factory mod issued for the original Omni 6, not the Omni 6+
Remove bottom cover Remove large lower shield covering the circuit boards Locate 81593 BPF/Front End board Refer to diagram and note the two resistors indicated by the arrows. Identify R-14, a 470 ohm resistor immediately adjacent to connector 24. Either tack solder another 470 ohm resistor across it (parallel) or remove it entirely and replace with a 220 ohm resistor. Now - look for the other 470 ohm resistor indicated by the arrow in the diagram, directly to the left of connector 24. There will be three other resistors between it and connector 24. Either remove that resistor and replace with a jumper, or simply tack solder a jumper wire across it to remove it from the circuit. |
One of the most dramatic changes I performed was replacing the three 1N4007 T/R diodes with Microsemi UM-2110 types. These are 1KW F.F. PIN diodes that improved the main-to aux receive antenna isolation to better than 70 dB. Now, an extrmemely strong 40M BC station is barely audible when the aux Rx antenna input is connected to a dummy load. Prior to that, perhaps only 40 dB of isolation was achieved with the stock diodes. With the same 40M BC signal, the S meter would often read S9 or more on the aux RX antenna with the dummy load attached. |
I installed the mod reported by Rick, N9THC, in the mike preamp on my Omni VI. It was very similar to one I had already devised but I decided to install a more "official" change. The mod (change R55 from a 330k to a 470k and R54 from a 47k to a 22k) does increase the gain needed by the Heil cartridges. The approach I used was to just shunt R54 with a 39k and insert a 139k in series with R55. An additional mod I added was to shunt C50 (.1 ufd) with a 10ufd capacitor. My voice is quite low and, by doing this, the preamp accommodates my voice characteristics. |
The stock Omni VI(+) suffers from a very constricted passband in ssb. ARRL measured about 1600hz in their review. After experimenting a bit, I found a way to completely open the passband up to the full width of the xtal filters while providing clear natural sounding audio. I've uploaded info on my DSP bypass mod for the Omni 6 to the Ten-Tec Wiki: http://tentecwiki.org/doku.php?id=563ssbaud |