Apache selenium rectifiers or 6AL5 rectifier

[k3pf]

Thanks Jim WD5JKO for this info ..."An easy fix is to put a silicon diode(s) (such as 1N4007) plate to cathode on the bias rectifier tube. On the 20A they only use 1/2 the tube as a bias rectifier. Maybe the Apache uses both sides".


I think you mean to place the diode's anode to the tube's plate and the diode's cathode to the tube's cathode.  That appears to effectively parallel the 6AL5's function.  Maybe its best for me to remove the 6AL5 completely and use silicon diodes like other Apache owners have done.  It would be an easy thing to do and it certainly should not hurt anything.

Note: The Apache uses both of the tube's rectifiers.

[k3pf]

My friend Larry (K3PEG) pointed out that the 1959 March issue of QST has a writeup about the then new Apache transmitter.  On page 44 there is a picture showing a vacuum tube (presumably a 6AL5) exactly in the same location as my Apache's 6AL5.  The article says that the Apache comes with 2 selenium rectifiers for the -150V supply even though the picture on page 44 shows the tube.  In the picture, the tube is located just above the 5V4 low voltage rectifier.  Its the 2nd tube from the bottom on the left hand side of the picture.

Larry (K3PEG) found the article in the ARRL QST archives.

[Pete, WA2CWA]

Maybe you have the rig from which the picture was taken. You can now add fame and fortune to your Apache.