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Interesting KPA100 partial power control loss

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E Turk

Interesting KPA100 partial power control loss

Good evening all,

K2/100 #5822 started yesterday producing nearly double the requested
power. Below 10W fine. 50W requested gave about 100W and max power
was approaching 160W on lower bands!! I searched the reflector
archive to confirm my memory of posts on the problem over the years.
As suggested by Don W3FPR in the past, I replaced D16-17 with 1N4148
diodes to see what happened before delving further, fearing damage to
U5 or U6. On reassembly the problem was fixed!

I checked the removed 1N5711's with a Peak DCA55 and both appeared
normal (low voltage test only I suppose).

Have been playing with a kit built Linear Amp Ranger (572B) recently
(circuit similar to Ameritron AL-811HD) and I am suspicious that on
powering down the heavy toroidal mains transformer may be producing a
small 'EMP' since occasionally it freezes up a nearly G4 iMac. The
antenna is either disconnected or switched to a dummy load when off-
air. No recent thunderstorm activity here - midwinter.

Does anyone have any ideas on how to reduce this turn-off spike, in
case this is the cause? All gear is fed from UK 240V mains via surge
protected power outlets. Meanwhile I will be even more vigilant with
antenna disconnection and grounding.

73,

Ted G7BQM

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David Herring-2

Re: Interesting KPA100 partial power control loss

Does the AL-811H come with the necessary relay cable that will work with the K3, or is that an add-on purchase? If it's an add-on, then which one would one get? I only see YaeKenCom cables listed at Ameritron.com.

Thanks,

David, K6DCH

On Jan 23, 2010, at 11:55 AM, Ted Turk wrote:

> Good evening all,
>
> K2/100 #5822 started yesterday producing nearly double the requested
> power. Below 10W fine. 50W requested gave about 100W and max power
> was approaching 160W on lower bands!! I searched the reflector
> archive to confirm my memory of posts on the problem over the years.
> As suggested by Don W3FPR in the past, I replaced D16-17 with 1N4148
> diodes to see what happened before delving further, fearing damage to
> U5 or U6. On reassembly the problem was fixed!
>
> I checked the removed 1N5711's with a Peak DCA55 and both appeared
> normal (low voltage test only I suppose).
>
> Have been playing with a kit built Linear Amp Ranger (572B) recently
> (circuit similar to Ameritron AL-811HD) and I am suspicious that on
> powering down the heavy toroidal mains transformer may be producing a
> small 'EMP' since occasionally it freezes up a nearly G4 iMac. The
> antenna is either disconnected or switched to a dummy load when off-
> air. No recent thunderstorm activity here - midwinter.
>
> Does anyone have any ideas on how to reduce this turn-off spike, in
> case this is the cause? All gear is fed from UK 240V mains via surge
> protected power outlets. Meanwhile I will be even more vigilant with
> antenna disconnection and grounding.
>
> 73,
>
> Ted G7BQM
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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Elecraft mailing list
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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N3PSJ-2

Re: Interesting KPA100 partial power control loss

I don't think it comes with the amp. It is just a cable with RCA
connectors on each end, one half of a left right speaker cable will
do. Some claim it should be shielded cable, but I have used
unshielded with no problems.

KEN. KE3C

On Feb 21, 2010, at 3:09 PM, David Herring <[hidden email]> wrote:

> Does the AL-811H come with the necessary relay cable that will work
> with the K3, or is that an add-on purchase? If it's an add-on, then
> which one would one get? I only see YaeKenCom cables listed at Ameritron.com
> .
>
> Thanks,
>
> David, K6DCH
>
>
>
> On Jan 23, 2010, at 11:55 AM, Ted Turk wrote:
>
>> Good evening all,
>>
>> K2/100 #5822 started yesterday producing nearly double the requested
>> power. Below 10W fine. 50W requested gave about 100W and max power
>> was approaching 160W on lower bands!! I searched the reflector
>> archive to confirm my memory of posts on the problem over the years.
>> As suggested by Don W3FPR in the past, I replaced D16-17 with 1N4148
>> diodes to see what happened before delving further, fearing damage to
>> U5 or U6. On reassembly the problem was fixed!
>>
>> I checked the removed 1N5711's with a Peak DCA55 and both appeared
>> normal (low voltage test only I suppose).
>>
>> Have been playing with a kit built Linear Amp Ranger (572B) recently
>> (circuit similar to Ameritron AL-811HD) and I am suspicious that on
>> powering down the heavy toroidal mains transformer may be producing a
>> small 'EMP' since occasionally it freezes up a nearly G4 iMac. The
>> antenna is either disconnected or switched to a dummy load when off-
>> air. No recent thunderstorm activity here - midwinter.
>>
>> Does anyone have any ideas on how to reduce this turn-off spike, in
>> case this is the cause? All gear is fed from UK 240V mains via surge
>> protected power outlets. Meanwhile I will be even more vigilant with
>> antenna disconnection and grounding.
>>
>> 73,
>>
>> Ted G7BQM
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Ken Nicely (N3PSJ)