This is the exact combination I use. I also have the
MFJ-998 High Power autotuner for a rather simple push
button station, albeit with less automatics than with my
Kenwood rigs. It works just as well as my friend's Icom
7800/PW1 station, which is where my inspiration came from
:)
First, I agree with Jim concerning ALC. I have never used
this connection with my ALS-600 (the version 2 kind) and any
rig. I set the rear apron ALC pot to 50 % and with around
95 watts out from the K3 on 80m, with the front ALC pot set
to 50%, I see the red ALC LED flicker every once in a while
on peaks, especially during contest times when I run more
dense modulation.
DO NOT put more than 100w into the ALS600 input for any
apreciable length of time unless you want to constantly
replace the swamping resistor! You *will* fry it, even with
the fast fan mod!
Its a very simple hookup.
Wire RCA cables thusly: K3 PTT out to, in my case, a
Ameritron ARB704 key in (You dont *need* this box at all,
but I owned it, and it has a nice big red light on it, and I
have two rigs on my bench with two of these boxes in line,
it they are to the left and right of my wattmeter and tell
me which rig is keyed at a glance, so I use it!) then from
the ARB key out to the 998's tuner enable then from the
tuner key out to the ALS600 key in. Press on the
footswitch, the red light goes on the K3 panel, the ARB704
and the ALS600.
My Kenwoods have an interface to the Autotuner that forced a
low power tune cycle from the front panel of the rig. The
K3 doesnt have this feature, but I can get close to this
with the K3/MFJ998/ALS600 combination.
The ALS600 hates SWR above 2.0. I set the SWR bypass
limiter on the MFJ998 to 1.9. If the SWR is above 1.9, the
amp automatically bypasses driven by the tuner circuitry.
If the tuner doesn not notice (sometimes it forgets), the
amp will auto bypass on its own at 2.0.
But, if I attempt to tune my antennas with the ALS600 being
driven at full power, the tuner gives up and sends QRP! I
dont want to bypass the amp all the time to tune, so to get
around this, I use this proceedure:
Bypass the K3 Internal tuner
Set Tune Power out to exactly 10 watts globally on the K3
Set the MFJ998 to Sticky Tune
Set the MFJ998 to autotune when SWR exceeds 1.5
Then, to emulate my Kenwood radio's tune cycle I do this:
Memorize your antenna system into the tuner by starting a
manual tune cycle every 10kHz across all the bands you
operate by pressing and holding the Transmit button on the
K3 then hitting the Tune button on the MFJ998. This sets
the tuner's memories up for all the bands you plan on using
with all the antennas you use for those particular bands.
Dont worry, there is LOTS of memory space in the 998!
In normal QRO operation, I do this:
Go to a band, switching the K3 bandswitch then switching the
ALS600 bandswitch (soon to be replaced by auto band
switching from the K3 BCD outputs), then press and hold the
Transmit (tune) button on the K3. This outputs a 10w
carrier from the radio to the amp, which then outputs
aproximately 40-50 watts to the tuner, which then looks up
the frequency you are transmitting on in its memory and
snaps the L/C combinations in line with your feedline in
less than a second. Release tune by pressing and holding
the Transmit button again.
Youre all set to go!
I have found that, with my Version 2 ALS600, I can get
full 500w cw - 600w PEP output with no more than 75-80w from
the K3 (95w on 80m, where the ALS600 is traditionally soft).
On RTTY, keeping the K3 around 70w and switching the ALS600
into RTTY mode gives me a cool 300w out and the amp never
trips off for overtemp.
I may develop a more elegant autotuner interface to the
ALS600 using ideas and a couple of resistors plus a small
reed relay from information gathered in the Kenwood AT300
manual... But I bet Phil AD5X beats me to this (I have his
ALS600 QSK relay mod installed and it is WONDERFUL!)
Regards
Lu - W4LT
Message: 6
Date: Mon, 21 Dec 2009 10:02:31 -0800
From: Jim Brown j...@audiosystemsgroup.com
Subject: Re: [Elecraft] K3 to ALS600 Amplifier
To: Elecraft List elecraft@mailman.qth.net
Message-ID: 20091221180232.15b6658...@gw1.nlenet.net
Content-Type: text/plain; charset=us-ascii
On Mon, 21 Dec 2009 08:20:32 -0800 (PST), w4grj wrote:
I am hooking up my new K3 to a ALS600 and would appreciate
comments from
anyone with this combo concerning connecting without ALC
control and any
relay delay settings in the K3
In general, ALC should NEVER be used to set drive level --
doing so will
generally cause MASSIVE splatter and clicks. I have no
experience with the
ALS600, but I've used my K2/100, K3/100, TS850, and Omni V
to drive Ten Tec
Titans (tubes), Herc I (solid state), and Herc II (solid
state) power amps.
1) There IS a delay built into the K3's circuitry that keys
the power amp.
The delay is adjustable, and the defalut settings work very
well with most
amps. You can easily change the delay with a menu
