All Ten Tec Titan series amplifiers DO have an ALC output, adjustable. I
don't own any of the other amps, so can speak about them.
Tom - W4BQF
----- Original Message -----
From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
To: <tentec@contesting.com>
Sent: Thursday, August 19, 2004 5:06 PM
Subject: TT [TenTec] re Ten Tec amps and ALC
> According to this then, Ten Tec ought to include an ALC output (I
> erroneously called it an input earlier, sorry for my haste) with their
amps
> so they may be operated properly with other mfr's exciters. It almost
seems
> as if there is an assumption that you are only going to drive a ten tec
amp
> with a ten tec exciter.
>
> BTW, the amps made by specialty companies (Command for example) include
ALC
> circuits, no doubt so they may be operated with the widest variety of rigs
> possible.
>
> Rob/K5UJ
>
> <<<This has been a very interesting discussion on TT and ALC. A lot
> of good information has been included but the real question
> hasn't been answered clearly.
> TT amps and rigs lack an ALC jack because they don't need
> them.
> To answer why requires a discussion of why ALC and how developed.
> ALC is used to keep from overdriving the amplifier past it's
> linear point. If it is an AB1 amp then when it starts drawing
> grid current it becomes nonlinear and at that point the amplifier
> starts generating a ALC voltage that is fed back to the
> transmitter and tells it to reduce power. If AB2 then some grid
> current is allowed but when that current is reached the amplifier
> then starts to generate the ALC voltage. There are several
> methods to generate the ALC voltage but it doesn't matter how as
> long as it's generated at the correct value in the amplifier. Now
> remember that the amplifier will NEVER be over-driven until this
> point is reached and it's excess power that causes the amplifier
> to go past this point.
> The ALC control on a TT transceiver is really a MAXIMUM power
> control. If set to a setting that allows an output of say 80
> watts at the transceiver then no matter how loud you speak into
> the microphone you will not get more that the 80 watts. This is
> not true with most of the other brands. Take the Kenwood TS-830s,
> they don't have a power control just mic gain. If you talk louder
> you get more output. With a TT and ANY brand of amplifier you can
> advance the ALC control until you get maximum power out of the
> amplifier or you drive it to it's maximum linear grid current
> and back off very slightly (5 watts) and you can never drive the
> linear into non-linear operation. Once you have set the power
> out of the transceiver to the level the amplifier needs then you
> should adjust the mic gain until the ALC LED on the transceiver
> "winks" on modulation peaks and stays lit about 25-40 % of the
> time. However if you watch it on a scope and you advanced the mic
> gain all the way you still will not overdrive the linear
> amplifier though the transceiver may have some distortion.
> From this discussion you can see that a TT transceiver and ANY
> amplifier doesn't need an ALC to prevent overdrive. With other
> brands and models of transceivers and ANY amplifier you MAY well
> need the ALC unless you have a way to set the power out of the
> transceiver. I believe the any of the transceiver manufactures
> that have a linear, design the linear to work properly with their
> equipment. It would be very hard for them to design something
> that will work with 100% of other brands though it may work fine
> with most of them.
> I run an Ameritron AL-80 and a Jupiter. I set the Jupiter to
> about 80 watts for maximum output and never over drive the amp,
> 100 watts drives it into distortion easily. With my TS-830s I
> MUST use the ALC or I will frequently drive it into distortion.
>
> 73 Jim K4CGY
> >>>
>
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