[amsat-bb] Re: Power output for using AO-73 transponder

Wyatt Dirks wyattdirks at msn.com
Sun Dec 8 20:39:40 PST 2013

Well tonight I was trying a few things on ao-73. But mid pass I got bored if you will and I turned around and grabbed my ft817. I had the mic hooked up and had the stock rubber duck installed already. I dialed in the correct uplink frequency and did I quick test call and sure enough I saw a trace on the water fall. I thought I had it set to five watts but after pass looked and I had it set to 2.5w out. So I heard myself through the transponder using 2.5w into the stock rubber duck on ft817. The link below is a short recording of the audio I got. 


Anyway it doesn't take much power to work ao73. 

73 Wyatt

> Date: Sun, 8 Dec 2013 15:13:24 -0500
> From: n8hm at arrl.net
> To: amsat-bb at amsat.org
> Subject: [amsat-bb] Power output for using AO-73 transponder
> FYI - In a sidebar on their website, AMSAT-UK requests that stations limit
> power output to 25W EIRP for using the AO-73's transponder.
> "FUNcube-1 / AO-73
> Radio Communications Subsystem
> • 145.935 MHz BPSK Telemetry 30 or 300 mW
> • Inverting SSB/CW transponder 300 mW PEP
> - 435.150 – 435.130 MHz Uplink LSB
> - 145.950 – 145.970 MHz Downlink USB
> Educational Telemetry beacon is 300 mW during day and 30 mW at night.
> Transponder is only active during night passes.
> Please use a maximium uplink power of 5 watts to a 7 dBi gain antenna (25 w
> EIRP). Lower power will also work well.
> If adjusting for Doppler shift manually try tuning the uplink frequency
> while transmitting to keep the downlink constant."
> http://amsat-uk.org/
> 73,
> Paul Stoetzer, N8HM
> Washington, DC
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