[Elecraft] K2 Transmitter Problems

[Don Wilhelm]

Ron,

You should hear a bit of 'band noise' on all bands - in other words, the 
noise level should increase when the antenna is connected.
Do not rely on continuity readings for T3 and T4.  Look at the leads 
carefully.  There should be a bit of tinned lead showing above the board 
and on the solder side, if there appears to be a depression in the 
solder right next to the lead, it is not well tinned and soldered.  An 
apt description has once been given - The solder joints should look like 
'mountains', but not 'volcanoes' - that is especially true for toroid leads.
Continuity tests of the Low Pass Filter are similarly misleading because 
everything will appear to be grounded.  If you want to do continuity 
testing of the LPF, you must remove T4 lead 4 from ground, then switch 
to the band to be measured - you should then find continuity between W1 
and the center of the BNC jack.

Have you done the transmit bandpass filter alignment yet? If not, that 
can explain the weakness in both transmit and receive for those bands. 
Did you find a peak on all bands? You should see a definite peak - the 
peak on 80 meters is broad, but the other bands have a sharper peak.

73,
Don W3FPR

Ron McCurdy wrote:
>
> Don,
>
>  
>
> I tested the transformers T3 & T4 at their solder pads for continuity 
> and they were all about 0.1 ohms and I checked them through the full 
> set of windings that are connected and got 0.2 ohms.  I also checked 
> the number of turns, etc. and found nothing wrong.
>
>  
>
> On the LPF sections I was only able to use the "K2 Cheap & Dirty" 
> method and I can get signals through all bands up to 20 meters.  >From 
> 20 meters up, there doesn't seem to be enough signal in my 40 meter 
> inverted V antenna or there is something stopping the signal through 
> the LPF for those bands.
>
>  
>
> Should the antenna provide enough signal to more than click in the 
> headphones?  It certainly does on 80, 40 & 30 meters.  Any more 
> suggestions?
>
>  
>
> Ron
>
>  
>
>