compatible radio mics

[raymond.faccini]

We are a small reasonably inexpeirienced theatre group working mainly in variety type shows.We purchased two v.h.f.radio mic sets both from diffeant suppliers one in october 2009 one in 2010, they are Skytronic 171.316 [173.8MHz+174.8MHz] and 171.317

[175.0MHz+174.0MHz] wa were ashored that these two sets would be compatible but when one set is swiched on the mics from the other will work on it, when both are switched on together we get all sorts of interfierenc problems.

Got any idears

[Jivemaster]

Sadly cheaper mics do sometimes break over into other channels.

[Brian]

If a vendor sold you a 171.nnn mic ...

171.nnn is the part number :)

 

 

[EDIT]

Ok,

 

these are dual channel units; part number number 171.316 works on 173.8 and 174.8, part number 171.317 works on 175.0 and 174.0

 

173.8 and 175.0 are fine, however, 174.0 and 174.8 are not licensed frequencies.

 

174.8 on the first unit is too close to 175.0 on the second to work.

 

173.8 on the first is too close to 174.0 on the second to work.

[paulears]

The VHF license exempt channels are:

173.800

174.000

174.200

174.400

174.600

174.800

175.000

 

In practice this usually means 3 or 4 depending on type can be used reliably together, but these channels are just the ones detail in the regulations, they can't just be tuned to and used, or you end up with a very compromised system.

 

These channels popped up to replace the older 5 (in the same band) about 4 years ago - the actual available block of exempt channels is actually 173.7 to 175.1 - but these are the extreme band edges, whereas the channels above are centre frequencies.

 

Intermod products will be all over the place depending on the spec of your system, so the chances of them working together are a little bleak, I'm afraid.

[Bobbsy]

It's not just intermod. I used to have a few really good VHF mics (Audio Ltd. RMS 2000) on the dereg frequencies and they played together nicely. However, one show somebody handed me a cheapie mic to try to use alongside--and the TX pack was picked up on all four of my receivers! I had a look at the output on a spectrum analyser from work and the FM output was splattered across the whole band and well outside the legal frequencies as well!

 

Needless to say I didn't use it!

 

Bob

[Brian]

...These channels popped up ...

So quietly I missed the change!

 

To the OP.

 

You're trying to run adjacent channels just 200kHz apart on budget units. It isn't going to work. If it would then why is the pair of frequencies in a single unit 1MHz apart?

 

I'm guessing that you've got the two receivers sitting next to each other. You might, as a very long shot, try putting them a good distance apart (several metres). It's a long shot but will reduce any coupling of RF signals from one unit to the other.

[boswell]

wa were ashored that these two sets would be compatible .

 

 

Take the set back that you bought in 2010 and ask for your money back as they are not compatible with existing equipment (my bold) and therefore not fit for purpose. The step after that is trading standards.

But if you bought them from flebay, best of luck!!

[paulears]

I doubt this would work - as the individual units are perfectly ok. The snag seems to be that the system has two switched pairs of channels. Did the supplier actually sell them as a 4 channel system? That's the critical bit. If they did, then you have a case. If not, then there could be nothing wrong (technically) just incompatibility.

[boswell]

Paul,

The point being that the second supplier assured them that the 2nd system was compatible with the first (according to the way I read the OP)

As they are not compatible then the 2nd supplier is responsible as they gave duff info.

It's worth a go!!

[raymond.faccini]

We are a small reasonably inexpeirienced theatre group working mainly in variety type shows.We purchased two v.h.f.radio mic sets both from diffeant suppliers one in october 2009 one in 2010, they are Skytronic 171.316 [173.8MHz+174.8MHz] and 171.317

[175.0MHz+174.0MHz] wa were ashored that these two sets would be compatible but when one set is swiched on the mics from the other will work on it, when both are switched on together we get all sorts of interfierenc problems.

Got any idears

 

 

thank you to all those who tried to help us, it would appear that we have been stupid and should have done a lot more home work and a lot more research with people who know [like your good selvs].We have now got to live with our stupidity.Thanks again.

Regards Ray