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KPA-500 AMP Question

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Dave Anderson, K4SV

KPA-500 AMP Question

Hi All,

Still assembling my KPA-500 SN 436

I am at the stage of installing the transformer and actually have installed the transformer. Upon close inspection it appears that the front left (as viewed from the front) foot held to the chassis bottom using pan head screws may cause damage to the transformers windings. The head of the screw closest to the transformer, is directly under the transformer and when the transformer is torqued down it rides on the screw. The thin clear plastic wrap is the only thing keeping the wire from contacting the screw head. Yes the transformer is up against the bumpers equally and installed per the manual rev d.

My plan was to take this amp on DXpeditions but it appears it would not last one trip before the winding breaks through and touches the screw.

Would anyone know if there is some preventative measures to keep the transformer safe? It would be a shame to find the transformer/amp damage only to have it explode as you plug it in upon arrival to some rare DX place.

At the very least these two screws should be flat head screws and have countersunk holes.

Suggestions?

Thanks in advance,

Dave Anderson, K4SV
Tryon, NC
828 777-5088

www.K4SV.com
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Ken Wagner K3IU

Re: KPA-500 AMP Question

I think that you have put the screws in
the wrong way. See page 8 of the
Assembly Manual, particularly the bold
type sentences.
73, Ken K3iU

On 3/27/2012 2:42 PM, Dave Anderson,
K4SV wrote:

> Hi All,
>
> Still assembling my KPA-500 SN 436
>
> I am at the stage of installing the transformer and actually have installed the transformer. Upon close inspection it appears that the front left (as viewed from the front) foot held to the chassis bottom using pan head screws may cause damage to the transformers windings. The head of the screw closest to the transformer, is directly under the transformer and when the transformer is torqued down it rides on the screw. The thin clear plastic wrap is the only thing keeping the wire from contacting the screw head. Yes the transformer is up against the bumpers equally and installed per the manual rev d.
>
> My plan was to take this amp on DXpeditions but it appears it would not last one trip before the winding breaks through and touches the screw.
>
> Would anyone know if there is some preventative measures to keep the transformer safe? It would be a shame to find the transformer/amp damage only to have it explode as you plug it in upon arrival to some rare DX place.
>
> At the very least these two screws should be flat head screws and have countersunk holes.
>
> Suggestions?
>
> Thanks in advance,
>
> Dave Anderson, K4SV
> Tryon, NC
> 828 777-5088
>
> www.K4SV.com
> ______________________________________________________________
> 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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Ken Wagner K3IU

Re: KPA-500 AMP Question

Oops... sorry, Dave. I see now that you
said that the interference is with the
head of the screw which is correctly on
the inside of the bottom cover. I have
assembled 2 of the amps and have noticed
this problem.
73,
Ken K3iU

On 3/27/2012 3:08 PM, Ken Wagner K3IU
wrote:

> I think that you have put the screws
> in the wrong way. See page 8 of the
> Assembly Manual, particularly the bold
> type sentences.
> 73, Ken K3iU
>
> On 3/27/2012 2:42 PM, Dave Anderson,
> K4SV wrote:
>> Hi All,
>>
>> Still assembling my KPA-500 SN 436
>>
>> I am at the stage of installing the
>> transformer and actually have
>> installed the transformer. Upon close
>> inspection it appears that the front
>> left (as viewed from the front) foot
>> held to the chassis bottom using pan
>> head screws may cause damage to the
>> transformers windings. The head of
>> the screw closest to the transformer,
>> is directly under the transformer and
>> when the transformer is torqued down
>> it rides on the screw. The thin
>> clear plastic wrap is the only thing
>> keeping the wire from contacting the
>> screw head. Yes the transformer is
>> up against the bumpers equally and
>> installed per the manual rev d.
>>
>> My plan was to take this amp on
>> DXpeditions but it appears it would
>> not last one trip before the winding
>> breaks through and touches the screw.
>>
>> Would anyone know if there is some
>> preventative measures to keep the
>> transformer safe? It would be a
>> shame to find the transformer/amp
>> damage only to have it explode as you
>> plug it in upon arrival to some rare
>> DX place.
>>
>> At the very least these two screws
>> should be flat head screws and have
>> countersunk holes.
>>
>> Suggestions?
>>
>> Thanks in advance,
>> Dave Anderson, K4SV
>> Tryon, NC
>> 828 777-5088
>> www.K4SV.com
>> ______________________________________________________________
>>
>> 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
>>

Scott Manthe-2

Re: KPA-500 AMP Question

In reply to this post by Dave Anderson, K4SV

Hi Dave,
A quick Google search indicates that the KPA500 has been used on at
least 5 DXpeditions that I've found: T2T, HK0NA, 5V7V, ZD8D, and J68/W0MU.

Since the amp was designed specifically for that purpose in my, I'd be
surprised if the design team let a potential issue like that survive the
process. You might check the assembly manual again to see if it's
possible you missed something.

Regards,
Scott, N9AA

On 3/27/12 2:42 PM, Dave Anderson, K4SV wrote:

Don Wilhelm-4

Re: KPA-500 AMP Question

I think one important matter is being overlooked - when properly
installed, the transformer will not move. The fact that the screwhead
is touching the plastic wrap on the transformer is likely OK. If things
do not move about, that spacing should stay the same.

73,
Don W3FPR

On 3/27/2012 3:25 PM, Scott Manthe wrote:

> Hi Dave,
> A quick Google search indicates that the KPA500 has been used on at
> least 5 DXpeditions that I've found: T2T, HK0NA, 5V7V, ZD8D, and J68/W0MU.
>
> Since the amp was designed specifically for that purpose in my, I'd be
> surprised if the design team let a potential issue like that survive the
> process. You might check the assembly manual again to see if it's
> possible you missed something.
>
> Regards,
> Scott, N9AA
>