra I was looking for the other day. Regrettably I may have sold them at a hamfest over the summer. There's one more place they could be but they're quite large so I think I would have noticed if they were there.
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Quoted: Looked through the shed this morning and can't find the Syntors. Same story with a Spectra I was looking for the other day. Regrettably I may have sold them at a hamfest over the summer. There's one more place they could be but they're quite large so I think I would have noticed if they were there. View Quote Thanks for looking though. |
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Quoted: Looked through the shed this morning and can't find the Syntors. Same story with a Spectra I was looking for the other day. Regrettably I may have sold them at a hamfest over the summer. There's one more place they could be but they're quite large so I think I would have noticed if they were there. View Quote A guy in our area bought the site and is big into ham stuff so all we had to do was ask. It has internet as well due to the WISP on top. |
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Disregard. I'm just going to cut the coils as the instructions indicate.
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One would think just shorting out the end coil would
have the same effect as cutting one off. Area circled below.. Attached File However, I'm not an engineer, just an amateur. It's quite possible there will be some adverse interaction with the unused section of coil at those freqs. |
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Once we get the duplexer, feedline and antenna part sussed out I might have to take you up on that offer. A roadtrip would be nice anyway. |
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Quoted: One would think just shorting out the end coil would have the same effect as cutting one off. Area circled below.. https://www.AR15.Com/media/mediaFiles/108158/6MCav_jpg-1372711.JPG However, I'm not an engineer, just an amateur. It's quite possible there will be some adverse interaction with the unused section of coil at those freqs. View Quote I edited it because I talked with a friend who is extremely knowledgeable and has built tons of stuff like this and he said it would work but would probably have a lower Q factor. He suggested cutting them as indicated. I was just trying to avoid trying to silver solder them because I've never had luck with that stuff. It seems to be an art and I have no talent. I can solder surface mount stuff and whatever else all day but that big stuff never seems to go right. I tend to get it too hot and it just beads off then oxydizes and the joint turns to shit. Maybe I'll start a GD thread asking for tips or something on how to do it. |
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One down 7 to go. It wasn't as bad as I expected. I learned that it's not like regular soldering. You have to keep the work each side of the joint hot too by moving the torch back and forth. You can't just keep it in one spot like a soldering iron. I used some old Oatey silver bearing non lead stuff I had around and some flux paste. I kind of looks fractured in the pic but after closer inspection it seems to be a shadow.
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How I was taught and always did silver soldering was to clean the joint, coat with flux, and then put little chips of solder on the joint. Apply heat where you want the solder to flow to.
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Quoted: Quoted: How I was taught and always did silver soldering was to clean the joint, coat with flux, and then put little chips of solder on the joint. Apply heat where you want the solder to flow to. I'll try that next. It's essentially a jewelry-making technique which works well when working with small parts. |
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Ok screw this soldering. Problem is I need to stretch the coils to realign with the mounting holes. Really the only way to do that accurately is after they are soldered together. This breaks or fractures the joint. I'm not sure my solder is the right type or if I'm doing it wrong. It's probably not meant to be that strong anyway. Hmmm
Really wish I could get them copper braised back together. Maybe I'll try to find some 1/4" butt connectors and different new solder. |
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I would try putting something more substantial on the inside than the wire U. I'd try some smaller copper tubing that was slit and hammered on until it fit inside like a rollpin.
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I remember reading somewhere a guy was very specific that - for radio use - it needed to be "hard silver solder," which is apparently different than the common silver solder.
Maybe? |
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Solder generally melts at less than 800 degrees F with jeweler's much less.. Braze is above that. Some silver "solders" melt above 1000 degrees F and are for brazing dissimilar metals with a high strength joint. I would think any good grade of solder rated for electrical copper would be okay. The last Sinclair VHF high band duplexer I worked on had joints the looked like yours but tuned okay.
RS |
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Maybe find a smaller piece of copper tubing to slide inside the existing to hold it while you solder it. Does the plastic tubing go inside the main tuning slides? I haven't seen that before. The local guys are running what you have although they called it a half wavelength cavity set. I wasn't involved in setting it up. Seems like it was an ex-natural gas utility unit on 47 megahertz or so. Their repeater works pretty good as I can hear it ID on my scanner. Might need to either find my ALD-06 or just get a TYT quad band for about $220 with a little tax money refund.
RS |
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Quoted: Maybe find a smaller piece of copper tubing to slide inside the existing to hold it while you solder it. Does the plastic tubing go inside the main tuning slides? I haven't seen that before. The local guys are running what you have although they called it a half wavelength cavity set. I wasn't involved in setting it up. Seems like it was an ex-natural gas utility unit on 47 megahertz or so. Their repeater works pretty good as I can hear it ID on my scanner. Might need to either find my ALD-06 or just get a TYT quad band for about $220 with a little tax money refund. RS View Quote It was probably one of the same ones. This too was on gas company freqs in the 48/49 range. The tubing is just a structural support. The main tuning plugers enters the large copper tube the coils are soldered to. |
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My HP8935 kind of crapped out so I started messing with the NANO-VNA. I know it's far from precision and doesn't have the dynamic range but do you guys think it's a appropriate in this application? I have been working on making the pass band stubs. I used stacked N adaptors to get an approximate length while watching for maximum return loss at the pass band frequency. I then took a slightly longer hunk of RG-214/U and started cutting off 1/2" bits while watching the peak. Here's one of the Reject Low cans (reject 51.150 and pass 52.850). Would you trust this and run with it?
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Maybe use what is used for hvac. It’s a braze and quite strong.
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Silvaloy is the product that I use and it requires oxygen/accty torch.
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