Questions from a Possible Builder/Owner

[Jim Harris-4]

I've only been licensed about three years but have
been building electronic kits and related hardware
since 1954.  My intent is to build a K2/100 with most
of the bells and whistles but have been unable to find
specific answers to three questions.

1.  How does the K2/100 key an RF amplifier (AL-811)?
I have a Heil footswitch with a second cable for
amplifier keying.  But, would prefer to use keying
from the rig itself.

2.  How is ALC sent from my RF amplifier back to the
K2/100?  I've reviewed the K2/100 manuals and cannot
find how it is done.  Maybe it really isn't needed.

3.  How do I adapt my Heil Headset Pro and Goldline
microphones.  They currently are used with an
IC-746pro by using a Heil adapter cable.  They now go
thru a homebrew switchbox with the adapter cable
between the rig and switchbox.

I cannot see any other major problems.  I've wound
baluns and view winding toroids a bit tedious but
there is nothing like "rolling your own."  My
background includes professional soldering training
and experience.  I have a scope, DVM and other minor
pieces of test equipment. Am I over looking any major
areas that need to be covered before starting?

Thank you for your response.

Jim, AB0UK


               
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[Vic K2VCO]

Jim Harris wrote:

> 1.  How does the K2/100 key an RF amplifier (AL-811)?
> I have a Heil footswitch with a second cable for
> amplifier keying.  But, would prefer to use keying
> from the rig itself.

It has a built-in transistor switch that will switch +200V at 1A.  It goes low
at least 15ms before the RF starts flowing and has an adjustable hold time.

> 2.  How is ALC sent from my RF amplifier back to the
> K2/100?  I've reviewed the K2/100 manuals and cannot
> find how it is done.  Maybe it really isn't needed.

Amplifier ALC isn't supported.  My feeling is that it isn't needed, especially
in view of the K2's closed-loop power control system.

> 3.  How do I adapt my Heil Headset Pro and Goldline
> microphones.  They currently are used with an
> IC-746pro by using a Heil adapter cable.  They now go
> thru a homebrew switchbox with the adapter cable
> between the rig and switchbox.

Sorry, I'm a CW operator!  But lots of guys are using them.

> I cannot see any other major problems.  I've wound
> baluns and view winding toroids a bit tedious but
> there is nothing like "rolling your own."  My
> background includes professional soldering training
> and experience.  I have a scope, DVM and other minor
> pieces of test equipment. Am I over looking any major
> areas that need to be covered before starting?

Nope, just follow the instructions carefully and don't work when you haven't
slept for the past couple of days and you will do fine.  And if you have a
problem, there's plenty of experienced help available.

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco

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[Don Nesbitt]

Hi Jim,

> 1.  How does the K2/100 key an RF amplifier (AL-811)?
> I have a Heil footswitch with a second cable for
> amplifier keying.  But, would prefer to use keying
> from the rig itself.

The KPA100 has a built-in solid state keying circuit for positively keyed
amplifiers (like your AL-811).  There is an RCA jack on the back of the
KPA100 and you simply connect an RCA male cable from it to the Relay jack on
the AL-811.  There is no need for a second cable.

> 2.  How is ALC sent from my RF amplifier back to the
> K2/100?  I've reviewed the K2/100 manuals and cannot
> find how it is done.  Maybe it really isn't needed.

The K2/100 does not have any provision for ALC input from an external
source.  ALC from the AL-811 amplifier back to the K2 is not necessary.
Since ALC from an external amplifier is generated "after the fact" it does
little to control the generation of distortion products that result from the
amplifier being overdrive.  In most amateur amplifiers, in order for an ALC
voltage to be generated , the amp must be overdriven in the first place!
Obviously this is not good!  Of couse, the power control on the K2/100 can
always be set to a level such that various amplifiers are not overdriven.

> 3.  How do I adapt my Heil Headset Pro and Goldline
> microphones.  They currently are used with an
> IC-746pro by using a Heil adapter cable.  They now go
> thru a homebrew switchbox with the adapter cable
> between the rig and switchbox.

The microphone input circuit in the K2 has provisions on a jumper block to
route functions to various pins according to which microphone you wish to
use.  These options are explained and individual choices are made during
construction of the K2.  I am not familier with the requirements of the Heil
Headset Pro and the Goldline microphones but at the worst, you might have to
construct a simple one transistor pre-amplifier to use them with the K2.
I'm sure you will get responses from others who have use these microphones
with their K2's.

Have fun - it's quite the impressive rig!! 73 es gud dxing --don n4hh
K2/100/KAT100 #2028



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