[Elecraft] RF into K3 via serial port?

Don Wilhelm w3fpr at embarqmail.com
Sat Apr 5 20:39:31 EDT 2014


Bill,

It is usually more effective to put the ferrite on the feedline.  A good 
current choke at the antenna feedpoint, and perhaps another at the shack 
entry end.
If the feedline runs away from the radiator at right angles and is not 
otherwise run in the field of the antenna, the one at the shack end is 
normally not needed.

Of course, if the shack is in close proximity to the radiator, all bets 
are off because the shack is being bombarded with RF and ferrites on the 
various devices in the shack is the only choice.

Yes, my perception is that many electronic devices (notably computer 
peripherals) are getting more and more susceptible to RF.

73,
Don W3FPR

On 4/5/2014 8:10 PM, Bill Davis wrote:
>    In my transition to Win7, I added a 2 port serial PCI card (NewEgg purchase -- Sunix 5037A) to my Dell PC. I was going to use one of these 2 ports to communicate with my K3 Utility terminal program. Very handy CW / RTTY application. Shortly after installation I made a nice contact on 30m RTTY and then moved to 80m RTTY. SURPRISE!!  During TX the K3 hung in TX and only a couple of characters (if that) were ever transmitted. I was attempting to run about 70watts or so. Only by reducing power to a few watts would the RTTY transmission seemingly be successful.
>
>    The 80m antenna is resonate and very low SWR even without the KXPA100 tuner. (My K3/10 is for VHF/UHF/Microwave IF use mostly, hence the external PA/Tuner).
>
>    So RF is getting back into the K3 .. odd ... nothing is "hot" in the shack at all. My workaround is to use the new serial ports for other hardware/applications and use the one serial port in the Dell Dimension 4700 for the K3 / terminal program. Things are happy that way.
>
>    I may investigate and try a ferrite core on the serial cable. But I will need to get an "HF" core since all of mine are for higher freq use. I just thought this was really odd. My serial cable is "homebrew" minimum conductor cable and I don't recall if it is shielded or not.
>
>
>    Anyone else had any similar experiences??
>
> 73 Bill  K0AWU
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