[Elecraft] KPA/100 displays wrong PS current (much lower)

[Ioannis Kassotakis]

Don,
I think that the voltage drops to 13 V or lower at key down.
I will follow your advice.
Thanks again.

73,

Ioannis PA1EQP

On Monday, 25 April 2016, Don Wilhelm <donwilh at embarqmail.com> wrote:

> Ioannis,
>
> Back the CAL CUR down to 3.50.
> It may be that you will have Hi Cur messages if you turn the POWER knob to
> full clockwise, but if you set the power control at 100 watts, that message
> should not appear.
>
> If it does, check the connections from the power supply to the K2/KPA100.
> If the voltage at the K2 (observe with the K2 voltage display) drops
> significantly during keydown, that could explain the Hi Cur warnings.
> Tighten the power supply terminals and check to be certain the APP
> connector is properly assembled with the connector blades fully inserted.
> If you look at the end of the APP connector and can see the spring blades
> that normally lock the contact blade, the contact blade has not been fully
> inserted and will not make full contact (and cause a significant voltage
> drop).
> If you can increase your power supply voltage to 14.3 volts or above, you
> should increase the voltage.  The K2 will operate with voltages up to 15
> volts.  For linearity and best transmit IMD, the higher the voltage, the
> better.
>
> 73,
> Don W3FPR
>
> On 4/24/2016 4:07 PM, Ioannis Kassotakis wrote:
>
>> Thanks Don,
>> I understand that the PS current reading is only for the Base K2.
>> I will rely on the bench PS display to read the 13.8 DC current.
>> I have already set the CAL CUR to 3.8 Amps so that I do not get HI CUR
>> alert at 10 Watts.
>>
>> 73,
>> Ioannis PA1EQP
>>
>>
>> On Sunday, 24 April 2016, Don Wilhelm <donwilh at embarqmail.com <mailto:
>> donwilh at embarqmail.com>> wrote:
>>
>>     The current display on the K2 is only for the current used by the
>>     base K2.  I use it when testing the K2 for 'good health' and
>>     normal RF Gain, but during operating I see no need to monitor it
>>     on a regular basis.
>>     The Base K2 will indicate Hi Cur if the current draw goes above
>>     the value set by the CAL CUR parameter, and will reduce power if
>>     that occurs.  Should you continue to get Hi Cur messages, that is
>>     an indication of something that should be investigated.
>>
>>     73,
>>     Don W3FPR
>>
>>     On 4/24/2016 3:14 PM, Ioannis Kassotakis wrote:
>>
>>         Thanks Don,
>>         That means that at HI PWR (>11 Watts) should disregard the
>>         displayed PS current figures.
>>         I thought that KPA100 processor would communicate the I Sense
>>         back to the MCU and display the correct current figure after
>>         rescaling. I understand that is not the case.
>>
>>         73,
>>
>>         Ioannis PA1EQP
>>
>>         On Sunday, 24 April 2016, Don Wilhelm <donwilh at embarqmail.com
>>         <mailto:donwilh at embarqmail.com>> wrote:
>>
>>             Ioannis,
>>
>>             The current display on the K2 indicates only the current
>>         for the
>>             base K2, not for the K2 and KPA100 combination.
>>             That is why you set the CAL CUR to 3.50 amps even though the
>>             KPA100 will draw much more current.
>>
>>             Yes, the KPA100 does have a scaling on the amount of RF
>>         voltage
>>             that is being detected.  That is used for power control
>>         and has
>>             nothing to do with the current displayed.  The result of that
>>             voltage is sent to the VRFDET signal in the K2 (Voltage of
>>         the RF
>>             Detected).
>>
>>             73,
>>             Don W3FPR
>>
>>
>>
>>
>> --
>> Ioannis Kassotakis
>>
>
>

-- 
Ioannis Kassotakis