[amsat-bb] 9600 baud packet

[<alan_bloom@xxxxxxxxxxx>]

I have three questions.  The third might be the most interesting.

1.  What are people using to send/receive 9600 baud packet to the satellites?  I recall from times past that the standard method was to modify a 1200-baud TNC-2 or compatible (MFJ-1270 or whatever) by adding a G3RUH modem.  I know there are programs to do the entire function using a PC with a sound card.  How well do they work?  Do you have to modify the sound card to pass DC (or at least get better low-frequency response)?  Which is the best sound card software for satellite operation?

Or do I need to buy a hardware 9600-baud TNC like the Kantronics KPC-9612?

2.  Do I need to modify the IF of my FT-736 to widen the bandwidth to accomodate 9600 baud with doppler shift?  In my web searches I found a little add-on IF filter/demod board for the '736 to widen the bandwidth for 9600-baud packet: http://symek.com/g/index-g.html (click on "Satellite radio" then scroll down to the "F-ZFD").  The unit is out of production but they give the schematic so I suppose I could build one.  I'd prefer just to buy one if anyone still makes such a device.

3.  I am involved with a quick-turnaround project to take advantage of a possible opportunity to get an experiment into space on the cheap.  We'd have to provide our own telemetry and uplink/downlink radio, most likely on the 70 cm band.  Since we will likely be operating from a non-rechargeable battery, low power consumption is important.  In the interest of fastest possible development I'd prefer to buy as much as possible rather than build.

I found a German company that sells a little 430-440 MHz transceiver with built-in TNC.  http://www.wimo.com/packettrx_e.htm  (model PR-430)  There is no front panel - the user interface is on a PC via an RS-232 cable.  For that reason the unit is small and fairly low power.  TX power is 6W which is a little more than we need.  (2-3W should be about right.)

Is there a better transceiver/TNC choice?  Another alternative would be a stand-alone 9600-baud TNC plus Hamtronics RX/TX boards.  What is a good low-power 9600-baud TNC?

Al N1AL
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