How many simultaneous channels on VHF radio mics?

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   Got a call today, friend of an existing client has asked me to look at and advise on his PA setup. He has purchased 2 cheap and not cheerful dual radio mic systems (seem to be oem Chinese), working on VHF band. Actually they bought 3 systems, so 6 mics in total, but have discovered that 2 out of the 3 sets, use the same frequencies!!! I’ve not used/hired/bought VHF mics since Adam was a lad; even then only 1 or 2 frequencies at a time. Bearing in mind that these are NOT diversity systems, how many mics would you guys dare to operate, at any one time? Perhaps worth mentioning that transmitting distance is never likely to be more than 15’. Thoughts please gentle ladies and men!!

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TMH Music Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 07 April 2011 Location: London Status: Offline Points: 637	Post Options Post Reply Quote TMH Music Report Post Thanks(0) Quote Reply Topic: How many simultaneous channels on VHF radio mics? Posted: 09 March 2019 at 1:38am
	Got a call today, friend of an existing client has asked me to look at and advise on his PA setup. He has purchased 2 cheap and not cheerful dual radio mic systems (seem to be oem Chinese), working on VHF band. Actually they bought 3 systems, so 6 mics in total, but have discovered that 2 out of the 3 sets, use the same frequencies!!! I’ve not used/hired/bought VHF mics since Adam was a lad; even then only 1 or 2 frequencies at a time. Bearing in mind that these are NOT diversity systems, how many mics would you guys dare to operate, at any one time? Perhaps worth mentioning that transmitting distance is never likely to be more than 15’. Thoughts please gentle ladies and men!!
	Nothing is foolproof because fools are so ingenious

csg Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 17 September 2007 Location: bedford Status: Offline Points: 6086	Post Options Post Reply Quote csg Report Post Thanks(0) Quote Reply Posted: 09 March 2019 at 3:56pm
	On the old de-reg mpt1345 channels between 173.8 and 175MHz you should be ok with 4 channels namely 173.8, 174.1, 174.5 and 175MHz. 174.8MHz was also available but won’t work reliability with the 2 channels to either side. There are other VHF channels available up to 216MHz if memory serves but these are generally site specific licenced channels. Diversity won’t have any effect on the number of channels which behave together. Being cheap Chinese rigs, chances of MPT1345 compliance or anything else are limited
	“The fact is this is about identifying what we do best and finding more ways of doing less of it better”

TMH Music Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 07 April 2011 Location: London Status: Offline Points: 637	Post Options Post Reply Quote TMH Music Report Post Thanks(0) Quote Reply Posted: 10 March 2019 at 1:19pm
	Thanks for that mate!! I’ve persuaded client to use one set, i.e 2 mics and a pair of wired mics, for the moment, until I can actually test all of them, on site, to make sure.
	Nothing is foolproof because fools are so ingenious