[Elecraft] Multiple KUSB Connects

Wed Aug 26 22:04:17 EDT 2015

Jack, reporting back, as promised:
I could not replicate my red light experience tonight. Carefully keeping the KUSAB-KPA500 cable well away from any coax, I connected as I did yesterday to the Apple display and Mac Mini.
Did a TEN WATT xmit (KPA500 in stand-by). All green lights. Same for 20 watts.
Engaged OPER at 25 watts. Produced 500 watts from the KPA500. Smooth as silk.
I clearly laid the KUSB right smack on top of the power out coax. No other explanation. 
So, case closed. 

And in the words of the very wise moderator of this list, Eric Swartz, (he’s thinking of this right now), “let’s close this discussion on Multiple USB Connects.” Thanks much. Thread closed.

David A., KC0XT 

> On Aug 26, 2015, at 4:32 PM, Jack Brindle <jackbrindle at me.com> wrote:
> 
> Welcome to the world of high power. You will find a lot of things in your shack may not be designed to handle the higher power you now can run.
> For example, take a good look at the specs for your MA5B. It is rated at 350 watts key down for any length of time, further rated at 600 watts CW,
> with a low duty cycle. Make sure that all cables and connectors in the antenna path are rated for the higher power you now run. You might want
> to add a good RF Choke to the MA5B to eliminate problems with RF on the outside of the coax shield. K9YC has a very good tutorial for this.
> See:  http://audiosystemsgroup.com/RFI-Ham.pdf <http://audiosystemsgroup.com/RFI-Ham.pdf>
> Take a good look at some of the other things in your shack that also might benefit from good choking. The USB cables will be included in this,
> especially the one from the computer to the KPA500.
> 
> The problem you are seeing isn’t too hard to resolve, but it will take some patience and experimenting to take care of them. There are a lot of us
> on the reflector who have been through this who can help with suggestions. And realize that what you saw was not normal, but is actually not
> a problem in the amplifier or radio. It’s just a result of using them. Once you get them licked, things become a lot more fun!
> 
> Jack, W6FB
> 
> 
>> On Aug 26, 2015, at 3:44 PM, David Ahrendts <davidahrendts at me.com <mailto:davidahrendts at me.com>> wrote:
>> 
>> Interesting, Jack. K3S to KPA500 to KAT500 and a W2 to MA5B typically 1:1.2. Perfecto!
>> Connected the just received KUSB-KPA500 cable to the amp and to a USB port on my Apple Thunderbolt 27.5 display running with the MacMini.  
>> Downloaded KAT500 Utility and checked to see I have current firmware. I did. Saved the config. Left the cable in place.
>> Did a low power (amp in stand-by/amp in stand-by) 20M tune just to check if the KAT500 needed to adjust. Every red light lit up on the amp. Did not dare engage high power. No red lights on the KAT500 or the W2.
>> Removed the KUSB cable and all was back to normal.
>> Has to be RF traveling back through the new cable to the KPA500. Let me duplicate the situation again taking great care to separate the KUSB cable from any coax, and I’ll report back.
>> 
>> David A., KC0XT
>> 
>>  
>> 
>>> On Aug 26, 2015, at 2:46 PM, Jack Brindle <jackbrindle at me.com <mailto:jackbrindle at me.com>> wrote:
>>> 
>>> I do. No problems here from development through current use, and I put it through worse conditions that just about anyone when testing.
>>> It sound like you are having problems with RFI getting into the KUSB or rather the KUSB-KPA500 cable. Tell me more about how you have things
>>> connected in your shack, being specific for the computer to KPA connection.
>>> 
>>> Jack Brindle, W6FB
>>> Elecraft Engineering
>>> 
>>>> On Aug 26, 2015, at 1:09 PM, David Ahrendts <davidahrendts at me.com <mailto:davidahrendts at me.com>> wrote:
>>>> 
>>>> Just took delivery of the KUSB for the KPA500. Discovered I am up to speed on FW and saved the config. Left the KUSB connected. Did a 30W K3S tune up and EVERY RED LIGHT on the KPA500 came on. Awesome experience. Sorta like LA’s notorious 405 most nights! Checked everything. Did a quick 30W tune transmission again. KAT500 says 1:1.2 or less. W2, the same. RED LIGHT city again on the KPA500. Removed the cable and we return to sweet green all around. 
>>>> So: ya don’t operate the KPA500 with the KUSB attached, right?  
>>>> 
>>>> David Ahrendts   davidahrendts at me.com <mailto:davidahrendts at me.com>   
>>>> 
>>>> 
>>>> 
>>>> 
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>>> 
>> 
>> 
>> 
>> 
>> David Ahrendts   davidahrendts at me.com <mailto:davidahrendts at me.com>   
>> 
>> 
>> 
>> 
> 

David Ahrendts   davidahrendts at me.com   