Indeliblesound Posted October 23 Report Posted October 23 So I'll be working a gig in a couple weeks where I will be fed 4 cabled mix-minus feeds for IFB to 4 talents. I've done this plenty in the past but used a rack mount unit, easy peasy. Due to the workflow and small footprint required for camera and sound department, I have to get this done in a bag-on-cart. My plan is to run a Mini Circuits ZFSC-4-1-S+ using a combination of IFBT4, SMV, SMQV, SMDWB all set to 250w except the latter at 100w in the same block running into a Betso Bowtie transmitting to R1as. I'm OK with the 6db loss, that's actually going to be the least of my challenges! Does this layout sound correct? Expert feedback appreciated. I've never used these passive circuits before... Quote
r.paterson Posted October 23 Report Posted October 23 3 hours ago, Indeliblesound said: So I'll be working a gig in a couple weeks where I will be fed 4 cabled mix-minus feeds for IFB to 4 talents. I've done this plenty in the past but used a rack mount unit, easy peasy. Due to the workflow and small footprint required for camera and sound department, I have to get this done in a bag-on-cart. My plan is to run a Mini Circuits ZFSC-4-1-S+ using a combination of IFBT4, SMV, SMQV, SMDWB all set to 250w except the latter at 100w in the same block running into a Betso Bowtie transmitting to R1as. I'm OK with the 6db loss, that's actually going to be the least of my challenges! Does this layout sound correct? Expert feedback appreciated. I've never used these passive circuits before... Others may have different experience but I tried the same multiple iem tx into mini circuits ZFSC 4-1 as a combiner and I had very poor results, it was full of nulls etc.. I ended up using 4 x dipole (sna 600) on each iem tx. Others may have had different experience but m now of the opinion multiple iem tx rf outs need to go thru an active iem tx combinerblike the shure one. If going yo use mini circuits I'd definetly do a proper test beforehand.. Quote
edward chick Posted October 24 Report Posted October 24 You did not mention how far the throw will be from your bag to the talen’t s ifb receiver. You might get by with just the antennas on the transmitters. 250mw is pretty powerful.. I have used Smqv for years to hit my bag on a football field, while the transmitter is several stories up outside a press box for radio calls. The Betso Bow ties are not powered, you may want to look into a powered antenna like Lectrosonics, Shure, Wisycom RF Venue etc. Quote
Indeliblesound Posted October 24 Author Report Posted October 24 2 hours ago, r.paterson said: Others may have different experience but I tried the same multiple iem tx into mini circuits ZFSC 4-1 as a combiner and I had very poor results, it was full of nulls etc.. Bummer to hear. I've used the Shure combiner many times and wish there was a way to get that on my cart. I may still, but it'll be if other more compact options don't work. 56 minutes ago, edward chick said: You did not mention how far the throw will be from your bag to the talen’t s ifb receiver. You might get by with just the antennas on the transmitters. 250mw is pretty powerful.. I have used Smqv for years to hit my bag on a football field, while the transmitter is several stories up outside a press box for radio calls. The Betso Bow ties are not powered, you may want to look into a powered antenna like Lectrosonics, Shure, Wisycom RF Venue etc. Distance is going to be short, 10-15ft. Mostly standing on no more than two spikes. If I run the antennas, and keep them separated from each other, what is the best practice for that? I hear optimally a foot apart so that nulls the "compactness" of what I'm trying to achieve. Quote
edward chick Posted October 24 Report Posted October 24 If it’s that short a distance I would not bother with external antenna’s on the transmitters. I would definitely use a frequency coordinator app if you plan on using all ifb on same block. Try to park you rig so you have a decent line of sight. Quote
Philip Perkins Posted October 24 Report Posted October 24 Anything like the MiniCircuits in the line has insertion loss. As was said, why not just use the onboard antennas if the range can be really short? I've done combining when there was no choice (as on certain kinds of car rigs) and it worked fine but the range wasn't tremendous. Quote
Fred Salles Posted October 24 Report Posted October 24 Hi, I recommend BSRF products for these situation. Unfortunately their dedicated active combiner is just 2 to 1 but wide band and very reliable, I have used it with 2 tx T4 VHF (so 50mW each) and it worked great: https://www.bs-rf.com/en/products/combiner/ I am wondering if you could use an active splitter in reverse ? I have never tried but I was told once that it works. Maybe if you have time try an active diversity splitter (BSRF AS122, PSC, ... ) using just one channel. You might need to put 50ohm termination plug on unused SMA connectors. Beware that most combiner/splitter have a maximum power input. In your case the Mini Circuits ZFSC-4-1-S+ has a max 1w so you are hitting the max with 4 times 250mw, although you said with one tx running at 100mw so that is fine. Quote
LarryF Posted October 24 Report Posted October 24 Since active splitters have an amplifie(s) to overcome losses, they won't work in reverse. Passive splitters will work either way. https://lectrosonics.com/product/m2c/ as an example. Best Regards, Larry Fisher Quote
ivanovich Posted October 24 Report Posted October 24 BSRF unit works great. If splitter/combiner is necessary, and range is critical, turn TX power down(maybe medium power) going into the splitter, then put an amp at the splitter output to then feed the antenna. it’s all about gain staging just like in the sound wave spectrum. some of those amps don’t want to see a strong signal coming in and if they do it’ll just square wave the signal and have poor performance Quote
Indeliblesound Posted October 24 Author Report Posted October 24 Thanks all for all the feedback. So I'm going to test using the whips only. Originally was not a fan of this idea as I thought antennas had to be rather far apart, negating (or at least challenging) the goal of staying small footprint. What's the best practice for this with all 4x IFBs within the same block? Reading further it's probably not a good idea to run full power, maybe max out at 100w (max for SMDWB of course) and maybe lower given the short distance to minimize interference. I do have coax dipole antennas in the kit, too. Also, did not mention but will have 2-4 inbound wires, but will be in the other side of the spectrum. Quote
Derek H Posted October 24 Report Posted October 24 I think you’re overthinking it. Whips, 100mW. Indoors. Scan and coordinate. You’ll be fine. Quote
LarryF Posted October 25 Report Posted October 25 On 10/24/2025 at 6:42 AM, ivanovich said: BSRF unit works great. If splitter/combiner is necessary, and range is critical, turn TX power down(maybe medium power) going into the splitter, then put an amp at the splitter output to then feed the antenna. it’s all about gain staging just like in the sound wave spectrum. some of those amps don’t want to see a strong signal coming in and if they do it’ll just square wave the signal and have poor performance Digital modulation in almost all forms has both frequency and amplitude modulation components. It is unlike FM modulation that is frequency only. Common transmitter antenna combiners can work with FM modulation satisfactorily but totally destroy digital modulation by distorting the AM component. Several years ago we were getting numerous service calls of digital range problems due to antenna combiners. In every case, removing the transmitters outputs from the combiner and using common whips instead magically increased the range by factors of 50. As Ivanovich stated above, the amplifier after the combiner output must be extremely robust. If you read the specs of the Lectro M2C combiner, you will see it has three fans and pulls a max of 60 Watts. Most of that "ridiculous" power goes to the final amplifier and one of the fans is full time dedicated to cooling the final amplifier. This is to provide enormous headroom for the AM component and to keep third order intermod products from the 8 transmitter RF signals at very low levels. The Shure antenna combiner is also a power hungry device for the same reasons. Best Regards, Larry Fisher Quote
Derek H Posted October 25 Report Posted October 25 Digital wireless: 100% more pain in the ass, 10% improvement in end result. Kinda joking, kinda not. Quote
Indeliblesound Posted October 25 Author Report Posted October 25 My current state of testing.... Quote
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