[Elecraft] KPA100 Power Malfunction

[Don Wilhelm]

John,

I am using the 6 position antenna relay design that appeared in QST a 
couple years back by Bill Smith (call?).  FAR Circuits has a board and 
the 12 volt relays are American Zettler, Inc. AZ755-1C-12DE.

You may want to search for the original article, it had ARRL test data 
on the SWR and loss and there was some information about where you could 
obtain the relays without encountering a high minimum order.  I did 
order 24 of them for my purposes, and used the 24 volt relays, but your 
situation would likely use the 12 volt version.

73,
Don W3FPR

John [K7SVV] wrote:
> Don,
>        I am going to be installing a simpler antenna switching system 
> here. Mine will be keyed off of the 12v power supply.  When it is turned 
> off,  the antennas on my two operating positions will be switched from 
> rigs to ground. The relays will be located outside in a weather proof 
> box attached to 8' ground rods.  My only problem is choosing the spdt 
> relays.  May I ask what type and brand of relays are you using?
> 
> John   [K7SVV]
> 
> ----- Original Message ----- From: "Don Wilhelm" <w3fpr at earthlink.net>
> To: "eKotz" <norift at bmi.net>
> Cc: <w3fpr at arrl.net>; <elecraft at mailman.qth.net>
> Sent: Monday, June 18, 2007 8:43 PM
> Subject: Re: [Elecraft] KPA100 Power Malfunction
> 
> 
>> Ed,
>>
>> For the future, consider your antenna situation carefully.  When the 
>> station is not operational, all my antennas are grounded (via relays) 
>> and the K2 is connected to a dummy load.  I do have an extensive 
>> antenna switching system here (not yet complete, but almost there) 
>> which relies on the Elecraft KRC2 along with remote relays to select 
>> the antenna to be used for each band - yours may be less complex, but 
>> consider a switching system to ground the antennas not in use and 
>> connect the K2 to a ground (or better a dummy load) when the K2 is not 
>> powered on.
>>
>> 73,
>> Don W3FPR
>>
>> eKotz wrote:
>>> Don,
>>>
>>> You were spot on.   The SWR Bridge diodes D16 and D17 had failed.   
>>> The diodes arrived today in the mail, I replaced them and my K2 is 
>>> up. Thank you very much for your help.
>>>
>>> 73,
>>> Ed  -  AD7GR
>>> K2 #6050
>>>
>>>
>>>
>>> Don Wilhelm wrote:
>>>> Lack of power control with the KPA100 installed normally points to a 
>>>> failure of the KPA100 wattmeter circuit.
>>>>
>>>> Start with replacing the 1N5711 diodes D16 and D17...
>>>>
>>>> If your KPA100 was working at one time and there is *any* 
>>>> possibility that you encountered a lightning surge, then D16 and D17 
>>>> are the most likely suspects.
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> 
> 
>