-------- Original Message --------
Subject: Re: [Elecraft] K2/100 pwr out control problem
Date: Fri, 22 Apr 2011 20:33:40 +0000
From: Robert G. Strickland <rc...@verizon.net>
To: d...@w3fpr.com
Hello, Don and others..
Thanks for everyone's suggestions. Much appeciated. The problem
persists regardless of using an antenna or a dummy load. I carried out
Don's suggestions as described below.
I don't have a watt meter, so I used the RF probe on a 50ohm resistive
load and calculated the Vrms for the various power levels. Calculated
and observed readings are as follows:
Power Vrms [cal] Vrms [observed]
10w 22.36v 18.0v
5w 15.8v 18.0v
2w 10.0v 18.0v
Computed power out at 18.0Vrms is 6.48w
In addition, I notice the following LCD readings at all three power
levels: the moment the TUNE button is pressed a HI CUR reading appears
that immediately changes to a power out reading is 2.1w and an SWR
reading 9.9:1. Again these reading occur at all three power settings.
Don, I'm going to assume that your first suggestion to change D16 and
D17 still holds. Yes?
...robert
On 4/22/2011 15:47, Don Wilhelm wrote:
> Robert,
>
> Make the following setup and check into a dummy load with an external
> wattmeter between the K2 and the dummy load. Please follow the testing
> method given, there is a reason for that test methodology.
> 1) Remove the APP power cord from the KPA100 and power the K2 only from
> the coaxial power jack on the lower rear panel. Set the K2 to 40 meters.
> 2) Set the power requested knob to 5 watts and press TUNE - what is the
> power on the external meter?
> 3) Set the power to 2 watts and again press TUNE - what is the power on
> the external meter?
>
> If the actual power was 10 watts or more in both cases above, change
> diodes D16 and D17 in the KPA100.
> If the actual power tracked the requested power, then you have a
> different problem - power the KPA100 from the APP power cable and try
> again into a dummy load (not an antenna). Set the power requested to 50
> watts and do a TUNE - the actual power should be near 20 watts. If it
> goes to a large value, then we need to investigate your KPA100 - remove
> it from the base K2 and take the shield off, and let us know the status
> of your results.
>
> 73,
> Don W3FPR
>
> On 4/22/2011 10:46 AM, Robert G. Strickland wrote:
>> I'm running a K2/100 Ser# 5957, operational for about three years. Just
>> now, control of pwr out has become intermittant. I can control pwr out
>> in the basic K2 thru the range 0 -13w. Anything over that and the K2
>> meter sticks at about 13w, but the amp output jumps immediately and
>> somewhat randomly to between 50-100w with no "smooth" control.
>> Decreasing the K2 pwr out below 10w or so, and the overall pwr out drops
>> accordingly, the K2 meter reads "correctly," and the total unit pwr out
>> (external meter) agrees with the K2 meter. I've tried cycling on/off,
>> different bands, different modes. All the same. Any suggestions most
>> welcome.
>>
>> ...robert
>>
>
--
Robert G. Strickland, PhD, ABPH - KE2WY
rc...@verizon.net
Syracuse, New York, USA
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