Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Small transmitter antenna

OK, so I have one of these to repair, which is missing the "tail" antenna on
the transmitter.

http://www.samsontech.com/samson/pro...e/airline-ag1/



Now I know very little about RF, antennae etc.
I can't get a replacement antenna for this, so how feasible would it be to
make one?

I assume this will be a fine coil of wire covered in rubber, e.g. a tiny
rubber ducky?

Or could you just attach a long wire and roll/pack it up and attach the blob
to the guitar/guitarist?



Cheers,


Gareth.


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Default Small transmitter antenna

On Wed, 21 Feb 2018 18:37:08 -0000, "Gareth Magennis"
wrote:

OK, so I have one of these to repair, which is missing the "tail" antenna on
the transmitter.

http://www.samsontech.com/samson/pro...e/airline-ag1/



Now I know very little about RF, antennae etc.
I can't get a replacement antenna for this, so how feasible would it be to
make one?

I assume this will be a fine coil of wire covered in rubber, e.g. a tiny
rubber ducky?

Or could you just attach a long wire and roll/pack it up and attach the blob
to the guitar/guitarist?



Cheers,


Gareth.


Rather than the "fine coil of wire" you mentioned, it is likely just a
piece of wire. The length should be the about the same as the
original. The length would be similar to the length of the antennas
on the base unit.
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Default Small transmitter antenna

In article ,
says...

OK, so I have one of these to repair, which is missing the "tail" antenna on
the transmitter.

http://www.samsontech.com/samson/pro...e/airline-ag1/



Now I know very little about RF, antennae etc.
I can't get a replacement antenna for this, so how feasible would it be to
make one?

I assume this will be a fine coil of wire covered in rubber, e.g. a tiny
rubber ducky?

Or could you just attach a long wire and roll/pack it up and attach the blob
to the guitar/guitarist?




It would help to know the frequency range this operates on. Looks to be
about 6 inches of wire. If it is operating close to 450 MHz, then about
6 inches of wire is all that is needed. Measure the antenna on the
receiver and use a piece of wire that long.

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Default Small transmitter antenna

It can be, this is a topic that of late is near and dear to my career.

Antennas are a science to themselves. Any piece of wire can be an antenna, but if you want efficiency and range, things get a *lot* more complicated quickly.

It's far too broad a topic to cover here, and there is plenty written about it on the web (not all of which is correct). It's safe to say that for your application, a hunk of wire is sufficient.

Terry


Thanks, Ralph, you have made my day.

I thought it was much more complicated than a piece of wire.


Gareth.


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Default Small transmitter antenna

But a yagi would be fun.


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Default Small transmitter antenna

In article ,
says...

But a yagi would be fun.


Good exercise, you could say...

Mike.
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Default Small transmitter antenna

Gareth Magennis wrote:

----------------------

OK, so I have one of these to repair, which is missing the "tail" antenna on
the transmitter.

http://www.samsontech.com/samson/pro...e/airline-ag1/


Now I know very little about RF, antennae etc.
I can't get a replacement antenna for this, so how feasible would it be to
make one?

I assume this will be a fine coil of wire covered in rubber, e.g. a tiny
rubber ducky?


** While possible, it is just as likely to be a simple 1/4 wave whip.


Or could you just attach a long wire and roll/pack it up and attach the blob
to the guitar/guitarist?


** Err- no.


..... Phil


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Default Small transmitter antenna

Gareth Magennis wrote:

----------------------

From the manual:

It operates in the uncrowded 801 805, 863 865 MHz UHF frequency range


** Normally a straight, 1/4 wave length whip antenna does the job well. Helically wound antennas (rubber duckies) are not better, only shorter and less efficient. I note the owners manual says the antennas are 1/4 wave.

RF travels at 300,000 km/S so 830 MHz has a wavelength of 360mm, 25% of which gives you 90mm from the attachment point inside the Tx. A 5% "end correction" can be applied so make it 85mm.

Use wire that has a stiff cover like Teflon, to hold it out straight.



.... Phil



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Default Small transmitter antenna

Gareth Magennis wrote:

-----------------------


Well a piece of wire worked a treat.

With a bit of heatshrink for strain relief at the transmitter end and
another on the end of the tail, it even looks like a proper one.



** So now you know how to make a "rat tail" antenna.


Thanks to all for the calculations and info.



** 300 / MHz = wavelength in metres, is worth remembering.


FYI:

That AG-1 unit is about as basic as UHF FM links get, so has limited useful range and is prone to signal drops out due to multipath interference. The Tx signal can almost cancel itself after reflecting off objects and surfaces and then arriving at the Rx.

Better models have twin channel receivers, with two separated antennas, operating as a diversity pair that helps greatly to eliminate such drop outs.



..... Phil


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Default Small transmitter antenna

Gareth Magennis wrote:

-----------------------


Well a piece of wire worked a treat.

With a bit of heatshrink for strain relief at the transmitter end and
another on the end of the tail, it even looks like a proper one.



** So now you know how to make a "rat tail" antenna.


Thanks to all for the calculations and info.



** 300 / MHz = wavelength in metres, is worth remembering.


FYI:

That AG-1 unit is about as basic as UHF FM links get, so has limited useful
range and is prone to signal drops out due to multipath interference. The Tx
signal can almost cancel itself after reflecting off objects and surfaces
and then arriving at the Rx.

Better models have twin channel receivers, with two separated antennas,
operating as a diversity pair that helps greatly to eliminate such drop
outs.



Presumably the transmitter antenna should be straight for best efficiency.

If it is (worst case scenario) a semicircle, what changes?


** Every effort should be made to straighten it !

It's an FM signal, so the recovered audio is not affected until the RF level becomes very weak. Meaning there is usually plenty in reserve to allow for circumstances that reduce the RF level compared to free field.

Players buy units like this not to get long range, but merely to be free of that damn instrument cable.


..... Phil


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