This one had all sorts of bad behaviors, including a rumble on-air.
First stop is a new Fan. These Papst fans are pretty well built, but eventually the bearings wear.
Main filter cap is also long past it’s useful life. The new ones are much smaller and have better temp ratings.
Pass transistor needed replacing. Shorted. Looks like it’s not the first time. Fortunately the final transistor is still good. The 2N6200 is no longer available and the NTE 360 we used as a replacement is also discontinued.
Upper left is an optional output low pass filter, meaning this exciter can be used as a low-power transmitter.
This one still has the adjustment tool! Most have been swiped long ago.
Second problem- the meter movement had fallen apart causing the needle to stick. These have not been available from BE for quite a while..but there is a workable replacement that is reasonably priced. Just swap the meter face with a little trimming.
And here’s the Rumble. The FMO is sitting directly on the metal chassis. It was picking up vibration from the old noisy fan. Some models have rubber isolators for the FMO, others have a foam sheet underneath. Both require you remove the shipping screws before use for best noise. Please put them back before shipping.
This one needed the rubber isolators. BE no longer stocks these either. Fortunately I have some on hand.
They snap in the bottom of the FMO, isolating it from the chassis.
Power supply regulator still has the factory caps. They had failed to the point the regulator no longer functioned.
Same situation with the control board. Failed capacitors.
The AFC/ Frequency control board had the worst of them. Quite a few were bulged and leaking causing damage to the PC board. This took a bit of scrubbing and repair. I will also change all four dip switch packs as they get flaky over time.
Here is one of many capacitors that bulged and vented. Heat and age…
Bolt everything back together and off it goes!
32 watts into the dummy load with 100% modulation applied for 24 hours, a quick check into the Belar test set….. and back to it’s owner.