problem. There appears to be plenty of drive either way. I ordered a PA
replacement kit just to have it on hand. I can get the xstrs locally,
> Larry;
>
> I suggest you call Elecraft customer support on this. Something tells
> me they will want you to check out the KSB2 module to find the problem.
>
> Good luck!
>
> On Dec 12, 2005, at 7:52 AM, Larry Phipps wrote:
>
>>
>> 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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>
>
> -Jack Brindle, W6FB
> =======================================================================
>
>
>
>
>
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