[Elecraft] K3 Repair
Jack Brabham
kz5a at att.net
Sat Jul 17 15:44:35 EDT 2010
Don,
What I'm watching to see the "creep" is the W2 meter's Windows app with
the meters set to AVG and the peak hold bar ON. I'm interpreting this
as the "peak" of the fluctuating "average" power level???? This is the
number that rolls up around 50% during the first 20 seconds of an
initial transmission after a power cycle.
If I change the meters to "peak", the numbers change as you would
expect, the initial "peak" power starts off around 70 watts and drifts
up to around 95.
BTW normal PSK31 etc operation in DATA A seems to proceed as expected as
long as I stay above 1000 hz or so for the audio. Below that there is
an increasingly noticeable reduction in PO, but otherwise functions
normally.
I'm using my PSK31 program as an audio generator for these tests, not
having anything better to use. In this role it is not adjusted the
same way one would for actual PSK operation. Do not try this at
home...... ;)
I have tried, in the last hour or so, increasing the audio drive levels
and decreasing the mic and line-in gain. This somewhat reduced the
power creep issue, at least in terms of the number of transmission
cycles before it "settles", but the radio still seems to have to
"relearn" this from scratch after a power cycle.
Reducing the Mic gain from 18 to 6 and increasing the output from my mic
pre-amp to get 4-5 bars of ALC, did not seem to help the low output on
SSB problem.
Thanks for the tip about the ALC meter, makes more sense now.
73 Jack KZ5A
On 7/17/2010 1:18 PM, Don Wilhelm wrote:
> Jack,
>
> I see Wayne has responded and I am certain he will help get to the
> bottom of the problem.
>
> I do have one question about your SSB behavior - do you see the same
> drop-off in power if you set the wattmeter to read peak?
> The power rating of the K3 is expressed in Peak Envelope Power, so
> your metering should match when trying to compare apples to apples.
>
> On your PSK31 situation, are you driving the audio to the K3 high
> enough to produce 4 to 5 bars on the "ALC" meter, and setting your
> desired power output with the K3 power knob?
> If you are trying to use the audio level to control the power output,
> it will behave much as you have described. The K3 measures the power
> output, and decides there is not enough to match the setting of your
> power knob, so it increases the drive attempting to produce more power.
> Drive the audio input so you have at least 4 ALC bars with maybe the
> 5th flickering.
> The "ALC" meter on the K3 is not completely an indication of ALC - the
> first 4 bars act more like a VU meter to tell you the audio level.
> The 5th bar indicates the start of ALC action.
>
> 73,
> Don W3FPR
>
> Jack Brabham wrote:
>> Well, here's a follow up.
>>
>> A week after the assumed return posting date, I emailed, asking for a
>> status update and got a phone call from Elecraft the next day.
>> Nothing had happened during that week, apparently the return shipping
>> just fell thru a crack and didn't occur (and yes, they are swamped
>> with work).
>>
>> So we got that moving and I received the radio on the 15th.
>>
>> Still exhibits the same problem it had when I sent it in.
>>
>> So I'm now 3 and a half months into my K3 ownership and still can't
>> get on SSB. Considering that I bought the radio specifically for SSB
>> contesting and sold all my other radios to pay for the K3, this is
>> not making me a happy camper.
>>
>> I haven't the slightest doubt that what I was told by Elecraft was
>> 100% accurate, that the low output problem was confirmed on the bench
>> and that an EEINIT had "fixed" it, and it stayed "fixed" while at
>> Elecraft. However, as someone who spent 30 years or so
>> troubleshooting complex systems, the fact that several previous
>> EEINITs had failed to fix the problem would have been a big red flag
>> that I had not yet got to the root cause of the issue.
>>
>> So I emailed Rene and let him know the problem was back. I expect
>> I'll hear from him early next week and we will figure out the next step.
>>
>> BTW here's a quick summary of the "problem" in hopes someone on the
>> list may have an idea to try.
>>
>> (1) Low average output on SSB, typically 10 to 15 watts (AVG)
>> according to my W2 and confirmed in that it only drives my SB-200 to
>> about 150 watts when driven by voice. This occurs with what I take
>> to be normal metering indications from the K3, 5 to 7 bars of ALC, a
>> few bars of compression and the PO meter "hanging" around 50 watts
>> with peaks up around 100W.
>>
>> (2) Weird power fluctations in PSK31. With higher audio
>> frequencies, when PSK1 idle tones are transmitted, the power out will
>> start at about 50 to 60 watts and rise to a nominal 75 watts or so
>> over 15 to 20 seconds. If I preform this test repeatedly with a
>> few seconds "off" time between tests, the "starting" PO number gets
>> progressively higher each time. After 6 to 8 test cycles the power
>> will only vary a few watts.
>>
>> However if I power cycle the K3, changing nothing else, the PO
>> reverts to starting at 50 watts or so drifting up to normal over
>> several seconds, repeating the whole sequence.
>>
>> At lower audio frequencies, below around 800 hz, the overall PO
>> tapers off, and is down 50% at 300 hz. TX EQ is flat, and all config
>> parameters are still as received from Elecraft repair except RS-232
>> baud rate and the mic selection.
>>
>> To me, at this point, the two most likely possibilities are
>> something mechanically/physically intermittent in the K3 (although it
>> has never worked normally for me), or something in the local station
>> environment.
>>
>> I have tried 3 mics, a Heil PR22 and both elements of a Heil Pro-set,
>> FP, RP, and Line-IN, thru a pro-audio chain or direct connected with
>> no change. Recordings on the internal DVR sound fine on Monitor but
>> exhibit the same problem. The power supply is solid at 13.8V. High
>> quality station ground system. Everything else works fine, superb
>> reception, normal CW operation, PSK works if I keep the audio carrier
>> above 1000 hz.
>>
>> The DSP board was swapped out before sending the radio in.
>>
>> I would be just totally tickled to discover the problem is something
>> stupid I'm doing or not doing, or a function of some other problem in
>> my station setup, but I don't know what the heck it would be.
>>
>> Any ideas?
>>
>> 73 Jack KZ5A
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> On 7/2/2010 10:50 AM, Jack Brabham wrote:
>>> I agree that a posted repair queue length figure would probably
>>> eliminate a lot of angst by setting reasonable expectations. Probably
>>> eliminate a lot of phone calls to Elecraft as well. A weekly
>>> prognostication would be more than adequate for my purposes.
>>>
>>> Another thing that could use a little work is the level of
>>> communication.
>>>
>>> Last Friday I got a call from Elecraft stating that the symptoms (low
>>> SSB PO) had been confirmed, and that an EEINIT had resolved the
>>> problem.
>>> My K3 was going to "soak" over the weekend and shipout Monday (last)
>>> if was still good. I was glad to hear it was coming back but a bit
>>> curious as to why the first half a dozen or so times we did an EEINIT
>>> had not resolved the problem.
>>>
>>> Now its a week later, I don't know if my K3 is back in the shop (as I
>>> suspect) or if it is has been shipped and I need to hang around to
>>> receive it... I'm sure I could call and get an update but, being lazy,
>>> I would rather just get a short simple email periodically while the
>>> RSA is open or anytime there is a status update.
>>>
>>> 73
>>>
>>> Jack KZ5A
>>>
>>> K3 #4165
>>>
>>>
>>>
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>>
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