Signal One CX7A
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.
Click on thumbnails below for larger image.
Signal One Page
Created: January 22, 2006. Last
June 15, 2013
� Copyright 2006, PakRatz, Corpus Christi, Texas, USA