[TenTec] Built in SWR meter bannans

[Jim Brown]

On 4/23/2013 1:47 PM, Rick - DJ0IP / NJ0IP wrote:
> Jim,
>
> Thanks for the details.  I have noted your suggestion for future use.
> I'm not sure what THHN wire is, but I will google it.  I'm sure we have it
> here, but under a different name.
> You said ordinary house wire, but I don't know what ordinary (American)
> house wire is.

It is solid copper with a PVC insulation, and is the type used for 
wiring inside the walls of a building. AWG #12 describes the diameter 
and is rated for 20A.

>   Is that like Zip Cord?


>
> I had so much trouble burning up baluns back in the 80s that I have switched
> to using only Teflon insulated wire for my chokes and baluns.

Wrong change. Chokes fail because the common mode current is too high, 
and that happens because their common mode choking impedance is too 
low.  Study the discussion of chokes in my RFI tutorial.

>   What I
> typically use is a Teflon-coated twin-wire sourced locally with 0,75mm
> diameter.  This would be about AWG-21. You don't even have to tape it
> together.  For more power, then I use thicker Teflon insulated wire and tape
> it together, which is work I totally detest.  That's the hardest part of
> making a choke or balun.  And the special tape I bought must be gold-plated;
> I paid 25 EURO ($30) for a tiny little roll. (hi)

AWG #21 is quite under-rated for the current that can be present in a 
transmission line carrying a legal limit transmitter.  #21 may be enough 
for a 600 ohm line that is well matched, but not for a lower Z, and not 
if there's mismatch.

73, Jim K9YC