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K2 - REMOTE KPA100/KAT100

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CJA

K2 - REMOTE KPA100/KAT100

K2 6442 is working fine and I was able to make a number of contact on Field Day using an antenna hung from a crane at 103 feet. However, success at home has been frustrating as I am in a hole, in a valley, at the low end of the sun cycle, in a community that does not allow antennas. Currently, I am using a High Sierra screwdriver with tuned radials that I have to set up and break down every time I use it. 15 Watts max has not resulted in very many stations hearing me.

To make up for all of the above shortcomings, I am looking into ordering the KPA100 and KAT100 and mounting them together in the Elecraft enclosure. However, I am a little leery. This is an after market modification and will not include the awesome assembly manual that allowed a neophyte like me to successfully build a K2.

I would like to hear from anyone who has built a Remote KPA/KAT100. Any comments are welcome. However, I am most interested in the following:

1. Who has the best, most complete instructions on how to successfully build this mod? So far I have only found one source on the net.
2. What are the pitfalls that an inexperienced builder should be watchful for?
3. Any other comments welcome.

Thanks.

Chris
K7CJA
K2 #6442

73,

K7CJA

Don Wilhelm-4

Re: K2 - REMOTE KPA100/KAT100

Chris,
Installing the KPA100 and KAT100 together in an EC2 enclosure is really
easy. Order the KAT100-2 and you will have all the components needed to
connect the KPA100 into the KAT100 board. You will need a cable to
connect from the KIO2 to the KPA100 (or the KAT100) DE9 AUX I/O
connections - the materials needed are provided with the KAT100 kit. In
addition, you will need a short piece of coax with BNCs to connect from
the K2 antenna output to the KAT100 AUX RF input. Another short piece
of coax with PL259s is needed to connect from the KPA100 RF output to
the KAT100 ANT IN. If you already have the KAT2 installed in your K2,
it can stay - when the K2 determines the KPA100 is connected it bypasses
the KAT2 and provides RF on the KAT2 ANT1 connector.

This is not a kludge at all - it goes together nicely and is almost
'plug and play'. If you do not have the KIO2 in your K2, add it,
although there are a few solutions that substitute for the KIO2. You
will not be able to use the computer connection capability of the KPA100
when it is mounted remotely, so if you want computer control, you must
have the real KIO2.

73,
Don W3FPR

MTcja wrote:

> K2 6442 is working fine and I was able to make a number of contact on Field
> Day using an antenna hung from a crane at 103 feet. However, success at
> home has been frustrating as I am in a hole, in a valley, at the low end of
> the sun cycle, in a community that does not allow antennas. Currently, I am
> using a High Sierra screwdriver with tuned radials that I have to set up and
> break down every time I use it. 15 Watts max has not resulted in very many
> stations hearing me.
>
> To make up for all of the above shortcomings, I am looking into ordering the
> KPA100 and KAT100 and mounting them together in the Elecraft enclosure.
> However, I am a little leery. This is an after market modification and will
> not include the awesome assembly manual that allowed a neophyte like me to
> successfully build a K2.
>
> I would like to hear from anyone who has built a Remote KPA/KAT100. Any
> comments are welcome. However, I am most interested in the following:
>
> 1. Who has the best, most complete instructions on how to successfully
> build this mod? So far I have only found one source on the net.
> 2. What are the pitfalls that an inexperienced builder should be watchful
> for?
> 3. Any other comments welcome.
>
> Thanks.
>
> Chris
> K7CJA
> K2 #6442
>
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Jim Wiley-2

Re: K2 - REMOTE KPA100/KAT100

Chris -

I built up the KPA-100 / KAT-100 combo earlier this year. I second
Don's comments, and have a few more:

Build and test the KAT-100 first. Get the KAT-100-2 version which has
the larger enclosure.

If you are installing the KAT-100 and the KPA-100 in a separate
enclosure, and will always have them assembled this way, then there are
a few things that can be omitted when building the KPA-100.
Specifically, the internal RF cable that goes from the KPA-100 board to
the K2 main board. This function will be provided by the BNC-BNC cable
mentioned below.

The multi-colored control cable will reach between the proper connectors
in the amp and tuner without modification. Same for all other
interconnects.

I also skipped the steps involving mounting of the speaker on the
KPA-100. Since I was going to leave the K2 pretty much "stock", I chose
to leave the K2 speaker in place. As in the RF cable (above), this
means that the cables and connectors intended to bring speaker audio to
the KPA-100 mounted speaker are unnecessary, and may be omitted. You
end up with a "spare" speaker this way, which may be useful for some
other project. Same for installing the magnetic shield on the speaker.

I covered the hole (in the KPA-100 heatsink) that would have existed
because of the not-used speaker with some scrap plastic, painted flat
black. Glued it in place with RTV cement (bathroom sealer).

Do take Don's advice and get the KIO2 module.

Remember that the antenna switch and power level indicators on the
KAT-100 will not operate properly unless the high-power 12-volt source
for the KPA-100 / KAT-100-2 is on before the K2 is powered up. I think
you can do them simultaneously, but have not tried this.

I decided, after reading about the use of transistor thermal pads and
the need for re-tightening the mounting screws periodically, that I
would try the use of semiconductor thermal grease instead. This is a
white compound commonly sold as "heat sink compound", and is available
from Mouser electronics, among other vendors. I think it is a mix of
silicon grease and zinc-oxide. It might even be available from Radio
Shack. Hopefully, this compound, while somewhat messy to apply, will
make re-tightening the screws unnecessary. If you decide to use it,
remember a little goes a long way, and be sure the counting surface of
the transistor is evenly and completely covered with a _thin_ layer.
Any excess will squeeze out of the way when the mounting screws are
properly torqued. I have used this stuff for years and years, and never
had a failure attributable to lack of thermal contact between the active
device and whatever heat-sink was being used.

Good luck with your upgrade!

- Jim, KL7CC

Don Wilhelm wrote:

> Chris,
> Installing the KPA100 and KAT100 together in an EC2 enclosure is
> really easy. Order the KAT100-2 and you will have all the components
> needed to connect the KPA100 into the KAT100 board. You will need a
> cable to connect from the KIO2 to the KPA100 (or the KAT100) DE9 AUX
> I/O connections - the materials needed are provided with the KAT100
> kit. In addition, you will need a short piece of coax with BNCs to
> connect from the K2 antenna output to the KAT100 AUX RF input.
> Another short piece of coax with PL259s is needed to connect from the
> KPA100 RF output to the KAT100 ANT IN. If you already have the KAT2
> installed in your K2, it can stay - when the K2 determines the KPA100
> is connected it bypasses the KAT2 and provides RF on the KAT2 ANT1
> connector.
>

Jim Wiley-2

Re: K2 - REMOTE KPA100/KAT100

In reply to this post by Don Wilhelm-4

Chris -

I also remember something about increasing the current carrying
capabilities of the RFC on the KIO2 board. I think the recommendation
was to build a new choke from several turns of #24 or #26 wire threaded
through a spare toroid core. You will probably have one laying around
after building your K2. Or if not, then you can get one easily enough
from Elecraft. I ended up using a FT-43 core, if I remember correctly.
This is detailed in one of the modification guides available on line.

- Jim, KL7CC

>
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Don Wilhelm-4

Re: K2 - REMOTE KPA100/KAT100

In reply to this post by Jim Wiley-2

Jim,

The short RF Input coax on the KPA100 is still needed, it plugs into the
KAT100 board to receive the input RF that is attached to the KAT100 Aux
RF input. The BNC to BNC cable is entirely on the outside and connects
to the KAT100, not the KPA100. The KAT100 Aux RF input is only used for
this purpose.

The speaker cable is not needed because there is no place to plug it.

73,
Don W3FPR

Jim Wiley wrote:

>
> Chris -
>
>
> I built up the KPA-100 / KAT-100 combo earlier this year. I second
> Don's comments, and have a few more:
>
> Build and test the KAT-100 first. Get the KAT-100-2 version which has
> the larger enclosure.
>
> If you are installing the KAT-100 and the KPA-100 in a separate
> enclosure, and will always have them assembled this way, then there
> are a few things that can be omitted when building the KPA-100.
> Specifically, the internal RF cable that goes from the KPA-100 board
> to the K2 main board. This function will be provided by the BNC-BNC
> cable mentioned below.
>
>