The AM Forum

I recently aquired an Amp Supply AT-1200 antenna tuner I would like to use it for my 450 OHM ladderline fed Doublet,however it has one stub in the back that says "wire" and right next to it is an SO 239 connector. I was given this and do not have a manual for it. I looked online and didn't get any hits.I was wondering if anyone here has or had one and are familiar with how to connect the ladderline IE is there an adapter that I need ? Thanks in advance and 73 de KA3VID

Offhand, without a manual, I would say that is an unbalanced output tuner.  It may be designed for coax - or an end fed wire fed against ground. ( T-match)

Connecting your open wire to one terminal and ground will ruin the delicate antenna balance.

If so, maybe there is a way to modify it with a second coil or cap to make it a balanced output.

T


UPDATE:

And here's the manual.   Looks like they have an optional (unbal to bal)  "balun" available for balanced feed. (BL-1200)   I would prefer a real link coupled L/C balanced fed tuner, however.

file:///C:/Users/Owner/Downloads/Amp_Supply--AT-1200--user--ID9659.pdf

Here's a schematic from Google image:

this was a freebie and I do have 2 other tunas so it's not critical that I get it up and working. I was just looking for the way to connect the windowline if I needed to do so. Thanks for your help , Tom 73 !

if I may suggest a current balun with an SO-239, to connect to the coax output of the tuner. It should have wing nut terminals to hook to your line. Then the balun will push equal currents into the twin lead and your antenna. I mostly use a step up one (50 ohms in gives 200 out) and sometimes a 1:1  unit, depending on the band but it's not that critical. I got 2.5-3KW ones so they won't get hot  with mismatches and it works great.  I got them from DX Engineering. It looks like this one but is a current balun:
https://www.dxengineering.com/parts/dxe-un-43