Radio mic - remote aerials

Archived from groups: rec.audio.pro (More info?)

"glasgowsoundman" wrote ...
> It's my intention to try running some coaxial cable from the BNC
> connectors on the rear of the receiver to the top of the guardrail for
> the tech area (graphics & lighting) above the control room. I'll then
> attach the standard aerials to the end of the coaxial cabling.
>
> Can anyone foresee likely problems with this? The distance from
> transmitter - aerial will be similar to what we had before the control
> room was built. Should I move the remote coaxial ends further apart
> than the BNC connectors on the rear of the transmitter? Would this
> help
> reduce further the risk of dropout?
>
> I have thought that I may need to purchase the plate type of antennas
> (directional?) to get this to work instead of using the standard
> aerials that are on the receiver.

Yes, you can use directional antennas which have some gain.
Several vendors of wireless mics also sell antennas with
amplifiers built-in to increase their sensitivity.

However, note that just moving the antenna substitutes the
loss through the cable for the loss through the air/walls.
Far more reliable to move the whole receiver up to the
stage close to the transmitter. Use an existing mic line to
carry the audio output back to the mixing desk.

Archived from groups: rec.audio.pro (More info?)

"Richard Crowley"
> "glasgowsoundman"
> Yes, you can use directional antennas which have some gain.
> Several vendors of wireless mics also sell antennas with
> amplifiers built-in to increase their sensitivity.
>


** An RF amp at the antenna is there to overcome losses in the connecting
cable -it will not actually improve matters compared to an antenna mounted
on the receiver.


> However, note that just moving the antenna substitutes the
> loss through the cable for the loss through the air/walls.
> Far more reliable to move the whole receiver up to the
> stage close to the transmitter. Use an existing mic line to
> carry the audio output back to the mixing desk.


** This would be the preferred and cheaper solution.



........... Phil

Archived from groups: rec.audio.pro (More info?)

"Richard Crowley"
> "glasgowsoundman" wrote...
>>I know that moving the receiver would be a big help. I'm not sure how
>> easy it would be with our current setup. I'll have a think about how we
>> could do it.
>
> Unless you are very careful, you could lose more RF
> through a long antenna cable than you are losing through
> the air/wall. Moving the receiver closer to the transmitter
> is usually a more reliable solution.


** This reminds me of the time I got two Vega VHF radio mic systems with
the *usual* complaint that they has both lost range and were suffering drop
outs.

Distance from receivers to stage area was stated to be less than 20 metres
with a clear line of sight - the units were installed in a "bio box" high
above the dance floor.

Further inquiries produced the rest of the story - the so called "bio box"
was made from all steel framework and was surrounded in steel mesh.

A PERFECT Faraday cage !!!!!




............ Phil

Archived from groups: rec.audio.pro (More info?)

Many thanks to all for comments. Quick trial last night was useful, now
I need the go ahead to use better quality materials and then a decision
can be made, by others, as to whether to stick with coaxial or go for
proper antennas.

Thanks again,

glasgowsoundman

Archived from groups: rec.audio.pro (More info?)

glasgowsoundman wrote:

> Radio mic frequencies are: Handheld 863.900MHz and Tie 859.400MHz. We
> have used these mics for some time with no intermodulation problems.
> We've had no problems with other signals being picked up on these
> frequencies. Systems are both Sennheiser G1. One is ew100, one is
> ew500.
>
> The current antennae are attached to the receiver with BNC connectors.
> I was simply going to put suitable BNC connectors on each end of the
> coax in order to easily swap between the current setup and the proposed
> setup during testing.
>
> The long cables on the antennae won't get the antennae any closer to
> the transmitter but will get them past a wall and way above the heads
> of the congregation.

RG58 is not suitable for these high frequencies.
I suggest springing for some decent UHF feedline
to make your efforts worthwhile and keeping the
run as short as possible. Also take care making
the terminations to assure clean connections and
avoid kinks, etc.

good luck
rd

Archived from groups: rec.audio.pro (More info?)

PMFJI, but a little time spent in review of the following
might be time well spent:

http://www.locationsound.com/proau [...] ips14.html

and

http://www.locationsound.com/proau [...] ips15.html

and

http://www.locationsound.com/proau [...] ips16.html


You don't have to believe a word they say, but they pretty
much know their stuff (and they are nice folks to talk to,
as well). And the manufacturers of the equipment will
usually be quite helpful in providing specifics for getting
the best results. That's been my experience, at least.

What I find most puzzling about wireless is not the
technology or equipment, but the resistance of the people
wanting to use the technology to accept the basics of how it
works. Unreasonable expectations always seem to trump the
laws of physics. Amazing.

HTH


TM

glasgowsoundman wrote:
>
> What would you regard as "decent UHF feedline"? Is there any standard
> reference coding in a similar way to RG58 for a type of coaxial cable?

Archived from groups: rec.audio.pro (More info?)

"T Maki" wrote ...
> What I find most puzzling about wireless is not the
> technology or equipment, but the resistance of the people
> wanting to use the technology to accept the basics of how it
> works. Unreasonable expectations always seem to trump the
> laws of physics. Amazing.

Oh, I don't think that effect is limited to wireless systems!

Archived from groups: rec.audio.pro (More info?)

Whae type of directional... quad... yagi... is it a diversity
syetem...if you plan on yagi in a diversity system you will get more
problems with Rf phasing.

cheers
the islander



On Tue, 16 Aug 2005 06:49:45 -0700, "Richard Crowley"
<rcrowley@xpr7t.net> wrote:

>"glasgowsoundman" wrote ...
>> It's my intention to try running some coaxial cable from the BNC
>> connectors on the rear of the receiver to the top of the guardrail for
>> the tech area (graphics & lighting) above the control room. I'll then
>> attach the standard aerials to the end of the coaxial cabling.
>>
>> Can anyone foresee likely problems with this? The distance from
>> transmitter - aerial will be similar to what we had before the control
>> room was built. Should I move the remote coaxial ends further apart
>> than the BNC connectors on the rear of the transmitter? Would this
>> help
>> reduce further the risk of dropout?
>>
>> I have thought that I may need to purchase the plate type of antennas
>> (directional?) to get this to work instead of using the standard
>> aerials that are on the receiver.
>
>Yes, you can use directional antennas which have some gain.
>Several vendors of wireless mics also sell antennas with
>amplifiers built-in to increase their sensitivity.
>
>However, note that just moving the antenna substitutes the
>loss through the cable for the loss through the air/walls.
>Far more reliable to move the whole receiver up to the
>stage close to the transmitter. Use an existing mic line to
>carry the audio output back to the mixing desk.

Archived from groups: rec.audio.pro (More info?)

From what I am reading here through all these... it is not a
diversity system... I know the Sennheiser systems fairly well... Used
them lots.. Plus you only need to go s short distance.. with the
coax... so RG 58 should work well even above 700 mHz it is only
minimal line loss. May I suggest a Yagi antenna made for the
frequency for each of the transmitter/receivers.. 3 pole ones will
likely do well. A ham operator can help you with design and maybe
even constructioin. they will be small at 800 megs

cheers
the islander



On 18 Aug 2005 07:04:34 -0700, "glasgowsoundman"
<glasgowsoundman@yahoo.co.uk> wrote:

>TM,
>
>Thanks for that information. Very helpful. I'm not trying to trump the
>laws of physics, just trying to find the most cost-effective way of
>improving the situation I've got.
>
>Thanks again,
>
>glasgowsoundman

Archived from groups: rec.audio.pro (More info?)

"Islander" = another top posting wanker

> From what I am reading here through all these... it is not a
> diversity system...


** Of course it is - dimwit.


I know the Sennheiser systems fairly well... Used
> them lots..


** With zero comprehension.

Usual for a half-witted radio ham.




............ Phil

Archived from groups: rec.audio.pro (More info?)

Sigh.... I guess the islander is too old to know everything... and too
old to be nasty about it of others.

have a nice day.



On Sat, 20 Aug 2005 15:51:22 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

>
>"Islander" = another top posting wanker
>
>> From what I am reading here through all these... it is not a
>> diversity system...
>
>
> ** Of course it is - dimwit.
>
>
> I know the Sennheiser systems fairly well... Used
>> them lots..
>
>
>** With zero comprehension.
>
> Usual for a half-witted radio ham.
>
>
>
>
>........... Phil
>

Archived from groups: rec.audio.pro (More info?)

glasgowsoundman wrote:

> rd,
>
> What would you regard as "decent UHF feedline"? Is there any standard
> reference coding in a similar way to RG58 for a type of coaxial cable?

http://www.shure.com/support/techn [...] s.html#top

According to Shure:
Cable Length from Antenna to Receiver
Cable Type
Cable loss @ 800 MHz per 100 ft.

Up to 15 feet
RG-58C/U(Belden 8262 or similar)
18.5 dB per 100 ft.

Up to 25 feet
RG-8X/U(Belden 9258 or similar)
12 dB per 100 ft.

Up to 40 feet
RG-213/U (Belden 8267 or similar)
7 dB per 100 ft.

Up to 75 feet
RG-8/U(Belden 9913 or similar) for permanent installation only
3.9 dB per 100 ft.

There's also loss in the connectors so care
must be taken in assembly.

If the receiver is true diversity there should be
some indicator light that will show which receiver
is active. You can try replacing just one of the
inputs with a remote antenna and see if there's any
improvement. RG58 may be OK to get you just on the
other side of the wall, but you may have as good or
better results by placing the receiver on the other
side of the wall and feeding the audio through.

good luck
rd