Hi all,

My sensor has decided to pack up when the temperature drops below about
7C.
It's very difficult to tell what's occuring as trying to locate the
faulty component/s with freezer on these SMD boards is almost
impossible. The led still pulses but nothing is received even
re-registering doesn't work until the RF section warms up again. It's
not the crystal or the SAW device (I think that's what it is) as both
these when cold don't stop it from working.

I've tried to monitor the transmissions on a receiver at 433.92MHz but
I think these devices use some sort of frequency spread/shift
modulation and I can't pick up a carrier of any sort, even when it's
working?
Anybody got any experience with these things?

Happy new Year to all
Bob

What are you using to power it? Alkaline batteries are terrible
in cold weather.

wrote:
Hi all,

My sensor has decided to pack up when the temperature drops below about
7C.
It's very difficult to tell what's occuring as trying to locate the
faulty component/s with freezer on these SMD boards is almost
impossible. The led still pulses but nothing is received even
re-registering doesn't work until the RF section warms up again. It's
not the crystal or the SAW device (I think that's what it is) as both
these when cold don't stop it from working.

wrote:
Hi all,

My sensor has decided to pack up when the temperature drops below about
7C.
It's very difficult to tell what's occuring as trying to locate the
faulty component/s with freezer on these SMD boards is almost
impossible. The led still pulses but nothing is received even
re-registering doesn't work until the RF section warms up again. It's
not the crystal or the SAW device (I think that's what it is) as both
these when cold don't stop it from working.

I've tried to monitor the transmissions on a receiver at 433.92MHz but
I think these devices use some sort of frequency spread/shift
modulation and I can't pick up a carrier of any sort, even when it's
working?
Anybody got any experience with these things?

Happy new Year to all
Bob



It's probably the batteries, mine tends to drop out at cold temperatures
when the batteries start to get a bit weak.

Hi,

The batteries are OK. I actually measured them outside in the frost!
Must be mad.

wrote in message
oups.com...
Hi all,

My sensor has decided to pack up when the temperature drops below about
7C.
It's very difficult to tell what's occuring as trying to locate the
faulty component/s with freezer on these SMD boards is almost
impossible. The led still pulses but nothing is received even
re-registering doesn't work until the RF section warms up again. It's
not the crystal or the SAW device (I think that's what it is) as both
these when cold don't stop it from working.

I've tried to monitor the transmissions on a receiver at 433.92MHz but
I think these devices use some sort of frequency spread/shift
modulation and I can't pick up a carrier of any sort, even when it's
working?
Anybody got any experience with these things?

Happy new Year to all
Bob


What are you talking about? Your description of your problem presumes that
we can read your mind and know exactly what you have.
What kind of weather station?
What kind of sensor?
What's the circuit it's connected into?
What kind of transmitter and receiver are you using?
What is being re-registered? and how?

You gonna have to release a lot more info before you get any meaningful
help.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in
the address)

Never take a laxative and a sleeping pill at the same time!!

Fair comment I supose.
I did think these units were pretty much generic but maybe not, anyway
here goes.
The Weather station is made by RF Tech model 65R05 and the sensor just
reports the temperature.
Circuit it's connected into? Not sure what you mean but the receiver
unit displays inside/outside temp, humidity and pressure.
All I can tell you about the TX & Rx is they work on 433.92MHz
according to the docs.
The registering process is done by pressing reset buttons on both
devices. When it works you see a symbol flash on the Rx LCD screen and
it bleeps, then the outside temp is displayed.
What happens is once the temp of the Tx unit drops below about 7C the
RX unit doesn't receive the signal.
I've tried monitoring the frequency on a Yaesu FT50R at 433.92 and
there's nothing there even when it's working??
I do however manage to pick up some cross mod on a nearby carrier and
can hear the data stream when it transmits. This happens even when the
RX unit has lost the signal?

Happy New Year
Bob

I have installed a device to measure the wind speed ( my design) that
freezes when the temperature is below 0c.
To preventing from freezing I have installed a halogen lamp under the
unit that comes on when the environment is below 2 degrees C.
I know that isn't a wireless solution but may be a solution.

John

On 29 Dec 2005 02:56:09 -0800, "
wrote:

Hi all,

My sensor has decided to pack up when the temperature drops below about
7C.
It's very difficult to tell what's occuring as trying to locate the
faulty component/s with freezer on these SMD boards is almost
impossible. The led still pulses but nothing is received even
re-registering doesn't work until the RF section warms up again. It's
not the crystal or the SAW device (I think that's what it is) as both
these when cold don't stop it from working.

I've tried to monitor the transmissions on a receiver at 433.92MHz but
I think these devices use some sort of frequency spread/shift
modulation and I can't pick up a carrier of any sort, even when it's
working?
Anybody got any experience with these things?

Happy new Year to all
Bob

wrote in message
oups.com...
Fair comment I supose.
I did think these units were pretty much generic but maybe not, anyway
here goes.
The Weather station is made by RF Tech model 65R05 and the sensor just
reports the temperature.
Circuit it's connected into? Not sure what you mean but the receiver
unit displays inside/outside temp, humidity and pressure.
All I can tell you about the TX & Rx is they work on 433.92MHz
according to the docs.
The registering process is done by pressing reset buttons on both
devices. When it works you see a symbol flash on the Rx LCD screen and
it bleeps, then the outside temp is displayed.
What happens is once the temp of the Tx unit drops below about 7C the
RX unit doesn't receive the signal.
I've tried monitoring the frequency on a Yaesu FT50R at 433.92 and
there's nothing there even when it's working??
I do however manage to pick up some cross mod on a nearby carrier and
can hear the data stream when it transmits. This happens even when the
RX unit has lost the signal?

Happy New Year
Bob


Your transmitter is probably drifting off frequency as the temperature goes
lower. Probably not much you can do about it other than contact the vendor
that sold the unit to you and ask for a replacement or refund.
Alternatively, contact the manufacturer, if you can find them, and ask for
assistance, whether it be repair, replacement or refund.
My guess on the whole affair is that you will probably get no satisfaction
from anybody.
I googled for RF Tech weather station and hit on this link to
http://www.rftech.co.kr/eng/cs/cs_qna.php, which contains a significant
number of complaints similar to yours, but no evidence that the company is
responding to any of them.
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in
the address)

Never take a laxative and a sleeping pill at the same time!!

DaveM wrote:


Your transmitter is probably drifting off frequency as the temperature goes
lower. Probably not much you can do about it other than contact the vendor
that sold the unit to you and ask for a replacement or refund.
Alternatively, contact the manufacturer, if you can find them, and ask for
assistance, whether it be repair, replacement or refund.
My guess on the whole affair is that you will probably get no satisfaction
from anybody.
I googled for RF Tech weather station and hit on this link to
http://www.rftech.co.kr/eng/cs/cs_qna.php, which contains a significant
number of complaints similar to yours, but no evidence that the company is
responding to any of them.
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in
the address)

Never take a laxative and a sleeping pill at the same time!!

Thanks for that Dave, interesting on the web site although it's not the
actual maufacturer?
This things over a year old now so it looks like it could be destined
for the bin, shame but I thought it would give me an opportunity to see
how it works (or doesn't in my case)!
I agree with you about the frequency shift. Trouble is being as I can't
find a carrier as such, and that you can't set it to transmit
permanently, it's pretty much impossible to fault on. I wonder how they
set them up in the factory?

Cheers
Bob

On a related subject, does anyone have any weather station products
that they would recommend?

I too am finding that the reliability of these units are questionable
(false readings, nonrepeatibility, failing when they get too hot or
cold).

TMT

I've just decided to buy myself a WS2300 by La Crosse. By all accounts
these are supposed to be quite good for the money.
Obviously it depends how much you want to spend.
Do a search on deja and you'll find quite a few articles in
alt.sci.weather (I think).

As for the RF-Tech, I might try drawing out the cct to see if I can
make some sense of it.

Bob

One of the examples of questionable weather products I have come across
is a Uniden weather phone.

When I compared three different phones, the temperature and humidity
reading were different on all of them.

Also having the outside sensors sitting right next to the phones also
showed the temp/humidity readings to be off by alot.

TMT

Well, getting back to the RF-Tech....I've fixed it.
After tracing out the circuit, no easy task with all the SMD
components, it became obvious what the problem was.
For those interested, the RF section works around a one transistor
oscillator with a SAW device setting the desired frequency. The data
stream is fed into another transistor that is connected between the RF
transistor's emitter and ground. This turns on when the data stream is
present which then switches the RF stage on.
In my unit, when it got cold, the switching transistor stopped working
due to a bad joint on one of it's leads. This was proved by shorting
out the collector to emitter which then produced a good carrier at
433.86MHz.
If anyone wants anymore details drop me a line.

Bob

Getting back to the RF-Tech, I've fixed it.
After drawing out the RF part of the circuit I found that the one
transistor oscillator was controlled from it's emitter by a switching
transistor which in turn was controlled by the data stream. This had a
bad connection and consequently the rf osc was not even turning on.
If anyone wants anymore details drop me a line.
(I've already posted this once but it appears to have got lost?)

Bob

In article .com,
" wrote:

Getting back to the RF-Tech, I've fixed it.
After drawing out the RF part of the circuit I found that the one
transistor oscillator was controlled from it's emitter by a switching
transistor which in turn was controlled by the data stream. This had a
bad connection and consequently the rf osc was not even turning on.
If anyone wants anymore details drop me a line.
(I've already posted this once but it appears to have got lost?)

Bob

Thanks for the follow-up. So the bad connection was temperature
sensitive? Was this a solder joint we're talking about? Is temperature
dependence in a case like that common, or is it just something
coincidental that makes you look in the wrong place for the problem?

Well, things weren't as straighforward as they appeared. It started
going on the blink again so I removed the transistor, cleaned the pads
and resoldered. It's possible the transistor is playing up but it's so
intermittent. I'll see if I can find replacement for it.

Bob