I suggest you call Elecraft customer support on this. Something tells
>
> I think I checked the T/R switch already, but I'll double-check.
> The thing that's weird is that the DC voltages and resistance
> checks on the finals are OK. I never got a Hi-Cur warning at any
> time before the failure (or since). The rig draws about 600ma
> during xmit.
>
> Thanks for the feedback.
>
> Larry N8LP
>
>
>
> Don Wilhelm wrote:
>
>> Larry,
>>
>> With those RF voltage measurements, I would say that the final output
>> transistors have likely failed - that goes along with your earlier
>> report
>> that the power out decreased rapidly to zip.
>>
>> There is only one other possibility that I can think of, and that
>> would be
>> the transmit signal being shorted somewhere - so before blaming
>> the finals
>> themselves, check that Q2 is operating properly - the juction of
>> D3 and D4
>> in the TR switch should be at a low voltage during receive and go up
>> somewhere close to 8 volts during transmit.
>>
>> If the receiver is still functioning properly, a short in the Low
>> Pass
>> Filter is quite unlikly because that kind of fault would drag the
>> receiver
>> way down too.
>>
>> 73,
>> Don W3FPR
>>
>>
>>
>>
>>> -----Original Message-----
>>> From: Larry Phipps [mailto:
[hidden email]]
>>> Sent: Sunday, December 11, 2005 10:46 PM
>>> To:
[hidden email]
>>> Cc:
[hidden email]
>>> Subject: Re: [Elecraft] K2 dead xmtr
>>>
>>>
>>>
>>> Hi Don. The levels are high everywhere in the chain up through
>>> the bases
>>> of Q7-8. Requested power is immaterial in this case, since the
>>> ALC sees
>>> zero detected power, and therefore is pegged at 5v all the time.
>>>
>>> I measured the levels with a scope, and divided the p-p values by
>>> 2.82
>>> to compare with the voltage probe reference levels in the manual.
>>> BTW, I
>>> removed the KAT2 and KSB2 to simplify access and minimize the
>>> number of
>>> possible fault zones.
>>>
>>> W6 - .28 Vrms
>>> Q5 case- 1.4 Vrms
>>> Q6 tab- 3.5 Vrms
>>> Q7,8 base- 1.4 Vrms
>>> RF out- .55 Vrms
>>>
>>> Note: These waveforms are pretty dirty looking except on 10m,
>>> where I
>>> made these measurements.
>>>
>>> Larry N8LP
>>>
>>>
>>>
>>> Don Wilhelm wrote:
>>>
>>>
>>>> Larry,
>>>>
>>>> With the requested power set at 5 watts, send us the RF Voltage
>>>> levels at
>>>> the W6 jumper, Q5 collector (case), Q6 collector (tab), Q7,Q8
>>>>
>>> base, and the
>>>
>>>> RF Output jack. With that info, we should be able to home in on
>>>>
>>> the problem
>>>
>>>> area.
>>>>
>>>> 73,
>>>> Don W3FPR
>>>>
>>>>
>>>>
>>>>
>>>>> -----Original Message-----
>>>>>
>>>>> OK. I'm hoping someone has seen this before I start tearing
>>>>> into things
>>>>> (and tearing my hair out).
>>>>>
>>>>> My K2 started to lose power yesterday. Within an hour, the output
>>>>> dropped to close to zero (1mW on 160m, 40mW on 10m). There are
>>>>> no signs
>>>>> of distress or burning odors.
>>>>>
>>>>> I checked the ALC... pinned at 5v. Everything looks good in
>>>>> terms of
>>>>> levels/frequencies thru the XMIT mixer and filters, except the
>>>>> rf levels
>>>>> are higher than indicated in the manual. I suspect this is due
>>>>> to the
>>>>> ALC being wide open.
>>>>>
>>>>> The dc levels for Q5, Q6, and Q7-8 bases are normal, and the
>>>>> resistance
>>>>> checks on Q7-8 are OK. 8T looks fine. But the rf levels are all
>>>>> considerably high, and look pretty ratty except on 10m. The rig
>>>>> draws
>>>>> about 600ma in xmit.
>>>>>
>>>>> Anyone seen this before?
>>>>>
>>>>> Larry N8LP
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>> --
>>> No virus found in this incoming message.
>>> Checked by AVG Free Edition.
>>> Version: 7.1.371 / Virus Database: 267.13.13/198 - Release Date:
>>> 12/12/2005
>>>
>>>
>>>
>>
>>
>>
>>
>>
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