Michael P Clark Posted March 16, 2008 Report Share Posted March 16, 2008 Anyone have thoughts on how to best secure SMA antennas? Twice, I have had an SMA slightly loose, and it made for drop outs on Transmission. Luckily, it has been caught early(the second time), and it's double system, but it could happen at the wrong time(ie. no double system) and I'm screwed. I've been wrapping tape around them, but it looks ugly and and there needs to be a better way. I understand why the small footprint is nice for some manufacturers, but I need a locking antenna, before I'm doomed. A rubber washer or something? Peace! Quote Link to comment Share on other sites More sharing options...
jason porter Posted March 17, 2008 Report Share Posted March 17, 2008 Maybe you can try some nail polish near the base of the SMA connector to temporarily "glue" the antenna on. For the record, mine never loosen unexpectedly. -JP Quote Link to comment Share on other sites More sharing options...
Paul Graff Posted March 17, 2008 Report Share Posted March 17, 2008 I have been using the SM transmitter since 2004 and have never had any trouble with the antenna, if your antennas are malfunctioning you need to send them back to Lectro since that would be warranty work as Lectro guarantees them against breakage. I think Michael is referring to the SMA type connector, not the Lectro SMA. I don't have a solution, but I share your concern. So far I have only Zaxcom transmitters as camera hops and not on talent. I intend to use the TRX900 as a talent transmitter in the future, so my solution of constantly checking and snugging the antenna will not be adequate. I think a small lock washer might do the trick. I will look into it. PG Quote Link to comment Share on other sites More sharing options...
Jeff Wexler Posted March 17, 2008 Report Share Posted March 17, 2008 I intend to use the TRX900 as a talent transmitter in the future, so my solution of constantly checking and snugging the antenna will not be adequate. PG We used the TRX900's on talent a lot on this last movie and none of the antennas were ever loose. When I first put antennas on the transmitters they seem to be quite a snug fit and I did tighten them all the way down but without any force. They have just stayed tight --- am I lucky? - Jeff Wexler Quote Link to comment Share on other sites More sharing options...
Paul Graff Posted March 17, 2008 Report Share Posted March 17, 2008 We used the TRX900's on talent a lot on this last movie and none of the antennas were ever loose. When I first put antennas on the transmitters they seem to be quite a snug fit and I did tighten them all the way down but without any force. They have just stayed tight --- am I lucky? - Jeff Wexler That's good to know Jeff. Early on with Stereoline (2005) I lost transmission to camera (only time it's ever happened) and after feverishly scanning with the receiver for a new freq. with no change of results I realized the copper extension cable that goes to the RF filtering antenna had come a bit loose at the transmitter. Since then I always check it. I have never had this happen with the receiver antennas. The regular transmitter antenna seems to stay snug better than the copper cable. I just realized, of course, that all of my Lectro MM400 transmitters use the SMA connector and I have never had a problem with these coming loose. My transmitters (MM400A & all have a little rubber/plastic gasket the color of their freq block at the base of their antenna threads. It helps them stay put and I don't think the UM400's have this. I think a little O-ring there would make a big difference. What type of transmitter is giving you this problem, Michael? PG Quote Link to comment Share on other sites More sharing options...
Michael P Clark Posted March 17, 2008 Author Report Share Posted March 17, 2008 Paul, You are exactly correct! It's with the TRX900 as stereo hop. Sorry for the vagueness, I didn't think about the SMa from lectro. This has happened both times with the filtered antenna portion of the whole rig. Never had any problem with the receiver antennas, either. Only the filtered antenna. My thoughts are that it puts some torque on the connector, or if it moves it loosens it. Once, this happened with the Stereoline, and yesterday for the first time with the TRX900. Both times it had happened while in a bag situation. It just takes constant twisting every now and then, and searching for the green light on the receivers to have piece of mind. Only problem is, I have to keep my focus elsewhere, and don't want to be constantly checking. Not a good piece of mind, while in the battle of things. Quote Link to comment Share on other sites More sharing options...
Eric Toline Posted March 17, 2008 Report Share Posted March 17, 2008 A drop of semi-permenent "Loc-Tite" will solve all the problems. Keep in mind that a heat gun is required to dissolve the Loc-Tite so you can remove the antenna if required. Eric Quote Link to comment Share on other sites More sharing options...
wbrisett Posted March 17, 2008 Report Share Posted March 17, 2008 The only thing I could think of is a small piece of teflon plumbers tape around the threads to keep it tight. I wouldn't do that. Remember that the threads are part of the circuit, you have to have some contact and with the SMA connectors being so small, there isn't a lot of space for contact to begin with. Wayne Quote Link to comment Share on other sites More sharing options...
Glen Trew Posted March 17, 2008 Report Share Posted March 17, 2008 Actually, tests I've done show that when locktite is used in a tightened connection, there is negligible conduction loss. The the surfaces of the thread that are pushing against each other are essentially still metal-to-metal. The locktite is squeezed to the microgaps in the low pressure side of the threads and sets with the absense of oxygen. Glen Trew , I wouldn't do that. Remember that the threads are part of the circuit, you have to have some contact and with the SMA connectors being so small, there isn't a lot of space for contact to begin with. Wayne Quote Link to comment Share on other sites More sharing options...
wbrisett Posted March 18, 2008 Report Share Posted March 18, 2008 Thanks Glen. My concern was with the teflon tape which means even less surface than a dab of locktite is covering the connector. Wayne Quote Link to comment Share on other sites More sharing options...
Michael P Clark Posted March 18, 2008 Author Report Share Posted March 18, 2008 a heat gun is required to dissolve the Loc-Tite so you can remove the antenna if required. That seems scary. I'll just keep an eye on it more often. Quote Link to comment Share on other sites More sharing options...
Glen Trew Posted March 18, 2008 Report Share Posted March 18, 2008 Thanks Glen. My concern was with the teflon tape which means even less surface than a dab of locktite is covering the connector. Wayne I didn't see the teflon tape posting. I agree that would not be a good idea. But Loctite should be OK. Keep in mind you can get a weaker version of loctite that is not difficult to remove, but is still very unlikely to back out on its own. GT gt Quote Link to comment Share on other sites More sharing options...
curleysound Posted March 18, 2008 Report Share Posted March 18, 2008 I have also had this issue occasionally on my UM200c units. I have not tried to correct the issue, I just tighten them occasionally, and it stays for a while. If the talent is doing very active stuff, I'll check more often. Adding a tiny rubber grommet at the base of the antenna mount screw on the body of the xmtr should provide enough pressure to keep it from unraveling, but it's never been enough of a concern to try it. Quote Link to comment Share on other sites More sharing options...
DWsoundservice Posted March 19, 2008 Report Share Posted March 19, 2008 The Loctite idea is most likely the best. The problem with the Teflon tape is that it insulates the threads of the nut on the antenna, which is normally grounded through the threads on the SMA connector on the transmitter. Though the chances are small, it is still possible for noise to be created through the antenna when the nut is not correctly grounded. If you are going to use the Loctite, make sure that you use the correct adhesive formula. The 222 and 242 will work the best as they are the weakest of all the Loctite. Any stronger any you might cause damage to the antenna or the connector when trying to remove the antenna. David W White D.W. Sound Service www.dwsoundservice.com Quote Link to comment Share on other sites More sharing options...
Eric Toline Posted March 19, 2008 Report Share Posted March 19, 2008 That seems scary. I'll just keep an eye on it more often. If you get the weakest Loctite (222 or 242) as mentioned in a later post a heat gun may not be required but it won't unscrew with just your fingers. A pair of needle nose pliers will do the job. Eric Quote Link to comment Share on other sites More sharing options...
Michael P Clark Posted March 19, 2008 Author Report Share Posted March 19, 2008 If you get the weakest Loctite (222 or 242) as mentioned in a later post a heat gun may not be required but it won't unscrew with just your fingers. A pair of needle nose pliers will do the job. Thanks everyone, I'll look into that. Quote Link to comment Share on other sites More sharing options...
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