Hi members;
After putting some new 3-500Z tubes I could only obtain a very small bias
current of approximatly 60mA !!
Nothing is getting hot after power on for long time and running at "standby
position" hi.
the anode voltage measuring instrument on the front reads 2200 VDC and with key
down withou drive power it drops to 1150VDC with poor bias current of 60mA ??
The bias current should be 200mA by no anode voltage drop !!
Could it possible that the 1200VAC transformator has loose his life,without
obtaining any failure after 25 years of age on this unit ?
Or do I must search for bad rectifier capacitors ???
Same I have with the frontswitch (other HT power supply tap) in the SSB setup !!
Or do I have some of the series rectifier diodes witch are are gone in the
rectifier brigde ?
Do you have any suggestions who put me in the good direction in first instance ?
I do not have really a good fysic charge to put after the rectifier brigde to
see if the supply can deliver this power of 220VDC at 650mA plate values
I wish to be sure before changing capcitors due newer ones.
Are there any measurment suggestions witch I can do at this level without any
kind of resistance charge (witch I do not have for this HT purpose)
Behind that are all other supplys and electronic in good condition and work
well,I presume.
Pretty dangerous also and to be carefull at this stage !!
Regards Jean ON4AEF.
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