Greetings all,


We need a wireless dog fence, such as the PIF-300 shown at:


http://www.petsafestore.com/inwirfen.html


It forms a 90 foot diameter zone and runs at 17 khz. The transmitter
weighs 5 pounds (not including the wall wart power supply).


I have no idea what's inside the think, but it's an expensive item,
over $200 dollars for the transmitter and collar. I am hesitant to buy
one without any idea whether I can improve the range!


We would like to buy one, but want 500-700 feet range. Since the
collar assembly (the rx) is sealed, I was hoping to hop up the
transmitter.


Does anyone have any experience with these beasts. I have no idea what
type of antenna it uses, most likely a loop with a ferrite core and
the coil makes a resonant circuit at 13 khz, probably has a single
transistor....

My first thought is to add an external wire antenna, which should
increase the range alot even though it still wouldn't be very
efficient.


Does anyone have any practical knowledge of antenna technology at 17
khz? Best to add an amplifier or try to add an outbord antenna?

Thanks.


Al

Albert wrote:
Does anyone have any practical knowledge of antenna technology at 17
khz? Best to add an amplifier or try to add an outbord antenna?

External antenna. It's on their web page:


If you have a larger than average yard, consider purchasing an extra
boundary kit. The boundary kit includes additional wire and flags.

consider purchasing an extra
boundary kit. The boundary kit includes additional wire and flags

There is no wire in this kit, it's wireless.

The manufacturer sells an additional transmitter, which is very
expensive.

My question was regarding methods for hopping up the transmitter or
adding a better (external) antenna.

Can you help?

Thanks

Al.

Albert wrote:
My question was regarding methods for hopping up the transmitter or
adding a better (external) antenna.

Increasing the transmitter power significantly or adding an external
antenna would violate Part 15 rules and also invalidate the FCC type
acceptance. Having said that, here's the transmitter schematic.

https://gullfoss2.fcc.gov/prod/oet/f...ive_or_pdf=pdf

OK, thanks very much Travis.

It appears easy to modify or to bulid another unit, reproducing the
coil is probably the toughest part.

I'm not familiar with the ic's, but should be able to locate data for
them.

I'm really quite surprised to find that there is not a single
transistor oscillator, but that sure looks like the beast!

I don't think there is a part 15 regulation for 17 khz. because it's
almost audio frequency. If there was a part 15 for frequencies that
low, they would have to type accept every audio amp that has a
transormer or coil associated with the output, wouldn't they?

I can't imagine 17 khz going very far, especailly since the 'antenna'
is so short relative to the carier frequency.

I do thank you very much for the help and wish you the best.

Al


On Mon, 21 Mar 2005 14:13:13 GMT, "Travis Jordan"
wrote:

Albert wrote:
My question was regarding methods for hopping up the transmitter or
adding a better (external) antenna.

Increasing the transmitter power significantly or adding an external
antenna would violate Part 15 rules and also invalidate the FCC type
acceptance. Having said that, here's the transmitter schematic.

https://gullfoss2.fcc.gov/prod/oet/f...ive_or_pdf=pdf

Albert wrote:
I don't think there is a part 15 regulation for 17 khz. because it's
almost audio frequency. If there was a part 15 for frequencies that
low, they would have to type accept every audio amp that has a
transormer or coil associated with the output, wouldn't they?

The U.S. RF spectrum allocation starts at 9.0khz and unlicensed devices
must conform to Part 15.

9.0 to 14.0khz is allocated for radio navigation use (in the U.S. the
now mostly obsolete Omega system was the largest user of this spectrum).

Are you sure the transmitter actually uses such low "carrier" frequency? I
have not looked a the schematic that was posted, but I don't see how this
could actually work at that frequency since as you yourself admit, this is
in the high audible freq. range.

I would think that the collar based receiver might emit the 17Khz tone when
the animal wearing it strays beyond the RF transmitter's range. I would
think though that the transmitter itself would use an approved FCC RF
frequency in the Mhz or low Ghz range.

Bob

Albert wrote in message ...
OK, thanks very much Travis.

It appears easy to modify or to bulid another unit, reproducing the
coil is probably the toughest part.

I'm not familiar with the ic's, but should be able to locate data for
them.

I'm really quite surprised to find that there is not a single
transistor oscillator, but that sure looks like the beast!

I don't think there is a part 15 regulation for 17 khz. because it's
almost audio frequency. If there was a part 15 for frequencies that
low, they would have to type accept every audio amp that has a
transormer or coil associated with the output, wouldn't they?

I can't imagine 17 khz going very far, especailly since the 'antenna'
is so short relative to the carier frequency.

I do thank you very much for the help and wish you the best.

Al