[Amps] The Pin One Problem

[Larry Benko]

Let me make a brief comment.

I think it is more accurate to say Pin 1 problems are the most common 
cause of RF Suscepiblity (not RFI).  In industry terms, susceptibility 
is interference from an intentional radiator into a piece of equipment.  
RFI or EMI is interference from an unintentional radiator into equipment.

Pin 1 problems can cause RFI but I don't think they are a major cause 
compared to common mode cable currents and large differential cable 
currents which get partially converted to common mode currents via 
imbalance.  I don't believe that FCC Part 15 specifically tests 
susceptability but many other standards do.

73,
Larry, W0QE

On 6/8/2013 10:37 PM, Jim Brown wrote:
> On 6/8/2013 1:18 PM, Carl wrote:
>> None of these radios have hum problems 
>
> Repeat after me -- Pin One Problems are the most common cause of RFI.
>
> The FT1000MP has a Pin One Problem at its mic input that causes RF 
> feedback on 15M and 75M.  I confirmed this by driving it with an HP RF 
> generator, using the method described in the AES Paper.  I killed the 
> RF feedback with a common mode choke on the mic cable, which killed 
> the antenna current. I have no experience with the other radios.
>
> 73, Jim K9YC
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