I think I would try the easy fix first.  Replace the driver first.  My guess 
is that the 6146 tubes are tired.  By the way, I really like the 102.  I 
used to own one, should have kept it.

Chuck wa8vmo

--------------------------------------------------
From: "Pat Byrne" <[log in to unmask]>
Sent: Saturday, April 11, 2015 10:15 AM
To: <[log in to unmask]>
Subject: Re: Failing tube symtom

> The short answer is yes!  Tubes can fail over time or they can fail
> in a heartbeat.  Your finals dropping current after they are tuned
> could be a symptom of tired tubes - or is there perhaps a tube driver
> (12BY7) or the like?  It too could be dropping in emission resulting
> in lowered drive to the finals.   I suppose a quick check would be to
> put in your backup set of 6146s and see if you see the same
> symptoms.  And if you have a spare driver, try the same.
> Good luck.
> Pat, K9JAUAt 07:46 AM 4/11/2015, you wrote:
>>Hi all:=20
>>
>>What are the clear symptoms of failing tubes?=20
>>Is 1 of them when you have your plate and load adjusted for initial max =
>>output and each time after that, the output gets less and less?=20
>>Will a tube just go like a light bulb, 1 minute you got full output then =
>>boom, no output?=20
>>I'm thinking once again about my fuse blowing issue and according to =
>>NC4L, the 102 guy in FLA,=20
>>this is a sign of failing tubes because of miss tuning or too long key =
>>down in the tune up cycles.=20
>>He calls it thermal run away and it contaminates the screens and deforms =
>>them.=20
>>The only way to fix this is with a new set of tubes, which I have.=20
>>Well not brand new but a good set of backups.=20
>>
>>73:=20
>>Michael DE VO1AX=20