[Laser] laser blowed XE2AT

[Art]

Al,

Low power visible laser pointers are cheap.

Higher powered laser diode modules (with built in driver) cost more, much more!

Here is an ebay visible laser module, 50 milliwatt at 632nm. It closes in 3 
hours, and is currently priced at $72.

http://cgi.ebay.com/ws/eBayISAPI.dll?MfcISAPICommand=ViewItem&item=5705597446

There is no guarantee that the onboard driver circuit will switch at 18 Khz 
though, it might not be compatible with the Ramsey transmitter.

It might be large enough to run ok with a simple resistor though rather 
than a photodiode based power sensor.

Consider going IR at higher power. The laser diodes put out 1 watt and cost 
between 90 and 130 dollars. Since they operate at higher currents, the 
margin between threshold and burn out current is much larger and these type 
of diodes can be run with a simple constant current supply. Yes, it will 
put out much more power than you need,  but the answer here is to spread 
the beam out so it is much wider. It greatly eases the hardware aiming 
requirements and makes laser QSO's MUCH FASTER and easier.

Obey all safety rules however.

An example of a 1 watt near IR laser diode that is easy to collimate is at:

http://cgi.ebay.com/ws/eBayISAPI.dll?MfcISAPICommand=ViewItem&item=3821852969

This diode closed with no bidders.

Another diode of the same type is currently being auctioned and is at $60. 
and closes in 2 days. Most likely it will sell for around $100. Check it 
out at:

http://cgi.ebay.com/ws/eBayISAPI.dll?MfcISAPICommand=ViewItem&item=3823069459

That diode will probably run at a much safer and longer lasting 300 
milliwatt power level and can be driven with simple power supply.

I wish there was an easy answer for visible laser diodes to replace your 
Ramsey unit that failed. You might try purchasing another 1 milliwatt unit 
with the current limiting resistor, but it may not last long either.

Regards,

Art

PS: Before giving up on the laser that runs dim after a few minutes, you 
might want to check the value of the internal current limiting resistor. If 
they used a low power resistor, it might  have changed value due to the 
long transmissions you made with the Ramsey kits.


At 09:49 PM 6/24/04, you wrote:
>Thanks to all that answer the questions about pointers, yes I am using a 
>very cheaper chain laser made in china is only > 1mw and the price is only 
>1.10 USD !!! I know , I know .... but is the only that I can get here in 
>Mexico, I see today the 2 pointers used for the last 25 km and one of them 
>is very low !!!! I am using the K3PGP   diagram with a 9V battery and 7 
>diodes, I chek the volt supplied to the pointer and is just 2.3 volts, 
>this laser have 3 batteries of 1.5 volts and worked fine maybe 2 hours 
>what happen ?
>  The problem  is in the quality of the pointer or the is the power 
> suplied to the laser..
>  the other TX is working fine !!!
>there are some problem in the diagram ?
>Thanks
>Al XE2AT
>
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