[hpsdr] predistortion

[n3evl]

Hi Larry,

Based on a quick look at my notes, it's some kind of thin 25 Ohm coax 
cable.  I obtained my parts from Tim O'Rourke who also supplied this. 
I'll see if I can dig out the actual cable part number.  It's a little 
tricky to wind as getting four turns through the binocular core is a 
little tight but manageable.  There are different ways to approach this 
- I used the approach to wind the turns then strip the outer vinyl at 
the primary end and expose and separate the shield and solder to each 
side of the tubes.  I think Kjell used an approach involving four 
separate pieces of wire cut and fed through and soldered with the 
shields in parallel and the center conductors wired in series.  I'll dig 
out my pictures and send if that will help.  I believe this coax is what 
Kjell recommends for good performance through 6m.  Copper wire can be 
used as an alternative but with some loss of performance at the high 
frequency end (IIRC).  I believe the coax is likely available but 
apparently difficult to obtain in small quantities so some collaboration 
may be needed.

I'll dig out the pics and any other notes and post later today.

73, Pete, N3EVL

On 5/20/2013 6:59 AM, lgpignolet wrote:
> Hi Pete..
> Quick question for you,,,
> What did you use for the T4 output transfrmer coax windings..?
> What type of wire fit through the core..?
> Cheers,
> Larry   N1AXB

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