KX3 Juma Linear.

[Dave KD1NA]

Everyone I have a KX3 #700 that is working fine. I am providing you this
information for those that are interested. The linear works fine with the
KX3 on all modes.

I have ordered and built a Juma P100-D linear for use with the K3. With 3
watts drive the linear puts out 100 watts. You can see the linear at
www.jumaradio.com.
Below is an e-mail I sent the engineers at Juma radio with My experiances
in building this linear kit and I wanted to share this with you.

73
Dave KD1NA

( e-mail to JUMA )

Juha and Matti,
Last month I ordered and received one of your PA100-D kits. This e-mail
will convey my experiences and issues in assembling the kit.

First off let me inform you that the PA100-D is fully operational and has
met my total expectations.

I was quite satisfied with the quality of the components and design of the
amplifier. The documentation, though sparse, provided me enough information
needed to get everything together. The pictorial procedure to both winding
the toroidal  coils on the main board and the construction instructions on
the PA board were very good and well documented. The parts lists as well as
the printed circuit board layout documents gave me a good road map to where
everything goes. Your schematic drawings are very good quality and easy to
follow.

I will state that this kit is not for the beginner and in fact it would be
safe to say that over 50% of the hams in the United States would lack the
skills to assemble your kit. Having said that I will say after completing
your PA100-D kit I have a great amount of pride in the fact that I built
this unit and it performs so well.

My surface mount experience is limited and at first I was clearly
struggling to properly getting the components mounted. After completing the
control board ( I chose the most challenging board first ) I started to get
very comfortable working with surface mounted components. It was the small
resistors that was most challenging.

Construction issues:
The PA Board;
The copper wire that was to make the ground connection and also assembling
L3 was missing and in it's place was a small spool of solder.

The brass cores that make up transformer T1 on the PA board were not the
same diameter. One was 0.3 mm too large diameter and wouldn't slip into
it's core. I machined it down to make it fit and it is working fine.

The front panel board's holes that pass the push-button switches were too
small and caused the buttons to bind after mounting the panel on the
control board. I enlarged the holes about 1mm now the buttons pass through
freely.

On the PA board the Z1 and Q4 components were very hard to read the
printing on the components even under very high magnification. We had the
same problem on the Main board with Z1 and TR1. A suggestion is to tape the
component's package to a small piece of paper with it's identification
written on it. On some packages containing multiple devices you often had
labels attached so no problem even though reading the actual component's
number was near imposable.

Another observation is you refer to transistors as Q1 or Q2 on the PA and
control board parts list and schematic, but list them as TR1 and TR2 on the
main board parts list and schematics. I had no problem with this but this
could lead to  less experienced builders.

Overall the kit was fun to build and the end product works quite well. For
your information I am driving the linear with an Elecraft KX3.

I will copy this e-mail to your e-mail forum as well as to the Elecraft
forum for everyone's information. You make a great product.

73
Dave KD1NA
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[Jim Brown-10]

On 8/12/2012 11:32 AM, David Robertson wrote:
> I have ordered and built a Juma P100-D linear for use with the K3. With 3
> watts drive the linear puts out 100 watts. You can see the linear at
> www.jumaradio.com.

The kit LOOKS cute, but I see NO information about performance specs --
nothing about harmonic content, IMD, or sideband noise.  At Euro 460,
it's going to cost about $600 delivered to a US address for a kit with
NO performance specs other than power in/out.  13 dB of power gain is
easy.  Doing it CLEANLY is another matter.

Am I missing something?

73, Jim K9YC
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[k6dgw]

On 8/12/2012 1:28 PM, Jim Brown wrote:

> The kit LOOKS cute, but I see NO information about performance specs --
> nothing about harmonic content, IMD, or sideband noise.  At Euro 460,
> it's going to cost about $600 delivered to a US address for a kit with
> NO performance specs other than power in/out.  13 dB of power gain is
> easy.  Doing it CLEANLY is another matter.
>
> Am I missing something?

I sincerely doubt it.  Nothing about QSK either.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org


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