Radio Mics in Church

[dogcop]

Good evening blue room

I'm hoping I can get a definitive answer here.

 

At our church we are shortly to purchase 6 UHF radio mics. I have done a search on google but have not found the answer

 

1/ Do we need a licence?

2/ If so whats it called and what does it cover

3/ How much would it be

4/ Where do we obtain said licence if we need it

 

thanks

 

Andy

[Bobbsy]

To run six simultaneous channels yes, you will need a licence.

 

There is a small chunk of UHF bandwidth you can use licence-free, but the maximum number of channels you can squeeze in there would be four...and this is optimistic with two or three being more typical with real-world equipment.

 

The most cost effective way for you to go would be to use the "UK Shared" frequencies on UHF channel 69. Depending on the gear you buy, you'll be able to get at least 8 and often 12+ channels on these frequencies. These are also adjacent to the free channels so, if you want to expand in the future, you should have breathing space.

 

(Edit to clarify: A UK shared licence gives you 14 frequecies but how many you can use simutaneously will depend on the quality of the gear you buy. Cheap radio mics have to be spaced more carefully because they tend to interfere with each other due to containing lesser quality filters.)

 

Licences are issued by the Joint Frequency Management group (JFMG) at https://www.jfmg.co.uk/ .

 

A one year licence for the (up to) 14 UK Shared frequencies is £75. Two years is £135. These are online rates...you pay slightly more to apply by post.

 

Hope this helps.

 

Bob

[David Duffy]

Huh, you learn something new every day! In Australia there's no license for wireless mics and you're usually good for about 16 channels with moderately priced gear. Then again, wireless mics here are treated as secondary users so there's no real comeback when you get interference I believe.

[Bobbsy]

Now I'm learning things...useful ones at that since I plan to be moving down your way in the next few months once my house sale goes through!

 

Is there a specific UHF channel or channels allocated for radio mic/IEM use, or can you just pick any unused TV channel?

 

(And I know I'm going to have to dig out some old paperwork since I know the frequency vs. channel allocation is different in Australia!)

 

Bob

[David Duffy]

The frequency allocations and power limits are different in Oz compared to other parts of the world I believe. AFAIK, 10mW in the (designated for wireless mics) UHF bands is always allowed. Up to 50mW is also allowed, but only if the importer has them type approved by the Dept of Communications. (or whatever they call themselves this week)

 

Most of the major TV broadcasters are on VHF (175 - 220MHz IIRC) so the legal UHF spectrum here is the 7xx - 8xx range. The old 200Mhz frequencies have been pretty much taken over by DTV and it's no longer legal to import mics in that band I'm told. Not that stops all the crap eBay ones from being sold! Hope this helps.

[timtheenchanteruk]

do they specifically need to be UHF??

 

I run 4 VHF, and 4 UHF mics at the same time, with no problems, and no licence needed either, alot of people seem to be specifing UHF, but I have yet ot find a problem with my old VHF units.

[RobertKendall]

You may not no this, but some of the Frequencys are being moved over for use with DAB Digital Radio so it wont be legal to use radio mics on the same Frequencys??

 

might be worth checking out??

 

 

 

Robert Kendall

[Colin]

Hmm and here was me hearing rumours that DAB has been such a massive failure due to "it being out of date the day it was launched" that it could be switched off to make way for a new technology at very short notice. Then while he did work in the sort of job that might have inner knowledge of the radio industry I still am taking such things with a large handful of salt but anyone with more info I would be very grateful. Hmm thats got a bit OT

[Bobbsy]

THIS THREAD talks about the planning for changes in radio microphone frequencies and provides some links to the OFCOM consultation document. There are major changes afoot and it's not just to do with DAB.

 

As for the use of VHF, I still have some ancient VHF packs in my kit and, despite my best efforts, they keep working and refuse to die. However, I'd be curious to know what make and model of kit timtheenchanter is using. It's highly unusual to be able to use 4 of the 5 non-licence frequencies without encountering intermod problems on some of them.

 

Similarly, squeezing 4 channels on the 863.1-864.9 unlicenced UHF band without intermod is also pretty rare. Again, I'd be curious to know what equipment (and what frequency combination) he's using.

 

Bob

[Lamplighter]

.

 

Similarly, squeezing 4 channels on the 863.1-864.9 unlicenced UHF band without intermod is also pretty rare. Again, I'd be curious to know what equipment (and what frequency combination) he's using.

 

Bob

 

Bob

I inherited 4 licence free Trantec UHF licence free Channel 70 beltpack systems which work without any problems. The frequencies are:

863.025

863.727

864.300

864.650

These are now sold as S4.4 systems but I am not certian if the design has remained the same.

With a channel 69 licence you can add 6 more channels useing S4000 kit.

854.900

855.900

857.625

860.400

860.900

861.200

This 10 channel combination works well without any nasties appearing. The information on the Trantec website at the time I set this up was inacurate, but may have been ammended since. I did my own intermod calculations and found that you were not limited to 3 channel 70 frequencies. There are other combinations that work theoretically but I have not tried them. I use a dual channel combiner and the ultimate test is that all 10 packs used in a 1m space show no interaction.

Brian

[Bobbsy]

Hmmm...running an intermod check on your unlicenced frequencies I get a conflict warning:

 

Checked For:

Spectrum : On 0.000

Spacing : On 0.400

2Tx IM(3) : On 0.100

2Tx IM(5) : Off 0.100

3Tx IM(3) : On 0.100

 

Channel configuration: 4

863.025 MHz

863.725 MHz

864.300 MHz

864.650 MHz

 

------------------ Check results ---------------------------------------

Check results

 

864.300 MHz overlapped by 864.650 MHz Channel at 864.650

864.650 MHz overlapped by 864.300 MHz Channel at 864.300

 

Channel configuration is not compatible.

 

(I wasn't sure about your use of 863.727 since most systems won't tune down to the last digit so I used 863.725. In any case, this wasn't a problem frequency.)

 

However, I can't argue with results! Since the conflict is channel spacing, not intermod, the Trantecs probably have either good filters, more limited FM deviation, or both than the figure I used (which was a Sennheiser one).

 

As for the OP, whether it's 3 or 4, he'll certainly get his six channels with some room for growth between the UK shared and unlicenced channels. As he has to buy a licence anyway, UK shared might be slightly safer since there are a lot more people trying to use the unlicenced bandwidth.

 

Bob

 

Edit to add: Doing some playing, changing your third frequency to 864.250 gives a clean prediction with no overlap and no intermod. However, I've spotted one other potential issue. Your lowest frequency is 863.025; depending which reference you read this may not be technically legal. Though it's common to talk about 863-865, I've seen at least one official RA document that actually specifies 863.1-864.9 as the legal range. I'm honestly notsure which is right...but this minor difference could account for some of the pessimistic predictions if manufacturers use the slightly more limited range as gospel.

[soundo26]

Just a quick update on the DDR(Digital Dividend Review) better known as the sell off of the analogue TV frequency spectrum.

The review is still ongoing and the advice seems to be that you should buy with caution, the channel 69 band is one of those currently mooted to be available for auction under the DDR between 2008-2012 when the digital switchover occurs.

An announcement was recently made that we are a step closer to the Channel 69 band being reserved and being made license exempt in 2008. Until then license fees will be charged by JFMG with a small increase this year.

Hopefully that will be it, but the deal hasn't been done quite yet, so the possibility is still that if you buy mics now, you could lose the right to use them in 2008.

Keep everything crossed guys!

 

For more info, Google JFMG & BEIRG...........

[Lamplighter]

Bob

You have spotted my typo and 863.725 is the correct frequency. The suggested 4 channels are the Trantec recommended frequencies and at the time the units were purchased were the standard prprogrammed channels. The suggested overlaps in your calculator indicate that poor IF filtering is assumed and the band width is not an issue as the transmitter peak deviation is +/- 22.5 kHz so 863.025 only becomes a problem if the frequency stability of the unit is an issue. Some of the units that I have checked for other people have not met the stability and peak deviation limits required to operate at 863.025 and this could have resulted in the suggested 100kHz guardband.

 

Having checked the Trantec website the S4.4 is now programmed with 863.15, 863.725, 864.150 and 864.850 so I will rerun my calculations and see how this works with channel 69. The advantage of using a combination of chan 69 and 70 was that the four frequency channel 70 units were considerably cheaper than the multifrequency channel 69

models. I bought a couple of the four channel units with channel 69 frequencies then Trantec blocked the dealer programmers so that channnel 69 could only be programmed into the multi channel versions. The current website wording suggests that this block may have been withdrawn. This could prove useful to groups looking to use channel 69.

Brian

[timtheenchanteruk]

Hi, I'm using the trantec 4.4 system, one on each of the frequencies, same as lamplighter has posted, and some oldish beyerdynamic VHF mics, NE170, and then older version of it, 2 of each. I think the frequencies for the VHF are

 

173.800

174.100

174.500

175.000

 

I'm pretty sure these are right, I don't have the units in-front of me, and they are fixed frequency, so I don't think about it much.

[Lamplighter]

As promised an update on the possibility of adding channel 69 frequencies to a system which starts with the 4 currently recommended channel 70 frequencies.

863.150-- 863.735 --864.150-- 864.850

 

First a few caveats

1) I haven't tested these for real as my 4 available chan 70 frequencies are the older bloc

2) the current Trantec S4.4 models may not have the same filters as the S4.5 models

3)makes other than Trantec may have totally different characteristics

4) you still need your channel 69 JFMG licence

5) your experience may be different to mine.

 

That said the following frequencies should be compatible with the above if using Trantec S4000 models on chan 69.

 

861.750 -- 861.550 -- 861.200-- 860.900 -- 858.200 -- 856.175-- 854.900

 

This would give 11 UHF channels and with the 4 vhf listed by Tim above produce a total of 15 usable channels.

I would prefer to use the 14 channels in channel 69 but we don't all get the luxury of a clean slate!

Brian