[Laser] led txr success

[John Randall]

Hi all, Sounds like a good outing and fun. I have just completed a laser 
transceiver, which uses a torch head to house the ldr at its focal point, which 
seems to work well indoors...hi. The led option is new to me and I found this in 
the rs catalogue and would like some comments.
The rs part number is 449-1927.

Hope to get myself testing with someone, if I can find anyone in my area, either 
with laser or led

73
John
Dear all,
Mk2 led transverter has now been field tested at the weekend. The result was a 
full QSO From G8CYW to G8KPD across northern England, a distance of 46km during 
an optical comms night involving five stations at various locations. Signals on 
the transceiver on both SSB and FM were limiting the driver, an FT817. I also 
received a strength 7-8 SSB signal over 66km from a station in north yorkshire 
using the "wrong" kind of led, a batwing emitter with a large radiating area 
which illuminated a 1km dia patch at my end (instead of the 200m we achieve with 
golden dragons leds). The lens used was a 100mm dia magnifying glass in a 
plumbing tube, but I also have an A4 sized Fresnel lens system for when this 
stuff starts getting difficult.


We are going out again soon to have a proper QSO over 65km or so, and try for an 
82km contact, which if made, would I think make a new UK record, certainly for 
leds rather than lasers.


Mk2 consists of a RC coupled version of Clints simplified receiver with no low 
pass filtering, a relay to switch the led from forward bias on transmit to 
reverse bias on receive, with 43V from a stack of keyfob batteries and button 
cells. The led requires some "microsurgery" to remove the wire to the protection 
diode. It makes as good a photo diode as the purpose built SFH2030 we were using 
in a separate rx/tx system.


Regards to all


Stuart G8CYW






______________________________________________________________
Laser mailing list
Home: http://mailman.qth.net/mailman/listinfo/laser
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Laser at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html


________________________________

From: "stuart.wisher at talktalk.net" <stuart.wisher at talktalk.net>
To: laser at mailman.qth.net
Sent: Tue, 2 November, 2010 11:48:01
Subject: [Laser] led txr success