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Re: KAT100 Power Calibration Problem

Posted by Don Wilhelm-4 on Mar 01, 2014; 1:50pm
URL: http://elecraft.85.s1.nabble.com/KAT100-Power-Calibration-Problem-tp7584832p7584890.html

Jeremy,

How much power are you sending through that wattmeter?  If it is 20
watts or more, it may just be that 30 mV is OK.

73,
Don W3FPR

On 2/28/2014 9:55 PM, JeremyJones wrote:

> I've taken the watt meter out of the loop, and have the K2 set for 10W.
> Double checked the windings and solder on T1, and it still won't go below
> 30mV.  I definitely have C31 at the low spot as the voltage climbs on either
> side.  I still can't get anywhere the voltage needed at U5 pin 5 for the
> power calibration.
>
> Jeremy
> VA3ZTF
>
>
> Don Wilhelm-4 wrote
>> Jeremy,
>>
>> Tune the capacitor very slowly and use a non-metallic tool.  The null is
>> sharp and deep.
>> You must have a good 50 ohm dummy load connected.
>> You may want to take your external wattmeter out of line to do the
>> nulling.
>> The actual voltage will depend on the power level, at 5 watts it should
>> be less than 10 mV, but you should be able to get it below 15 or 20 mV
>> if the power is 10 watts.  If you are using 20 watts or more from the
>> KPA100, then your 30 mV is probably OK.
>>
>> Ideally, the voltage should go to zero, but being practical, one may not
>> be able to adjust the capacitor in fine enough increments to achieve
>> that goal.
>>
>> 73,
>> Don W3FPR
>>
>> On 2/28/2014 4:32 PM, JeremyJones wrote:
>>> I just reread Dons post, and he says less than 10mV, so I guess I have
>>> some
>>> trouble shooting to do with that first,
>>>
>>> Jeremy
>>> VA3ZTF
>>>
>>>
>>>
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