After removing the RF deck (twice - don't ask..) and, other than finding one of the mini-banana connectors on Z221 had let go of its post (again), I didn't find anything of interest so I reattached that mini-banana (using a bit more heat and making sure it was solidly connected), I reassembled the RF deck. After a touch-up on the realignment of Z219, Z220, and Z221, and resetting the RF gain, I can tell the noise level on BCB is down from the way it was. Not dramatic, but I think it's an improvement.
I then started back checking the stage gains and am still seeing low gain at the first mixer for all but the 0.5-1mc band; however, there's a few things about that process I don't understand. The table that defines the gain for Test Point E208 shows the acceptable signal generator voltage range to produce -7v at the DIODE LOAD for 0.5-8mc which makes sense. It also shows the 9-18mc range and that part doesn't make sense to me. In the circuit description for the First Mixer, it states that "In the 8- to 32-mc range, the front section of S210 grounds the output circuit of V203" and that can be seen on the schematic as well. With the output grounded, then how is any output of that part of the circuit realized on those bands? Thanks, Barry - N4BUQ ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
