[Elecraft] K3/KPA500 10 meter behavior

[Wayne Burdick]

Bob,

This can usually be corrected (at the K3) by re-doing the power  
calibration steps, or by manually setting CONFIG:TXGN HP to a somewhat  
lower value. This adjusts the open-loop gain on a per-band basis, and  
should correct the overshoot. To change the TXGN HP value you have to  
first set CONFIG:TX ALC to OFF. Further details in the K3 owner's  
manual. If this doesn't do it, please contact K3 support.

73,
Wayne
N6KR


On Aug 8, 2011, at 1:14 PM, Robert Redmon wrote:

> Actually, I think my original message was misleading. The problem is
> really the K3 with which I drive the KPA500, causing the overdrive
> condition. When first transmitting, instead of putting out the set  
> power
> (20 watts), my K3 generates significantly more (60 watts according to
> the display on the KPA500 in standby). My KPA500 only requires about  
> 20
> watts to drive it to 500 watts on 10. Consequently, until the K3  
> settles
> down (a matter of a second or so), it is overdriving the
> amp...significantly.
>
> 73,
>
> Bob K5SM
>
> On 8/8/2011 2:42 PM, Robert Garceau wrote:
>> No problem on 10 meters on my #165 KPA500
>> W1EQ, Bob
>>
>>
>> -----Original Message-----
>> From: elecraft-bounces at mailman.qth.net
>> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Klaus  
>> Koppendorfer
>> Sent: Monday, August 08, 2011 2:38 PM
>> To: Robert Redmon; elecraft at mailman.qth.net
>> Subject: Re: [Elecraft] KPA500 10 meter behavior
>>
>> yes kpa-500 serial 230 has exactly the same behavior
>>
>> ________________________________________
>> Von: elecraft-bounces at mailman.qth.net
>> [elecraft-bounces at mailman.qth.net]" im Auftrag von"Robert  
>> Redmon
>> [k5sm.bob at gmail.com]
>> Gesendet: Montag, 08. August 2011 19:16
>> Bis: elecraft at mailman.qth.net
>> Betreff: [Elecraft] KPA500 10 meter behavior
>>
>> I put my KPA500 on 10 today for the first time and noticed a rather
>> unexpected behavior. Often, on the first character of transmission,  
>> the
>> K3 drive power apparently spikes, driving the KPA500 to more than 700
>> watts. This seems to stabilize following that first dit or two, but I
>> have to reduce drive to below 12 w before that behavior stops.  
>> Seems the
>> 100 watt module in the K3 is behaving poorly. Anyone else noticed  
>> this?
>> Doesn't seem to be a problem on other bands. (SWR is 1.3:1).
>>
>> 73,
>>
>> Bob K5SM
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