if you do the coax mod to your sbm1, and want to put the 7pin dongle to good use, here is how
first get a rca mono splitter from ratshack
drill out the rivet in the center and open the sucker up
unsolder the rca terminals and toss the other crap inside
assuming youve already cut the dongle off.. seperate the wires. there are 2 grey wires inside that are for the transmit and recieve. each has a ground in it also. in our case here, the red will be the transmit.. (digi out) and brown will be the digi in. connect the 2 grounds from each of the grey wire together.
solder the red and brown to each of the rca terminals. a little tape will hold things together for now. the 2 connected ground wires will simply be soldered to the casing. i found it easier to run the ground thru the hole, so it can be better secured with the bolt and nut when assemble the case back. the solder doesnt seem to stick to the case very well.
bolt the sucker together, ull see the end of the ground wire popping out on the edge of the bolt.. a little drop of solder there doesnt hurt either.
label the in/out
and walla! your done!
*important*: one thing i didnt show is that you also need to connect the yellow wire in that cable to the braided sheilding in the cable. if you dont the digi input wont work.
its always good to do a continuity test with a multi-meter to check to make sure your in/out and going to the right pins and isnt shorted to another pin or somehting etc etc.