Merry Christmas and Happy New Year: On 160 m. (probably due to the close proximity to my inverted L) my NCC-1 rx antenna phasing box would snap crackle and pop on transmit, most likely the result of RF getting into the nine relay coils inside. If you employ phased rx antennas and a tx antenna, all in a small space, running over 1 KW you may have noticed this also. The stock box has some small bypass caps on the DC supply line in, and the T/R control line in, but they were not enough to keep RF out entirely. The fix for me was a small 100 micro-Henry choke inside the box in series with the floating center of the T/R line, along with a 0.015 mfd cap on the cold side of the choke to ground, and a pair of the same chokes in series with the DC +,- supply line into the box at its entrance. The DC supply jack has an adequate amount of stock bypass capacitance so I didn't add any more. 0.1 mfd if I remember correctly. These fixes quieted the NCC-1 down for me and were a lot easier than trying to bypass each relay coil to ground with capacitors.
73 Rob K5UJ _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector