[Elecraft] [K3] RE: K3 to ALS600 Amplifier

Tue Dec 22 15:12:32 EST 2009

Lu, Thank you for a very complete description of your K3 operation with
ALS600. I am confused about your control of the ALS600 ALC controls on the
back and the front since there is no ALC connection from the K3. What is the
effect of the ALC controls in this case?

From: Lu Romero - W4LT [via Elecraft]
[mailto:ml-node+4204417-69636379 at n2.nabble.com] 
Sent: Tuesday, December 22, 2009 11:31 AM
To: W4GRJ
Subject: Re: K3 to ALS600 Amplifier

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" <[hidden email]
<http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4204417&i=0> > 
Subject: Re: [Elecraft] K3 to ALS600 Amplifier 
To: "Elecraft List" <[hidden email]
<http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4204417&i=1> > 
Message-ID: <[hidden email]
<http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4204417&i=2> > 
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 setting. 

2) To set the power level, simply start with low output from 
the K3 (I'd 
start with 10-20 watts) and bring up the output power of the 
K3 (using the 
Power knob) until you hit the recommended power output of 
the amp. My Ten 
Tec amps all produce full power with less than 50 watts 
drive. 

73, 

Jim K9YC 

______________________________________________________________ 
Elecraft mailing list 
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]
<http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4204417&i=3>  

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

  _____  

View message @
http://n2.nabble.com/K3-to-ALS600-Amplifier-tp4199219p4204417.html 
To unsubscribe from K3 to ALS600 Amplifier, click
< (link removed) 
lbGQub3JnfDQxOTkyMTl8LTE1NTQ0MzE1MTk=>  here. 

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.430 / Virus Database: 270.14.116/2579 - Release Date: 12/22/09
08:09:00

-- 
View this message in context: http://n2.nabble.com/K3-to-ALS600-Amplifier-tp4199219p4205488.html
Sent from the [K3] mailing list archive at Nabble.com.