K2/100 into an Ameritron ALS-600 amp.

[Forrest Myers]

Hello All,
 I've been running a K2/100 SN 2827 for a couple of years now. It is a vy FB
rig. I recently purchased a linear amp to get above 100 watts. The K2 does
not have an external connection for ALC and I've been running it with the
external amp through the KPA100 and trusting the K2 ALC to keep control of
the drive power. I don't want to put over about 40 watts into the external
amplifier so have to always remember to cut the K2/100 power back to 40
watts before keying the rig using the external amp. This works fine as long
as I remember to cut back the power.
 Does anyone have any ideas on how to hook an external ALC control to the
K2/100? One way would be to limit the power output of the K2 to 40 watts but
that would require the use of the external amplifier for 40-100 watts. I'd
rather not make a mod that would limit the power of the KPA100.
 Any ideas?

 73,
Forrest Myers
AG4ND


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[Don Nesbitt]

Hello Forrest.  The K2/100 to the ALS-600 is a great combination.  I ran the
ALS-600 with K2/100 for quite a while and then gave up the ALS-600 to my
brother who had been eyeballing it from the time I got it!  It does a great
job for him as well.

I don't have an answer for you re: ALC from the ALS-600 to the K2.  I don't
know an acceptable way to put "external" ALC into the K2 - so I'm no help in
that area.  I always just ran mine by either cranking down the power control
on the K2 or leaving it up and running commensurately higher power out of
the ALS-600.  I might say that the ALS-600 performed very well (ran cool and
didn't "fault") with the higher drive.

However, there is one thing that you might want to look into depending on
the reason you want to limit the drive to 40 watts.  If  your interest in
limiting the drive is because you want to use - or are already using digital
modes with the combination, then what follows will not be of interest.  But,
if your interest in only using 40 watts of drive is related to only having a
limited amount of output from the ALS-600 - AND - you think that you won't
want to exceed that output any time soon, you could continue to leave the K2
power control "up" and reduce the output from the ALS-600 by using a larger
"swamping" resistor in the ALS-600.

Apparently Ameritron has changed the "default" value of the "swamping"
resistor used in the ALS-600 over the years (compare early part lists with
later part lists) - perhaps to compensate for the gain of individual units
or other circuit changes.  I believe the values have been 100, 45, 35 and 25
ohms - or at least values in those ranges.  The resistor is a high wattage
non-inductive type that mounts in a couple of large "fuse clips" and is
located on top of the amplifier board - easily accessible with the top of
the RF unit removed.

Ameritron sells the resistors (as I recall) for about $25 plus shipping and
a call to their factory number will put you in touch with someone (probably
"Willie") who can advise you.  I know all this because mine had the 45 ohm
resistor in it and it was attenuating the drive too much (evidenced by lower
than expected output from the ALS-600).   I replaced it with the 35 ohm
resistor which resulted in much better output.  There is no reason you
couldn't go to a higher value to limit the output if that met your needs.

Usual disclaimers, YMMV, etc, etc.  73 es gud dx  --don n4hh  K2/100 #2028,
KAT100, KX1 #243, etc, etc!

----- Original Message -----
From: "Forrest Myers" <[hidden email]>
Subject: [Elecraft] K2/100 into an Ameritron ALS-600 amp.


<snip>

>The K2 does  not have an external connection for ALC . . .
>I don't want to put over about 40 watts into the external . . .

>  Does anyone have any ideas on how to hook an external ALC control to the
> K2/100?
>  Any ideas?
>
>  73,
> Forrest Myers
> AG4ND


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[Douglas Westover]

I've used this same combination for a little over a year now
and it works beautifully, especially with the Ameritron QSK-5
pin diode T/R switch! I drive the ALS-600 to full output
without throttling back the K2/100 at all with no adverse
effects.

Doug
W6JD

----- Original Message -----
From: "Donald Nesbitt" <[hidden email]>
To: "Forrest Myers" <[hidden email]>; "Elecraft"
<[hidden email]>
Sent: Wednesday, August 04, 2004 6:20 AM
Subject: Re: [Elecraft] K2/100 into an Ameritron ALS-600 amp.


> Hello Forrest.  The K2/100 to the ALS-600 is a great combination.  I ran
the
> ALS-600 with K2/100 for quite a while and then gave up the ALS-600 to my
> brother who had been eyeballing it from the time I got it!  It does a
great
> job for him as well.
>
> I don't have an answer for you re: ALC from the ALS-600 to the K2.  I
don't
> know an acceptable way to put "external" ALC into the K2 - so I'm no help
in
> that area.  I always just ran mine by either cranking down the power
control
> on the K2 or leaving it up and running commensurately higher power out of
> the ALS-600.  I might say that the ALS-600 performed very well (ran cool
and

> didn't "fault") with the higher drive.
>
> >
> >  73,
> > Forrest Myers
> > AG4ND
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
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[Eric Swartz - WA6HHQ]

Hi Forrest,

We do not provide an external ALC input to the K2 or K2/100. To be honest,
using ALC to set your driving power limit to an amplifier, versus setting your
drive power manually, is a bad practice that causes a significant amount of
transmit IMD distortion and splatter. (All external amplifier ALC circuits
have a finite response time that results in leading edge overshoot and short
periods of amplifier overdrive.) In your case, if the driving rig was set to
100W and you relied on ALC feedback from the amplifier to limit it to 40W you
would be causing significant splatter across the band. :-0

Many external amplifier manufacturers (See ETO/Alpha as an example) no longer
recommend its usage.

73, Eric  WA6HHQ
Elecraft
---

Forrest Myers wrote:

> Hello All,
>  I've been running a K2/100 SN 2827 for a couple of years now. It is a vy FB
> rig. I recently purchased a linear amp to get above 100 watts. The K2 does
> not have an external connection for ALC and I've been running it with the
> external amp through the KPA100 and trusting the K2 ALC to keep control of
> the drive power. I don't want to put over about 40 watts into the external
> amplifier so have to always remember to cut the K2/100 power back to 40
> watts before keying the rig using the external amp. This works fine as long
> as I remember to cut back the power.
>  Does anyone have any ideas on how to hook an external ALC control to the
> K2/100? One way would be to limit the power output of the K2 to 40 watts but
> that would require the use of the external amplifier for 40-100 watts. I'd
> rather not make a mod that would limit the power of the KPA100.
>  Any ideas?
>
>  73,
> Forrest Myers
> AG4ND
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
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>
>

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