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Do we need those inline fuses between our radio and power supply, most if not all radios come with them but are they always needed? There was a time when I thought the more fusing the better and safer, but does it add to the safety or is it just redundant fusing? First off let me begin with, this is my own opinion and I do follow it whether you choose to or not it is absolutely up to you. 

I was having an issue with my Icom 7610 cycling off and then back on again while transmitting . The issue was narrowed down to resistance within the cable from the power supply to the radio. I first replaced the poor terminal connections on my Astron power supply. The issue returned again it was then further determined that the guilty party was the inline fuse/fuse holder connection. I cut out both inline power cable fuses...OMG, you say?
Well, not really if (the big if) you have a power supply with very good built-in protection meaning over-voltage protection (crowbar), over-current protection (fold-back current protection), over-temperature shutdown and an internal AC fuse I believe you are good to go without inline DC fusing between power supply and your rig. Again in the background I hear "OMG, you did what"

I do hear some saying "Wait what if there is an issue in my supply line from the power supply to the rig" This is true BUT keep the power cable as short as possible and if you have worries about overheating cables, moving parts or rodents then you have bigger issues than un-fused power cables. Having said that if something between the power supply to the radio power cable causes a sudden increase in current or voltage the power supply protection will quickly look after that. 

 Some who have a large rig such as the Icom 7610 or other manufacturers could be saying "there is no way this rig will be used as a mobile by the average ham but it has fused leads". My answer to that is the big 5 (Icom, Kenwood, Yaesu, Flex and Elecraft)  have no idea what power supply you are going to use. Also, some may opt to use a deep cycle battery at home on a trickle charge or whatever. 

After everything I have said about fuses I am not against them and as a matter of fact I have a Rigrunner fused rail and use it and I am thankful for it. I connect my external ATU, noise cancelling unit and SWR meter (for the light) to it. 

Now if you have no issue with your supplied power to your radio and things are not acting up like they were with me then by all means keep the fused line but for me, some radical thinking cured the problem and some power supply understanding allows me to sleep at night knowing the radio is in good power supply hands.

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.

Drill bits

 
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.

Finish product