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E.F. Johnson Courier Amplifier
I picked up this Courier Amplifier for a very reasonable price. I couldnt pass it up. It appears that the plate transformer was shot so it will need to be replaced.
It looks to need a new paint job but that is something that can be done with very little effort. This will be a nice project.
Appears that in an effort to keep the amplifier going a previous owner drilled holes in the back of the amplifier to help it run cooler Im guessing.This will have to be repaired to get it back to square one.
After taking the case off it really surprised me as to how clean it was under the chassis.
Amplifier has gone through the restoration process and is looking good and working quite well again with full designed power output.
Cant believe it! Not a fuse anywhere on this amp. No wonder it blew a plate transformer! Must have been some great fireworks that day.
First thing I did was add a 3 wire power cord and a fuse. It worked out great. I used the hole where the original power cord came out for the fuse holder. Then I drilled new hole further to the left for the new power cord.
There are some massive electrolytics in this amplifier that will get replaced very first thing.
Plate transformer was missing. A replacement came with the amp so I put it in for a short period of time and fired up the amp and found it worked just fine. The transformer was a bit under specs so it wouldn't get full output power as designed. I ordered a new one from Heybour.
The extra holes have been repaired on the back panel and now its looking good once again.
The 572B tubes are replacing the 811's and the rectifier tubes are 3B28's.
A new Heyboer plate transformer is installed and it now provides enough voltage to get full power output
Nice to have this 50 year old amplifier back up and running possibly for another 50 years.
New electrolytics to let that power supply rest easy.
In the inspection process I found a broken coupling switch. I picked up a couple of wafer switches at a hamfest and started swapping parts.
The switch was not making contact on most of the caps, so it obviously wouldn't let the radio work
on a number of bands.
The old broken switch and the replacement I started taking apart.
Here is the rebuilt wafer switch. I put it all back together with parts from the old switch and used very small nuts and bolts to assemble the unit. It works great.
Backside view of the rebuilt switch.