Signal One CX7A
S/N 01872

A ham in California found my website and wanted information on Signal Ones.  He had recently acquired one in an estate sale (I think).  The radio was originally purchased in March, 1970 by W6HEW.  Even thought he collects and restores tube type gear he really didn't have any interest in this one since it is solid state (except for the final).  So, desperately needing another CX7, I bought it from him.   At some point the original owner mounted a round power receptacle on the rear of the unit and even filed on the lip of the case to make it work. :-(( 
It had apparently been in storage for a long time and was very dirty.  After cleaning and numerous repairs this CX7 is almost working.  One problem with oscillation on the 5 volt supply is proving difficult to isolate but seems to be a filtering issue.  Fixing this radio required a lot of transistors including a driver transistor, resistors, feed-thru capacitors, a new power switch, line varistor (replaced with CL-60) and a new meter.  On-air tests revealed distorted transmit audio.  A very poor attempt at repairing a problem on the Audio Board resulted in a damaged trace on feeding Q2C.  The person attempting this repair never found the problem and this was probably one of the reasons this rig was retired.  The tube socket was also not making contact with all the pins on the tube and had to be fixed.  I removed the added power socket and restored the proper AC input circuitry.  At some point in the past there must have been a catastrophic failure in the lower tube assembly.  The repairs that were make were not very well done and the assembly frame had been hack sawed for some unknown reason.  Nothing I can do about that but after cleaning up some bad soldering it works fine.
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Created: January 22, 2006. Last Updated: June 15, 2013
� Copyright 2006, PakRatz, Corpus Christi, Texas, USA