[Elecraft] K3: 6M SSB audio hash

[Joe Subich, W4TV]

> This is NOT purist. The cell phone interference being discussed 
> in another thread could easily be the result of a jumper that 
> short. It is in those mics! 

Yes, a jumper that short would respond to 900/1200 MHz within 
6" or so.  The GSM phones drive TV crews and technicians crazy 
on a regular basis ... guests on many of the talk/news shows 
think they ca get away with putting their phones and crackberry 
devices on silent but they don't know about the polling that 
happens ever few minutes even if they don't get an e-mail or 
SMS.  

I'm still more concerned about the relatively "long" wavelengths 
up through 55 MHz.  

> Back in Chicago, I ran 160M and 80 on a long wire that ended at 
> the transmitter.   With only 13W (K2 barefoot) I could lock up 
> the keying loop between the computer and the radio. 

That would have been a relatively "long" loop and an end-fed wire 
would have made the radio part of the antenna.  It would have 
taken a lot of luck to prevent problems there. 

By the way, I measured the resistance from the Foster to ground 
lug on my K3 with the power off - it is about 0.5 ohms.  There is 
something strange going on when I turn on the power and have anything 
connected to the "Aux" (+12 V) Power output.  I will need to do some 
more research to figure out what is going on. 

73, 

   ... Joe, W4TV 
 


> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Jim Brown
> Sent: Sunday, June 08, 2008 11:53 PM
> To: Elecraft List
> Subject: RE: [Elecraft] K3: 6M SSB audio hash
> 
> 
> On Sun, 8 Jun 2008 20:33:15 -0400, Joe Subich, W4TV wrote:
> 
> >I'm aware that a short jumper is "wrong" from the purist point 
> >of view.  However, it is much better than mic return that is 
> >held above ground by an RF choke!   Most of the rigs I've seen 
> >have relatively good grounding for the "PTT ground" - the jumper 
> >is 1 cm or less or the circuit board layout includes the "PTT 
> >Ground" pin in a wide (large) ground plane.  
> 
> >Fortunately, most amateur equipment is not operated in strong 
> >(multi hundred KW ERP) UHF fields.   
> 
> This is NOT purist. The cell phone interference being discussed in 
> another thread could easily be the result of a jumper that 
> short. It is 
> in those mics!  The field is determined by inverse square law. A 2W 
> radio (cell phone) puts a pretty strong field at 6-12 inches. Back in 
> Chicago, I ran 160M and 80 on a long wire that ended at the 
> transmitter. 
> With only 13W (K2 barefoot) I could lock up the keying loop 
> between the 
> computer and the radio. 
> 
> >Which article?  I used many of the Neuman and AKG mics 30 years ago 
> 
> The AES paper on RFI in condenser mics has the greatest detail. I've 
> summarized it and used it tutorially in other publications. 
> 
> 73,
> 
> Jim Brown K9YC
> 
> 
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