[Elecraft] Re: New K3 Power output problem (Wrong trans. on KXV3)

[Eric Swartz WA6HHQ - Elecraft]

Hi Barry,

I apologize for the power control problem. We just confirmed Friday 
(yesterday) that a small number of our K3 KXV3 modules (less than 20) 
shipped between July 30 and August 5 may have an incorrect part 
installed. The problem modules will only be found in K3 kits. Factory 
assembled K3’s are not effected by this issue.

The resulting symptom is that the K3 will output much more RF power than 
the PWR control is set for. This most likely will be noticed when doing 
the 50 watt TX gain cal procedure. Instead of putting out 50 watts, the 
actual output will be around 70 watts on all bands. KXV3s with correct 
transistors will not exhibit this symptom.

To confirm if you have a KXV3 that is effected by this, the KXV3 (two 
board set) will need to be removed from the K3. (This is very easy - See 
instructions at the end of this email.)

The part in question is mounted on the PC board that does not have the 
BNC connectors. *If this board has a small sticker with the number 
“14704” and Q1 on the same board has '7AW' marked on it, you will need 
to exchange the KXV3 module for a replacement.*

Since some boards with 14704 number have been reworked and not marked, 
the best way to tell is to inspect Q1 and see if it is marked '7AW'. See 
picture below.

*Incorrect Transistor at Q1*

http://www.elecraft.com/K3/pics/Q1%20incorrect%20part.jpg

If your board has the incorrect part 'marked '7AW' please notify* * 
*parts at elecraft.com* or call 831 662 8345 and we will immediately 
replace your KXV3. /(Barry - I have already entered a KXV3 request into 
our parts request database - Eric.)/

Please also note that while waiting for the replacement you may continue 
using your K3 with the KXV3 removed. (Remember to set this option to 
'not installed' in the menu.)

Eric WA6HHQ

----

*KRX3 Board removal instructions.

*1. Remove the top cover of the K3.

2. Remove the two black screws on the top KIO3 rear trim panel. (do not 
remove the four "nuts" on the DB connectors)

3. Push the Digital IO board and trim panel assembly outward from the 
inside. (with rear of K3 facing you, press on the backs of the two DB 
connectors with both index fingers. The panel and digital IO boards come 
out together. See attached picture below.)

4. Remove the upper standoff from the KIO3 board. (this is only 
necessary if the KRX3 is installed.)

5. Pull the KIO3 board straight up and out of the K3 through the rear 
panel.

6. Reverse these steps to re-install the KXV3 assembly.

*Removal of KIO3 Digital Board (KXV3 is just below the KIO3.)*

http://www.elecraft.com/K3/pics/KXV3%20Removal_320.jpg

======

Barry Simpson wrote:
> I have just completed building K3 #1397. It includes the KPA3, KXV3, KBPF3
> and four filters.
>
> It went together very well and all is working fine so far except the power
> output.
>
> I have done the 50W calibration per band and that produces an output of 50W.
> However a setting on the power control of 71W gives 100W out and 76W gives
> an actual 120W out. From there the power controls gives an output of up to
> and beyond 150W.
>
> I have tried recalibrating and I have downloaded the latest but to no avail.
> I have also emailed Elecraft but given it is the weekend I do not expect to
> hear from them for a few days.
>
> I wonder if anyone else has had this problem and if so how it was cured. Or
> has anyone any suggestions. I think I might take out and reseat the KPA3 in
> case it is a bad contact but I don't think it is that.
>
> Barry Simpson  VK2BJ
>