[Elecraft] Pin 1 and Grounding Post on the K3s

[Lou Mecseri]

Dave, Thanks for the fascinating story. I always wondered about the 
purpose of those holes in TV tuners. No wonder, the secrete of the hole 
was kept inside a very tight group of "ins".

73, Lou KE1F

On 6/24/2021 21:40, David Gilbert wrote:
>
> This is all very true ... especially the higher in frequency you go 
> but even at HF.
>
> One of the early jobs in my career was as the tuning diode Product 
> Engineer for Motorola Semiconductor, and one of my first business 
> trips was to the biggest maker of mechanical TV tuners in the U.S. I 
> was trying to persuade them to convert to electronic tuning so we 
> could sell them tuning diodes.  I got in a meeting with their two 
> design engineers, who were almost three times older than me and at 
> least three times smarter.  They pulled out some of their mechanical 
> tuners and explained how they worked and what some of the advantages 
> were versus electronic tuning (and there are some).
>
> The thing that really got my attention was when they explained how 
> they managed the coupling between the RF, Mixer, and Oscillator 
> stages.  They would literally adjust some of the coupling by directing 
> the flow of the eddy currents in the walls of the stage shielding ... 
> which of course was all "grounded".  One of the guys pointed to a 
> couple of punched out slots in one of the side walls and told me he 
> did that to make more of the eddy current go where he wanted it to go.
>
> These guys were artists as much as they were engineers, but it 
> certainly taught me that, as you say, "where there is metal there is 
> resistance, and where there is current there is voltage" ... and I 
> will add that where there is current there are fields. Fields that can 
> couple to other bits of metal.
>
> 73,
> Dave   AB7E
>
>
>
> On 6/24/2021 12:49 PM, Hal Massey wrote:
>> Fixing a common misconception about grounding…
>>
>>
>> Grounding does not get all the devices at the same potential. It just 
>> minimizes the potential difference among them. “Where there is metal 
>> there is resistance and if there is any current there will be a 
>> voltage (period).
>>
>> This is one of the biggest urban myths around and the source of many 
>> difficulties for lay folks trying to understand grounding. -BSEE and 
>> MSEE here.
>>
>> A practical application of this for hams is to keep the runs short 
>> and low inductance too!
>>
>> 73
>>
>
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