Off subject

[Gerald C. Lemay]

I'm looking at the T-4XC manual. On page 3-1 and continuing on page 3-5 the
proper tuning procedure is described. Adjust PLATE for plate current dip and
adjust LOAD for maximum power out. Do this alternately until there is no
further increase in power output. It doesn't simply state to adjust both
PLATE and LOAD for maximum power out. Doing so will exceed the plate power
dissipation of the 6JB6A's. Sure it's possible to much more than 120 watts
out but your finals won't last too long at that rate. The plate dissipation
rating of those tubes is only 17.5 watts. I don't know about 6146's but I
suspect they could probably take much more of a beating because they're
transmitting tubes.

-----Original Message-----
From: Heathkit Owners and Collectors List
[mailto:HEATH at LISTSERV.TEMPE.GOV]On Behalf Of Garey Barrell
Sent: Saturday, December 07, 2002 4:17 PM
To: HEATH at LISTSERV.TEMPE.GOV
Subject: Re: Off subject


No-one has mentioned the downside of "lightly loaded" pentode or beam power
stages.

The screen current will increase, even to destruction.

Drake also says to "tune for maximum output", and running at reduced
loading will melt screens in 6JB6's.

The correct way to reduce the power output to increase tube life is to tune
for maximum (or tube specifications if less) and then reduce drive to lower
the output.

73, Garey - K4OAH
Atlanta

At 01:47 PM 12/7/2002, Glen Zook wrote:
>However, the comment that I replied to was that you
>tune ALL of the pre-1975 equipment, not just the
>TS-520, for maximum output which is definitely wrong!
>I did point out that the manuals for some equipment do
>tell you to tune for "maximum smoke", although those
>transmitters are in a very definite minority.

snip >>><<<

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