K2 Transmitter Problems

[Ron McCurdy]

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

 

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[Don Wilhelm-4]

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
>
>  
>
>

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