I have a telemetry system set up so I can have radio collars on
animals (wombats) which transmits to a directional Yagi 3 antenna and
through to a TR-5 Telonics receiver. I am getting activity data now
directional data.
The wombats are zoo animals so the range isn't far (about 100m) but my
problem is that their dens are made of concrete and seem to block too
much of the signal. This system was used previously with no problems
so I can't figure out why it isn't now. The antenna is mounted on the
roof of my office building. Would it help to place it vertically
instead of horizontally?
What else can I manually do to boost this signal? Otherwise what is
the easiest and cheapest ways to boost the signal. There are twelve
frequencies that I am getting but about 6 of them aren't great, The
frequencies operate about 151.000
Help!

Aghh, good old wombats!

I'd suggest that any adjustable gain isnt going to help much. I'd
concentrate more on your statement "This system was used previously with
no problems". Do you have a breakage somewhere? Are the troublesome
systems on one receiver? (if you have more than one) Are you sharing the
frequency with someone else and getting interference? Are there any
other sources of interference that may be the problem?

I suggest that horizontally is the best orientation as the antennas on
the animals are probably also horizontal.

In my situation I'd also tune the equipment for best output just in case
the attached wombats have damaged them. You *could* put a preamp on the
receiver but I think that will invite more problems than provide a
viable solution

If you have a scanning receiver have a listen separately for each collar
signal. If they are all there suspect the base anytenna/receiver as
being faulty. You may also hear interference.

Hope this helps

Cheers Bob VK2YQA

Krys wrote:
I have a telemetry system set up so I can have radio collars on
animals (wombats) which transmits to a directional Yagi 3 antenna and
through to a TR-5 Telonics receiver. I am getting activity data now
directional data.

"Bob Bob" wrote in message
...
Aghh, good old wombats!

I'd suggest that any adjustable gain isnt going to help much. I'd
concentrate more on your statement "This system was used previously with
no problems". Do you have a breakage somewhere? Are the troublesome
systems on one receiver? (if you have more than one) Are you sharing the
frequency with someone else and getting interference? Are there any other
sources of interference that may be the problem?

I suggest that horizontally is the best orientation as the antennas on the
animals are probably also horizontal.

In my situation I'd also tune the equipment for best output just in case
the attached wombats have damaged them. You *could* put a preamp on the
receiver but I think that will invite more problems than provide a viable
solution

If you have a scanning receiver have a listen separately for each collar
signal. If they are all there suspect the base anytenna/receiver as being
faulty. You may also hear interference.

Hope this helps

Cheers Bob VK2YQA

Krys wrote:
I have a telemetry system set up so I can have radio collars on
animals (wombats) which transmits to a directional Yagi 3 antenna and
through to a TR-5 Telonics receiver. I am getting activity data now
directional data.

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

All of what the respondent said, plus:

Was the coax leading to your base antenna weatherproofed using coax seal at
the outside connector? If not, it is possible that rain water has
contaminated the coax leading to your base radio. I've seen this type of
problem cause folks to pull their hair out while trying to "fix" all of the
remote units, when it was the base unit all the time.

What kind of connectors are used in your base system? If N-connectors it is
unlikely that the above problem is the cause. However, it is also unlikely
that your system is using N-connectors because of price considerations.

A passive radiator system (antenna inside structure connected to an antenna
outside of the structure the Wombats occupy connected by coax cable) could
help. But I would find out why the system is not performing as it was
before. As the respondent indicated, it could be something as simple as Tx
detuning or increased traffic on the frequencies that you are using.

Ed, NM2K

Most likely your problem has already been covered here, but when was the
last time the batteries were changed in the Wombat collars? Signals will
go down as batteries fade. How the heck do you change the batteries on
those Wombat collars, anyway? :^)


Ed K7AAT

Thanks guys for your advice. The collars are a mix of new and old but
it seems to be more location that is determining whether they work.
(eg. some of the wombat collars are good no matter where while some
are bad only in the dens). They are all new except one. I can hear
them all really well when I scan them one by one but when I use them
together I have the receiver in data acqiusition mode (to store all of
the data for later download) which doesn't allow me to adjust gain or
tuning. I guess that is why I assumed it was maybe not enough gain.
The antenna outside is connected to the receiver by a RG58 cable. It
is only covered in electrical tape at the connection. It was rusty but
I have changed that all and the signal is the same. I can check the
missing data on my video cameras and see that it is always when they
are in their dens.
I think you are all probably right. Perhaps the antenna or receiver
was damaged when it was stored or moved.

In article
,
Krys wrote:

I guess that is why I assumed it was maybe not enough gain.
The antenna outside is connected to the receiver by a RG58 cable. It
is only covered in electrical tape at the connection. It was rusty but
I have changed that all and the signal is the same.

There is your problem, right there.... RG-58 is not really very good at
VHF Frequencies in lengths longer than 25 Ft. You should get some good
cable, like Beldon 9913 or LMR400 and have someone who knows how to
install the proper connectors on it, do the work, of replacing the
Feedline. I suspect your losing over 50% of your signal in the Feedline
and connectors.

--
Bruce in alaska
add path after fast to reply

Krys wrote in news:6b12d81f-0ab6-4181-b4cd-
:

Thanks guys for your advice. The collars are a mix of new and old but
it seems to be more location that is determining whether they work.
(eg. some of the wombat collars are good no matter where while some
are bad only in the dens). They are all new except one. I can hear
them all really well when I scan them one by one but when I use them
together I have the receiver in data acqiusition mode (to store all of
the data for later download) which doesn't allow me to adjust gain or
tuning. I guess that is why I assumed it was maybe not enough gain.
The antenna outside is connected to the receiver by a RG58 cable. It
is only covered in electrical tape at the connection. It was rusty but
I have changed that all and the signal is the same. I can check the
missing data on my video cameras and see that it is always when they
are in their dens.
I think you are all probably right. Perhaps the antenna or receiver
was damaged when it was stored or moved.

How long is the RG58 cable? Did water get into it? If so, consider
replacing it with RG8X (same impedance, lower loss).


--
Dave Oldridge+
ICQ 1800667

It turns out that I have too many transmitters in a small area so the
frequencies are getting on top of each other. I can use half at any
one time. At the moment I have 6 running and am adding them one by one
to see how far I get before I start losing them. Hopefully I won't
have to change the frequencies on too many. Fingers crossed

"Krys" wrote in message
...
It turns out that I have too many transmitters in a small area so the
frequencies are getting on top of each other. I can use half at any
one time. At the moment I have 6 running and am adding them one by one
to see how far I get before I start losing them. Hopefully I won't
have to change the frequencies on too many. Fingers crossed

If they are sending data at the same intervals some will walk on each other
every time.