[Elecraft] KPA100 advice

[John Buck]

I do believe that Don's rationale quoted below is well considered.

I did it without first installing the KPA100 in the K2.  Absolutely no 
problems.
There were not any strange problems with putting it in the separate 
enclosure.  There may be advantages to using the external amp box to 
reduce heating and vfo drift in the K2.

I used the factory KIO2 I/O module in the K2 and added the non inductive 
termination resistor suggested to reduce the potential for instability 
if longer line between the K2 and the KPA box is used.  I do not 
recommend trying to avoid using the standard KIO2 for the interface.

The only real merit I can see to putting it in the K2 first is that you 
would know you can use it there if you ever want to.  I do not think 
that is worth the risk to a successful K2 with KIO2, battery and tuner 
installed.  Your mileage may vary. HI

The only special connection is the DB connector cable for amplifier to 
K2 to computer.
I wired the spare BNC on the Amp module for the amplifier input from the 
K2 so I just have a double ended  BNC jumper cable from the K2 to the 
Amp.   Then there is a short PL259 jumper from the amp output to the 
tuner input.

I also modified the KPA 100 speaker connection so that I can plug audio 
into the speaker connector to drive that speaker.  There is a location 
where simply jumpering 2 adjacent traces shorts out the speaker 
disconnect switch.  This is of course optional and should not be done if 
you intend to put the amp in the K2.

I have to admit that if I were not a fan of having the separate portable 
10 watt K2 with battery and built in tuner, then using the KPA100 in the 
K2 box with the smaller external tuner box does make sense.

Aloha,
John KH7T

> I am just at the end stages of KPA100 build.  I intend to mount in an 
> accessory cabinet along with the antenna tuner.  This is not exactly 
> addressed by instructions by Elecraft but is covered on a web page 
> that I have downloaded.
>
> My question is whether I should mount the KPA100 in the K2 first, then 
> transfer after testing?  Or would this be waste of time?
>
> Thanks,
> John AB8WH
>
> John,
>
> Two reasons for mounting it on the K2 first:
> 1) You will be following the instructions as written in the manual - it is just easier that way rather than trying to interpret the effects of working
> two sets of instructions at once.
> 2) When you have finished the testing, you will know that the KPA100 functions properly when connected directly to the K2, so if you have problems when it is moved to the external enclosure, you will know that the KPA100 is likely not the cause of the probelm.
> As an added third reason - the mounting of the KPA100 in an external enclosure is not directly supported by Elecraft (they do not discourage it either).
>
> If you feel confident that you can analyze and troubleshoot whatever strange problems may arise by mounting it in the external enclosure, then by all means do it that way - but then if you had that kind of confidence, you likely would not have had to ask the question.
>
> Step by step, one step at a time, is usually the best way to reach the
> goal - leaps and bounds can cause you to falter and fall.
>
> 73,
> Don W3FPR