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Thread: 7/8 comparison/preferences/sentiments

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    Default 7/8 comparison/preferences/sentiments

    What are people using for 7/8 runs? RFS Cellflex, Andrew-Commscope Heliax, Eupen?

    Which connectors are your favorite?

    RFS usually comes out ~$2.25 cheaper/ft than Heliax for some reason

    We usually spec andrew 7/8 and RG214/U (8268) for duplexer harness, and RG142 or RG400 for jumpers. Never had any issues with LMR on duplex, and sometimes use LMR400 for low power short runs.


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    I had problems with the early runs of AVA-5, the Commscope replacement for LDF5-50. The captive center pin (N male or female) would go open with a little side flex. ie: normal lateral flexing while lashed to a tower could make them go intermittently open. Later versions assembled correctly. I think early shipments mixed new and old stock which are not the same.

    Real Times Microwave captive center pin connectors have a similar problem for their entire series for larger diameter cable (LMR600 and up). You can use their REAL TMS cable prep tool, the canter wire will be fully inserted into the center socket, and it will be open. Absolutely open making no contact. We ran some examples through a band saw to verify we had built the things correctly, and even after that rough treatment, you could demonstrate the open center connection. We sent samples to Tessco and TMS. Tessco refunded our connector costs, but not our labor. TMS never responded. The trick with these was to not deburr the center cable tip, and to let it drift slightly off center. Then you got a solid contact.

    Tessco 14515 / RF Industries crimp-on LMR400 NM connectors don't always mate correctly with some equipment. The center pin has too steep of a taper - it's too pointy. It can be assembled perfectly, be perfectly centered in the mating connector, and be perfectly open making no connection. Cut the center wire long so the pin extends an extra millimeter out of the connector. ie: it should draw blood if you give it the thumb test.

    It doesn't happen often, but we've had bad reels of cable from just about every OEM. Sweep every reel if possible before taking them to the job. That foam dialectic doesn't always keep the center centered. I've seen the center shorted to the shield with the void partially filled with the foam. You get to find out how accurate the DTF test is when the bad run is already on the tower.
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    We have been using Eupen here with no issues in 1/2" and 7/8". Not sure of pricing though but remember the shop manager saying he could get Eupen for less than RFS and WAY less than Andrew.... your mileage may vary

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    On a slightly different note, we have had massive problems with BNC male with overly skinny pins not making contact on the Motorola SLR repeaters.

    If you look at different batches of SLR repeaters, the BNC female varies, sometimes even the REF and RX are different from each other on the same unit.

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    Only ever used Commscope Andrew personally, with a strong preference for LDF-5 for ease of connector prep. I've installed runs of AVA5 and it's not terrible/impossible to work with, but the connector complexity versus LDF5 is worse.

    I have had PIM problems when using LMR cable in full duplex runs (not to be confused with RG-400 mil-spec cable, which is fine for short jumper runs) and I won't use it in lengths of more than a foot or two. I also don't use captivated center pin connectors for LMR cable... clamp and solder, baby. Tessco parts 73565 and 45888 are excellent RF Industries sub connectors for LMR-400 (N male and female, respectively.)
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    I will not use the Andrew/Commscope cable anymore. It has become cheap junk. There is a 100% difference in the 1/2 and 7/8 cable from a short 7 years ago. Cheaper construction, less cooper, I don't know. The 1/2 cable has no rigidity to it and just kinks easily now. We here have standardized on the RFS cabling. Seems to be of good quality (similar to what Andrews used to be) and come in at a great price point.

    We have also phased out using regular captivated connectors. All JMA now. We feel it is a superior connection, and once on has to be cut off. You can hang a small SUV from a connector. Obviously for small applications JMA would not be cost effective at all. However, for day in and day out installs, it just cant be beat. We only have now 7 prep tools and stock on the trucks 2 types of connectors for each size, plenum and annular. At one point I had 15 different prep tools, multiple connectors for the same size cable (that was the A Holes at Commscope playing games changing cable types) and of course all new prep tools every time. Done with that for good.

    I have literally boxes and boxes of new connectors and prep tools in the shop doing nothing. Grrr

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    I second the RFS cable for new purposes.

    For ham applications I'm still using cable from a 12 year old 3,000' drum of Andrew 7/8" I purchased for cents per foot surplus a few years ago
    Last edited by Astro Spectra; Feb 04, 2018 at 02:44 AM. Reason: Clarify surplus cable type
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    Haven't seen modern CommScope RF cables, but old Andrew and RFS cables are OK. As well as Eupen. I also have access to Acome cables, but don't think that they are popular in US.

    The best ever made connectors come from Huber+Suhner (Swiss made). Amphenol, Andrew, Acome, Eupen, RFS, Spinner, etc. connectors for corrugated cable are not so perfect. They always have some flaw or even a few flaws, like silver plate with strong oxidation (most of Andrew), not good fit, getting out seal ring, brittle rear nut, significantly bigger rear hole than cable jacket dia, very complicated installation manual, etc. I've worked with connectors from all mentioned manufacturers and know what I am talking about. But H+S connectors 3-5 times more expensive than RFS.

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    The following statement answers a question that came up today.

    Tessco 14515 / RF Industries crimp-on LMR400 NM connectors don't always mate correctly with some equipment. The center pin has too steep of a taper - it's too pointy. It can be assembled perfectly, be perfectly centered in the mating connector, and be perfectly open making no connection. Cut the center wire long so the pin extends an extra millimeter out of the connector. ie: it should draw blood if you give it the thumb test.

    I had made some duplexer cables using the RG-214 version of this connector. It worked fine at first but after about a year there was about 40 dB loss on the receive side. I was in a hurry as usual so I replaced the duplexer with another. We finally got around to checking the defective duplexer when I needed it for another repeater.

    Inspection of the cables showed no problems bur replacing the receive cable solved the problem. As a precaution, we changed both cables.

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