On Wed, 11 Nov 1998 19:32:11 +0200 "Eric" <eric.mawhinney@usa.net>
writes:
>
>Can anyone please give me some advice on the following:
>
>I have a Kenwood TL911 Amplifier which is in good condition except for
>the
>output tubes.
>The tubes are TV sweep types 6JE6C. The ARRL hanbook rates these tubes
>at
>30 watts DC power dissipation at a plate voltage of 500V. The tubes
>are run
>in this "linear" with a plate voltage of 1300V (5 tubes in parallel.)
>and
>the amp's rated input power is allegedly 2.0 KW PEP(user's manual).
>These
>tubes are hard to come by and expensive in relation to the worth of
>the
>amplifier. I have some 6146 tubes which have a recommended maximum
>plate
>voltage of 800V i.e supposedly 300V higher than the 6JE6 and a rated
>DC
>power dissipation of 25 watts. My question is, can I substitute the
>6JE6s
>with the 6146s ?.
> If this is a No No are there any suggestions for an alternative
>substition
>(could be less than 5 tubes). Only looking for about 400W PEP output.
>Supplies available are as follows.
>Plate Voltage: 1300V Plate Current: 1.5A max.
>Screen Voltage: 70V (but could probably squeeze about 170V out of the
>existing supply).
>Bias Voltage: Variable down to -75V
>Heater Voltage 6.3V Heater Current 12.5 Amps.
>
>
>
>Any advice would be appreciated.
>
>Eric
>ZS5EWM
I am not familiar with that amp but you might want to consider similar
tubes with a higher filament voltage as used in series string
TV's....24LQ6, 30KD6, 31JS6, 40KD6, etc.
The European EL-509/EL-519 are also adaptable if you have a bit more
space since they are slightly longer.
Any of the above may be available cheaper in your part of the world or in
EU.
I'm not sure of the reason but the 6146 has not been considered as a
viable alternative...it may have something to do with peak emission
ratings.
Of course you could also adapt to any of the more available transmitting
tetrodes such as the 4CX250 series. Some serious metal work I'm sure but
the PS seems to have plenty of available kVA to supply plate and screen
voltages. Either via a voltage multiplier for the screens or ( Dont
holler too loud Ian!) dropping via the HT line.
Another choice would be 811A or 572B's if you have the room and air is a
problem with ceramic tubes. At least you have the proper filament voltage
.
Just a few ideas.
GL Carl KM1H
>
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>
>
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