HW-101 - shorted final amp.

[Kenneth G. Gordon]

I have been working on a couple of HW-101s here recently, repairing, 
aligning, neutralizing, upgrading.

I had just finished aligning one, using the later Heathkit method of 
removing plate and screen voltages from the final amp, hooking up an 
oscilloscope to the RF output jack, and adjusting everything for 
minimum RF output.

I put it all back together, turned it on and promptly 1) blew the PS fuse, 
a 4 amp slowblow, and 2) burned up the 2.2 Ohm @ 2 watts cathode 
resistor.

After much testing and checking, the upshot was that one of the final 
amp 6146As had shorted internally so badly that +HV from the plate 
supply was appearing various places where it wasn't wanted or needed.

I put in two new finals, re-neutralized, and everything seems fine now.

I was quite surprised, having never had a final amp tube do such weird 
things before.

Keeping my fingers crossed.

Ken W7EKB

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