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[Amps] TS950SD final amp

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Subject: [Amps] TS950SD final amp
From: yo9fzs at (Traian)
Date: Wed Jun 4 09:18:47 2003
Hi all,

I am checking the final power amplifier of a TS950SD (not SDX).
This 950SD is a high serial one (3xxxxxx).

The Kenwood Service Bulletin SB990 specify a 27 ohm value
for the R17 and R18 (finals B to E) resistors, but on the Final Unit
diagram from the transceiver's manual, these are specified for
a 15 ohm value each. Which is the correct value for R17 and R18?

For good stability I used two parallel 33 ohm resistors for each
of the R17 and R18 and have 150W out at full power for a 7 amp
final collector current.

I found that the 14 volt drivers (2SC3133) were biased to 1700 mA
which to me seems way too much (except if they need to work
in A class), and for safety, I already adjusted it to a 200 mA value
(think it shall be further lower).
The 50 volt finals (originals were MRF429 but were replaced
with BLW95) are biased at 200 mA. All these bias currents were
measured at the dedicated TP1 and TP2 test points, so the values
are for the respective pairs of transistors, not for each one.

Any comments about?
Anyone can help me with info about the specified values from
the TS950S Service Manual or from the respective devices
data sheet?

Traian, YO9FZS

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