[TenTec] Re: Toasting those cores....

[ac5e at comcast.net]

Cable Xperts (www.cablexperts.com) has a decent selection of teflon coax - and will sell you what you need. 

I have also noted roll ends of various and sundry teflon coax on E-bay, select business and industrial on the browse page, then wire and cable. The price per foot is less heart stopping - but you may have to buy more than you need. 

And on the subject at hand I have toasted a few cores in my day, and they always either recovered nicely or shattered. If you are going to use a ferrite current balun with more than a barefoot rig put it where serious overheating won't set something on fire. Especially your house!!! 

And finally, it seems the original question on this thread had to do with why a voltage balun didn't keep RF off the coax shield. Mainly because a voltage balun is more of an impedance matching transformer than a current blocking device.

There is still no such thing as a perfectly balanced matching transformer so some RF winds up on the outside of the coax shield where we don't want it.  A voltage balun at a beam's driven element immediately backed with a current balun makes a noticible difference in the beam's F/B - especially when W6 is from 140 to 220 degrees from the DX! That's most of the time in Mississippi.  

73  Pete Allen  AC5E


> Where can a person buy something like a Teflon insulated  RG-8X for high
> power hf?
> 
> Tnx,
> 
> Van N5HTY
> 
>  
> 
> -------Original Message-------
> 
>  
> 
> From: tentec at contesting.com
> 
> Date: 03/31/04 08:33:42
> 
> To: tentec at contesting.com
> 
> Subject: Re: [TenTec] Re: Toasting those cores....
> 
>  
> 
> "Manuel R. Alonso" wrote:
> 
>  
> 
> > I ORDERED THEIR TYPE "K" MATERIAL BECAUSE
> 
> > SHE SAID THAT IS WHAT THEY USE ON THE W2FMI BALUNS THAT THEY SELL. IS TYPE
> 
> > "K" MATERIAL THE RIGHT ONE, OR SHOULD I USE TYPE 43 OR 77?
> 
>  
> 
> "K" is an excellent choice, stick to it.
> 
>  
> 
>  
> 
> > I AM GOING TO WIND TWO (BIFFILAR) #12 ENAMEL INSULATED WIRES ABOUT 12
> TIMES AROUND THE
> 
> > CORE.
> 
>  
> 
> That makes a transmission line with a characteristic
> 
> impedance substantially higher than 50 Ohms. You may
> 
> wish to use a regular 50 Ohms coax, with Teflon
> 
> insulation for high power. Up to 1 kW RG58 will do,
> 
> or even Rg174 up to few hundred Watts.
> 
>  
> 
> Be sure to apply full power ONLY when the load is
> 

> known to be ~50 Ohms resistive, i.e SWR is below 3.
> 
>  
> 
>  
> 
> 73,
> 
>  
> 
> Sinisa  YT1NT, VA3TTN
> 
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