September last year I had an issue with my Icom 7610, it was shutting down and restarting. The issue was a supply low voltage situation. With the 7610 if the incoming voltage drops below 11.44 volts the radio turns off. This voltage drop happens during transmit (CW in my case) then the radio cycles off, the current draw stops and the voltage goes back up and the radio cycles back on again. This is a normal situation with the 7610 and is supposed to happen with a voltage drop at or below 11.44 volts DC. In my last post when this happened in September 2022 I narrowed it down to the Anderson power pole connectors for more details click the "In my last post link above.
On Wednesday I was taking part in the 1-hour CWops mini contest and out of the blue while transmitting my 7610 cycled off and then on again. I thought "Here we go again". I had a good idea where the problem was and to finish the contest I lowered my power from 100 watts to 50 watts. I have the Astron SS-30M power supply and for some reason beyond me, Astron decided to use screw-down terminals to connect your radio DC cables. It is a small slotted screw and to me just a problem waiting to happen. My old Astron power supply had studs with nuts and made a very solid connection. There is a new version of the Astron SS-30 and it offers Anderson connections on the front. But the screw type connections are still present on the back of the supply.
I decided it was time to do 2 things remove the inline automobile fuse holder and fuse on both the DC positive and negative radio cables supplied by Icom. It has been documented many times how these fuse holders have caused issues with voltage drop due to a poor connection over time. The other thing was a bit more ambitious which was to remove the screw-down positive and negative terminals on the Astron power supply. They were to be replaced with studs and nuts for a solid connection.
Old screw terminals
The Astron power supply is out of warranty as for sure doing this mod would certainly void the warranty. So lets get started....The screws fastening on the cover of the power supply are Torx-type screws and you will need the proper tool to get the cover off. Once the cover was off I removed the positive and negative cables from the back of the screw-type connectors. These 2 connectors were removed from the power supply and put in their proper place.....the garbage!
Out to the trash!
Two holes now had to be drilled in the case for the new studs and this is where success and disaster are a very fine line from one another. I placed tape on the inside and outside of the case as fewer filings from the drilling make their way into the power supply case. I also placed some protection on the inside of the power supply to also catch filings. I then marked off the holes and I used 3 drill bits to slowly move the hole up to the 3/8 size I was looking for. A word about the drill bits, I put a large amount of tape around the bit where I wanted it to stop once the hole was completed. No matter how good you are once that drill bit makes it way through the metal case it is going to want to keep going. You have a lot of pressure on that drill and well no one's reflexes are that good. I use the tape as a drill stop and it worked just fine as no damage was done to the parts in the power supply.
I used fibre inserts in the holes to insulate the studs from the case. These came from my other 20 amp Astron supply which are now on order from Astron. Then with the studs temporarily installed (no wires attached), I did a continuity check to ground and all was good, now the negative stud eventually does connect to ground and really does not matter but for poops and giggles I did it anyway.
I now connected the internal positive and negative wires to the studs and secured them. I then did the smoke test by turning on the power supply................all went well or this would be a much different blog post! I then tested the voltage at the Astron power supply new stud terminals and it was 13.86 VDC, then the cover when back on. I then added ring terminals to the Icom power cables (less the inline fuses and more on that in another post)
|Marked and ready to go
When I powered the Icom radio up and looked at the onboard voltage meter was reading 13.6 volts DC and during transmit using an FT8 carrier (into a dummy load) the voltage only dropped to 13.12 volts DC which is a great improvement.