Thanks for the fast reply, Eric. I also spent the past hour or so downloading and reviewing various LBIs, only to reach your same conclusion. Google and Yahoo only yielded a few classified listings of boards for sale, and one 9-land ham has a few pics of one in his 6m conversion project.
Probing around with the COM120B, a scope probe, and the remaining LBIs, it looks like it takes the post-pl filter de-emphasized audio just before the speaker amplifier, then squelch-gates it, and provides it at a proper level to drive a 600 ohm circuit, or something close, as used in remote voting receiver apps. I noticed it provided a nice receive audio source for an external controller at pin P931-15 (Audio To Line), but I would like to really see what exactly is taking place before I commit to using it. Currently, for my conversions, I have been taking rx audio from the IFAS board pin 16, which is downstream from the vol/sq high side, after it has been thru the volume control (in the case of the station units, a fixed pot on the main board, then thru the pl filter/high pass/de-emph filter. It provides a nice quality filtered and de-emph'ed rx audio source, although it is not squelch gated. Not an issue with most controllers, however. In fact, preferred when "COR or PL" mode is used. I simply solder a jumper on the A901 System Board from IFAS pin 16 (RX PA) to point H59, which is hardwired to SPARE J932-5, providing a rf feedthrough out of the rf deck alongside the rest of the needed external controller signals (ptt, tx audio, cos, pl detect, etc..). I simply set the fixed volume pot on the system board so as to obtain 1v pp (.353v rms) at J932-5. Then, if someone wants to vary the volume at the monitor speaker, simply use the low-mid-high and rec1-off-rec2 switches on the control shelf, rather than touching the pot on the system board inside the rf deck tray. Eric KE2D --- In [email protected], "Eric Lemmon" <wb6...@...> wrote: > > Eric, > > My GE microfiche reveals that LBI-4831, -30951, and -30965 contain > information about the 19C320671G2 module. Alas, none of these LBIs is on > the RBTIP GE listing. If you are unable to find any of the stated LBIs, I > may be able to extract a (barely-readable) schematic directly from the > microfiche. It won't be pretty, but it may meet your needs. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of kk2ed > Sent: Thursday, December 17, 2009 6:41 PM > To: [email protected] > Subject: [Repeater-Builder] Mastr2 19C320671G2 Intercom board info? > > > > Can anyone point me to an LBI for the following GE MastrII board? > 19C320671G2 Intercom module > > I would like to review a schematic of this board and see how I can utilize > it to source filtered/de-emphasized receive audio. > > Thanks > Eric > KE2D >
