5catfish Posted February 7, 2011 Share Posted February 7, 2011 And just on the point of VHF kit - does anyone still make decent diversity VHF radio mics any more? The old Trantec S2000 series are great bits of kit - only ones I can find now are the Kam cheapie ones (which aren't all that bad), but nothing diversity. Cheers,Alan This is very reliable VHF for not a lot of money - Chiayo VHF Link to comment Share on other sites More sharing options...
cedd Posted February 7, 2011 Share Posted February 7, 2011 Have you used them? Don't spose you could tell us the frequencies they can be selected to? How many simultaneously are we talking about? I've just got my 5th Sennheiser SK2012 working, pretty chuffed, took a lot of work and tweaking! Doesn't quite behave as well as its' friends, but on a minor character it might get me out of jail if I'm short. Link to comment Share on other sites More sharing options...
Simon Lewis Posted February 7, 2011 Share Posted February 7, 2011 Have you used them? Don't spose you could tell us the frequencies they can be selected to? How many simultaneously are we talking about? Brochure states "Frequencies available: 173.800, 174.000, 174.100, 174.200, 174.400, 174.500,174.600, 174.800, 175.000. The following channels are co-ordinated frequencies and require a licence to operate: 176.400, 177.000 " Out of those, 7 follow the new VHF allocation, and one (175) is supposedly for legacy equipment. The others need a co-ordinated licence. You'd have to check with the manufacturer regarding how many channels can play together... Link to comment Share on other sites More sharing options...
stagemic Posted May 24, 2012 Share Posted May 24, 2012 Hi, I've been looking into Ch38 using the free Audio Technica Frequency Planning tool. Based on the 10 channels JFMG suggests, there is a minimum intermod distance of 99KHz? I haven't bought any systems yet, however, I've spent ages trying to figure out various frequencies. Asuming 99KHz is acceptable (based on the JFMG advice), I've managed to get the following results on the Audio Technica tool: 16ch: (606.500 606.775 607.150 607.425 607.925 608.200 608.575 608.850 610.125 610.800 611.075 611.575 611.925 612.500 612.925 613.200) Min. IM distance 99KHz 15ch ( 606.500 606.775 607.150 607.425 607.925 608.200 608.850 610.125 610.800 611.075 611.575 611.925 612.500 612.925 613.200) Min. IM distance 99KHz 14ch (606.500 606.875 607.375 608.000 608.425 609.325 609.775 610.475 611.000 611.400 612.000 612.825 613.325 607.775) Min. IM distance 100 KHz 13ch (606.500 606.875 607.375 608.000 608.425 609.325 609.775 610.475 611.000 611.400 612.000 612.825 613.300) Min. IM distance 124 KHz 12ch (608.000 608.925 610.075 611.475 613.125 606.500 606.875 607.375 608.400 609.625 610.675 612.025) Min. IM distance 125 KHz If you get a chance to try these out let me know. Any suggestions re: Ch38 would be appreciated! Ch70: Sennheiser claim to get 6 intermod-free channels. I've looked at this on the AT tool too and found that 6ch (863.100, 863.375, 863.800, 864.100, 864.700 & 864.950MHz) has a minimum intermodulation distance of 124KHz, whereas the 4ch (863.100 863.700, 864.100 and 864.900) has a minimum intermodulation distance of at least 200KHz. Hope this helps someone, or helps someone to help us! Link to comment Share on other sites More sharing options...
Simon Lewis Posted May 24, 2012 Share Posted May 24, 2012 There's a bit more to it than channel spacing (important though that is). The intermodulation products are frequency dependent (see here for some good background). Furthermore, the selectivity of the RF front end wil determine whether or not such multiple frequency assignments in one channel will work. Sennheiser get six frequencies to work within 863.1 to 864.9MHz with their G3 gear, but only got four with their earlier Evolution systems. The intermod software you have been using should work this out for you, but it is gear dependent too... Link to comment Share on other sites More sharing options...
stagemic Posted May 24, 2012 Share Posted May 24, 2012 Hi Simon, Thanks for the input. I agree that it's gear-dependent. I understand that 16 channels is really pushing it, however, shurely there has to be a combination of frequencies that has the strongest possibility of working intermod free. Then it's simply down to the equipment. I'm hoping to import some new Ch38 systems in the near future and so I'm looking for the strongest combinations. I can choose up to 64 or 96 presets per system, so I have room to experement a little bit. The figures mentioned before were the minimum theoretical space before intermodulation occurred and not the channel spacing. The minimum channel spacing for the above info was around 274KHz for 15 &16ch, 225KHz for 14ch and 375KHz for 13 &12ch configurations. Link to comment Share on other sites More sharing options...
waster Posted May 24, 2012 Share Posted May 24, 2012 I was interested in only the shared ch.38 licence. I hire kit out to amateur groups doing shows and I often get asked for 12 and up to 14 channels sometimes. Getting the extra 2 channels to 14 is a hassle which I'd like to avoid if possible. I guess the solution may be to offer 12 in the ch.38 band plus keep 2 of my old sets in ch.70 for those cases where someone wants 14. Can you not just license the extra two channels for the hire period? So find out the venue that the client will be using the radio equipment in see if channels 39 - 43 are available and then book licenses for the extra two channels to cover the length of the hire. It is something like £8 per frequency per day. If you can not use 39-43 in the area then you would have to look to 2000 series (goes up to channel 46) or 3000 series (184mhz tuning range!) if you were to stick with sennheiser. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.