K2 power

[Earl Ritchie-2]

I am building a KPA100 and it is configured as
-12V supply attached
-12 v internal line connected to K2 at P3
-PA turned on in menu

In attempting the  power calibration the K2 shows i watt when set for 5 watts. Adj R26 has no effect. Checking back with the RF probe, I find that K2 shows 11-12 vRF and with the RF cable connected to KPA100 it shows 11-12 VRF at the input of K1.  However at TP2 there is no RF.
 I took the board off the heat sink and I find that the RF goes to the n.o. terminal rather than to the nc terminal.  So the signal is lost in Ki

Has anyone had this experience  with the KPA100 or can anyone give me any ideas how to correct this?
 Thanks, Earl
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[Don Wilhelm-4]

Earl,

The RF should come out of K1 NC contact when the power is set to less
than 11 watts.  Since you report that there is RF at K1 NO contact,
check to see if the K1 coil is activated - the voltage at U2 pin 13
should be zero when K1 is activated, but 12 volts when not activated.
If U2 pin 13 is at zero volts at both low and high power levels, look
for a solder splash that is grounding the circuit.  Also check U1 pin 21
- it should be zero volts at low power and near 5 volts at high power -
if that condition is true, turn power off and check the resistance to
ground from U2 pin 13.  If you find that it is near zero ohms, continue
to look for the solder splash or bridge.
If any of your solder connections look like they have a pile of solder
on them, too much solder was applied and can create similar problems.

73,
Don W3FPR

Earl wrote:

> I am building a KPA100 and it is configured as
> -12V supply attached
> -12 v internal line connected to K2 at P3
> -PA turned on in menu
>
> In attempting the  power calibration the K2 shows i watt when set for 5 watts. Adj R26 has no effect. Checking back with the RF probe, I find that K2 shows 11-12 vRF and with the RF cable connected to KPA100 it shows 11-12 VRF at the input of K1.  However at TP2 there is no RF.
>  I took the board off the heat sink and I find that the RF goes to the n.o. terminal rather than to the nc terminal.  So the signal is lost in Ki
>
> Has anyone had this experience  with the KPA100 or can anyone give me any ideas how to correct this?
>  Thanks, Earl
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft   
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>
>  

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