[Elecraft] NG0R - K2 Build/Alignment Issue

[Don Wilhelm]

JH,

I would definitely say the 20/30 meter low pass filter needs to be 
checked.  Low power output combined with HI CURR messages normally 
indicate a low pass filter problem.
I am not certain how you are getting power output on 10 meters, but not 
on 12.  That may be a bandpass filter problem.
The low power on 80 may be a bandpass problem too, or it could be a 
lowpass filter problem - that lowpass is only used on 80.

Look carefully at all the toroid leads - there should be a bit of tinned 
lead above the top of the board, and when you look down on the soldered 
connection, the joints should look like mountains, but not volcanoes.  
If there is a ring around the wire lead, it was not properly tinned - 
remove it, clean the lead and re-tin.

Since some of the bands transmit at 6 watts, that may be an indication 
that only one of the PA transistors is working.  Do the Hi Curr messages 
on 40m cease if you set the power at 5 watts?  If so, suspect one of the 
PA transistors is bad.

Repeat the transmit tuning for the bandpass filters for all bands that 
you can obtain some output - you should find a definite peak, if you do 
not, that is an indication of a bandpass filter problem.

If you don't find anything substantial in the above steps, build the RF 
probe from the parts that came with your K2 and do the Transmit Signal 
Tracing steps in Appendix E of the manual to find the failing stage.  
Once you identify that stage, do the DC Voltages checks for that stage.  
If you have not figured out the failure by that time, ask about it again 
on the reflector.

73,
Don W3FPR

John Hoaglun wrote:
> Hello,
>  
> I am working on the receiver and transmitter alignment at the end of 
> the build process.  I used a signal generator to peak up all of the 
> band pass filters and they works as expected. When I try to check the 
> transmit alignment I am not getting to the proper power output. Even 
> peaked up for max smoke I am not getting the proper power out.
>  
>  3.750mhz    2.5w    Hi Cur
>  7.100mhz    6.1w    Hi Cur
> 10.100mhz    0.3w    Hi Cur
> 14.100mhz    0.3w    Hi Cur
> 18.100mhz    9.5w   
> 21.100mhz    4.1w
> 24.900mhz    0.5w
> 28.200mhz    6.0w
>  
> All of these were tested with a external wattmeter & the internal 
> meter. I also validated that dummy load not the issue by testing this 
> using a triband antenna on 20m and the measurements matched.
>  
> Do you have any suggests on some places to look?
>  
> It is possible that it could be an issue with the low pass filters but 
> I find it hard to believe that I messed up all five filters. You would 
> think that at least one of them would be ok.  :-)
>  
> Thoughts?
>  
> Please respond direct as well as to the list... I get the digest 
> version so it could be a while before I see next digest email.
>  
> Thanks, JH
>  
> -----------------------------
> John Hoaglun
> NG0R - EN25
> http://www.hoaglun.com
>  
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