Josh Tucker Posted May 30, 2012 Report Share Posted May 30, 2012 Hey guys. Yesterday was day one of a 10-day shoot for me, and I had a rather nagging issue that I'm hoping to sort out. I recently purchased an IFB100 and a couple ERX's for use as camera hops and TC feed. So far, I've used them on a couple shoots with great results. However, this is the first time I've had to bring out my Comteks as well, and I've found that they don't play well together in a bag. I'm using the Zaxcom rig for camera feed and director's IFB, and the Comteks for the boom op (not ideal I know, but I work with what I got). The problem is that the Comteks receive a TON of interference from the IFB100 and no matter how much I tune them, I can't seem to fix it. I even moved the Comtek tx to the other side of the bag (a rather large Petrol) but still no change. The signal to the ERX's as well as all talent wireless is clean. it's just a Comtek issue. I'm still unsure WHY exactly this happening, given the broad difference in operating frequencies. Have any of you run into the same problem? Have you found ways to reduce the interference? Thanks. Quote Link to comment Share on other sites More sharing options...
Josh Tucker Posted May 30, 2012 Author Report Share Posted May 30, 2012 Zaxcom is like a weed. Always kills everything around it. Ha. That's certainly how it seems. So have I inadvertently made my Comteks obsolete? At least judging by this experience, it would seem that I can't use them in the same vicinity as the IFB100. My boom op and I even got an extension and did a walk test with the PR216. We were still getting garbage 6-8ft. away. This would really suck, since the Comteks are my primary IFB system and the IFB100 is now my main TC and scratch to camera option. Quote Link to comment Share on other sites More sharing options...
Zack Posted May 30, 2012 Report Share Posted May 30, 2012 Your test was clean with the ifb100 off in that same location? Quote Link to comment Share on other sites More sharing options...
Josh Tucker Posted May 30, 2012 Author Report Share Posted May 30, 2012 Your test was clean with the ifb100 off in that same location? ...as a whistle. As soon as I unplugged the IFB100 everything was fine. Quote Link to comment Share on other sites More sharing options...
MatthewFreedAudio Posted May 30, 2012 Report Share Posted May 30, 2012 What different tests have you performed with the units? Which units powered off, on, plugged in with audio, etc. How are you powering the Comtek? What sort of garbage are you hearing? RF hits? Solid RF but fuzzy audio? Electrical noise? Something else? Production Sound Mixing for TV, Film, and Commercials. www.matthewfreed.com Quote Link to comment Share on other sites More sharing options...
Zack Posted May 30, 2012 Report Share Posted May 30, 2012 Hummm, I have not had this issue before, but I run things slightly different. I have QRX on camera, and Comtek Tx in bag. I'm curious if I get similar behavior if I bring those two close together. I don't know if you can adjust the output power of the IFB100, but it would be interesting if that helped your comtek when lowered maybe? Quote Link to comment Share on other sites More sharing options...
RadoStefanov Posted May 30, 2012 Report Share Posted May 30, 2012 I don't own an IFB100 but the Nomad Ifb antenna messes with my Lectros if the antennas are close together. Quote Link to comment Share on other sites More sharing options...
MT Groove Posted May 30, 2012 Report Share Posted May 30, 2012 I don't know for sure if this even matters, but check your output cable from the mixer to the Comtek transmitter. I believe Comtek uses a filtered cable (has a bulge close to the 1/8" connector). If you're using cable w/o the filter, it may be prone to interference. I could be completely wrong about this though. My Comteks plays nice with my TRX900/STA100 an Lectro IFB in bag. I am using a Comtek ourput cable. Quote Link to comment Share on other sites More sharing options...
Josh Tucker Posted May 30, 2012 Author Report Share Posted May 30, 2012 What different tests have you performed with the units? Which units powered off, on, plugged in with audio, etc. How are you powering the Comtek? What sort of garbage are you hearing? RF hits? Solid RF but fuzzy audio? Electrical noise? Something else? Production Sound Mixing for TV, Film, and Commercials. www.matthewfreed.com Comtek is running on 9 volts. I believe it's an RF issue, though I could be wrong. The signal comes in clean (well...Comtek clean) but with a high pitched buzz that varies in intensity. It's worst, of course, when I get the Comtek receiver near the IFB100 antenna. (Note: I'm not using a separate 2.4GHz amp as the manual suggests. Perhaps that's a problem?) I've had limited time to run tests. So far, I've had the IFB100 powered on with and without audio plugged in, with and without TC plugged in. No change. I also unplugged the IFB100 completely. This fixed the issue, but is obviously not a solution. I then move the PR216 to the other side of the bag. A little better but not much. Also, tried retuning the Comteks several times. Some frequencies got interference worse than others, but none of them were completely clean. Quote Link to comment Share on other sites More sharing options...
RadoStefanov Posted May 30, 2012 Report Share Posted May 30, 2012 The signal comes in clean (well...Comtek clean) but with a high pitched buzz that varies in intensity. It's worst, of course, when I get the Comtek receiver near the IFB100 antenna. Exactly the same with my Nomad and Lectro RXs Quote Link to comment Share on other sites More sharing options...
Josh Tucker Posted May 30, 2012 Author Report Share Posted May 30, 2012 I don't know for sure if this even matters, but check your output cable from the mixer to the Comtek transmitter. I believe Comtek uses a filtered cable (has a bulge close to the 1/8" connector). If you're using cable w/o the filter, it may be prone to interference. I could be completely wrong about this though. My Comteks plays nice with my TRX900/STA100 an Lectro IFB in bag. I am using a Comtek ourput cable. Huh. Interesting. The cable I've been using was put together by Pro Sound. It's a TA3 to mono 1/8". It hasn't been an issue when not being used with IFB100 though. I'll give Pro Sound a shout though and see if they have any insight. Quote Link to comment Share on other sites More sharing options...
Josh Tucker Posted May 30, 2012 Author Report Share Posted May 30, 2012 Exactly the same with my Nomad and Lectro RXs So how do you deal with it? Quote Link to comment Share on other sites More sharing options...
Zack Posted May 30, 2012 Report Share Posted May 30, 2012 So, I just did a quick test and put my QRX with the ducky on and sat it right next to my PR-216 (which is being fed using the filtered 3.5mm cable). Both units are powered separately. QRX IFB output is 50mW and I'm also hearing the high pitch whine you describe when I play with the correlation of the two antenna. When the QRX ducky antenna is 90 degrees perpendicular to the Comtek's the whine goes away almost entirely, but when vertical (parallel) with the Comtek's it's bad and can intensify greatly with just small distance changes between the two units. I've never noticed this at all before since my IFB signal originates from the Camera where the QRX sits usually. Rado, you say the Nomad IFB is causing havoc on your Rx? Are you hearing this whine in your Rx returns too? Quote Link to comment Share on other sites More sharing options...
Zack Posted May 30, 2012 Report Share Posted May 30, 2012 Putting an extra ferrite filter around the Comtek Tx audio cable seemed to help a bit just FYI. Quote Link to comment Share on other sites More sharing options...
RadoStefanov Posted May 30, 2012 Report Share Posted May 30, 2012 So how do you deal with it? Physical separation... Quote Link to comment Share on other sites More sharing options...
RadoStefanov Posted May 30, 2012 Report Share Posted May 30, 2012 Rado, you say the Nomad IFB is causing havoc on your Rx? Are you hearing this whine in your Rx returns too? Yes. Quote Link to comment Share on other sites More sharing options...
Josh Tucker Posted May 30, 2012 Author Report Share Posted May 30, 2012 Zack, thanks so much for the tip. I'm going to mess with the antenna configuration today. I'm also going to look into the filtered cable. Though call time is in a couple hours, so it'll probably have to wait till tomorrow. I checked into adjusting the power setting on the IFB100, but I'm not sure if I'll have time to do a thorough test before we start shooting today. The power is adjusted in arbitrary increments (from 0-7) so its hard to judge what's going to be too low. Without the luxury of a proper camera return, I'm hesitant to just start cutting the power. Either way, I'll report back with the results of any adjustments I make. Cheers. Quote Link to comment Share on other sites More sharing options...
Zack Posted May 30, 2012 Report Share Posted May 30, 2012 Yes. Wow! No bueno Quote Link to comment Share on other sites More sharing options...
PTA Posted May 30, 2012 Report Share Posted May 30, 2012 Yes. How often do you notice this? I would imagine it would make your talent Rx useless if you had the IFB on all the time. Quote Link to comment Share on other sites More sharing options...
RadoStefanov Posted May 30, 2012 Report Share Posted May 30, 2012 I had My IFB antennaa bending front and back with the right angle adapter. Every time it got close to the RX antenna I would here the Buzz/Whine. Now I use the short IFB antenna safely on the side of Nomad. Quote Link to comment Share on other sites More sharing options...
Zack Posted May 30, 2012 Report Share Posted May 30, 2012 short antenna? I don't know what's supplied with the Nomad, but how short is the one you talk about compared to the QRX one? Quote Link to comment Share on other sites More sharing options...
Joel Jameson Posted May 30, 2012 Report Share Posted May 30, 2012 Zack, thanks so much for the tip. I'm going to mess with the antenna configuration today. I'm also going to look into the filtered cable. Though call time is in a couple hours, so it'll probably have to wait till tomorrow. I checked into adjusting the power setting on the IFB100, but I'm not sure if I'll have time to do a thorough test before we start shooting today. The power is adjusted in arbitrary increments (from 0-7) so its hard to judge what's going to be too low. Without the luxury of a proper camera return, I'm hesitant to just start cutting the power. Either way, I'll report back with the results of any adjustments I make. Cheers. Since you have an external amp, try using a setting of 5 for power. Typically you have an external antenna setup with an amp, are you using both in a bag setup? From changing the power settings 7 to 5 off a standalone IFB100 I seem to loose a rough average of about 20 feet of range, but YMMV Another thing to try is power the IFB on a separate battery/power source than the comtek, that's helped me on random occasions where I can't solve it through the normal troubleshooting methods. Sent from my HoboPad Quote Link to comment Share on other sites More sharing options...
John Blankenship Posted May 30, 2012 Report Share Posted May 30, 2012 I just played around with a Comtek 216 transmitter in my Nomad bag rig. I have the Nomad's antenna on a short extender cable so I can resposition it wherever it works best in the bag. When the Comtek x-mitter was in close proximity to the 2.4gHz antenna (initially, I had it running horizontally below the Comtek), I had a good bit of squeal coming through the Comtek system (the Comtek transmitter is using a floppy antenna and I'm feeding the transmitter with a filtered cable). As I moved things around (Nomad antenna now on the left side of the bag -- near where it would be if it were attached directly), it wasn't too difficult to totally eliminate the squeal. No doubt YMMV, of course. When time permits (probably not for a few days), I'll try the Nomad on the cart and see how it affects the many transmitters I have on that setup (3 Comtek 216 transmitters, a Comtek 72, a Sennheiser wireless feed for 5Ds and the like, and various other goodies). Quote Link to comment Share on other sites More sharing options...
Jack Norflus Posted May 31, 2012 Report Share Posted May 31, 2012 I don't own an IFB100 but the Nomad Ifb antenna messes with my Lectros if the antennas are close together. Not sure what is going on in your bag - but as far as I know nobody else has reported this. I know my Zaxnet antenna has no affect on my 411's - blocks 25 and 26. Quote Link to comment Share on other sites More sharing options...
Josh Tucker Posted May 31, 2012 Author Report Share Posted May 31, 2012 Since you have an external amp, try using a setting of 5 for power. Typically you have an external antenna setup with an amp, are you using both in a bag setup? From changing the power settings 7 to 5 off a standalone IFB100 I seem to loose a rough average of about 20 feet of range, but YMMV Another thing to try is power the IFB on a separate battery/power source than the comtek, that's helped me on random occasions where I can't solve it through the normal troubleshooting methods. Sent from my HoboPad As I said earlier, I'm NOT using an external amp. I am also powering the Comtek and IFB100 separately. Comtek on 9volts and IFB100 on BDS system (is there any other way?). I've never needed an amp, as I'm usually in the bag very close to camera. Range has never been an issue (well, not yet at least). Anyways, I tried Zack's suggestion of putting the IFB100 antenna perpendicular to the Comtek's. This solved 90% of the problem. I was able to eliminate any remaining interference by simply maintaining sufficient distance between myself and the boom op's Comtek rx. Thanks so much for the help you guys. Once again, you've saved the day. Cheers. Quote Link to comment Share on other sites More sharing options...
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