18-03-2019, 09:00 AM
During the JMMFD over the weekend, I encountered an unusual fault : the Icom 7400 went dead when I was transmitting. The AC power supply was still on and producing 13.8V so it was a bit intriguing.
When I moved the DC power lead to the back of the radio, power returned. The fuseholder for the positive supply was quite hot so I opened up the clam-shell holder and discovered that the incoming wires are simply crimped. Using a screwdriver from the actual copper conductor to the fuse end connector returned the DC power.
I took the power lead off, soldered the previously-just-crimped connection and the radio ran faultlessly for the remainder of the event and was producing a higher RF transmit power than earlier. The fuseholder was also quite cool, even with high duty cycle transmit.
If you have the Icom-supplied power leads with the in-line fuseholders shown in the image below, take a few minutes to solder each crimp connection - it might save you a lot of aggravation.
The fuseholders in the 6 pin power lead - the partially-visible clamp-on ferrite is my addition
Solder each end where the crimps are. Red arrows indicate approx positions.
When I moved the DC power lead to the back of the radio, power returned. The fuseholder for the positive supply was quite hot so I opened up the clam-shell holder and discovered that the incoming wires are simply crimped. Using a screwdriver from the actual copper conductor to the fuse end connector returned the DC power.
I took the power lead off, soldered the previously-just-crimped connection and the radio ran faultlessly for the remainder of the event and was producing a higher RF transmit power than earlier. The fuseholder was also quite cool, even with high duty cycle transmit.
If you have the Icom-supplied power leads with the in-line fuseholders shown in the image below, take a few minutes to solder each crimp connection - it might save you a lot of aggravation.
The fuseholders in the 6 pin power lead - the partially-visible clamp-on ferrite is my addition
Solder each end where the crimps are. Red arrows indicate approx positions.
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
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http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.