RCI Ranger SS 3900EGHP Alignment Question

[KD8HMO]

Im trying to restore an SS 3900eghp that has had tr-32 clipped out and I am trying to set the driver and final bias current settings. Service manual says 20ma for the driver and 160ma total for the dual finals. I am assuming this means 80ma for each final. When I try to set the two final bias pots, I can get each one up to 60ma, then it goes to 0ma then right to about 240 on each VR. Can anyone tell me what this should be set at? and does the missing tr32 affect this? I am going to replace it as soon as I can find one.

thx

 

[Yeti Communications Ltd]

the original rci2950 used the same finals (2sc2312x2 ) and driver (2sc2166) but say 100-120ma

180ma seems really too high generally 50-60ma per device is about right for a 2sc2312 final
assuming it is a bipolar final radio as per the service manual for the 3900

 

[loosecannon]

my guess is that its a typo in the service manual. it happens more than you would think.

try setting each final bias pot to 30mA for a total of 60mA.
the way to do this is to turn them both down, then turn the first one up to 30mA, and then turn the other one up to 60mA.
LC

 

[KD8HMO]

Thanks for the replies. Does 20ma for the driver sound about right? Every radio out there seems to have different specs, even though they use the same transistor.

 

[loosecannon]

depends on the specific circuit its being used it.
start with 20mA, and if you get SSB radio checks that come back as distorted, try going up to 30mA or so.
LC