[Elecraft] Microham Microkeyer II, RFI in mike with my K3

[Jim Brown]

Joe,

Perhaps that's what you're selling now, and if it is, that's great. But 
what I described is what is at W6OAT. As it happens, I rode into San 
Francisco tonight with him to meet a visiting JA contester for dinner. 
He confirmed that what I wrote was an accurate description of what's in 
his station. He's agreed to grab a few photos that I'll be happy to send 
you if you would like to refresh your memory.

73, Jim K9YC

On Tue,2/16/2016 5:54 AM, Joe Subich, W4TV wrote:
>
> Jim,
>
> On 2/16/2016 2:04 AM, Jim Brown wrote:
>> Indeed, it would darn near impossible to do it right without starting
>> from scratch withunit a properly made cable from the MicroHam unit to
>> the radio, with each signal path having its own coaxial cable.
>
> Please confine your comments to areas where you are knowledgeable.  The
> microHAM cables *DO* use a separate coaxial cable (or shielded twisted
> pair) for each signal path.  The shields are connected to the shell of
> the respective connector on each end of the cable.  With properly
> designed transceivers, this design will minimize RFI issues.  When good
> engineering practice is used in the station installation - including
> antenna systems - there should be no RFI problems with a properly
> implemented microKEYER II, MK2R+ or micro2R system.
>
> Schematics for every microHAM cable are available from the support 
> area at www.microham.com or www.microHAM-USA.com/support.html.
>
> 73,
>
>    ... Joe, W4TV
>
>
> On 2/16/2016 2:04 AM, Jim Brown wrote:
>
>> Bernhard,
>>
>> It's NOT common mode, it's the simple fact that the audio interface is a
>> mess. The antenna on the roof transmitting high power is doing its job,
>> putting a lot of RF in the shack. If it didn't (based on proxmiity), it
>> would be a lousy antenna. The problem is that the interface (wiring plus
>> electronics plus termination) does not reject RF because it fails to
>> conform to fundamental principles that reject RF. That is, every cable
>> must be a transmission line, every shield must be terminated at the
>> shielding enclosure of the equipment at both ends, and every equipment
>> chassis must have a short, fat, bond to every other equipment chassis.
>> Yes, the signal is audio, but the interference is RF, and it takes
>> proper transmission line techniques to reject that RF.
>>
>> I have VERY limited experience with MicroHam, but the jumble of wires
>> that I encountered with the MicroHam unit at W6OAT violated all
>> principles of good engineering practice for operation in a high RF
>> environment. It was nothing more than a multipin connector with a lot of
>> wires soldered to that connector.  Indeed, it would darn near impossible
>> to do it right without starting from scratch withunit a properly made
>> cable from the MicroHam unit to the radio, with each signal path having
>> its own coaxial cable.
>>
>> I have no idea if that describes ALL MicroHam units, but it does
>> describe Rusty's. And don't ask the model number -- I was so disgusted
>> by what I saw that I just rolled my eyes.
>>
>> 73, Jim K9YC
>>
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