[Kenwood] Power level control on TS-430S

[Ziv Amit]

Hi Rob

Here is the answer to your problem... (took from www.mods.dk)

This modification allows the squelch control to vary the power of the
TS430s from a couple of watts to full power. The squelch control still
operates on FM mode but is disabled on SSB. [ not very useful anyway.] 

Remove top cover of transceiver. The main board on show is the IF unit.
Locate socket 26, with front of set towards you socket 26 is to the left
of the board about midway back to front.
Cut the wire to pin 6 leaving about 3cms wire on the plug. This wire is
usually brown. The wire tail from the plug has to be connected to
ground, This enables SSB receive, pin 4 is ground and can be used.
The brown lead you have just cut comes from the small PCB behind the
squelch control. It runs to pin 6, socket 6 on this board. It is the end
pin to your right looking from the front of the set. Pull this brown
wire free of the harness so that you have a free lead from the plug. 

Locate R211, a 1K resistor which connects the source of Q41 to ground.
>From the front of set.. right hand side, towards the front of the board.
Cut the ground side of R211 leaving sufficient lead to solder to.
The ground side should be the top end of the resistor, but check. Take
the brown lead from the squelch board, suitably shortened, to the
resistor. The squelch control , SSB section, is now in series with R211
and gives excellent control over the RF output level. Replace cover. Job
done. 

In use, Maximum power is with the control fully anticlockwise.
With the squelch pot set anticlockwise and the set in CW mode, Transmit
a carrier [ you will need to short the key jack] and set the carrier
control for full power. You can then vary power on all modes using the
squelch control.
Check the carrier control setting required for different bands, it will
probably vary slightly between 160 and 10 metres. The protection
circuits will still operate as before but if running low power the set
will tolerate poor aerial matching without using the protection
circuits. 



Ziv - 4Z4OQ
-----Original Message-----
From: kenwood-bounces at mailman.qth.net
[mailto:kenwood-bounces at mailman.qth.net] On Behalf Of Rob Stampfli
Sent: Saturday, August 29, 2009 9:02 AM
To: Kenwood List
Subject: [Kenwood] Power level control on TS-430S

I have a TS-430S that I'm trying to use as an exciter for a linear
amplifier.  The 430 is a delightful little transceiver, but it lacks
a power level control on SSB -- it only has a mike gain adjustment,
which by itself does a poor job of throttling PEP output levels.
I don't want to be constrained to running the amp full bore all the
time, however.

At first, I thought I could use the amp's ALC to control the 430.
After fabricating a harness and connecting it, I found it works
well for dialing the power down on CW, but I am still seeing near
full PEP out of the amp in voice peaks, even with the amp's ALC SET
turned to it's most sensitive setting.  I believe this is because
the 430 is not responding fast enough to the ALC the amp is sending
it.  Thus, even though increasing the amp's ALC sensitivity causes
the 430 to throttle back and reduces average talk power, it still
allows near full power momentarily during the onset of the voice
peaks.  (Interestingly, though, people still claim the audio sounds
good.)

As a test, I wired a 9V battery across a pot allowing me to feed
a fixed ALC voltage into the 430.  The front panel meter shows the
430's ALC was responding to the battery voltage, and the constant
ALC seemed to help reduce the voice peaks on normal spoken voice,
but sounds with sharp attacks, such as when I'd click my tongue
into the mike, still produced near 100W peaks even with the ALC
dialed to full scale.

I've run out of ideas.  Short of building a high-power T-network
to put between the 430 and the amp, can anyone suggest anything
else to try?

Thanks in advance,
Rob
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