Well, here I am again :-)
This time I am working on a Yaesu FL-2100Z linear amplifier. I am currently working on it so this post, I hope, will be more interactive than my first one.
I got the unit in a pretty sad condition (yes, it seems all units I get lately are that way!). Price was right, though, so I ended buying it.
Here you have some pictures of the unit so you can see the condition.
Trust me, it looks better in the pictures than in the real world... cabinet has several dents as it has in the front panel top (not seen in these upside down pictures)
Well, let's see the inner top side in detail:
Besides the dirt, it can be seen tubes are Cetron and, probably, original ones. I got a set of chinese National tubes... they were dirty so they had been inside the unit for some time. Why were they removed?... I found it easily, as the top cap snapped in one of the tubes (it seemed burnt!) just when carefully cleaning it and in the other tube, it was loose...
I tried to resolder it but it seems they use some special soldering alloy... I guess it has perhaps some silver. Does anybody know what they use?
Well, let's see the lower side of the unit. I found several things which needed some care. First, there is a relay which is used to modify tube polarization when it is or not transmitting and it was flooded with oil. Not a good thing!
As I had some spares for my FT-102, I decided to replace it:
Once the relay was replaced, I checked one of the problems I knew in advance the unit had: it didn't read SWR... do you guess why?. Check pictures...
I got all the faulty items, from completely dark resistors to dead 1SS97 diodes. I also cleaned the PCB and finally got this:
So I need to replace all the parts and, specially, 1SS97 diodes. I have thought on using 1N5711 Schottky diodes. Any opinion regarding this?
See you on Part II !
73 JOSE EB5AGV