[Elecraft] Low power with K2/100

[Don Wilhelm]

Peter,

The fastest way to determine if you have a problem with the Low Pass 
Filter in the KPA100 is to check it with an antenna analyzer.

Disconnect the small coax to the K2 RF board and terminate it with a 50 
ohm (51 is OK) resistor.  Power only the base K2 (the ribbon cable must 
be connected). Then switch the K2 to the band of interest and connect 
the antenna analyzer to the SO239 antenna jack and sweep the band.  If 
the SWR in the band is about 1:2, then the Low Pass filter for that band 
is OK.  If something is wrong, you will see a much higher SWR.

An analysis of the sweep results along with a look at the schematic of 
the relay contacts should reveal whether you have a bad relay.

73,
Don W3FPR

Peter wrote:
> Hi
> 
> After a few years of good service,I  have a problem with the K2 output.
> I  have the K2 with K2/100.
> 
> The barefoot K2 put full power out on all bands via the bnc connector
> When I connect the K2/100 with PA off with the menu there will be low 
> power on the ant connector on the higher bands (15/12/10 meter).
> Since 10/12/15 are combined, I suspect the bandpass filter
> 
> I tested from TP2 and ANT. out and see NO interruption  when change to 
> an other band.
> All C's, L's  and solders look good.
> 
> So I guess there will a bad relais thats stay ON when I go to 10/12/15M
> 
> The relais in the BPF  are  N.O. when not selected, right?
> If so, I can measure between de N.O. and COMMON to see if the connection 
> goes away
> 
> Futher more, there is 12V at U2 (pin 14 18,17,16,15,14) when the relais 
> in NOT selected. If selected the needs pin good down to 0V, right?
> 
> Any other thing to look at?
> 
> Peter
> PC2A